bims-proteo Biomed News
on Proteostasis
Issue of 2026–03–01
fifty papers selected by
Eric Chevet, INSERM
  1. Co-translational control of protein stability and quality in plants.
  2. SEL1L-HRD1 ER-associated degradation facilitates prohormone convertase 2 maturation and glucagon production in islet α cells.
  3. Structure-guided analysis and prediction of human E2-E3 ligase pairing specificity.
  4. Encephalopathy-linked UFM1 variants impede neuronal protein translation, development, and function.
  5. Targeted shedding of extracellular membrane proteins by induced protease recruitment.
  6. Mitofusin MFN2 acts as a molecular sensor preventing protein aggregation and mitophagy, with a protective effect against apoptosis in Charcot-Marie-Tooth type 2A disease.
  7. Stress adaptation of mitochondrial protein import by OMA1-mediated degradation of DNAJC15.
  8. Mutant PLP1 impairs COPII vesicle formation via ER calcium depletion in Pelizaeus-Merzbacher disease.
  9. TDP-43 pathology is linked to motor neuron loss but is independent of stress granules in vivo.
  10. VAMP7-dependent late endosomal secretion of ER and mitochondrial proteins impacts the tumor microenvironment and macrophage engagement.
  11. Pharmacological Inhibition of SLC33A1 Promotes Endoplasmic Reticulum Hyperoxidation and Induces Adaptive IRE1/XBP1s Signaling.
  12. Stalled translation on transcripts cleaved by RNase L activates signaling important for innate immunity.
  13. A lineage-specific selective autophagy receptor module mediates P-body turnover.
  14. Src promotes tumor cell invasion by hijacking the translation machineries.
  15. RNase L regulates the antiviral proteome by accelerating mRNA decay, inhibiting nuclear mRNA export, and repressing transcription.
  16. An ER retention motif controls the heteromeric stoichiometry of hERG1a/1b channels.
  17. TRIM32-UBQLN2-p62 axis promotes TDP-43 inclusion formation and amyloid aggregation through shuttle condensates.
  18. Heterobifunctional proteomimetic polymers for targeted degradation of MYC and KRAS.
  19. Inhibition of the integrated stress response rescues a histidyl-tRNA synthetase variant associated with Charcot-Marie-Tooth disease.
  20. Autophagosome turnover requires Arp2/3 complex-mediated maintenance of lysosomal integrity.
  21. The endoplasmic reticulum in mitochondrial protein targeting: A neuronal perspective on organelle crosstalk.
  22. Integrated Stress Response Signatures Drive Monocyte Dysfunction in GBA1- and LRRK2-Linked Parkinson's Disease.
  23. Dynamic regulation of protein homeostasis underlies thermopriming-mediated acquired thermotolerance in Arabidopsis.
  24. Optimization of protein UFMylation modification method and its application in substrate identification in human cells.
  25. Stemness factor Mex3a times translation and protein trafficking to ensure robust differentiation of olfactory sensory neurons.
  26. Context-dependent translation inhibition as a cancer therapeutic modality.
  27. Proximity labeling of the Listeria monocytogenes surface reveals pathogen control of a host deubiquitinase.
  28. Sub-stoichiometric Degradation is Dispensable for Potent PROTACs: A Case Study for Irreversible Covalent BTK Degraders.
  29. Nup42 safeguards heat-induced mRNAs from nuclear condensation to support chaperone synthesis.
  30. Control of phagophore membrane expansion: Atg8-Atg1 as the master switch.
  31. Disruption of tRNA threonylation triggers RIG-I mediated anti-tumour immune response.
  32. From molecular logic to therapeutic modulation: advances in Ub/UBL signalling.
  33. Unveiling BCL-xL-specific PROTAC efficiency and dissociation pathways using native mass spectrometry.
  34. A testis-specific E3 ubiquitin ligase complex governs spermiogenesis and male fertility.
  35. CLCC1 promotes hepatic neutral lipid flux and nuclear pore complex assembly.
  36. Hoi1 targets BLTP2 to ER-PM contact sites to regulate lipid homeostasis.
  37. RuPHOTACs Provide Photocontrol Over Protein Degradation with Optimized Properties for Biological Applications.
  38. Translational buffering tunes gene expression in mice and humans.
  39. Regulation of mitophagy by Fis1 and Fascin1-organized actin.
  40. High-throughput chemical proteomics workflow for profiling protein citrullination dynamics.
  41. Gl Rac Regulates a Noncanonical, ATG8-Independent Autophagy-Like Pathway in Giardia lamblia.
  42. STARD3 regulates lysosome positioning and contacts via a GSK3-controlled phosphorylation switch.
  43. ERAD Component MoHrd3 Facilitates Pathogenicity and Establishes a Direct Regulation on Autophagy in Magnaporthe Oryzae.
  44. PROTAC-based synthetic lethality strategy endogenously activates systemic STING to boost antitumor immunity.
  45. Diterpene Molecular Glue Stabilizes Protein-Protein Interactions of a Disordered Phosphoprotein that Controls Translational Repression.
  46. CLCC1 governs ER bilayer equilibration to maintain lipid homeostasis.
  47. Ubiquitin ligase Nedd4 regulates the abundance and toxicity of mutant huntingtin.
  48. PML targets and resolves structured protein inclusions to mitigate neurodegeneration.
  49. Membrane-embedded polar residues target membrane proteins for degradation by the quality control protease FtsH.
  50. A novel potent and selective GCN2 inhibitor, APL-4098, has anti-leukemic activity through dysregulation of mitochondrial function.
  1. J Exp Bot. 2026 Feb 24. pii: erag103. [Epub ahead of print]
    Co-translational control of protein stability and quality in plants.
    Daniel J Gibbs.
      Proteostasis relies on the coordinated control of protein synthesis, folding, modification and degradation, and an increasingly clear picture is emerging that many important decisions governing protein fate occur co-translationally. As nascent chains first appear at the ribosome exit tunnel, they encounter a suite of ribosome-associated enzymes that begin to shape whether proteins fold productively, acquire the correct N-terminal imprinting modifications, or require surveillance and removal. This review focuses on two major facets of co-translational control that determine protein and proteome stability, with particular attention to recent advances in plants. First, N-terminal (Nt-) methionine excision, Nt- acetylation and Nt-myristoylation are examined as early imprinting steps that define the chemical identity and regulatory trajectories of newly synthesized proteins, including how they influence targeting to N-degron pathways of proteolysis. Second, ribosome-associated quality control (RQC) pathways that sense ribosome stalling or collision are outlined, along with their roles in directing aberrant nascent chains towards ubiquitylation, extraction and degradation before they can accumulate and trigger proteotoxic stress. Together, these modification and surveillance mechanisms form an integrated decision-making network that establishes protein stability at the earliest stages of synthesis, contributing to proteostasis and impacting plant growth, development, and stress adaptation.
    Keywords:  Co-translational and ribosome-associated quality control; N-degron pathway; N-terminal acetylation (NTA); N-terminal methionine excision (NME); N-terminal myristoylation; protein degradation; ubiquitin proteasome system
    DOI:  https://doi.org/10.1093/jxb/erag103
  2. Nat Commun. 2026 Feb 25.
    SEL1L-HRD1 ER-associated degradation facilitates prohormone convertase 2 maturation and glucagon production in islet α cells.
    Wenzhen Zhu, Linxiu Pan, Xianwei Cui, Anna Chiara Russo, Rohit Ray, Brent Pederson, Xiaoqiong Wei, Liangguang Leo Lin, Mauricio Torres, Hannah Hafner, Brigid Gregg, Neha Shrestha, Chengyang Liu, Ali Naji, Peter Arvan, Darleen A Sandoval, Iris Lindberg, Ling Qi, Rachel Byerley Reinert.
      Proteolytic cleavage of proglucagon by prohormone convertase 2 (PC2) is required for islet α cells to generate glucagon. However, the regulatory mechanisms underlying this process remain largely unclear. Here, we report that SEL1L-HRD1 endoplasmic reticulum (ER)-associated degradation (ERAD), a highly conserved protein quality control system responsible for clearing misfolded proteins from the ER, plays a key role in glucagon production by regulating turnover of the nascent proform of the PC2 enzyme (proPC2). Using a mouse model with SEL1L deletion in proglucagon-expressing cells, we observe a progressive decline in stimulated glucagon secretion and a reduction in pancreatic glucagon content. Mechanistically, we find that endogenous proPC2 is a substrate of SEL1L-HRD1 ERAD, and that degradation of misfolded proPC2 ensures the maturation of activation-competent proPC2 protein in the ER. Here, we identify ERAD as a regulator of PC2 biology and an essential mechanism for maintaining α cell function.
    DOI:  https://doi.org/10.1038/s41467-026-69928-6
  3. bioRxiv. 2026 Feb 12. pii: 2026.02.10.700855. [Epub ahead of print]
    Structure-guided analysis and prediction of human E2-E3 ligase pairing specificity.
    Brianna Jarboe, Roland L Dunbrack.
      Protein ubiquitination, directed by specific E3 ligases, constitutes the primary cellular pathway for selective protein degradation. In addition to targeting proteins for degradation, ubiquitination can mediate new protein-protein interactions, and otherwise modulate protein function, thereby regulating key cellular processes such as DNA repair and immune responses. Recently, Proteolysis-Targeting Chimeras (PROTACs), and related proximity-inducing agents, have revealed the significant therapeutic potential of co-opting ubiquitin ligase activity to induce the selective degradation of disease-relevant proteins. Despite the biological and clinical significance of this pathway, fundamental gaps remain in our understanding of ubiquitination networks, particularly regarding the specificity of E2-E3 interactions and their substrate preferences. In this study, we leverage analysis of experimental structures in the Protein Data Bank (PDB) and use AlphaFold to generate structures of thousands of ubiquitin-E2-E3 ternary complexes. Using these predicted structures and complementary analyses, we develop a machine learning model to predict functional E2-E3 pairings, advancing our ability to map ubiquitination networks and providing structural insights into functional ubiquitin-E2-E3 complexes. We demonstrate the utility of our model by predicting E2 partners for 88 putative E3 ligases lacking any previously known E2 interactors. Notably, we identify a predicted pairing between UBE2C and RNF214, two proteins recently implicated in hepatocellular carcinoma separately but through interrelated pathways, suggesting a potential functional link mediated by RNF214-dependent ubiquitination in partnership with UBE2C. Additionally, we present our web-resource, UbiqCore, making the E2-E3 pairing predictions and ternary complex structures available to the scientific community ( https://dunbrack.fccc.edu/ubiqcore ).
    Significance Statement: Ubiquitination is an essential protein modification that regulates nearly all aspects of biology and is mediated by dozens of ubiquitin-conjugating enzymes (E2s) and hundreds of ubiquitin ligases (E3s). These enzymes are frequently implicated in cancer and other diseases, and their activities can also be harnessed for targeted protein degradation therapies. Despite the biological and clinical significance of ubiquitination, there remains no systematic understanding of which E2s and E3s function together. Here, we combine bioinformatic analysis of experimentally determined structures and AlphaFold modeling of thousands of ubiquitin-E2-E3 complexes with machine learning to predict functional E2-E3 pairings. We also introduce UbiqCore, a web resource that makes these predictions and structures broadly accessible, providing a foundation for mapping ubiquitination networks and guiding future biological and therapeutic discovery.
    DOI:  https://doi.org/10.64898/2026.02.10.700855
  4. EMBO Mol Med. 2026 Feb 23.
    Encephalopathy-linked UFM1 variants impede neuronal protein translation, development, and function.
    Catarina Perdigão, Josefa Torres, Helge M Magnussen, Janina Koch, Elena Rudashevskaya, Frederieke Moschref, Maksims Fiosins, Fritz Benseler, Sally Wenger, Tanja Nilsson, Sabine Beuermann, Stefan Bonn, Silvio O Rizzoli, Yogesh Kulathu, Olaf Jahn, Benjamin H Cooper, Mateusz C Ambrozkiewicz, JeongSeop Rhee, Nils Brose, Marilyn Tirard.
      Genetic variants that hinder post-translational protein modifications by UFM1, UFMylation, cause encephalopathies. UFMylation regulates endoplasmic reticulum (ER) homeostasis, but how UFMylation deficiencies cause selective neurological defects is unknown. Using murine UFM1-deficient neurons, we investigated two types of UFMylation pathologies, UFM1 loss and expression of a pathogenic UFM1-R81C variant. We found that UFM1-deficiency confounds neuron development and synapse function. Mechanistically, UFM1 loss is associated with induction of ER stress, activation of the unfolded protein response (UPR) pathway, and reduced protein translation. These defects are rescued by wild-type UFM1, but only partially by UFM1-R81C. UFM1-deficient and UFM1-R81C-expressing neurons display distinct responses to ER stress, indicating that UFM1-R81C is not merely a loss-of-function variant. Exploring therapeutic options, we show that Trazodone, an inhibitor of the UPR, restores protein translation solely in UFM1-R81C-expressing neurons, and increases synapse numbers in both UFM1-KO and UFM1-R81C-expressing neurons. Our study unveils a pivotal role for UFMylation in neuronal development, provides a molecular understanding of the signaling mechanisms altered in UFM1-associated encephalopathies, and offers important insights into potential treatments for these disorders.
    Keywords:  Encephalopathies; Neuron; Synapse; UFM1; Unfolded Protein Response
    DOI:  https://doi.org/10.1038/s44321-026-00389-6
  5. bioRxiv. 2026 Feb 18. pii: 2026.02.17.706468. [Epub ahead of print]
    Targeted shedding of extracellular membrane proteins by induced protease recruitment.
    Zi Yao, Fangzhu Zhao, Kun Miao, Trenton M Peters-Clarke, Yun Zhang, Snehal D Ganjave, Angel L Vázquez-Maldonado, Yan Wu, Kaan Kumru, Hammam Jumaa, Kevin K Leung, James A Wells.
      Extracellular targeted protein degradation has emerged as a promising therapeutic modality to eliminate proteins of interest (POIs) at the cell surface, by using bifunctional molecules to recruit natural recycling receptors or membrane-bound E3 ligases that redirect POIs to the lysosome. Another natural mechanism involves extracellular proteases that cleave and shed extracellular domains. Here, we exploit this endogenous mechanism by engineering bispecific antibody Shedders , that recruit a classic sheddase ADAM10 to POIs, inducing selective ectodomain shedding. We first targeted the immune checkpoint receptor LAG-3 and observed robust depletion of surface LAG-3 accompanied by accumulation of soluble LAG-3 fragments in both engineered cell lines and primary human T cells. Using biochemical and imaging assays, we confirmed that this antibody-induced shedding is restricted to extracellular protease activity and occurs independently of lysosomal trafficking. Notably, induced shedding of LAG-3 on activated primary T cells partially alleviated inhibitory signaling and reinvigorated IFN γ secretion. We extended the scope of induced shedding by developing Shedders that recognize synthetic epitope-tags that enabling rapid assessment of substrate compatibility across diverse targets. Using this platform, we identified multiple immune modulatory cell-surface receptors, including IL6Rα, CD62L and MIC-A that can be targeted for shedding. In summary, this work establishes a new paradigm for targeted extracellular proteolysis and expands the toolkit for studying extracellular proteolysis with potential therapeutic benefit.
    DOI:  https://doi.org/10.64898/2026.02.17.706468
  6. Autophagy Rep. 2026 ;5(1): 2629624
    Mitofusin MFN2 acts as a molecular sensor preventing protein aggregation and mitophagy, with a protective effect against apoptosis in Charcot-Marie-Tooth type 2A disease.
    Mariana Joaquim, Maike F Dohrn, Arnaud Chevrollier, Mafalda Escobar-Henriques.
      Mitochondria are central hubs for cellular fitness, empowered by plastic remodeling of their shape, proteome composition, and/or metabolic state. MFN2 (mitofusin 2) mediates mitochondrial fusion and ensures adaptations in response to metabolic changes and stresses. Besides this canonical role, MFN2 serves as a communication hub with other organelles. It tethers mitochondria to the endoplasmic reticulum (ER), lipid droplets, and peroxisomes, regulating calcium buffering, apoptosis, lipid biosynthesis, and lipolysis. Dysfunctional MFN2 causes the hereditary neuropathy Charcot-Marie-Tooth type 2A (CMT2A) and is linked to several metabolic diseases. In a recent publication, we described another fusion-independent role of MFN2 in proteostasis and mitophagy. MFN2 binds the chaperone HSPA8/HSC70 (heat shock protein family A [Hsp70] member 8) and the proteasome, a key function in maintaining mitochondrial and cellular protein quality control, which appears to be lost in the context of CMT2A-associated MFN2 variants.
    Keywords:  Charcot–Marie–Tooth type 2A (CMT2A); HSPA8/HSC70; MFN2; protein import; proteasome; VCP/p97; PINK1; apoptosis; mitophagy; proteostasis
    DOI:  https://doi.org/10.1080/27694127.2026.2629624
  7. Nat Struct Mol Biol. 2026 Feb 27.
    Stress adaptation of mitochondrial protein import by OMA1-mediated degradation of DNAJC15.
    Lara Kroczek, Hendrik Nolte, Yvonne Lasarzewski, Ishita Agrawal, Thibaut Molinié, Daniel Curbelo Piñero, Kathrin Lemke, Elena Rugarli, Thomas Langer.
      Mitochondria dynamically adapt to cellular stress to ensure cell survival. The stress-regulated mitochondrial peptidase OMA1 orchestrates these adaptive responses, which limit mitochondrial fusion and promote mitochondrial stress signaling and metabolic rewiring. Here, we show that cellular stress adaptation involves OMA1-mediated regulation of mitochondrial protein import and OXPHOS biogenesis. OMA1 cleaves the mitochondrial chaperone DNAJC15 and promotes its degradation by the m-AAA protease AFG3L2. Loss of DNAJC15 impairs mitochondrial protein import and restricts OXPHOS biogenesis under conditions of mitochondrial dysfunction. Non-imported mitochondrial preproteins accumulate at the endoplasmic reticulum, inducing an unfolded protein response. Our results demonstrate stress-dependent changes in mitochondrial protein import as part of the OMA1-mediated mitochondrial stress response and highlight the interdependence of proteostasis regulation between different organelles.
    DOI:  https://doi.org/10.1038/s41594-026-01756-0
  8. Neurobiol Dis. 2026 Feb 24. pii: S0969-9961(26)00073-2. [Epub ahead of print] 107329
    Mutant PLP1 impairs COPII vesicle formation via ER calcium depletion in Pelizaeus-Merzbacher disease.
    Heng Li, Reiko Mishima, Yu-Ichi Goto, Ken Inoue.
      Pelizaeus-Merzbacher disease (PMD) is a devastating, X-linked hypomyelinating leukodystrophy caused by mutations in a myelin gene, PLP1. While overwhelming endoplasmic reticulum (ER) stress caused by the accumulation of mutant PLP1 is widely recognized, blockade of the apoptotic arm of the unfolded protein response (UPR) failed to rescue the phenotypes in murine disease models, suggesting the involvement of additional, critical cellular mechanisms in oligodendrocyte dysfunction. Herein, we identified ER Ca2+ depletion and disrupted ER-Golgi trafficking as key cellular pathologies in PMD. Mutant PLP1 impairs COPII vesicle formation by destabilizing its key components, including Sec31A at ER exit sites due to the Ca2+ transport dysregulation and deconstruction of the ALG-2/Sec31A/AnxA11 interaction. Pharmacological restoration of ER Ca2+ levels rescued COPII formation. These findings highlight how PLP1 mutations affect the intracellular trafficking of membrane and secretory proteins through the ER Ca2+ depletion, which may be associated with the clinical consequences of PMD and other inherited myelin disorders.
    Keywords:  COPII; ER calcium depletion; ER stress; Oligodendrocyte; PLP1; Pelizaeus-Merzbacher disease (PMD); Vesicle trafficking
    DOI:  https://doi.org/10.1016/j.nbd.2026.107329
  9. bioRxiv. 2026 Feb 13. pii: 2026.02.11.705439. [Epub ahead of print]
    TDP-43 pathology is linked to motor neuron loss but is independent of stress granules in vivo.
    Alicia Dubinski, Ala Ferdi, Mariam Choughari, Holly Spence, Arpita Adhikary, Carolane Fauchon, Melissa Touati, Myriam Gagné, Martha Liu, Sarah Peyrard, Jenna Gregory, Christine Vande Velde.
      Nuclear depletion and cytoplasmic aggregation of TDP-43 are pathological hallmarks of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer's disease, and the recently defined limbic-predominant age-related TDP-43 encephalopathy (LATE). Chronic activation of the integrated stress response (ISR) and persistence of stress granules, phase-separated assemblies proposed to function as a protective mechanism, have been hypothesized to initiate the formation of pathological TDP-43 inclusions observed in post-mortem neurons. However, recent clinical trials targeting the ISR and stress granule dissolution failed to demonstrate clinical benefit despite robust target engagement, calling this model into question. Here, we employ a recurrent hyperthermia paradigm to directly examine the relationship between stress granules and TDP-43 pathology in vivo . We find that RNA-binding proteins classically associated with stress granules persist as phase-separated cytoplasmic structures in spinal motor neurons of both non-transgenic and mutant TDP-43 mice. Importantly, these structures are reversible and spatially distinct from TDP-43 puncta. Moreover, in a mutant TDP-43 mouse model with an impaired acute stress granule response, stress exposure induces TDP-43 nuclear export and cytoplasmic accumulation. Recurrent stress in these mice leads to a selective loss of spinal α-motor neurons. Together, our findings demonstrate that TDP-43 nuclear clearance and cytoplasmic demixing occur independently of stress granules in vivo , challenging prevailing models of TDP-43 pathogenesis and highlighting important implications for therapeutic strategies targeting the ISR.
    DOI:  https://doi.org/10.64898/2026.02.11.705439
  10. Nat Commun. 2026 Feb 21.
    VAMP7-dependent late endosomal secretion of ER and mitochondrial proteins impacts the tumor microenvironment and macrophage engagement.
    Somya Vats, Pedro Dionisio, Quentin Lemercier, Raphael Pineau, Ludivine Therreau, Joanna Lipecka, Béatrice Cholley, Jean-Baptiste Moog, Jose Wojnacki, Céline Keime, Diana Zala, Philippe Bun, Sofia Freire, Neuza Domingues, Lydia Danglot, Ida Chiara Guerrera, Cédric Delevoye, Eric Chevet, Nuno Raimundo, Thierry Galli.
      Late endosomal secretion is an unconventional secretion mechanism that depends on the SNARE protein VAMP7. We previously showed that VAMP7 mediates the secretion of the ER protein Reticulon3. However, the functional relevance and molecular mechanism of this secretory pathway remain unclear. Here, we show that VAMP7 knockout cells exhibit impaired secretion of ER- and mitochondrial-derived proteins and signs of ER and mitochondrial stress. In addition, pharmacological induction of organellar stress enhances the VAMP7-dependent secretion. We assess the pathophysiological significance of this mechanism using a preclinical glioblastoma model. VAMP7 knockout glioblastoma cells implanted in male rat brain develop into more necrotic tumors with reduced macrophage infiltration compared to controls, suggesting that VAMP7-dependent late endosomal secretion contributes to the tumor microenvironment and affects macrophage infiltration. Together, our results support a model in which late endosomal secretion functions as an organelle quality-control and stress-communication mechanism, with particular relevance to cancer.
    DOI:  https://doi.org/10.1038/s41467-026-69900-4
  11. bioRxiv. 2026 Feb 18. pii: 2026.02.17.706344. [Epub ahead of print]
    Pharmacological Inhibition of SLC33A1 Promotes Endoplasmic Reticulum Hyperoxidation and Induces Adaptive IRE1/XBP1s Signaling.
    Sergei Kutseikin, Maria Rafiq, Prerona Bora, Shanshan Liu, Rick A Homan, Jeffrey T Mindrebo, Matthew Holcomb, H Michael Petrassi, Huang Qiu, Anastasiya Redkina, Justyna Sosna, Thanh-Trang Lee, Xiao Hu, Stefano Forli, Christopher G Parker, Gabriel C Lander, Kivanc Birsoy, Enrique Saez, R Luke Wiseman.
      The endoplasmic reticulum (ER) transporter solute carrier family 33 member 1 (SLC33A1) has emerged as an attractive therapeutic target in etiologically diverse diseases, ranging from lung cancer to neurodegenerative disorders. Yet, no pharmacologic SLC33A1 modulators have been described. Here, we show that the small molecule IXA4, a highly selective activator of the adaptive IRE1/XBP1s signaling arm of the unfolded protein response (UPR), binds to SLC33A1 and inhibits its activity. Genetic depletion of SLC33A1 phenocopies the selective induction of IRE1/XBP1s signaling brought about by IXA4 treatment. Chemoproteomic analyses and cryo-electron microscopy show that IXA4 binds SLC33A1 within the central channel to inhibit transport of its substrate metabolite(s). Binding of IXA4 to SLC33A1 leads to the accumulation of oxidized glutathione within the ER, hyperoxidizing the ER lumen and inducing activation of adaptive IRE1/XBP1s signaling. Consistent with this function, we find that pharmacologic inhibition of SLC33A1 with IXA4 selectively reduces viability of KEAP1-deficient lung adenocarcinoma cells that have elevated levels of glutathione, mimicking the sensitivity of these cells to genetic deletion of SLC33A1. Our work demonstrates a new physiologic role of SLC33A1 in regulation of ER redox homeostasis and designates IXA4 as a pharmacologic inhibitor of SLC33A1 that can be used to evaluate the biological impact and therapeutic utility of SLC33A1 inhibition in homeostasis and in disease.
    DOI:  https://doi.org/10.64898/2026.02.17.706344
  12. RNA. 2026 Feb 26. pii: rna.080699.125. [Epub ahead of print]
    Stalled translation on transcripts cleaved by RNase L activates signaling important for innate immunity.
    Agnes Karasik, Grant D Jones, Nicholas R Guydosh.
      RNase L is an endonuclease that responds to infections by cleaving most host- and pathogen-derived single-stranded RNAs. This widespread RNA cleavage can lead to death of the infected cell via the ribotoxic stress response (RSR). An ongoing challenge is to understand how RNase L's endonuclease activity triggers cell death to benefit the host. To address this question, we used nanopore-based long-read sequencing to show that 3' mRNA fragments in the cell were not fully degraded after RNase L activation and that these fragments were translated by ribosomes. We further asked whether ribosomes on mRNA fragments stall when they reach 3' ends created by RNase L. We used ribosome profiling to capture footprints protected by these ribosomes, which can be identified by their short length (15-18 nt). We found that RNase L activation increased the number of stalled ribosomes at RNase L cleavage sites. Loss of the ribosome rescue factor PELO increased the number of short footprints derived from stalled ribosomes and augmented the RSR. Our work therefore establishes a role for fragmented mRNA in causing ribosome stalling that promotes innate immunity via the RSR.
    Keywords:  PELO; endonuclease; mRNA fragments; nanopore; ribosome profiling
    DOI:  https://doi.org/10.1261/rna.080699.125
  13. Dev Cell. 2026 Feb 23. pii: S1534-5807(26)00040-7. [Epub ahead of print]
    A lineage-specific selective autophagy receptor module mediates P-body turnover.
    Alibek Abdrakhmanov, Elizabeth Ethier, Aleksandra S Anisimova, Nenad Grujic, Ranjith K Papareddy, Marion Clavel, G Elif Karagöz, Erinc Hallacli, Yasin Dagdas.
      Processing bodies (P-bodies) are conserved ribonucleoprotein granules central to RNA metabolism across eukaryotes. Although the mechanisms underlying their assembly are well understood, the pathways governing their selective turnover remain unclear. Here, we identify the conserved decapping proteins Enhancer of mRNA decapping 4 (EDC4) and decapping protein 1 (DCP1) as a selective autophagy receptor pair responsible for P-body turnover in the model plant Marchantia polymorpha. MpEDC4 engages ATG8 via a canonical ATG8-interacting motif, while MpDCP1 contains a previously unrecognized reverse ATG8-interacting motif within its intrinsically disordered region. Mutations disrupting these motifs impair the autophagic degradation of P-bodies, demonstrating a cooperative receptor mechanism. Notably, this autophagic function is lineage-specific, as orthologs in Arabidopsis and humans lack ATG8-binding capacity. Strikingly, the heterologous expression of MpEDC4 in human cells promotes the degradation of α-synuclein, a protein linked to Parkinson's disease etiology. Our findings uncover an evolutionary innovation that links RNA metabolism to selective autophagy and open avenues for the cross-kingdom engineering of targeted protein degradation pathways.
    Keywords:  ATG8; Marchantia; P-body; RNP-granules; autophagic flux; receptor engineering; selective autophagy; selective autophagy receptor; targeted protein degradation; α-synuclein degradation
    DOI:  https://doi.org/10.1016/j.devcel.2026.01.017
  14. Cell Rep. 2026 Feb 23. pii: S2211-1247(26)00067-7. [Epub ahead of print]45(3): 116989
    Src promotes tumor cell invasion by hijacking the translation machineries.
    Benjamin Bonnard, Anouk Chatefau, Cyril Dourthe, Sylvaine Di Tommaso, Jean-William Dupuy, Isabelle Mahouche, Jacobo Solorzano, Morgane Le Bras, Anne-Aurélie Raymond, Violaine Moreau, Arnaud Jabouille, Anne Blangy, Yvan Martineau, Frédéric Saltel.
      The Src oncogene controls cancer cell invasiveness by promoting invadosome formation and extracellular matrix (ECM) degradation. Invadosomes are translational hotspots enriched in the eukaryotic translation initiation factor 3 (eIF3) complex that is mandatory for their maintenance. Here, we determined that Src regulates mRNA translation and controls the expression of eIF3 subunits, including eIF3h, eIF3e, and eIF3d. These subunits are crucial for invadosome formation and ECM degradation. Src also modulates both canonical eIF4E-dependent translation via the activation of the phosphoinositide-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and the non-canonical translation mechanism through eIF3d overexpression, both of which are necessary for invadosome function. Moreover, overexpression of Src and eIF3h/e/d correlates with poor prognosis in patients with hepatocellular carcinoma (HCC), promoting ECM degradation and tumor invasiveness of HCC cells. This study identifies Src as a major regulator of translation initiation, modulating invadosome formation, ECM degradation, and tumor cell invasion.
    Keywords:  CP: cancer; CP: molecular biology; Src; cancer; eIF3; invadosomes; invasion; translation initiation
    DOI:  https://doi.org/10.1016/j.celrep.2026.116989
  15. Cell Rep. 2026 Feb 25. pii: S2211-1247(26)00002-1. [Epub ahead of print]45(3): 116924
    RNase L regulates the antiviral proteome by accelerating mRNA decay, inhibiting nuclear mRNA export, and repressing transcription.
    J Monty Watkins, Cameron J Douglas, Renee Cusic, Ciaran P Seath, James M Burke.
      Ribonuclease L (RNase L) is an antiviral endoribonuclease that triggers widespread degradation of cellular mRNAs. Here, we show that RNase L-mediated decay of cellular mRNA is a conserved response to flaviviruses, including Zika virus (ZIKV), dengue virus serotype 2 (DENV-2), and West Nile virus (WNV). Quantitative mass spectrometry shows that RNase L downregulates proteins with short half-lives involved in cell-cycle progression, cellular metabolism, and protein synthesis. However, mRNAs encoding antiviral proteins that are induced by interferon-stimulated genes (ISGs) initially evade degradation by RNase L, allowing for the synthesis of critical antiviral proteins. At later times during the antiviral response, RNase L dampens ISG protein synthesis by triggering a block in nuclear mRNA export and repressing transcription. These findings show that RNase L regulates the antiviral proteome through an intricate balance of mRNA decay and nuclear RNA biogenesis, which is crucial for preventing overproduction of pro-inflammatory proteins.
    Keywords:  CP: molecular biology; RNase L; Zika virus; dsRNA; innate immunity; interferon; interferon-stimulated genes; mRNA; mRNA export; transcription; virus
    DOI:  https://doi.org/10.1016/j.celrep.2026.116924
  16. bioRxiv. 2026 Feb 20. pii: 2026.02.20.707017. [Epub ahead of print]
    An ER retention motif controls the heteromeric stoichiometry of hERG1a/1b channels.
    Sudharsan Kannan, Liliana R Ernandez, Gail A Robertson.
      The human ether-à-go-go related gene ( hERG ) encodes a potassium channel essential for cardiac repolarization and neuronal excitability. In the heart, heteromeric assemblies of hERG1a and hERG1b subunits produce cardiac I Kr , and mutations in either subunit are associated with long QT syndrome. Although hERG1a and 1b contain identical transmembrane and C-terminal cytosolic domains, they differ in N-terminal cytosolic domains, with hERG1b harboring an arginine-based endoplasmic reticulum (ER) retention/retrieval motif that limits its surface expression in the absence of hERG1a. While the association of hERG1a and 1b subunits is known to influence channel function, the stoichiometry of heteromeric hERG channels and mechanisms that regulate it have remained unresolved. Here, using single molecule photobleaching step analysis in HeLa cells, we show that heteromeric hERG1a/1b channels assemble predominantly with a fixed 2:2 stoichiometry. Mutation of the hERG1b ER retention motif disrupts this bias, resulting in a broader, near-random distribution of subunit compositions. Independent functional assays using dominant-negative pore mutants in Xenopus oocytes yielded quantitative current suppression consistent with a 2:2 assembly and similarly revealed loss of stoichiometric bias upon RXR mutation. Together, these results establish the oligomeric composition of hERG1a/1b channels and identify ER retention as a previously unrecognized determinant of heteromeric stoichiometry.
    Statement of Significance: Subunit stoichiometry is a key determinant of ion channel function, yet how defined stoichiometries are established during biogenesis remains poorly understood. Here we demonstrate that heteromeric hERG1a/1b channels assemble with a fixed 2:2 stoichiometry and that an arginine-based ER retention motif in hERG1b is required to maintain this assembly bias. Using single-molecule photobleaching and independent functional assays, we show that disrupting this motif leads to a broadened, near-random distribution of tetrameric subunit compositions. These findings reveal that ER retention contributes not only to quality control and trafficking but also specifies subunit stoichiometry during ion channel assembly.
    DOI:  https://doi.org/10.64898/2026.02.20.707017
  17. bioRxiv. 2026 Feb 13. pii: 2026.02.11.705390. [Epub ahead of print]
    TRIM32-UBQLN2-p62 axis promotes TDP-43 inclusion formation and amyloid aggregation through shuttle condensates.
    Ziyan He, Jiechao Zhou, Rongzhen Zhang, Fei Meng, David W Nauen, Juan C Troncoso, Paul F Worley, Wenchi Zhang.
      Aberrant protein aggregation is a hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), which share overlapping genetic and pathological features. Similar aggregates are increasingly recognized in Alzheimer's disease (AD) and limbic-predominant age-related TDP-43 encephalopathy (LATE). However, it remains unclear whether a shared molecular pathway drives this pathological aggregation. Here, we report that the E3 ubiquitin ligase TRIM32, together with the shuttle factor UBQLN2 and the autophagy adaptor p62/SQSTM1, form condensates that depend on E3 ligase activity and a network of intermolecular interactions. These condensates act as scaffolds that capture UBQLN2 client proteins, including TDP-43 and ANXA11, and modulate their mobility. A unique hydrophobic loop within TRIM32's substrate-binding domain mimics low-complexity motifs in ANXA11 and TDP-43, enabling selective retention via competitive binding mediated by UBQLN2 STI1 domain. Moreover, TRIM32 condensates promote amyloid aggregation of TDP-43, an effect that is exacerbated by pathogenic UBQLN2 mutation. In brains from individuals with diverse neurodegenerative diseases, TRIM32 co-localizes with pathological phospho-TDP-43 (pTDP-43) inclusions, supporting a model in which TRIM32-driven condensates function as selective proteostasis sorting compartments that broadly contribute to TDP-43 proteinopathy.
    DOI:  https://doi.org/10.64898/2026.02.11.705390
  18. Nat Commun. 2026 Feb 24. pii: 1706. [Epub ahead of print]17(1):
    Heterobifunctional proteomimetic polymers for targeted degradation of MYC and KRAS.
    Max M Wang, Mihai I Truica, Brayley S Gattis, Julia Oktawiec, Vinay Sagar, Ananya A Basu, Paul A Bertin, Xiaoyu Zhang, Sarki A Abdulkadir, Nathan C Gianneschi.
      Targeted protein degradation (TPD) has enabled modulation of previously undruggable proteins. However, existing small-molecule approaches require arduous optimization and are largely confined to targets bearing ligandable pockets. To address these challenges, we introduce the HYbrid DegRAding Copolymer (HYDRAC), a polymeric platform that integrates target‑binding peptides with peptide-based or small‑molecule degrons to orchestrate selective degradation of disease‑relevant proteins. HYDRACs are amenable to scalable synthetic methods, exhibit broad structural tunability, and support multivalent payload conjugation. This intrinsic modularity enables incorporation of a diverse repertoire of target‑binding motifs and E3‑ligase recruiters. These include von Hippel-Lindau protein (VHL), Kelch-like ECH-associated protein 1 (KEAP1), and Cereblon (CRBN). We deploy HYDRACs against two historically intractable targets, Myelocytomatosis proto-oncogene (MYC) and Kirsten rat sarcoma viral oncogene homolog (KRAS), achieving potent degradation in vitro and durable tumor suppression in murine models. Notably, HYDRACs bearing consensus RAS-binding motifs effectuate degradation of KRAS across multiple alleles, suggesting pan‑KRAS potential. We envision HYDRACs as a generalizable paradigm that substantially expands the TPD armamentarium.
    DOI:  https://doi.org/10.1038/s41467-026-68913-3
  19. NAR Mol Med. 2026 Jan;3(1): ugag013
    Inhibition of the integrated stress response rescues a histidyl-tRNA synthetase variant associated with Charcot-Marie-Tooth disease.
    Maria Mahmood, Sarah D P Wilhelm, Marisa I Mendes, Desiree E Smith, Rosan Kenana, Kyle Hoffman, Angelica A Moresco, Victoria Mok Siu, Ilka U Heinemann.
      Cytoplasmic histidyl-tRNA synthetase (HARS1) is an essential protein in translation, ligating histidine to its cognate tRNAHis. HARS1 is one of several aminoacyl-transfer RNA (tRNA) synthetases associated with Charcot-Marie-Tooth disease, an axonal peripheral neuropathy. Advances in genetic testing identify many variants of uncertain significance. We characterize a novel heterozygous allele in HARS1, c.1200G > T (p.Leu400Phe) with a familial inheritance pattern of peripheral neuropathy. Using a humanized yeast model and biochemical assays, we determined that HARS-L400F causes HARS aggregation, reduced thermal stability, and a temperature-dependent reduction of aminoacylation activity. In humanized yeast, L400F leads to a pronounced growth defect, especially at elevated temperatures. Contrary to previously described pathogenic HARS alleles, cognate amino acid or tRNA substrate supplementation does not ameliorate the growth defect. We show that, in a humanized yeast model, HARS L400F leads to the activation of the integrated stress response (ISR) and upregulated chaperone expression. The yeast growth phenotype can be rescued by inhibition of the ISR using a specific inhibitor of general control non-depressible 2 (GCN2) kinase, opening a novel therapeutic avenue for pathogenic HARS1 alleles that do not respond to substrate supplementation.
    DOI:  https://doi.org/10.1093/narmme/ugag013
  20. Mol Biol Cell. 2026 Feb 25. mbcE24030109
    Autophagosome turnover requires Arp2/3 complex-mediated maintenance of lysosomal integrity.
    Corey J Theodore, Lianna H Wagner, Kenneth G Campellone.
      Autophagy is an intracellular degradation process that maintains homeostasis, responds to stress, and plays key roles in preventing aging and disease. Autophagosome biogenesis, vesicle rocketing, and autolysosome tubulation are controlled by multiple actin cytoskeletal factors, but the impact of actin assembly on completion of the autophagic degradation pathway is not well understood. Here we studied autophagosomes and lysosomes in mouse fibroblasts harboring an inducible knockout (iKO) of the Arp2/3 complex, an essential actin nucleator. Arp2/3 complex ablation resulted in increased basal levels of autophagy receptors and lipidated membrane proteins from the LC3 and GABARAP families. Such phenotypes were accompanied by the steady-state presence of abnormally high numbers of autolysosomes and an inability of the Arp2/3 complex-deficient cells to complete autolysosome turnover due to lysosomal damage. When normal cells were treated with a lysosomal membrane-disrupting agent, the Arp2/3-activating protein WHAMM was recruited to lysosomes, and Arp2/3 complex activity was required for restoring intact lysosomal structure. Deletion of WHAMM in mouse or human fibroblasts decreased Arp2/3 localization to lysosomes and increased lysosomal damage. These results reveal the importance of the Arp2/3 complex and WHAMM for autophagic degradation and uncover a new role for the actin nucleation machinery in maintaining lysosomal integrity.
    DOI:  https://doi.org/10.1091/mbc.E24-03-0109
  21. Protein Sci. 2026 Mar;35(3): e70506
    The endoplasmic reticulum in mitochondrial protein targeting: A neuronal perspective on organelle crosstalk.
    J Tabitha Hees, Angelika B Harbauer.
      Neurons depend on tightly regulated spatial proteostasis to maintain function across their extended morphology. The endoplasmic reticulum (ER), traditionally known for its function in protein synthesis, folding, and trafficking, has long been recognized as a central platform for directing proteins to organelles of the secretory and endocytic pathways. In contrast, its involvement in the targeting of mitochondrial proteins, which are not directly connected to classical trafficking routes, remains less well understood and has only recently gained attention. Growing evidence implicates the ER in post-translational delivery of mitochondrial precursors through mechanisms that integrate local translation, chaperone activity, and dynamic organelle contact sites. ER-mitochondria contacts form dynamic platforms for precursor translation, stabilization and transfer, as exemplified by pathways such as ER-SURF. Endolysosomes add an additional layer of regulation by influencing both ER function and mitochondrial proteostasis. However, how these processes are mechanistically coordinated, particularly in neurons with their complex architecture, remains incompletely understood. In this review, we synthesize the current understanding on ER-mediated mitochondrial protein targeting, highlight the role of membrane contact sites between ER, mitochondria and endolysosomes, and discuss how chaperone networks and signaling pathways shape mitochondrial precursor handling. We further explore how disruption of these systems might contribute to neurodegeneration, positioning organelle crosstalk as a critical determinant of mitochondrial proteostasis and neuronal health.
    Keywords:  ER‐SURF; endoplasmic reticulum; mitochondrial protein targeting; neurodegeneration; organelle crosstalk
    DOI:  https://doi.org/10.1002/pro.70506
  22. Res Sq. 2026 Feb 16. pii: rs.3.rs-8615050. [Epub ahead of print]
    Integrated Stress Response Signatures Drive Monocyte Dysfunction in GBA1- and LRRK2-Linked Parkinson's Disease.
    Daniele Mattei, Erica Brophy, Mikaela Rosen, Oriol Narcis Majos, Aloysius Domingo, Elena Meijia, Claudia De Sanctis, Beomjin Jang, Tarek Khashan, Mengxi Yang, Deborah Raymond, Casey Young, Jack Humphrey, Elisa Navarro, Amanda Allan, Katherine Leaver, Viktoriya Katsnelson, Alexander Chung, Benjamin Muller, Matthew Swan, Vicki L Shanker, Mariel Pullman, Adina Wise Adina Wise, Roberto Ortega, Kelly Astudillo, Steven Frucht, Susan Bressman, Giulietta Riboldi, Laurie J Ozelius, Rachel Saunders-Pullman, Towfique Raj.
      Monocytes are increasingly implicated in Parkinson's disease (PD) pathogenesis, with idiopathic cases showing mitochondrial and lysosomal dysfunction. However, the impact of PD-associated mutations on monocytes remains unclear. To address this, we investigated transcriptomic and functional disturbances in peripheral monocytes from patients with GBA1 - and LRRK2 -associated PD and idiopathic PD. Transcriptomic data revealed shared and mutation-specific signatures, including those related to immune dysregulation, and consistent defects in lysosomal, proteasomal and mitochondrial pathways. Network and pathway analyses further uncovered downregulation in protein translation and enrichment of integrated stress response (ISR) signatures, alongside aberrant expression of genes linked to ER stress, mitophagy and type-I interferon signaling. Protein levels of heat-shock proteins and ISR effectors were elevated at baseline and following α-synuclein exposure, consistent with impaired proteostasis. Live-cell assays demonstrated defects in lysosomal function, mitochondrial dynamics, and phagocytosis, most pronounced in GBA1 - and LRRK2 -associated PD but evident across all PD groups. Together, these findings define a PD-associated myeloid state of immunodegeneration , marked by impaired clearance, proteostasis failure, and mitochondrial dysfunction across genetic and idiopathic PD.
    DOI:  https://doi.org/10.21203/rs.3.rs-8615050/v1
  23. Plant Commun. 2026 Feb 26. pii: S2590-3462(26)00090-8. [Epub ahead of print] 101782
    Dynamic regulation of protein homeostasis underlies thermopriming-mediated acquired thermotolerance in Arabidopsis.
    Mayur Bajaj, Annapurna Devi Allu, Basuthkar J Rao.
      Rapid climate change demands the development of heat-resilient plants. Elevated temperatures perturb cellular protein homeostasis, and its timely restoration is crucial for plant survival after stress. Thermopriming, which involves pre-exposure to sublethal heat stress, has emerged as a promising strategy for enhancing heat stress tolerance. However, the impact of thermopriming on protein homeostasis remains unclear. Here, we demonstrate that priming-mediated acquired thermotolerance involves the dynamic regulation of protein maintenance and clearance mechanisms. Priming facilitates the activation of heat shock response (HSR) via HSFA1, and unfolded protein response (UPR). Simultaneously, priming induces the protein clearance pathway, namely autophagy, potentially through the dynamic modulation of autophagy-negative regulators. Contrastingly, unprimed seedlings fail to mount HSR and UPR, resulting in disrupted proteostasis and the accumulation of aggregates, and ultimately fail to survive. While the loss of UPR was found to have a minimal impact on priming-mediated outcomes, the HSR response proved essential, as its absence led to lethality under heat stress. Additionally, the absence of HSR was found to enhance the autophagy response post-stress. Our results highlight the critical role of protein maintenance mechanisms over clearance pathways in ensuring survival. Taken together, our study demonstrates that thermopriming enhances heat stress resilience by temporally coordinating autophagy, HSR and UPR responses to maintain proteostasis.
    Keywords:  Autophagy; Heat Shock Factor A1; Priming; Proteostasis; Thermotolerance
    DOI:  https://doi.org/10.1016/j.xplc.2026.101782
  24. J Biol Chem. 2026 Feb 25. pii: S0021-9258(26)00190-0. [Epub ahead of print] 111320
    Optimization of protein UFMylation modification method and its application in substrate identification in human cells.
    Yaoyao Fang, Xue Wang, Juexi Dong, Xingling Yi, Zhaopeng Lv, Chen Bu, Xianliang Ma, Yu-Sheng Cong, Qian Liang.
      UFMylation plays an essential role in regulating intracellular physiological and pathological processes. Accumulating evidence has demonstrated that dysregulation of UFMylation is closely associated with the progression of various diseases, including cancers and developmental disorders. However, efficient and specific methods for detecting UFMylated substrate proteins remain challenging. In this study, we generated the UFM1-specific proteases knockout (UFSP1KO/UFSP2KO) HEK293T cell line and validated it as the most suitable cellular model for the screening, identification, and confirmation of UFMylated substrate proteins. Furthermore, exogenous expression of the E3 ligase components UFM1-specific ligase 1 (UFL1) and DDRGK domain-containing protein 1 (DDRGK1) significantly enhances protein UFMylation levels, enabling the large-scale enrichment of UFMylated substrates. Collectively, we have established a more efficient, specific, and reliable method for UFMylation substrates research, facilitating in-depth investigation into its biological functions and regulatory mechanisms.
    Keywords:  DDRGK1; Substrate; UFL1; UFMylation; UFSP
    DOI:  https://doi.org/10.1016/j.jbc.2026.111320
  25. bioRxiv. 2026 Feb 09. pii: 2025.12.26.696633. [Epub ahead of print]
    Stemness factor Mex3a times translation and protein trafficking to ensure robust differentiation of olfactory sensory neurons.
    Martín Escamilla Del Arenal, Lauren C Tang, Albana Kodra, Hani Shayya, Aileen Ugurbil, Olga Stathi, Keskin Abdurrahman, Adan Horta, Joan Pulupa, Junqiang Ye, Marko Jovanovic, Stavros Lomvardas, Rachel Duffié.
      During the switch from progenitor to differentiated cell, cellular physiology must change to accommodate increased translation and trafficking of membrane-bound proteins. We identify RNA-binding and E3 ubiquitin ligase Mex3a as a key driver of proper neuronal differentiation by regulating mRNA translation and trafficking of cell surface proteins in the context of Unfolded Protein Response (UPR) signaling. Loss of Mex3a in immature olfactory sensory neurons (OSNs) leads to defects in cilia structure, cell surface protein expression, and planar cell polarity in mature OSNs. Proteomics reveal a Mex3a-dependent decrease in proteins related to vesicle transport, lipid metabolism, and ribosome biogenesis. We identify RNA and ubiquitin targets of Mex3a and provide evidence that Mex3a may confer K27 ubiquitin linkage on substrates. Finally, modulating cellular levels of Mex3a changes the recruitment of translation factors Serbp1 and p-eEF2 to ribosomes with possible effects on translation. Our data reveal how a stemness factor regulates development post-transcriptionally and post-translationally to ensure robust differentiation.
    Highlights: Loss of stemness factor Mex3a in immature olfactory neurons leads to defects in mature olfactory neurons.Translation/Trafficking of cell surface proteins, cilia structure, and planar cell polarity are compromised in the absence of Mex3a.Mex3a may confer K27 ubiquitination on stress granule protein Serbp1 and ribosome protein Rps7.Mex3a levels are associated with Serbp1 and p-eEF2 recruitment to ribosomes.
    DOI:  https://doi.org/10.64898/2025.12.26.696633
  26. Nat Commun. 2026 Feb 24. pii: 1963. [Epub ahead of print]17(1):
    Context-dependent translation inhibition as a cancer therapeutic modality.
    Paige D Diamond, Paul V Sauer, Mikael Holm, Canessa J Swanson-Swett, Lucas Ferguson, Natalie M Bratset, Grant W Wienker, Justin Seiwert Sim, Hailey K Adams, Lillian Kenner, Margot Meyers, David Gygi, Zef A Könst, Sogole Sami Bahmanyar, Lawrence G Hamann, Anthony P Schuller.
      Recent work has demonstrated that some bacterial antibiotics that inhibit protein synthesis by binding the peptidyl transferase center (PTC) of the ribosome act in a context-dependent manner, inhibiting translation elongation only at specific amino acids. However, this phenomenon has yet to be documented for compounds that inhibit the PTC of the human ribosome. Here, we use structure-based design to guide the synthesis of such PTC-binding, context-dependent inhibitors of the human ribosome, termed interdictors. In the PTC, these compounds preferentially interact with nascent protein residues that exhibit complementary physiochemical properties to the moieties of the small molecule, causing structural rearrangements in both the nascent polypeptide chain and ribosomal RNA. Further, the compounds differentially impact ribosome surveillance pathways, including the ribotoxic stress response. Finally, we confirm their anti-tumor activity after oral dosing in a mouse xenograft model of triple-negative breast cancer. Together, our data establish targeting oncogenic dependency factors through context-dependent inhibition of translation as a potential small molecule therapeutic modality for historically difficult to address cancers.
    DOI:  https://doi.org/10.1038/s41467-026-69891-2
  27. bioRxiv. 2026 Feb 18. pii: 2026.02.17.706400. [Epub ahead of print]
    Proximity labeling of the Listeria monocytogenes surface reveals pathogen control of a host deubiquitinase.
    Patrick J Woida, Maisie W Smith, Rebecca L Lamason.
      Intracellular pathogens must navigate the crowded cellular environment to establish infection. Listeria monocytogenes achieves this by recruiting host factors to its surface to hijack the host actin cytoskeleton for motility, form membrane protrusions, and spread from cell to cell. Although these types of Listeria -host interactions are critical for infection, systematic characterization of this interface has been limited. Here, we implement surface display of the promiscuous biotin ligase split-TurboID to profile host proteins recruited to the surface of L. monocytogenes during intracellular infection. This approach identified the host deubiquitinase CYLD as a protein selectively enriched at the pathogen surface. While CYLD promotes infection by suppressing autophagy and innate immunity in macrophages, how L. monocytogenes recruits and appropriates CYLD function in other cell types has remained unclear. We demonstrate that the E3 ligase RNF213 decorates bacterial poles with M1-linked linear ubiquitin, thereby redirecting CYLD to the bacterial surface. We further show ubiquitin is not sufficient to recruit CYLD but requires the L. monocytogenes secreted effector internalin C (InlC). Despite its presence at the bacterial surface, CYLD does not deubiquitinate bacteria or regulate autophagic bacterial clearance in infected epithelial cells. Instead, CYLD and InlC protect L. monocytogenes from IFN-γ- and RNF213-dependent restriction of cell-to-cell spread. Overall, our work profiling the bacterial surface-host interactome has identified a new mechanism by which InlC spatially reprograms CYLD activity, uncoupling its canonical immune functions to promote cell-to-cell spread in epithelial cells. These findings highlight how L. monocytogenes exploits, a host deubiquitinase, to perform cell-type-specific functions during infection.
    DOI:  https://doi.org/10.64898/2026.02.17.706400
  28. bioRxiv. 2026 Feb 15. pii: 2026.02.14.705950. [Epub ahead of print]
    Sub-stoichiometric Degradation is Dispensable for Potent PROTACs: A Case Study for Irreversible Covalent BTK Degraders.
    Ran Cheng, Hanfeng Lin, Xin Yu, Shrilekha Misra, Andrew D Mitchell, Jennifer A Woyach, Xiaoli Qi, Jin Wang.
      Proteolysis-targeting chimeras (PROTACs) represent a transformative therapeutic modality, yet the viability of covalent PROTACs remains debated, as irreversible binding seemingly contradicts the catalytic mechanism central to their function. Here, we develop and characterize PSIRC3, a highly potent covalent PROTAC for Bruton's tyrosine kinase (BTK) that addresses this ambiguity. PSIRC3 induces potent and selective BTK degradation with a sub-nanomolar DC 50 of 0.75 nM and a D max greater than 85%, while its non-covalent counterpart is completely inactive. This degradation activity is strictly dependent on covalent bond formation with the Cys481 residue, as evidenced by a total loss of efficacy against the C481S BTK mutant. PSIRC3 acts with remarkable speed, achieving maximum BTK degradation within 30 minutes, a kinetic profile linked to rapid cell permeation and efficient ternary complex formation. In vivo , a single administration of PSIRC3 leads to substantial BTK degradation in both PBMCs (>80%) and splenocytes (>50%). Computational modeling, parameterized with experimental data, reveals that degradation efficacy is governed by a delicate balance between E3 ligase and target protein affinities. Specifically, excessively high E3 affinity is detrimental by inducing a hook effect, while higher target affinity is generally beneficial. Our findings provide strong evidence that covalent engagement can drive potent and selective protein degradation, challenging the prevailing notion that catalytic turnover is indispensable for PROTAC efficacy. This work establishes a new benchmark for covalent degraders and opens new avenues for targeting previously intractable proteins.
    DOI:  https://doi.org/10.64898/2026.02.14.705950
  29. bioRxiv. 2026 Feb 11. pii: 2026.02.10.705189. [Epub ahead of print]
    Nup42 safeguards heat-induced mRNAs from nuclear condensation to support chaperone synthesis.
    Eduardo Tassoni-Tsuchida, Angel Madero, Magda Zaoralová, Sebastian Alfonso, Brian Alford, Onn Brandman.
      Cells exposed to acute stress selectively express stress-adaptive genes while repressing growth-related genes. Upon heat shock, most pre-existing mRNAs localize to translationally repressed biomolecular condensates. How heat-induced mRNAs evade condensation and remain translationally competent remains unclear. Here, we show that ribosomal protein-coding transcripts preferentially accumulate in condensates during heat shock, whereas heat-induced chaperone mRNAs are selectively excluded and preferentially translated. Using a whole-genome CRISPRi screening platform, Fractionation of Reporter-Seq (FRep-Seq), we identify the nucleoporin Nup42 as the strongest suppressor of heat-induced mRNA condensation. Loss of Nup42 triggers temperature- and transcription-dependent nuclear condensation of chaperone mRNAs, which are exported but remain translationally incompetent, leading to impaired chaperone production and thermosensitivity. Co-transcriptional mRNP packaging is a critical determinant of condensation in the absence of Nup42. Together, our findings reveal a nuclear, translation-independent layer of mRNP solubility control that enables heat shock gene expression.
    DOI:  https://doi.org/10.64898/2026.02.10.705189
  30. Autophagy. 2026 Feb 25. 1-3
    Control of phagophore membrane expansion: Atg8-Atg1 as the master switch.
    Yi-He Feng, Jing Zhu, Yu Ding, Fan Yan, Zhiping Xie.
      Autophagosome formation is catalyzed by multiple branches of Atg protein machineries, calling for the existence of a master regulator to coordinate their distinct activities. A prime candidate of such a regulator is Atg8. This protein has a well-established role in controlling phagophore expansion. But the signaling mechanism has been unclear. Our recent work demonstrates that Atg8 recruits activated Atg1 to the phagophore, together forming such a master switch. Our data indicate that different branches of Atg proteins localize to spatially separated zones. The physical distances among the zones, at times exceeding 250 nm, would limit signal transduction efficiency if a signaling molecule were exclusively localized to a single zone. By covering the phagophore surface, Atg8 maintains physical proximity to different Atg machineries, and transmits a permissive signal by recruiting activated Atg1. Compromising Atg8-mediated Atg1 recruitment leads to confinement of Atg1 to the initiation protein condensate and failure of phagophore expansion. Conversely, the Atg8-Atg1 switch can be manually augmented to substantially increase autophagosome size and autophagic flux. Our work thus reveals a critical regulatory circuit of macroautophagy/autophagy that is built on the spatial organization of Atg protein machineries.
    Keywords:  Autophagy; kinase; membrane biogenesis; membrane expansion; protein trafficking; ubiquitin-like protein
    DOI:  https://doi.org/10.1080/15548627.2026.2636092
  31. Nat Commun. 2026 Feb 25.
    Disruption of tRNA threonylation triggers RIG-I mediated anti-tumour immune response.
    Cléa Dziagwa, Christian Seca, Coralie Capron, Chloe Maurizy, Ning An, Denis Heusdens, Timothy Budden, Lorena Martin-Morales, Miguel Susaeta Ruiz, Elodie Renaude, Najla El-Hachem, Raphael Vanleyssem, Marine Leclercq, Arnaud Blomme, Alain Chariot, Jochen Utikal, Amaya Viros, Francesca Rapino, Sylvain Delaunay, Pierre Close.
      Tumour-induced mechanisms of immune evasion hinder immune response to cancer, particularly in melanoma. mRNA translation, by ensuring accurate protein synthesis, regulates cancer phenotypes and immune response, but the underlying mechanisms remain unclear. Here, we reveal how O-sialoglycoprotein endopeptidase (OSGEP), catalysing the tRNA modification N6-threonylcarbamoyladenosine (t6A), drives protein homeostasis in cancer cells to maintain T-cell exclusion and prevent anti-tumour immune response. t6A-deficient melanoma cells disrupt efficient cytoplasmic translation of ANN codons (trinucleotides with A in the first position and N = any nucleotide), causing specific protein aggregation and the formation of integrated stress response-dependent stress granules. We discovered that OSGEP loss triggers melanoma regression by relocating RIG-I to stress granules, leading to its pathway activation. As a result, T-cells are recruited to the tumour site and orchestrate an anti-tumour immune response. Finally, an OSGEP-driven gene signature in melanoma patients is associated with T-cell infiltration and improved overall survival. Together, our findings position t6A tRNA modification as a promising therapeutic target for melanoma treatment.
    DOI:  https://doi.org/10.1038/s41467-026-69964-2
  32. Essays Biochem. 2025 Dec 22. pii: EBC20250062. [Epub ahead of print]69(4):
    From molecular logic to therapeutic modulation: advances in Ub/UBL signalling.
    Benjamin M Foster, Chiara Maniaci.
      Ubiquitin (Ub) and ubiquitin-like proteins (UBLs) are central regulators of cell signalling, with roles spanning proteasomal degradation, immune defence, DNA repair, autophagy, and the stress response. Their conserved β-grasp fold provides a remarkably versatile protein architecture that can be redeployed across diverse signalling pathways and modulated in disease contexts. Conjugation and removal through dedicated E1-E2-E3 and protease systems generate a rich regulatory code, further diversified by chain topology, hybrid architectures, and emerging non-canonical modifications. This special issue highlights recent advances in Ub and UBL biology, from specialised UBL pathways to host-pathogen interactions and non-protein conjugation events, as well as translational applications such as targeted protein degradation. Together, these reviews showcase the breadth, adaptability, and therapeutic potential of these small but powerful modifiers.
    Keywords:  post translational modification; therapeutics; ubiquitin signalling
    DOI:  https://doi.org/10.1042/EBC20250062
  33. Chem Sci. 2026 Feb 19.
    Unveiling BCL-xL-specific PROTAC efficiency and dissociation pathways using native mass spectrometry.
    Mohamed I Gadallah, Kailyn L Nonhof, Digant Nayak, Peiyi Zhang, Olivia Dioli, Guangrong Zheng, Shaun K Olsen, Daohong Zhou, Jennifer S Brodbelt.
      Overexpression of anti-apoptotic proteins such as BCL-xL is a hallmark of various cancers and a major driver of resistance to conventional chemotherapies. While small-molecule BCL-xL inhibitors have shown promising outcomes, their clinical use is hindered by dose-limiting toxicities, especially thrombocytopenia. Proteolysis-targeting chimeras (PROTACs) offer a promising alternative by promoting selective degradation of target proteins via the ubiquitin-proteasome system, thereby reducing off-target effects associated with small molecule inhibitors. However, rational design and optimization of PROTACs remain challenging due to the need to balance simultaneous interactions with both an E3 ubiquitin ligase and the target protein. Here we employ native mass spectrometry (MS) as a rapid, label-free platform to screen and characterize the formation and stability of ternary complexes between BCL-xL, VHL E3 ligase complex (VCB), and various targeting PROTACs. Native MS enables direct detection of binary BCL-xL·PROTAC and ternary BCL-xL·PROTAC·VCB complexes and provides semi-quantitative insights into PROTAC affinity and cooperativity with both binding partners. Furthermore, we explore the dissociation pathways of these complexes in the gas phase using collision-induced dissociation (CID) and ultraviolet photodissociation (UVPD), revealing distinct fragmentation and subunit release patterns that reflect the structural organization and gas-phase stability of the complexes. Variable-temperature ESI-MS (vT-ESI) further allows assessment of thermal stabilities of the complexes in solution. Together, our study demonstrates the power of native MS to both screen and mechanistically characterize PROTAC-induced ternary complex formation.
    DOI:  https://doi.org/10.1039/d5sc07400b
  34. Nat Commun. 2026 Feb 24.
    A testis-specific E3 ubiquitin ligase complex governs spermiogenesis and male fertility.
    Tiantian Wu, Chaofeng Tu, Yuxuan Feng, Wenying Qu, Jinyi Chen, Huan Wu, Wenxin Gao, Bingya Xu, Xiangling Yu, Mingyuan Bao, Jinfu Xu, Nianchao Zhou, Haoyue Hu, Bing Jiang, Qingsong Xie, Lanlan Meng, Chen Tan, Ge Lin, Cong Shen, Xia Chen, Yueshuai Guo, Tao Zhou, Yuting Liang, Rong Hua, Yunxia Cao, Mingxi Liu, Jun Yu, Xiaoyan Huang, Yue-Qiu Tan, Bo Zheng.
      The ubiquitin-proteasome system (UPS) represents an evolutionarily conserved machinery governing proteostasis through spatiotemporal regulation of protein degradation. While spermatogenesis involves multilayered regulatory mechanisms spanning translation to dynamic post-translational modifications (PTMs), the identity of UPS-associated E3 ligases orchestrating germ cell-specific protein turnover remains elusive. Here, we identify a testis-specific E3 ubiquitin ligase complex comprising elongin B/C, Cullin-2 (CUL2), RING-box protein-1 (RBX1), and SOCS box protein ASB9, designated ECSASB9. Genetic ablation of ECSASB9 in mice via ubiquitous Asb9 knockout (KO) or spermatid-specific elongin B/C conditional KO disrupts spermiogenesis and compromises fertility. Mechanistic studies reveal that ECSASB9 engages tubulin beta 4 A (TUBB4A) through substrate recognition, catalyzing K48-linked polyubiquitination at lysine 379 (K379) to promote proteasomal degradation. Notably, Tubb4aK379R knock-in (KI) mice phenocopy the spermiogenesis defects observed upon ECSASB9 deficiency. Clinically, we identify three hemizygous missense variants in X-linked ASB9 among Chinese males with idiopathic infertility. Male mice bearing orthologous ASB9 variant exhibit oligoasthenoteratozoospermia (OAT) and subfertility, mirroring human phenotypes. Taken together, our findings establish ECSASB9 as an important regulator of spermatogenic proteostasis and provide mechanistic insights into UPS-mediated tissue-specific degradation, while implicating ASB9 variants in male infertility pathogenesis.
    DOI:  https://doi.org/10.1038/s41467-026-70025-x
  35. Nature. 2026 Feb 25.
    CLCC1 promotes hepatic neutral lipid flux and nuclear pore complex assembly.
    Alyssa J Mathiowetz, Emily S Meymand, Güneş Parlakgül, Niek van Hilten, Emily F Torres, Leonardo L Artico, Kirandeep K Deol, Mike Lange, Stephany P Pang, Cody E Doubravsky, Melissa A Roberts, Danielle M Jorgens, Reena Zalpuri, Misun Kang, Casadora Boone, Brian W Parks, Yaohuan Zhang, David W Morgens, Emily Tso Newman, Yingjiang Zhou, Saswata Talukdar, Michael Grabe, Gregory Ku, Tim P Levine, Ana Paula Arruda, James A Olzmann.
      Imbalances in lipid storage and secretion lead to hepatic steatosis, the accumulation of lipid droplets in hepatocytes1,2. Our understanding of the mechanisms that govern the channelling of neutral lipids in hepatocytes towards cytosolic lipid droplets or secreted lipoproteins remains incomplete3,4. Here we performed a series of CRISPR-Cas9 screens under different metabolic states that led to the identification of CLCC1 as a critical regulator of neutral lipid storage and secretion in hepatocytes. Loss of CLCC1 resulted in the buildup of large lipid droplets in hepatoma cells and Clcc1 knockout in mice caused liver steatosis. Lipid droplets were present in the lumen of the endoplasmic reticulum of the Clcc1-knockout hepatocytes and exhibited properties of lipoproteins, indicating a profound shift in neutral lipid flux. The loss of CLCC1 also led to the accumulation of nuclear membrane herniations accompanied by a reduction in nuclear pores. Remote homology searches identified a domain in CLCC1 that is homologous to yeast Brl1 and Brr6, factors that promote nuclear envelope fusion during nuclear pore complex assembly. Molecular dynamics simulations and mutagenesis studies support a model in which CLCC1 mediates membrane bending and fusion. We propose that CLCC1 mediates membrane fusion to promote hepatic neutral lipid flux and nuclear pore complex assembly.
    DOI:  https://doi.org/10.1038/s41586-025-10064-4
  36. J Cell Biol. 2026 May 04. pii: e202502131. [Epub ahead of print]225(5):
    Hoi1 targets BLTP2 to ER-PM contact sites to regulate lipid homeostasis.
    Samantha K Dziurdzik, Vaishnavi Sridhar, Hailey Eng, Sarah D Neuman, Junran Yan, Michael Davey, Stefan Taubert, Arash Bashirullah, Elizabeth Conibear.
      Membrane contact sites between organelles are important for maintaining cellular lipid homeostasis. Members of the recently identified family of bridge-like lipid transfer proteins (BLTPs) span apposing membranes at these contact sites to enable the rapid transfer of bulk lipids between organelles. While the VPS13 and ATG2 family members use organelle-specific adaptors for membrane targeting, the mechanisms that regulate other bridge-like transporters are unclear. Here, we identify the conserved protein Ybl086c, which we name Hob interactor 1 (Hoi1), as an adaptor that targets the yeast BLTP2-like proteins Fmp27/Hob1 and Hob2 to ER-plasma membrane (PM) contact sites. Two separate Hoi1 domains interface with α-helical projections that decorate the central hydrophobic channel on Fmp27, and loss of these interactions alters cellular sterol homeostasis. The mutant phenotypes of BLTP2 and HOI1 orthologs indicate these proteins act in a shared pathway in worms and flies. Together, this suggests that Hoi1-mediated recruitment of BLTP2-like proteins represents an evolutionarily conserved mechanism for regulating lipid transport at membrane contact sites.
    DOI:  https://doi.org/10.1083/jcb.202502131
  37. Res Sq. 2026 Feb 10. pii: rs.3.rs-8483849. [Epub ahead of print]
    RuPHOTACs Provide Photocontrol Over Protein Degradation with Optimized Properties for Biological Applications.
    Edith Glazer, Dmytro Havrylyuk, Ainsley LaMore, Majd Al Hamaly, Jessica Blackburn, David Heidary.
      PROteolysis TArgeting Chimeras (PROTACs) are bifunctional molecules that catalyze degradation of selected proteins by inducing protein:protein interactions (PPIs) between E3 ubiquitin ligases and the protein of interest. A critical limitation is undesired effects in untargeted tissues, necessitating approaches to impose spatiotemporal control over PROTAC function. Here we present Ru(II) photocages that can be released with low energy light, providing triggered PROTAC activity on demand. The systems, termed Ruthenium-based PHOToActivated Chimeras (RuPHOTACs), were validated by targeting bromodomain-containing proteins, which act as crucial epigenetic regulators, and also strongly reduced levels of c-MYC and PIM1. The novel RuPHOTACs demonstrate that the incorporation of metal components within organic PROTACs confers multiple advantages for light-controlled systems for chemical biology applications, including the highest selectivity for activation in the light vs. the dark, improved potency against the target proteins of interest, and increased efficacy in vivo using low energy red light. To efficiently monitor protein degradation via optical means, a new strategy was implemented by creating a fusion of a photoconvertible protein, Dendra2, with the proteins of interest. This bifunctional reporter system for live cell analysis decouples protein degradation efficiency and rates from signals arising from new protein production, and is superior to prior reporter systems described for PROTACs because it directly measures the true degradation rate of the target protein in intact, viable cells while simultaneously tracking newly synthesized protein without perturbing translation, proteostasis, or cell health.
    DOI:  https://doi.org/10.21203/rs.3.rs-8483849/v1
  38. Genome Biol. 2026 Feb 26.
    Translational buffering tunes gene expression in mice and humans.
    Shilpa Rao, Aden Y Le, Logan Persyn, Can Cenik.
       BACKGROUND: Translational buffering refers to the regulation of ribosome occupancy to offset the effects of transcriptional variation. While previous studies have primarily investigated translational buffering in yeast under genetic variation or environmental stress, it remains unclear how widespread this is across mammalian genes in various cellular contexts.
    RESULTS: We performed a uniform analysis of 1,515 matched ribosome profiling and RNA-seq datasets from humans and mice. This resource enabled us to assess translational buffering through comparative analysis of variation in ribosome occupancy and RNA expression, and by examining the relationship between mRNA abundance and translation efficiency. We found that translational buffering is partly conserved between humans and mice; homologous genes showed moderate cross-species correlation in mRNA-translation efficiency relationships and strong enrichment of shared buffered genes, particularly those encoding ribosomal, RNA-binding, and proteasomal proteins. Although identified buffered genes associate with specific sequence features, these alone are insufficient to predict translational buffering, highlighting the importance of cellular context. Genes exhibiting translational buffering show lower variation in protein abundance in cancer cell lines and tissues. We also observed that translationally buffered genes are more likely to be haploinsufficient and triplosensitive, suggesting a demand for stringent dosage limits.
    CONCLUSIONS: We hypothesize two models of translational buffering, namely the "differential accessibility model" and the "translation initiation rate model", suggesting that different transcripts align with one or the other. Our study explores the translational buffering potential of genes across diverse conditions, elucidates their distinctive features, and provides insights into the mechanisms driving this effect.
    Keywords:  Ribosome occupancy; Translation efficiency; Translational buffering; mRNA variation
    DOI:  https://doi.org/10.1186/s13059-026-04010-4
  39. Curr Biol. 2026 Feb 24. pii: S0960-9822(26)00134-X. [Epub ahead of print]
    Regulation of mitophagy by Fis1 and Fascin1-organized actin.
    Shintaro Nakajima, Ting-Yu Wang, Tsui-Fen Chou, Yogaditya Chakrabarty, David C Chan.
      Mitophagy, the autophagic degradation of mitochondria, plays a central role in controlling the quality and quantity of mitochondria, thereby ensuring cellular health. The mitochondrial outer membrane protein Fis1 is important for several types of mitophagy, but its mechanism of action remains unclear. F-actin is recruited to autophagic cargo and is important for autophagic progression, but the mechanism for its recruitment is poorly understood. To address the molecular function of Fis1, we performed affinity purification of Fis1 and mass spectrometry and identified the actin-bundling protein Fascin1 as a physical interactor. We demonstrate that Fis1 is required for recruitment of Fascin1 as well as F-actin to mitochondria under stress conditions, including mitochondrial depolarization and iron chelation. Iron chelation also triggers mitophagy that is independent of the Parkinson's associated gene Parkin, and we show that Fis1 enables recruitment of Fascin1-organized F-actin to facilitate proper morphogenesis of autophagosomes and the ensuing mitochondrial degradation. In contrast, although Parkin-mediated mitophagy also relies on Fis1, it is unaffected by loss of Fascin1 or F-actin recruitment. These findings indicate that Fis1 has distinct modes of action in mitophagy, depending on the triggering cellular stress. They establish Fis1 as a key driver of Fascin1 and F-actin recruitment to mitochondria, events that are critical for autophagosome morphogenesis during iron-chelation-induced mitophagy.
    Keywords:  Fascin1; Fis1; actin; autophagy; mitochondria; mitophagy
    DOI:  https://doi.org/10.1016/j.cub.2026.01.062
  40. Nat Commun. 2026 Feb 21. pii: 1982. [Epub ahead of print]17(1):
    High-throughput chemical proteomics workflow for profiling protein citrullination dynamics.
    Rebecca Meelker González, Sophia Laposchan, Erik Riedel, Anna Fürst, Naomi O'Sullivan, Wassim Gabriel, Mathias Wilhelm, Percy A Knolle, Guillaume Médard, Bernhard Kuster, Chien-Yun Lee.
      Citrullination is a post-translational modification implicated in autoimmune and inflammatory diseases, yet its low abundance and lack of effective enrichment tools have limited proteome-wide analysis. Here, we develop a robust chemical proteomics workflow with improved specificity and throughput. This method builds upon glyoxal-based derivatization and incorporates a cleavable biotin linker for efficient peptide enrichment, release, and identification via mass spectrometry. Benchmarking demonstrates a > 10-fold increase in the detection of citrullinated peptides at sub-0.1% abundance. Applying this workflow to primary human neutrophils, we successfully monitor dynamic regulation, quantifying dose-dependent activation and inhibition by the PAD4 inhibitor GSK484. Furthermore, stimulation with the fungal pathogen Candida albicans reveals a "core citrullinome" conserved across distinct stimuli. Notably, extensive citrullination of linker histone H1 and structural proteins like lamin B1 suggests broad remodeling of cell architecture during NET formation. This workflow enables proteome-wide mapping of citrullination sites and facilitates its study across diverse biological contexts.
    DOI:  https://doi.org/10.1038/s41467-026-69490-1
  41. bioRxiv. 2026 Feb 19. pii: 2026.02.17.706457. [Epub ahead of print]
    Gl Rac Regulates a Noncanonical, ATG8-Independent Autophagy-Like Pathway in Giardia lamblia.
    Angélica Hollunder Klippel, Grant Reed, Corryn Newman-Boulle, Dule Dule, Saanya Kedia, Wai Pang Chan, Han-Wei Shih, Alexander R Paredez.
      Autophagy is a conserved catabolic process essential for cellular homeostasis and stress adaptation. The protozoan parasite Giardia lamblia lacks most canonical autophagy-related (ATG) genes, including the hallmark ATG8, raising longstanding questions about whether it can perform autophagy. Here, we show that Giardia mounts a regulated autophagic-like response. Double-membrane compartments resembling autophagosomes are induced in up to 30% of encysting cells and 91% of starved trophozoites, supporting roles in differentiation and survival under nutrient stress. Their clearance is triggered by amino acid replenishment but not by glucose, indicating a nutrient-specific sensing mechanism. Gl Rac, the parasite's sole Rho family GTPase, labels these structures and regulates their formation, as evidenced by a threefold increase in compartment levels upon constitutive activation and a significant reduction after knockdown. This extends the conserved role of Rho GTPases in regulating autophagy to an evolutionarily early-branching eukaryote. Of nine putative ATG orthologs tested, none localized as clearly as Gl Rac to autophagic structures. These organelles acidify and recruit cathepsin proteases, consistent with degradative capacity. A newly developed live-cell actin marker reveals robust recruitment to these structures, implicating actin-driven remodeling. Finally, quinacrine, an FDA-approved antigiardial drug, promotes the accumulation of autophagic structures, consistent with its known effects on mammalian autophagy. Together, our findings establish Gl Rac as a regulator of an ATG8-independent autophagic response in Giardia , demonstrate that this parasite retains key features of autophagy despite its streamlined genome, and highlight this pathway as a potential therapeutic target.
    Significance: Autophagy is a self-degradative process essential for stress adaptation and cellular recycling. Although considered ancient and broadly conserved, this pathway was long thought to be absent in the protozoan parasite Giardia lamblia , which lacks many canonical autophagy genes, including the classic marker ATG8. Here, we demonstrate that Giardia performs a regulated autophagic-like response. We identify Gl Rac, the parasite's sole Rho family GTPase, as a regulator that marks autophagosome-like organelles, underscoring the conserved role of Rho GTPases in autophagy across eukaryotes. We also show that quinacrine, a clinically used antigiardial drug, perturbs the autophagic response in this organism. These findings reveal an unrecognized aspect of Giardia biology and support autophagy as a promising therapeutic target for this widespread parasite.
    DOI:  https://doi.org/10.64898/2026.02.17.706457
  42. EMBO J. 2026 Feb 25.
    STARD3 regulates lysosome positioning and contacts via a GSK3-controlled phosphorylation switch.
    Julie Eichler, Corinne Wendling, Sophie Huver, Mehdi Zouiouich, Victor Hanss, Anna Cardinal, Victoria Fimbel, Catherine Birck, Alastair G McEwen, Céline Knorr, Catherine Fromental-Ramain, Maxime Boutry, Marie-Pierre Chenard, Guillaume Drin, Catherine Tomasetto, Fabien Alpy.
      Membrane contact sites (MCS) are dynamic regions where the membranes of two organelles come into close apposition. MCSs play many roles in cellular homeostasis by facilitating inter-organelle lipid exchange and organelle positioning. The late endosome/lysosome (LE/Lys) cholesterol transfer protein STARD3 forms reversible contacts between LE/Lys and the endoplasmic reticulum (ER). This tether protein contains a Phospho-FFAT motif (two phenylalanines in an acidic tract) whose interaction with ER-resident VAPs (vesicle-associated membrane protein-associated proteins) is phosphorylation-dependent. In this study, we identify GSK3α and GSK3β as the kinases responsible for phosphorylating serine 209 within the Phospho-FFAT motif of STARD3. This phosphorylation event is both necessary and sufficient to activate STARD3's tethering activity, thereby promoting ER-LE/Lys contacts. Furthermore, we show that when ER-LE/Lys tethering is prevented, STARD3 triggers LE/Lys homotypic interactions, revealing an additional function for STARD3 on endosome biology. Our findings establish a direct and critical role for GSK3 in regulating MCS via STARD3 phosphorylation, and expand our understanding of the molecular basis of inter-organelle communication.
    Keywords:  Endoplasmic Reticulum; Endosome; Lipid Transfer Protein; Membrane Contact Site; Phosphorylation
    DOI:  https://doi.org/10.1038/s44318-026-00705-3
  43. Adv Sci (Weinh). 2026 Feb 23. e20627
    ERAD Component MoHrd3 Facilitates Pathogenicity and Establishes a Direct Regulation on Autophagy in Magnaporthe Oryzae.
    Huiqing Xia, Yunna Zheng, Nan Yang, Jing Chen, Xi Wu, Ximing Zheng, Danrui Cui, Ruijin Wang, Xunli Lu, Dongli Wang, You-Liang Peng, Qian Chen.
      Both ER-associated degradation (ERAD) and autophagy play crucial roles in maintaining ER protein homeostasis. However, the regulatory relationship between ERAD and autophagy has remained unclear. Here, we report that MoHrd3 is an ERAD component that regulates autophagy in Magnaporthe oryzae, which causes devastating blast disease on rice and wheat. We found that MoHrd3 is important for growth, conidiation, appressorium formation, and expansion of infection hyphae. Further studies showed that the autophagy level is reduced with an impaired fusion between the autophagosome and the vacuole in the MoHrd3 deletion mutant. Interestingly, MoHrd3 directly interacts with MoAtg8, located on the autophagosome, and MoYpt7, situated on the vacuolar membrane. respectively. By serving as a mediator of the protein interaction between MoAtg8 and MoYpt7, MoHrd3 facilitates the fusion of these organelles. Further, we showed that the MoHrd3-dependent fusion between the autophagosome and the vacuole is crucial for pathogenicity. In addition, MoHrd3 also works as an adaptor protein to promote the autophagic degradation of a GPCR protein MoPth11, which is required for appressorium formation and pathogenicity. Our discovery of MoHrd3's role in autophagy establishes a direct connection between ERAD and autophagy, revealing the intricate mechanisms governing protein quality control in this devastating plant pathogen.
    Keywords:  ERAD; MoAtg8; MoHrd3; autophagy; magnaporthe oryzae; pathogenicity
    DOI:  https://doi.org/10.1002/advs.202520627
  44. Sci Adv. 2026 Feb 27. 12(9): eado7448
    PROTAC-based synthetic lethality strategy endogenously activates systemic STING to boost antitumor immunity.
    Ye Liu, Maolin Jiang, Mengchao Ding, Ihsan Ullah, Haiyang Wang, Wenjiao Xie, Kewei Wang, Youyong Yuan.
      Activation of the stimulator of interferon genes (STING) pathway drives natural killer (NK) cells and T cells to orchestrate multidimensional antitumor immune responses. While cytosolic DNA accumulation represents a superior endogenous strategy for STING activation, DNA repair machinery substantially constrains its immunogenic potential. Here, we propose a promising therapeutic strategy that leverages proteolysis-targeting chimera (PROTAC)-mediated degradation of PARP1 [poly(ADP-ribose) polymerase 1] and BRD4 (bromodomain-containing protein 4) to induce synthetic lethality, thereby disrupting DNA repair machinery that drives nuclear-to-cytosolic DNA leakage, surpassing the STING activation threshold to ignite cGAS-STING-mediated innate immunity. Our strategy demonstrates superior antitumor efficacy across multiple tumor models, eliciting robust CD8+ T cell- and NK cell-mediated immunity while suppressing pulmonary metastasis progression. This strategic integration of synthetic lethality with an immunogenic stress response establishes a previously unidentified paradigm for expanding broad applications by cGAS-STING-mediated innate immunity.
    DOI:  https://doi.org/10.1126/sciadv.ado7448
  45. JACS Au. 2026 Feb 23. 6(2): 973-985
    Diterpene Molecular Glue Stabilizes Protein-Protein Interactions of a Disordered Phosphoprotein that Controls Translational Repression.
    Nanami Ogino, Ryoma Masuda, Shota Igaue, Mei Arita, Ami Matsumura, Yumi Ieda, Makoto Muroi, Ken Matsumoto, Reiko Nakagawa, Yusuke Higuchi, Hiroyuki Osada, Minoru Yoshida, Isao Kii, Junko Ohkanda.
      Chemical stabilization of protein-protein interactions involving intrinsically disordered phosphoproteins is an emerging yet challenging problem. Synthetic agents capable of achieving this goal are desirable for advancing understanding of the biological roles of these transient interactions and for developing new therapeutics. 12-Deoxyfusicoccin (12-dFC), a semisynthetic derivative of the phytotoxin fusicoccin A, exhibits significant antitumor activity in animal models while its parent compound and 12-hydroxyfusicoccin (12-hFC) are inactive, although the molecular mechanism underlying this differential activity has remained unclear. Here, through tandem-affinity proteomics, we identified GRB10-interacting GYF protein 2 (GIGYF2), a largely disordered scaffold protein in mRNA translational repression complexes as a 14-3-3 binding partner selectively stabilized by 12-dFC but not 12-hFC. Biochemical analyses revealed that 12-dFC promotes cooperative binding of 14-3-3 to the mode-1 consensus motif KGVpS546IP in GIGYF2, enhancing binding affinity by approximately 50-fold. This stabilization enhanced GIGYF2's translational repressor function, suppressing protein synthesis and inhibiting cell proliferation. We further demonstrated that activation of AMP-activated protein kinase (AMPK), the cellular energy sensor kinase, enhanced 14-3-3 binding to wild-type GIGYF2 but not the S546A mutant, indicating that AMPK mediates S546 phosphorylation. Importantly, S546 phosphorylation increased significantly under starvation conditions, suggesting a GIGYF2-regulated stress-responsive pathway that suppresses protein synthesis to conserve ATP through reversible 14-3-3 binding. These findings demonstrate that 12-dFC is a potent molecular glue stabilizer of 14-3-3 interactions with intrinsically disordered phosphoproteins and offers a robust chemical basis for developing synthetic agents that target 14-3-3-mediated control of metabolic homeostasis.
    Keywords:  14-3-3; AMPK; GIGYF2; intrinsically disordered phosphoproteins; molecular glue; protein−protein interactions; stress responses; translational repression
    DOI:  https://doi.org/10.1021/jacsau.5c01403
  46. Nature. 2026 Feb 25.
    CLCC1 governs ER bilayer equilibration to maintain lipid homeostasis.
    Lingzhi Wu, Jianqin Wang, Yawei Wang, Junhan Yang, Yuanhang Yao, Yonglun Wang, Dong Huang, Yating Hu, Xinxuan Xu, Renqian Wang, Wenjing Du, Yiting Shi, Quan Li, Lu Liu, Yuangang Zhu, Shijie Li, Feng-Jung Chen, Xiuqin Zhang, Xiao Wang, Qiang Guo, Li Xu, Peng Li, Xiao-Wei Chen.
      Orchestration of lipid production, storage and mobilization is vital for cellular and systemic homeostasis1,2. Dysfunctional plasma lipid control represents the major risk factor for cardiometabolic diseases-the leading cause of human mortality3,4. Within the cellular landscape, the endoplasmic reticulum (ER) is the central hub of lipid synthesis and secretion, particularly in metabolically active hepatocytes in the liver or enterocytes in the gut5,6. Initially assembled in the ER lumen, lipid-ferrying lipoproteins necessitate the cross-membrane transfer of both neutral and phospholipids onto the lumenal apolipoprotein B (APOB), in a poorly defined process7-10. Here we show that the ER protein CLCC1 regulates cellular lipid partition and, consequently, systemic lipid homeostasis by participating in trans-bilayer equilibration of phospholipids. CLCC1 partners with the phospholipid scramblase TMEM41B11,12 to recognize imbalanced bilayers and promote lipid scrambling, thereby supporting lipoprotein biogenesis and the subsequent bulk lipid transport. Loss of CLCC1 or TMEM41B leads to the emergence of giant lumenal lipid droplets enclosed by imbalanced ER bilayers and, consequently, accelerated pathogenesis of metabolic-dysfunction-associated liver steatohepatitis. The results reveal that phospholipid scrambling at the ER is essential for establishing a dynamic equilibrium. Considering the requirement of trans-bilayer phospholipid equilibration in numerous biological processes, ranging from catabolic autophagy to viral infection13-16, we anticipate that future work will elucidate a homeostatic control mechanism intrinsic to ER function in lipid biogenesis and distribution.
    DOI:  https://doi.org/10.1038/s41586-026-10161-y
  47. JCI Insight. 2026 Feb 23. pii: e181013. [Epub ahead of print]11(4):
    Ubiquitin ligase Nedd4 regulates the abundance and toxicity of mutant huntingtin.
    Hyunkyung Jeong, Yiyang Qin, Fangke Xu, Katarina Trajkovic, Myung Jong Kim, Nicolas Marotta, Kana Hamada, Ravi Allada, Su Yang, Dimitri Krainc.
      Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the gene encoding huntingtin. Since accumulation of mutant huntingtin (mHtt) leads to dysfunction of numerous cellular pathways and toxicity, reducing levels of the mutant protein represents a key therapeutic objective in HD. We found that ubiquitination of mHtt by E3 ubiquitin ligase Nedd4 promotes clearance of the mutant protein. Knockdown of Nedd4 increased toxicity of mHtt in mouse primary neurons and in a fly model of HD, suggesting the protective role of Nedd4. Importantly, levels of Nedd4 were decreased in mHtt-expressing neurons through impaired mTORC1 activity, suggesting a feedback loop of mHtt accumulation and Nedd4 reduction that leads to accumulation and, ultimately, toxicity of mHtt. These findings suggest that restoring Nedd4 activity may offer a novel therapeutic opportunity for HD.
    Keywords:  Cell biology; Neurodegeneration; Neuroscience
    DOI:  https://doi.org/10.1172/jci.insight.181013
  48. Nat Cell Biol. 2026 Feb 25.
    PML targets and resolves structured protein inclusions to mitigate neurodegeneration.
    Yang Wang, Jia-Xin Zhu, Fei-Xia Zhan, Yinfeng Guo, Yuchen Xia, Jiaqi Liu, Peng Dai, Ying Hu, Yan-Hao Chen, Xing-Hua Luan, Xi-Ya Shen, Yu-Wen Cao, Xiaojun Huang, Xin Zhang, Li Cao, Steven X Hou.
      Intranuclear inclusions are defining features of many neurodegenerative diseases, yet their assembly mechanisms and pathological roles remain poorly understood. Here, we investigate polyglycine (polyG) inclusions in neuronal intranuclear inclusion disease (NIID) and show that they recruit intrinsically disordered proteins to form stratified, immobile condensates that disrupt nuclear protein quality control and DNA damage repair. Leveraging their ordered and stepwise assembly, we identify promyelocytic leukaemia protein (PML) as a key factor that actively recognizes and eliminates polyG inclusions through chaperone-mediated disaggregation and proteasome-dependent degradation. Engineered PML variants selectively clear both nuclear and cytoplasmic aggregates, including polyG, polyGA, polyQ, TDP-43 and SOD1. Systemic PML delivery alleviates cognitive and motor deficits in mouse models of NIID and TDP-43 proteinopathy. These findings uncover a conserved spatial organization of nuclear inclusions and establish PML as a therapeutic effector for neurodegenerative diseases linked to protein aggregation.
    DOI:  https://doi.org/10.1038/s41556-026-01894-z
  49. Nat Commun. 2026 Feb 23.
    Membrane-embedded polar residues target membrane proteins for degradation by the quality control protease FtsH.
    Michal Chai-Danino, Noy Ravensary-Modin, Vasiliy I Vladimirov, Tetiana Onyshchuk, Martin Plöhn, Alon B D Barshap, Aseel Bsoul, Hadas Peled-Zehavi, Nir Fluman.
      The biogenesis of membrane proteins (MPs) is inherently error-prone, and is therefore monitored by quality control mechanisms that remove faulty MPs. A key challenge for this surveillance is to recognize misfolded MPs, but how this is achieved remains poorly understood. Here we reveal how FtsH, the main MP quality control protease in Escherichia coli, specifically targets faulty MPs. By analyzing the in vivo degradation of two substrates, we show that lipid-facing polar residues trigger FtsH-mediated degradation. In folded MPs, such polar residues are usually buried in the protein core. Their exposure to the membrane can therefore signal misfolding and promote degradation. Strikingly, lipid-facing polar residues can even trigger degradation of a folded protein, and do not require the extended cytosolic regions typically needed for other FtsH substrates. Recognition depends on the FtsH transmembrane domain and on specific polar residues within it. Thus, sensing misfolding within the membrane helps maintain the integrity of the membrane proteome.
    DOI:  https://doi.org/10.1038/s41467-026-69829-8
  50. Clin Cancer Res. 2026 Feb 23.
    A novel potent and selective GCN2 inhibitor, APL-4098, has anti-leukemic activity through dysregulation of mitochondrial function.
    Monica Román-Trufero, Gavin Whitlock, Claire Seydoux, Kevin Blighe, Bianca Perfler, Armin Zebisch, Richard Butt, Matthew J Fuchter, Holger W Auner, Nadine Clemo.
       PURPOSE: GCN2, one of the four kinases that activate the Integrated Stress Response to maintain proteostasis, has been shown to support cancer cell growth and survival in multiple preclinical cancer models. Acute myeloid leukemia (AML) is an aggressive hematological malignancy with dismal prognosis and high relapse rates that is marked by a dependency on finely tuned proteostasis. Here, we investigate the anti-leukemic potential of a new small-molecule GCN2 inhibitor, APL-4098.
    EXPERIMENTAL DESIGN: selectivity and potency of APL-4098 were assessed using biochemical and cell-based assays. Anti-leukemic effects were evaluated ex vivo in primary patient-derived AML and in vivo using cell line-derived (CDX) and patient-derived (PDX) xenograft models. Synergy of APL-4098 and venetoclax was examined in the PDX. RNA sequencing and metabolic assays were used to explore APL-4098 mechanism of action.
    RESULTS: APL-4098 exhibited nanomolar-range potency against and high selectivity for GCN2. APL-4098 showed strong anti-proliferative activity ex vivo across two independent cohorts of primary AML patient cells, including cytotoxic effects on the leukemia stem cells (LSCs) and in vivo, achieving 98% tumor growth inhibition in an AML CDX. In a PDX, APL-4098 preferentially depleted the LSC-enriched compartment and, in combination with venetoclax, reduced leukemia burden by over 98%. Transcriptomic and metabolic analyses revealed APL-4098 compromises mitochondrial function and elicits the mitochondrial unfolded protein response.
    CONCLUSIONS: APL-4098 is a novel, potent and selective GCN2 inhibitor with strong preclinical efficacy against AML cells, including LSCs. Our findings support APL-4098 as a promising candidate for AML treatment.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-25-1444
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