bims-nenemi 2025-06-01 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2025–06–01
fifteen papers selected by
Marco Tigano, Thomas Jefferson University

Deciphering the multifaceted role of double-stranded RNA sensor protein kinase R: pathophysiological function beyond the antiviral response.
Mitochondria-Nuclear Crosstalk: Orchestrating mtDNA Maintenance.
Radiation Exposure Induced Blood-Brain Barrier Injury via Mitochondria-Mediated Sterile Inflammation.
Immunoproteasome-specific subunit alterations as a potential therapeutic target for mitochondriopathies.
Arginase 1 drives mitochondrial cristae remodeling and PANoptosis in ischemia/hypoxia-induced vascular dysfunction.
Mitochondrial Antiviral Signaling Protein Activation by Retinoic Acid-Inducible Gene I Agonist Triggers Potent Antiviral Defense in Umbilical Cord Mesenchymal Stromal Cells Without Compromising Mitochondrial Function.
In vivo structure profiling reveals human cytosolic and mitochondrial tRNA structurome and interactome in response to stress.
Tipping the balance: innate and adaptive immunity in mitochondrial disease.
Cell death and iron deposition in the liver in two murine models of acute radiation syndrome.
Mitochondrial clonal mosaicism encodes a biphasic molecular clock of aging.
Deep learning-driven automated mitochondrial segmentation for analysis of complex transmission electron microscopy images.
Major Traumatic Injury and Exposure to Mitochondrial-Derived Damage-Associated Molecular Patterns Promotes Neutrophil Survival Accompanied by Stabilisation of the Anti-Apoptotic Protein Mcl-1.
P5CS deacetylation mediated by SIRT2 facilitates tumor growth by enhancing mitochondrial respiration in hepatocellular carcinoma.
Lysine acetylation modulates s-OPA1 GTPase activity and oligomerization in mitochondrial membrane remodeling.
Inhibition of mitochondrial protein import and proteostasis by a pro-apoptotic lipid.

RNA Biol. 2025 Dec;22(1): 1-14

Deciphering the multifaceted role of double-stranded RNA sensor protein kinase R: pathophysiological function beyond the antiviral response.

Jiyoon Chung, Yerim Lee, Jimin Yoon, Yoosik Kim.

  Protein kinase R (PKR) is a serine/threonine kinase that recognizes double-stranded RNAs (dsRNAs) to initiate innate immune signalling during viral infection. PKR dimerizes on long dsRNAs and undergoes autophosphorylation. Phosphorylated/Activated PKR then catalyses the phosphorylation of numerous substrates to control global translation, inflammatory response, and cell signalling pathways. While primarily known for its antiviral role, emerging evidence suggests that PKR can play multifaceted roles in uninfected cells by interacting with cellular dsRNAs and protein regulators. The misactivation of PKR in uninfected cells is associated with many degenerative and inflammatory diseases. Even in healthy cells, PKR can affect gene expression by controlling mRNA splicing and gene-specific translation under stress. In addition, PKR can modulate cell cycle progression and promote cellular differentiation in several tissue types. This review explores PKR function in various pathological and physiological contexts in the absence of viral stimuli. By elucidating these diverse functions, we aim to highlight the perspectives in cellular dsRNA research and the therapeutic implications of targeting PKR, stimulating further research into this versatile and essential RNA-dependent kinase.

Keywords:  Protein kinase R (PKR); cell cycle; differentiation; gene regulation; inflammatory diseases; splicing

DOI:  https://doi.org/10.1080/15476286.2025.2512610
Environ Mol Mutagen. 2025 May 26.

Mitochondria-Nuclear Crosstalk: Orchestrating mtDNA Maintenance.

Ghazal Darfarin, Janice Pluth.

  The mitochondria (mt) and nucleus engage in a dynamic bidirectional communication to maintain cellular homeostasis, regulating energy production, stress response, and cell fate. Anterograde signaling directs mt function, while retrograde signaling conveys metabolic and stress-related changes from mt to the nucleus. Central to this crosstalk is mitochondrial DNA (mtDNA), which encodes key oxidative phosphorylation components. MtDNA integrity is preserved through quality control mechanisms, including fusion and fission dynamics, mitophagy, and nuclear-encoded DNA repair. Disruption in these pathways contributes to mt dysfunction, oxidative stress, and genetic instability-hallmarks of aging and diseases. Additionally, redox signaling and NAD+ homeostasis integrate mt and nuclear responses, modulating transcriptional programs that support mt biogenesis and stress adaptation. This review explores the molecular mechanisms coordinating mito-nuclear interactions, emphasizing their role in maintaining mtDNA integrity and cellular equilibrium. Understanding these processes provides insights into how mt dysfunction drives aging and disease, paving the way for targeted therapeutic strategies.

Keywords:  anterograde and retrograde signaling; cellular homeostasis; mitochondrial biogenesis; mitochondrial dynamics; mtDNA maintenance, mitochondrial‐nuclear communication; redox signaling

DOI:  https://doi.org/10.1002/em.70013
Adv Sci (Weinh). 2025 May 28. e02356

Radiation Exposure Induced Blood-Brain Barrier Injury via Mitochondria-Mediated Sterile Inflammation.

Peng Wang, Jiayue Liu, Min Zhang, Juan Yang, Peihan Lian, Xiu Cheng, Jianhua Qin.

  Radiation-induced brain injury (RIBI) is caused by exposure to high doses of ionizing radiation and characterized by severe cognitive dysfunction and brain necrosis. However, the pathogenesis of RIBI is not fully understood, and no effective intervention is available. This work describes a blood-brain barrier (BBB) microphysiological system (MPS), that allowed to explore the responses of BBB and distinct brain cells to radiation exposure. Following acute exposure to radiation of X-ray or γ-ray, characteristic RIBI-associated pathological responses are observed, including BBB compromise, DNA breaks, inhibited cell proliferation, cell hypertrophy, and proinflammatory cytokine release. Among the distinctive types of cells, brain endothelial cells show the highest radiosensitivity as compared to other cells in the MPS. Intriguingly, X-ray and γ-ray radiation consistently induce prominent sterile inflammation responses, especially type I interferon response, in the BBB MPS. These responses are mediated by radiation-induced mitochondrial DNA release and subsequent activation of cGAS-STING signaling pathway. Furthermore, it is found abrocitinib (JAK1 inhibitor) and idebenone (mitochondrial protectant) can attenuate radiation-induced inflammation and ameliorate injuries in the BBB MPS. These findings reveal the involvement of mitochondria-mediated sterile inflammation in RIBI pathogenesis, identifying mitochondria as a potential target for new radioprotective measures.

Keywords:  blood–brain barrier; microphysiological system; mitochondria; radiation‐induced brain injury; sterile inflammation

DOI:  https://doi.org/10.1002/advs.202502356
J Mol Biol. 2025 May 23. pii: S0022-2836(25)00295-5. [Epub ahead of print] 169229

Immunoproteasome-specific subunit alterations as a potential therapeutic target for mitochondriopathies.

Agata Kodroń, Konrad Kowalski, Ben Hur Marins Mussulini, Cem Hazir, Mayra A Borrero-Landazabal, Sonia Ngati, Michal Wasilewski, Agnieszka Chacinska.

  Mitochondria are double-membrane organelles crucial for eukaryotic cells due to their role in ATP production by oxidative phosphorylation (OXPHOS). Most of the ∼1500 proteins of the mitochondrial proteome are encoded in the nuclear genome, synthesized in the cytosol, and actively transported into mitochondria. The proteasome, a major cellular proteolytic machinery, plays an important role in the quality control of their transport by degradation of inefficiently imported mitochondrial proteins in the cytosol. Proteasome inhibition by bortezomib was described as a strategy to alleviate deficiencies stemming from an inefficient import of proteins into the mitochondria. Notably, an impairment of the respiratory complexes was shown to induce a rearrangement of the proteasome composition to incorporate some of the immunoproteasome catalytic subunits, such as PSMB9. In this study, we demonstrated that targeting immunoproteasome inhibited degradation, and thus restored the abundance of inefficiently imported respiratory complex IV proteins in the patient derived fibroblasts. Furthermore, we demonstrated that the immunoproteasome-specific inhibitors displayed a decreased toxicity compared to bortezomib. Our results indicate that immunoproteasome subunits present a novel molecular target for future therapies of mitochondriopathies.

Keywords:  PSMB9; immunoproteasome inhibitors; immunoproteasome subunits; mitochondria; mitochondrial diseases

DOI:  https://doi.org/10.1016/j.jmb.2025.169229
Signal Transduct Target Ther. 2025 May 28. 10(1): 167

Arginase 1 drives mitochondrial cristae remodeling and PANoptosis in ischemia/hypoxia-induced vascular dysfunction.

Han She, Jie Zheng, Guozhi Zhao, Yunxia Du, Lei Tan, Zhe-Sheng Chen, Yinyu Wu, Yong Li, Yiyan Liu, Yue Sun, Yi Hu, Deyu Zuo, Qingxiang Mao, Liangming Liu, Tao Li.

Ischemic/hypoxic injury significantly damages vascular function, detrimentally impacting patient outcomes. Changes in mitochondrial structure and function are closely associated with ischemia/hypoxia-induced vascular dysfunction. The mechanism of this process remains elusive. Using rat models of ischemia and hypoxic vascular smooth muscle cells (VSMCs), we combined transmission electron microscopy, super-resolution microscopy, and metabolic analysis to analyze the structure and function change of mitochondrial cristae. Multi-omics approaches revealed arginase 1 (Arg1) upregulation in ischemic VSMCs, confirmed by in vivo and in vitro knockout models showing Arg1's protective effects on mitochondrial cristae, mitochondrial and vascular function, and limited the release of mtDNA. Mechanistically, Arg1 interacting with Mic10 led to mitochondrial cristae remodeling, together with hypoxia-induced VDAC1 lactylation resulting in the opening of MPTP and release of mtDNA of VSMCs. The released mtDNA led to PANoptosis of VSMCs via activation of the cGAS-STING pathway. ChIP-qPCR results demonstrated that lactate-mediated Arg1 up-regulation was due to H3K18la upregulation. VSMCs targeted nano-material PLGA-PEI-siRNA@PM-α-SMA (NP-siArg1) significantly improved vascular dysfunction. This study uncovers a new mechanism of vascular dysfunction following ischemic/hypoxic injury: a damaging positive feedback loop mediated by lactate-regulated Arg1 expression between the nucleus and mitochondria, leading to mitochondria cristae disorder and mtDNA release, culminating in VSMCs PANoptosis. Targeting VSMCs Arg1 inhibition offers a potential therapeutic strategy to alleviate ischemia/hypoxia-induced vascular impairments.

DOI: https://doi.org/10.1038/s41392-025-02255-2
Int J Mol Sci. 2025 May 14. pii: 4686. [Epub ahead of print]26(10):

Mitochondrial Antiviral Signaling Protein Activation by Retinoic Acid-Inducible Gene I Agonist Triggers Potent Antiviral Defense in Umbilical Cord Mesenchymal Stromal Cells Without Compromising Mitochondrial Function.

Sebastián Castillo-Galán, Felipe Grünenwald, Yessia Hidalgo, J César Cárdenas, Maria Ignacia Cadiz, Francisca Alcayaga-Miranda, Maroun Khoury, Jimena Cuenca.

  Mesenchymal stromal cells (MSCs) represent a promising therapeutic approach in viral infection management. However, their interaction with viruses remains poorly understood. MSCs can support antiviral immune responses and act as viral reservoirs, potentially compromising their therapeutic potential. Innate immune system recognition of viral pathogens involves pattern recognition receptors (PRRs), including RIG-I-like receptors (RLRs), which activate mitochondrial antiviral signaling protein (MAVS). MAVS triggers antiviral pathways like IRF3 and NF-κB, leading to interferon (IFN) production and pro-inflammatory responses. This study explores the antiviral response in umbilical cord-derived MSCs (UC-MSCs) through targeted stimulation with influenza A virus-derived 5'triphosphate-RNA (3p-hpRNA), a RIG-I agonist. By investigating MAVS activation, we provide mechanistic insights into the immune response at the molecular level. Our findings reveal that 3p-hpRNA stimulation triggers immune activation of the IRF3 and NF-κB pathways through MAVS. Subsequently, this leads to the induction of type I and III IFNs, IFN-stimulated genes (ISGs), and pro-inflammatory cytokines. Critically, this immune activation occurs without compromising mitochondrial integrity. UC-MSCs retain their capacity for mitochondrial transfer to recipient cells. These results highlight the adaptability of UC-MSCs, offering a nuanced understanding of immune responses balancing activation with metabolic integrity. Finally, our research provides mechanistic evidence for MSC-based interventions against viral infections.

Keywords:  MAVS; RIG-I agonist; cellular and mitochondrial function; mesenchymal stromal cells; viral RNA

DOI:  https://doi.org/10.3390/ijms26104686
Nat Commun. 2025 May 30. 16(1): 5041

In vivo structure profiling reveals human cytosolic and mitochondrial tRNA structurome and interactome in response to stress.

Noah Peña, Yichen Hou, Christopher P Watkins, Sihao Huang, Wen Zhang, Christopher D Katanski, Tao Pan.

Transfer RNA (tRNA) is the most abundant cellular RNA family in terms of copy numbers. It not only folds into defined structures but also has complex cellular interaction networks involving aminoacyl-tRNA synthetases, translation factors, and ribosomes. The human tRNAome is comprised of chromosomal-encoded tRNAs with a large sequence diversity and mitochondrial-encoded tRNAs with A/U-rich sequences and noncanonical tertiary interactions. How tRNA folding and interactions in a eukaryotic cell respond to stress is poorly understood. Here, we develop DM-DMS-MaPseq, which utilizes in vivo dimethyl-sulfate (DMS) chemical probing and mutational profiling (MaP) coupled with demethylase (DM) treatment in transcriptome-wide tRNA sequencing to profile structures and the cellular interactions of human chromosomal and mitochondrial-encoded tRNAs. We found that tRNAs maintain stable structures in vivo, but the in vivo DMS profiles are vastly different from those in vitro, which can be explained by their interactions with cellular proteins and the ribosome. We also identify cytosolic and mitochondrial tRNA structure and interaction changes upon arsenite treatment, a type of oxidative stress that induces translational reprogramming, which is consistent with global translation repression in both compartments. Our results reveal variations of tRNA structurome and dynamic interactome that have functional consequences in translational regulation.

DOI: https://doi.org/10.1038/s41467-025-59435-5
Curr Opin Immunol. 2025 May 26. pii: S0952-7915(25)00042-1. [Epub ahead of print]95 102566

Tipping the balance: innate and adaptive immunity in mitochondrial disease.

Andrew Phillip West, Peter J McGuire.

Mitochondrial diseases (MtD) provide a unique window into the complex interplay between metabolism and immune function. These rare disorders, caused by defects in oxidative phosphorylation, result in bioenergetic deficiencies that disrupt multiple organ systems. While traditionally studied for their metabolic impact, MtD also profoundly affect the immune system, altering both innate and adaptive responses. This review explores how mitochondrial dysfunction shapes immune dysregulation, influencing thymocyte maturation, regulatory T cells, and B cell function while also driving innate immune activation through mitochondrial DNA instability and type I interferon signaling. Additionally, MtD highlight an emerging overlap between inborn errors of metabolism and inborn errors of immunity, revealing shared pathways that connect mitochondrial dysfunction to immune deficiencies and inflammatory disease. Studying MtD not only advances our understanding of immunometabolism but also provides critical insights into more common inflammatory and autoimmune conditions, offering potential therapeutic targets that extend beyond rare mitochondrial disorders.

DOI: https://doi.org/10.1016/j.coi.2025.102566
PLoS One. 2025 ;20(5): e0324361

Cell death and iron deposition in the liver in two murine models of acute radiation syndrome.

Dmitry T Bradfield, John E Slaven, W Bradley Rittase, Milan Rusnak, Aviva J Symes, Grace V Brehm, Jeannie M Muir, Sang-Ho Lee, Joseph A Anderson, Regina M Day.

Different tissues exhibit differential sensitivity to ionizing radiation exposure and display different time courses of pathologies that are not well understood. Ionizing radiation causes hemolysis of red blood cells, causing the release of iron that is taken up by a variety of tissues. The increased iron has been associated with altered expression of iron binding proteins and, in some cases, markers of ferroptosis. Here we examined the time course of iron uptake in murine liver following 60Co total body irradiation (TBI) at 7.9 Gy (LD90/30) and 6.85 Gy (LD0/30). 7.9 Gy induced hydropic degeneration, micro-vesicular steatosis, and inflammatory cell infiltration, whereas at 6.85 Gy the livers displayed only inflammatory cell infiltration. In both cases, iron levels increased significantly, maximal at ~21 days post-TBI. Increased iron was associated with altered expression of ferritin, heme oxygenase, an enzyme required for iron recycling, and the pro-inflammatory cytokine serum amyloid A, maximal ~16-21 days. 7.9 Gy induced liver caspase-3 activation consistent with apoptosis. In contrast, 6.85 Gy induced markers of ferroptosis but not of apoptosis. Our data indicate that iron is deposited in the liver at a delayed time point following radiation and is associated with increased ferritin, HO-1, and inflammatory cytokine production.

DOI: https://doi.org/10.1371/journal.pone.0324361
Nat Aging. 2025 May 27.

Mitochondrial clonal mosaicism encodes a biphasic molecular clock of aging.

Zhenguo Wang, Zhe Li, Hongyu Liu, Chenghua Yang, Xin Li.

Mitochondria rapidly accumulate mutations throughout a lifetime, potentially acting as a molecular clock for aging and disease. We profiled mitochondrial RNA across 47 human tissues from 838 individuals, revealing rapid development of clonal mosaicism with two distinct tissue-specific aging signatures. Tissues with constant cellular turnover such as the gastrointestinal tract or skin exhibit accelerated accumulation of sporadic mutations and clonal expansions, implicating increased susceptibility to age-related tumorigenesis and dysfunction. By contrast, post-mitotic tissues, such as the heart and brain, accumulate mutations at deterministic hotspots (tissue-specific, recurrently mutated sites), reflecting the cumulative burden of high energy demand and mitochondrial turnover independent of cell division. These findings support a biphasic model of the mitochondrial clock: stochastic clonal expansion of sporadic replication errors in proliferative tissues, versus age-dependent heteroplasmy increases at hotspots in high-metabolic tissues. This mutational landscape provides a map of tissue-specific vulnerabilities during aging and offers potential therapeutic targets.

DOI: https://doi.org/10.1038/s43587-025-00890-6
Sci Rep. 2025 May 30. 15(1): 19076

Deep learning-driven automated mitochondrial segmentation for analysis of complex transmission electron microscopy images.

Chan Jang, Hojun Lee, Jaejun Yoo, Haejin Yoon.

  Mitochondria are central to cellular energy production and regulation, with their morphology tightly linked to functional performance. Precise analysis of mitochondrial ultrastructure is crucial for understanding cellular bioenergetics and pathology. While transmission electron microscopy (TEM) remains the gold standard for such analyses, traditional manual segmentation methods are time-consuming and prone to error. In this study, we introduce a novel deep learning framework that combines probabilistic interactive segmentation with automated quantification of mitochondrial morphology. Leveraging uncertainty analysis and real-time user feedback, the model achieves comparable segmentation accuracy while reducing analysis time by 90% compared to manual methods. Evaluated on both benchmark Lucchi++ datasets and real-world TEM images of mouse skeletal muscle, the pipeline not only improved efficiency but also identified key pathological differences in mitochondrial morphology between wild-type and mdx mouse models of Duchenne muscular dystrophy. This automated approach offers a powerful, scalable tool for mitochondrial analysis, enabling high-throughput and reproducible insights into cellular function and disease mechanisms.

Keywords:  Automated quantification; Deep learning segmentation; Interactive segmentation; Mitochondrial morphology; Transmission electron microscopy imaging; Uncertainty analysis

DOI:  https://doi.org/10.1038/s41598-025-03311-1
Cells. 2025 05 21. pii: 754. [Epub ahead of print]14(10):

Major Traumatic Injury and Exposure to Mitochondrial-Derived Damage-Associated Molecular Patterns Promotes Neutrophil Survival Accompanied by Stabilisation of the Anti-Apoptotic Protein Mcl-1.

Thomas Nicholson, Michael Macleod, Antonio Belli, Janet M Lord, Jon Hazeldine.

  Traumatic injury leads to an extension of the half-life of circulating neutrophils. However, how quickly neutrophil apoptosis is delayed post-injury is currently unknown, as are the underlying mechanisms and factors that promote this extension of lifespan. During the ultra-early (≤1 h) and acute (4-12 and 48-72 h) post-injury phases, we collected blood samples from 73 adult trauma patients. Following ex vivo culture, neutrophil apoptosis was measured, alongside caspase-3 activation and expression of the anti-apoptotic protein Mcl-1. To identify factors that may promote neutrophil survival post-trauma, neutrophils from healthy controls (HCs) were cultured with mitochondrial-derived damage-associated molecular patterns (mtDAMPs) or mitochondrial DNA (mtDNA). Accompanied by reduced mitochondrial membrane depolarisation, delayed Mcl-1 turnover, and reduced caspase-3 activation, the ex vivo lifespan of neutrophils from trauma patients was significantly enhanced in a protein synthesis-independent manner within minutes to hours after injury. Neutrophils from HCs exhibited delayed apoptosis when cultured in media supplemented with trauma patient serum, which occurred alongside stabilisation of Mcl-1. Culturing HCs neutrophils with mtDAMPs or mtDNA significantly delayed apoptosis rates, promoted stabilisation of Mcl-1, and reduced caspase-3 activation. The release of mtDAMPs from damaged tissue may drive post-trauma immune dysregulation by promoting the survival of dysfunctional neutrophils.

Keywords:  apoptosis; critical care; injury; mitochondrial-derived damage-associated molecular patterns; neutrophils; trauma

DOI:  https://doi.org/10.3390/cells14100754
Oncogene. 2025 May 27.

P5CS deacetylation mediated by SIRT2 facilitates tumor growth by enhancing mitochondrial respiration in hepatocellular carcinoma.

Xiaofang Geng, Mengyao Li, Lu Zhang, Yihan Cai, Xin Chen, Xiayue Mu, Jie Wang, Bowen Liu.

Cancer cells typically exhibit enhanced mitochondrial metabolism to fulfill their energy and biosynthetic demands for growth. The mitochondrial response to fluctuations in cellular energy demand is essential for cellular adaptation and proper organ function. The mitochondrial delta-1-pyrroline-5-carboxylate synthase (P5CS) encoded by the ALDH18A1 gene, the key enzyme for proline synthesis, is frequently up-regulated during tumor development. However, the regulatory mechanisms governing P5CS activity in the occurrence and development of hepatocellular carcinoma (HCC) remain largely unknown. In this study, we observe that P5CS is highly expressed in HCC tissues, and elevated levels of P5CS expression are associated with poor prognosis in HCC patients. Notably, the knockdown of P5CS inhibits the proliferation, migratory and invasive capabilities of HCC cells by reducing mitochondrial respiration. Furthermore, we demonstrate that SIRT2 interacts with P5CS and mediates the deacetylation of P5CS at lysines K311 and K347, thereby activating its enzymatic activity. Activated P5CS significantly enhances mitochondrial respiration, which supports the proliferation and tumorigenesis of HCC cells. In addition, SIRT2 knockdown inhibits the proliferation, migratory and invasive capabilities of HCC cells. These observations suggest that SIRT2-mediated P5CS deacetylation is a crucial signaling event through which cancer cells sustain mitochondrial respiration and promote HCC progression. This finding offers the potential for targeting SIRT2-mediated P5CS deacetylation as a therapeutic strategy for HCC.

DOI: https://doi.org/10.1038/s41388-025-03456-3
Protein Sci. 2025 Jun;34(6): e70179

Lysine acetylation modulates s-OPA1 GTPase activity and oligomerization in mitochondrial membrane remodeling.

Javaid Jabbar, Bakht Afroze, Naomi X Y Ling, Jonathan S Oakhill, Isabelle Rouiller.

  Mitochondrial dynamics are regulated by coordinated fission and fusion events that rely on key proteins and lipids organized spatially within the mitochondria. The dynamin-related GTPase Optic Atrophy 1 (OPA1) is essential for inner mitochondrial membrane fusion and cristae structure maintenance. While post-translational modifications, particularly lysine acetylation, are emerging as critical regulators of mitochondrial protein function, their impact on OPA1 remains poorly characterized. In this study, we explored the effects of lysine acetylation on the short form of OPA1 (s-OPA1) using acetylation and deacetylation mimetic mutations. Through a combination of in silico analyses and functional assays, we identified lysine residues in s-OPA1 that are conserved across species and significantly influence protein stability, GTPase activity, and oligomeric assembly upon acetylation or deacetylation. Our findings reveal that acetylation at K328 and deacetylation at K342 within the G domain enhance the GTPase activity of s-OPA1 upon lipid membrane binding, whereas deacetylation at K772 abolishes membrane binding-induced GTPase activity. Negative-stain transmission electron microscopy indicated that while lysine acetylation does not alter the ability of s-OPA1 to bind and tubulate liposomes, it significantly impacts higher-order filament formation. These findings provide novel insights into how acetylation modulates s-OPA1 function, highlighting a potential mechanism for post-translational regulation of mitochondrial dynamics. Our study contributes to the understanding of how molecular changes influence broader cellular processes, with implications for mitochondrial function and related disorders.

Keywords:  GTPase activity; OPA1; acetylation; membrane remodeling; oligomeric assembly

DOI:  https://doi.org/10.1002/pro.70179
Elife. 2025 May 30. pii: RP93621. [Epub ahead of print]13

Inhibition of mitochondrial protein import and proteostasis by a pro-apoptotic lipid.

Josep Fita-Torró, José Luis Garrido-Huarte, Lucía López-Gil, Agnès H Michel, Benoit Kornmann, Amparo Pascual-Ahuir, Markus Proft.

  Mitochondria-mediated cell death is critically regulated by bioactive lipids derived from sphingolipid metabolism. The lipid aldehyde trans-2-hexadecenal (t-2-hex) induces mitochondrial dysfunction from yeast to humans. Here, we apply unbiased transcriptomic, functional genomics, and chemoproteomic approaches in the yeast model to uncover the principal mechanisms and biological targets underlying this lipid-induced mitochondrial inhibition. We find that loss of Hfd1 fatty aldehyde dehydrogenase function efficiently sensitizes cells for t-2-hex inhibition and apoptotic cell death. Excess of t-2-hex causes a profound transcriptomic response with characteristic hallmarks of impaired mitochondrial protein import, like activation of mitochondrial and cytosolic chaperones or proteasomal function and severe repression of translation. We confirm that t-2-hex stress induces rapid accumulation of mitochondrial pre-proteins and protein aggregates and subsequent activation of Hsf1- and Rpn4-dependent gene expression. By saturated transposon mutagenesis, we find that t-2-hex tolerance requires an efficient heat shock response and specific mitochondrial and ER functions and that mutations in ribosome, protein, and amino acid biogenesis are beneficial upon t-2-hex stress. We further show that genetic and pharmacological inhibition of protein translation causes t-2-hex resistance, indicating that loss of proteostasis is the predominant consequence of the pro-apoptotic lipid. Several TOM subunits, including the central Tom40 channel, are lipidated by t-2-hex in vitro and mutation of accessory subunits Tom20 or Tom70 confers t-2-hex tolerance. Moreover, the Hfd1 gene dose determines the strength of t-2-hex mediated inhibition of mitochondrial protein import, and Hfd1 co-purifies with Tom70. Our results indicate that the transport of mitochondrial precursor proteins through the outer mitochondrial membrane is sensitively inhibited by the pro-apoptotic lipid and thus represents a hotspot for pro- and anti-apoptotic signaling.

Keywords:  S. cerevisiae; apoptosis; biochemistry; chemical biology; genetics; genomics; lipid signaling; mitochondrial protein import; proteostasis; sphingolipid metabolism; yeast

DOI:  https://doi.org/10.7554/eLife.93621