bims-toxgon 2025-07-13 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2025–07–13
33 papers selected by
Lakesh Kumar, BITS Pilani

The apicoplast localized isocitrate dehydrogenase is needed for de novo fatty acid synthesis in the apicoplast of Toxoplasma gondii.
Furan derivative affects the cell division and mitochondrial integrity of tachyzoites of Toxoplasma gondii.
The Plasmodium falciparum homolog of Vps16 interacts with the core members of the Vps-C tethering complex.
Advances of SIRT4 in cancer metabolism and therapy.
Development and optimization of an ELISA method to detect Toxoplasma gondii oocyst infection in cats.
PLGA nanoparticles as an efficient carrier in Toxoplasma GAP45: a more effective vaccine against acute toxoplasmosis than traditional ones.
High Levels of Protection Against Acute and Chronic Toxoplasmosis in Institute of Cancer Research Mice with a Novel Low-Temperature Inactivated Toxoplasma gondii Candidate Vaccine Adjuvanted with HA201/HA203.
Sirtuin 3 as a promising target in disease therapy: Model action and drug discovery.
The latent threat of Toxoplasma gondii infection for neurologic disease.
The development and excretion of Toxoplasma gondii oocyst manipulate the gut microbiota in its definitive host.
The ribosomal RNA transcription landscapes of Plasmodium falciparum and related apicomplexan parasites.
Acetyl-CoA subcellular compartmentalization regulates T cell adaptation.
Contribution of histone deacetylases (HDACs) to the regulation of histone and non-histone proteins: implications for fibrotic diseases.
Dynamic acetylation of a conserved lysine impacts glycerol kinase activity and abundance in the haloarchaeon Haloferax volcanii.
Mechanisms of host exploitation by a microsporidian parasite.
Dual single-cell and bulk RNA sequencing reveal transcriptional profiles underlying heterogenous host-parasite interactions in human peripheral blood mononuclear cells.
Beyond Histones: Unveiling the Functional Roles of Protein Acetylation in Prokaryotes and Eukaryotes.
Diverse Subpopulations of Reactive Astrocytes Following Chronic Toxoplasma Infection.
Activation of the impaired NAMPT/SIRT7/SOD2 axis restores alveolar progenitor cell homeostasis in idiopathic pulmonary fibrosis and reverses pulmonary fibrosis in mice.
Comparative evaluation of live attenuated and killed tachyzoites as vaccine candidates for toxoplasmosis.
DCAF16-Based Covalent Molecular Glues for Targeted Protein Degradation of Histone Deacetylases.
Identification of Cytosol-Facing Organelle Membrane-Proximal Proteins via Proximity-Dependent Biotinylation.
Ulk1(S555) inhibition alters nutrient stress response by prioritizing amino acid metabolism.
Annexin A1 is crucial during Toxoplasma gondii infection promoting the modulation of inflammation and intestinal and central nervous system barrier functions.
AMPK alters proteasome phosphorylation status and prevents persistent proteasome condensates.
Essential role for PfHSP40 in asexual replication and thermotolerance of malaria parasites.
Loss of serine/threonine protein phosphatase 6 severely impairs sexual stage development in malaria parasite Plasmodium berghei.
Targeting neuroblastoma with hydroxamic acid based HDAC1 and HDAC2 inhibitors: Insights from in vitro and in vivo studies.
Chemical perturbations impacting histone acetylation govern colorectal cancer differentiation.
Histone deacetylase 6: A new player in oxidative stress‑associated disorders and cancers (Review).
The small GTPase ARF6 regulates sphingolipid homeostasis and supports proliferation in acute myeloid leukemia.
Sirtuin 2 regulates NOD-like receptor protein 3/nuclear factor kappa B axis to promote cartilage repair in osteoarthritis.
Post-translational modifications of cancer immune checkpoints: mechanisms and therapeutic strategies.

Front Cell Infect Microbiol. 2025 ;15 1542122

The apicoplast localized isocitrate dehydrogenase is needed for de novo fatty acid synthesis in the apicoplast of Toxoplasma gondii.

Ke Pan, Ao Zeng, Xiaodie Ruan, Xinyu Mo, Bang Shen, Junlong Zhao, Yanqin Zhou.

  Toxoplasma gondii (T. gondii), an apicomplexan parasite, infects a wide range of warm-blooded animals and poses significant risks to human health. The fatty acid synthesis II (FASII) pathway in the apicoplast, which is the major source of fatty acids in parasites, is considered a potential drug target. The apicoplast also harbors some enzymes of central carbon metabolism, which are crucial for its survival, but their biological roles remain unclear. In this study, we focused on apicoplast-localized isocitrate dehydrogenase 1 (ICDH1) and deleted it using CRISPR-Cas9 technology. The Δicdh1 mutant tachyzoites displayed markedly impaired growth kinetics, with further suppression under serum-deprived conditions. However, this deletion did not affect the viability or virulence of the Δicdh1 mutant in mice. NADPH, a product of ICDH1-mediated decarboxylation of isocitrate, is an essential cofactor for fatty acid synthesis. Using ¹³C6 glucose as a metabolic carbon source, we showed that the mutant strains had reduced incorporation of glucose-derived carbons into medium-chain length fatty acids (C14:0 and C16:0). Additionally, the growth of the mutant was partially restored by supplementation with exogenous C14:0 and C16:0 fatty acids. These results indicate that ICDH1 deletion affects the FASII pathway and parasite growth. Consistent with previous studies, this study confirms that T. gondii has metabolic flexibility in the apicoplast that allows it to acquire fatty acids through various pathways.

Keywords:  FAS 2; Toxoplasma gondii; apicoplast; isocitrate dehydrogensase; metabolism

DOI:  https://doi.org/10.3389/fcimb.2025.1542122
Exp Parasitol. 2025 Jul 08. pii: S0014-4894(25)00093-1. [Epub ahead of print] 108988

Furan derivative affects the cell division and mitochondrial integrity of tachyzoites of Toxoplasma gondii.

Juliana de Araujo Portes, Anushree Achari, Jayaraman Vinayagam, Pinaki Bhattacharjee, Sourav Chatterjee, Parasuraman Jaisankar, Wanderley de Souza.

  Toxoplasma gondii is an obligate intracellular protozoan, the causative agent of toxoplasmosis. The current treatment against toxoplasmosis is based on the combination of sulfadiazine and pyrimethamine, which are toxic and unable to clear the infection. Due to the need for new active drugs against T. gondii, we have described here the effects of Furan derivatives on T. gondii in vitro. They were previously used with relevant activity against Leishmania amazonensis and Trypanosoma cruzi. The anti-Toxoplasma effects of the furan derivatives were evaluated using tachyzoites of T. gondii from RH strain and as host cells the human foreskin fibroblast (HFF) and the epithelial lineage from Macaca mulatta LLC-MK2. High-content screening and other microscopy techniques were employed to analyze the infected cells after incubation in the presence of the compounds tested. The most effective derivative was 3g, presenting a 50% inhibitory concentration (IC50) of 4.3 μM after 48 h of incubation. The 50% cytotoxic concentration (CC50) in the host cells was 50 μM after a 72-hour treatment. The ultrastructural analysis showed that after treatment the parasites presented cytoplasmic emptying, mitochondrial swelling, and interference with cell division. It was revealed by TUNEL assay that the parasites dyed in part due to an apoptosis-like cell death. These findings suggest that the furan derivative 3g is a potential candidate for further studies in vivo to find alternative drugs to treat T. gondii infections.

Keywords:  Furan derivatives; Toxoplasma gondii; chemotherapy; tachyzoites; ultrastructure

DOI:  https://doi.org/10.1016/j.exppara.2025.108988
mSphere. 2025 Jul 08. e0028725

The Plasmodium falciparum homolog of Vps16 interacts with the core members of the Vps-C tethering complex.

Florian Lauruol, Thomas Galaup, Alexandra Bourgeois, Audrey Sergerie, Dave Richard.

  The organelles of the apical complex (rhoptries, micronemes, and dense granules) are critical for erythrocyte invasion by the malaria parasite Plasmodium falciparum. Though they have essential roles in the parasite lifecycle, the mechanisms behind their biogenesis are still poorly defined. The Class C Vps proteins Vps11, Vps16, Vps18, and Vps33 constitute the core of the CORVET and HOPS complexes implicated in vesicle tethering and fusion in the eukaryotic endolysosomal system. Work in the model apicomplexan Toxoplasma gondii has revealed that TgVps11 is essential for the generation of the apical complex. P. falciparum possesses all four subunits of the Vps-C complex, and recent work has shown that some of its components were critical for host-cell cytosol trafficking and the biogenesis of the apical complex. We here show that the P. falciparum ortholog of Vps16, a member of the Vps-C complex, is expressed throughout the asexual erythrocytic cycle and that it is potentially associated with the Golgi apparatus and the rhoptries in schizont stage parasites. We then demonstrate by immunoprecipitation and mass spectrometry that PfVps16 interacts with all the members of the canonical Vps-C complex along with the Vps3 CORVET component. Interestingly, three uncharacterized Plasmodium-specific proteins are also found as interactors of PfVps16, and structural predictions revealed that two of them possess folds commonly found in proteins present in membrane tethering complexes. These findings suggest that P. falciparum may possess both conserved and parasite-specific features within its endosomal tethering machinery.IMPORTANCEThe malaria parasite relies on special compartments to invade red blood cells. These are key to the parasite's ability to infect, but how these are generated is not well known. In eukaryotic cells, certain protein assemblies, called tethering complexes, help move and fuse small transport vesicles, which is important for building and maintaining organelles. Plasmodium falciparum possesses some of these proteins, and recent studies suggest they play an important role in building its infection machinery and transporting material inside the parasite. We found that the malaria parasite possesses additional components associated with the typical tethering proteins and that these are not found in other eukaryotes. These results suggest that P. falciparum uses both common and unique tools to create the cellular machinery it needs to infect red blood cells. We propose that the Plasmodium-specific components might represent interesting targets for the development of antimalarials with potentially reduced side effects since they are not present in humans.

Keywords:  malaria; micronemes; protein trafficking; rhoptries; tethering complex

DOI:  https://doi.org/10.1128/msphere.00287-25
Pediatr Discov. 2023 Sep;1(2): e17

Advances of SIRT4 in cancer metabolism and therapy.

Xiaohan Yue, Yulu Shi, Qing Luo.

  The Sirtuins family consists of SIRT1-SIRT7, which belong to class III of the histone deacetylases, a family of highly conserved NAD (nicotinamide adenine dinucleotide)-dependent enzymes expressed in the nucleus, cytoplasm, and mitochondria. In addition to having ADP-ribosyltransferase, NAD+-dependent deacetylase, lipoamide, and long-chain deacetylase activities, it can also regulate the function of substrate proteins through ADP-ribosylation, diacylation, and long-chain deacylation. These enzyme activities also confer many critical biological functions on SIRT4, making SIRT4 involved in many mitochondrial energy metabolic processes, such as promoting insulin secretion, participating in the glycolytic process in concert with glycolysis inhibitors, inhibiting glutamate dehydrogenase from regulating glutamine metabolism, and participating in reactions such as DNA damage. Because SIRT4 has such diverse functions, it plays a role in the metabolism and treatment of tumors. Here, we review the progress of SIRT4 research in tumor metabolism and therapy.

Keywords:  SIRT4; cancer; cancer metabolism; cancer therapy

DOI:  https://doi.org/10.1002/pdi3.17
Parasitol Res. 2025 Jul 07. 124(7): 79

Development and optimization of an ELISA method to detect Toxoplasma gondii oocyst infection in cats.

Mingfeng He, Bufan Zhang, Shuai Han, Jiahui Qian, Zhengming He, Yulian Wei, Yanqin Zhou, Bang Shen, Rui Fang.

  Toxoplasmosis caused by Toxoplasma gondii (T. gondii) is a zoonotic disease with great medical and veterinary significance. Felines, the definitive hosts of T. gondii, play a crucial role in the transmission of toxoplasmosis. The booming pet industry has led to more cats and cat-owning families, increasing the risk of toxoplasmosis transmission from animals to humans. Monitoring feline T. gondii infection accurately is crucial for reducing transmission risks. However, existing diagnostic methods focus on detecting whether cats are infected with T. gondii but fail to trace whether feline toxoplasmosis infections originate from oocysts or cysts. In this study, we assessed four late-stage development abundant proteins that were highly expressed specifically in sporulated oocysts to evaluate their specificity in binding to cat anti-T. gondii-oocyst serum. The LEA880 protein can only specifically react with cat anti-T. gondii-oocyst positive serum, but not with cat anti-T. gondii-cyst positive serum or negative cat serum. The optimized indirect enzyme-linked immunosorbent assay (iELISA) method based on the LEA880 protein exhibits good specificity and sensitivity in detecting T. gondii oocyst infection in cats.

Keywords:   Toxoplasma gondii ; Feline toxoplasmosis; IELISA; LEA880; Oocyst infection

DOI:  https://doi.org/10.1007/s00436-025-08523-y
Front Immunol. 2025 ;16 1600399

PLGA nanoparticles as an efficient carrier in Toxoplasma GAP45: a more effective vaccine against acute toxoplasmosis than traditional ones.

Pan Zhou, YanLi Yu, WeiYu Qi, XiaoJuan Wang, YouLi Yu, JianDong Wang, Li Zhang, ZhengQing Yu, TingLi Liu.

   Introduction: Toxoplasma gondii (T. gondii), as a strict intracellular parasite, can infect nearly all mammals, including humans, posing significant threats to public health. Toxoplasmosis in animals also leads to substantial economic losses in animal husbandry. Currently, no effective treatments are available for toxoplasmosis, creating an urgent need for safe and efficient therapeutics.
Methods: In this study, we constructed a subunit vaccine using T. gondii glidesome-associated protein 45 (TgGAP45). To enhance immunogenicity, poly (lactic-co-glycolic acid) (PLGA) nanoparticles were employed as delivery carriers to prepare TgGAP45-PLGA nanospheres. For comparison, two oil adjuvants, Montanide™ ISA 660 VG and Montanide™ ISA 206 VG, were used to formulate TgGAP45-206VG and TgGAP45-660VG emulsions. Following safety evaluation, protective immunity was assessed in animals. Antibody levels, cytokine profiles, dendritic cell (DC) maturation and differentiation, and T lymphocyte proliferation and differentiation were analyzed.
Results: The results demonstrated that TgGAP45-PLGA nanospheres induced a mixed Th1/Th2 immune response against T. gondii. Furthermore, parasite burden analysis in spleen and heart tissues revealed that TgGAP45-PLGA nanospheres provided the strongest immunoprotection among the tested vaccines.
Discussion: These findings indicate that TgGAP45 delivered via PLGA nanospheres is a promising candidate for preventing acute toxoplasmosis. Further studies and applications are warranted to explore its full therapeutic potential.

Keywords:  PLGA nanoparticles; Toxoplasma gondii; glidesome-associated protein 45; immunoprotection; mice

DOI:  https://doi.org/10.3389/fimmu.2025.1600399
Foodborne Pathog Dis. 2025 Jul 07.

High Levels of Protection Against Acute and Chronic Toxoplasmosis in Institute of Cancer Research Mice with a Novel Low-Temperature Inactivated Toxoplasma gondii Candidate Vaccine Adjuvanted with HA201/HA203.

Shao-Yuan Bai, Guo-Qing Zhou, Yu-Yuan Li, Ming Pan, Lizhi Fu, Si-Yang Huang.

  Toxoplasma gondii is a highly complex protozoan parasite that poses significant health risks to humans and livestock. Traditional inactivated vaccines have simple preparation and high safety characteristics, but the protection is insufficient. This study aimed to find a new way to prepare an inactivated vaccine and find a suitable adjuvant to evaluate the immunoprotection. Inactivated vaccine (IVAC) was prepared by a novel low-temperature inactivation method, and different adjuvants were selected to evaluate the immune response. To assess immune protection, cytokines and other quantifiable factors associated with protection were examined, and then acute and chronic immune-protected experiments were carried out. IVAC has good integrity and biosafety. Immunizing mice with the adjuvant vaccine resulted in increased immunoglobulin G antibody and interferon-gamma levels, indicating the induction of a mixed Th1/Th2 immune response. Most notably, vaccination significantly improved the survival rate of mice. The IVAC can achieve a 10% protection rate, and the protection rate with adjuvant HA201 and HA203 can reach 50% and 70%, respectively. We found a new method to prepare IVAC and identified two adjuvants that could improve survival rates by 40-60%. These results provide valuable insights for future research on the Toxoplasma vaccine.

Keywords:  Toxoplasma gondii; adjuvant; inactivated vaccine; protective immunity

DOI:  https://doi.org/10.1089/fpd.2024.0159
Eur J Med Chem. 2025 Jul 06. pii: S0223-5234(25)00694-4. [Epub ahead of print]297 117929

Sirtuin 3 as a promising target in disease therapy: Model action and drug discovery.

Dongmin Yu.

  Sirtuin 3 (SIRT3) belongs to the Class III histone deacetylase (HDACIII) family and is an enzyme of significant importance in epigenetic regulation. Many studies have demonstrated that the aberrant expression of SIRT3 is closely associated with a variety of diseases, including inflammation, cancer, cardiovascular diseases, and disorders of the central nervous system disorders. SIRT3 is involved in the regulation of multiple intracellular processes, such as cell migration and apoptosis, and thus, has emerged in recent years as a promising therapeutic target for disease treatment. This review first summarizes the structure of SIRT3 and its pharmacological actions, followed by an analysis of the cocrystal structures of representative SIRT3 inhibitors/activators. Subsequently, we focus on the development of SIRT3 modulators (including inhibitors and activators) from a drug-design perspective in recent years. Finally, we present challenges encountered in the discovery of small-molecule modulators targeting SIRT3 and potential future developments.

Keywords:  Activators; Challenges; Inhibitors; Modulators; Sirtuin 3

DOI:  https://doi.org/10.1016/j.ejmech.2025.117929
Brain Behav Immun. 2025 Jul 04. pii: S0889-1591(25)00256-9. [Epub ahead of print]129 664-665

The latent threat of Toxoplasma gondii infection for neurologic disease.

Daniel C Anthony.

  Toxoplasma gondii, a ubiquitous neurotropic parasite, infects roughly one-third of the global population. In immunocompetent individuals, infection is typically asymptomatic, yet recent evidence suggests that latent T. gondii infection can subtly impair brain function and increase vulnerability to neurological disorders. This commentary, prompted by recent findings by Baker et al., highlights how chronic infection may exacerbate seizure susceptibility and neuroinflammation, particularly under a 'second hit' model. The implications of such latent infections in public health and the importance of considering infection history in neurological disease models are discussed.

Keywords:  Latent infection; Neuroinflammation; Sex differences in neuropathology; Temporal lobe epilepsy; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.bbi.2025.06.039
Parasit Vectors. 2025 Jul 09. 18(1): 273

The development and excretion of Toxoplasma gondii oocyst manipulate the gut microbiota in its definitive host.

Gui-Hua Zhao, Bei-Bei Zhou, Zhi-Heng Cao, Ting Xiao, Ya-Nan Li, Wen-Ju Zhu, Hang Sun, Huan-Huan Xie, Xiao-Man Xie, Jun-Mei Zhang, Qi Wang, Xin Zhang, Jin-Jing Xie, Hong-Jie Dong, Chao Xu, Kun Yin.

   BACKGROUND: Oocysts serve as the primary source of Toxoplasma infection. Therefore, understanding oocyst development and exploring effective strategies to prevent oocyst excretion are crucial for controlling toxoplasmosis.
METHODS: In this study, shotgun metagenomics was employed to characterize the functional and compositional changes in the gut microbiota of cats during oocyst development. The Spearman correlation test was utilized to analyze the correlation between differential Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and carbohydrate-active enzymes (CAZymes) in key bacteria regulating oocyst excretion.
RESULTS: The results revealed that group A (sexual initiation stage) displayed a lower number of functional genes, which were restored to normal levels in group B (oocyst excretion stage), compared with group C (Toxoplasma-uninfected samples). The abundance of 39 KEGG pathways, 106 CAZymes, and 98 virulence factors (VFs) varied significantly among the three groups. The atrazine degradation pathway, associated with sexual development, was upregulated in group B. CAZymes involved in restoring the intestinal mucosal barrier and VFs related to iron metabolism, antibiotic resistance, and suppression of host immunity were enriched in group B. Sexual initiation and oocyst excretion resulted in reduced gut bacterial diversity and microbiota dysbiosis. Probiotics and bacteria related to linoleic acid (LA) uptake were dominant in both group A and group B. Bacteroides stercoris was the most significantly upregulated bacterium and could influence the expression of carbohydrate-binding modules (CBMs) and glycoside hydrolases (GHs) in group B.
CONCLUSIONS: During the oocyst development/excretion stage, the function and composition of the cat gut microbiota changed significantly. In addition, Bacteroides stercoris may play a crucial role in oocyst excretion by regulating key candidates of CBMs and GHs. Our findings lay the foundation for investigating the regulatory mechanisms of oocyst excretion.

Keywords:   Toxoplasma gondii ; Cat; Function and composition; Gut microbiota; Oocyst excretion

DOI:  https://doi.org/10.1186/s13071-025-06925-6
Nucleic Acids Res. 2025 Jul 08. pii: gkaf641. [Epub ahead of print]53(13):

The ribosomal RNA transcription landscapes of Plasmodium falciparum and related apicomplexan parasites.

Gunnar Mair, Julia L Daiß, Christoph Engel, Konstantin I Panov.

Ribosome biogenesis is essential for the rapid proliferation and life cycle transitions of Plasmodium falciparum, the causative agent of malaria. In eukaryotes, ribosomal RNA synthesis is carried out by RNA polymerase I (Pol I), highly specialized transcriptional machinery. This review provides a comparative analysis of Pol I transcription apparatus in yeast and humans, serving as a reference framework to examine its evolutionary divergence in P. falciparum and related apicomplexans and alveolates. Bioinformatic analyses revealed that some of these organisms lack any identifiable homologues or orthologs of several canonical eukaryotic transcription factors essential for Pol I-mediated transcription, including initiation factor RRN3, activator UBF, and all specific subunits of the promoter recognition complexes. Interestingly, the parasite retains core Pol I subunits, incorporating unique parasite-specific structural domains characterized through AI-based protein complex modeling of P. falciparum Pol I. These adaptations may compensate for the absence of traditional regulatory factors, enabling the parasite to employ distinct mechanisms for promoter recognition and transcription initiation. The substantial differences between parasite and host Pol I transcription machinery create potential targets for therapeutic intervention with parasite-specific elements representing potential drug targets. By integrating evolutionary, structural, and functional perspectives, this review advances our understanding of Pol I transcription in alveolates and its implications for the development of novel antimalarial strategies.

DOI: https://doi.org/10.1093/nar/gkaf641
Cell Immunol. 2025 Jun 28. pii: S0008-8749(25)00086-3. [Epub ahead of print]414 105000

Acetyl-CoA subcellular compartmentalization regulates T cell adaptation.

Annefien Tiggeler, Paul J Coffer.

  Upon activation, naïve T cells undergo rapid proliferation and differentiation, giving rise to clonally expanded populations specifically tailored for an effective immune response. To meet the heightened bioenergetic and biosynthetic demands associated with activation, T cells adapt and reprogram both their metabolism and transcriptome. Beyond this, T cells are also able to dynamically adapt to fluctuations in the microenvironmental nutrient levels. While the adaptability of T cells is a well-established hallmark of their functionality, the molecular mechanisms by which metabolic responses underpin this flexibility remain incompletely defined. Acetyl-CoA, with its role as a central metabolite in mitochondrial ATP production, and a substrate for nuclear histone acetylation reactions, emerges as a key player in a metabolic-epigenetic axis. Recent evidence indicates that enzymes responsible for generating acetyl-CoA can translocate to the nucleus, supporting sub-cellular local acetyl-CoA production. Here, we explore the impact of acetyl-CoA metabolism on T cell functionality within different subcellular compartments and highlight the potential for intervention in acetyl-CoA metabolic pathways in T cell-driven autoimmune diseases and cancers.

Keywords:  Acetyl-CoA; Epigenetic remodelling; Metabolic reprogramming; Nuclear metabolism; T cells

DOI:  https://doi.org/10.1016/j.cellimm.2025.105000
BMB Rep. 2025 Jul 10. pii: 6322. [Epub ahead of print]

Contribution of histone deacetylases (HDACs) to the regulation of histone and non-histone proteins: implications for fibrotic diseases.

Sunyoung Jang, Nayun Choi, Jong Hoon Park, Kyung Hyun Yoo.

Histone deacetylases (HDACs) are essential enzymes that play a pivotal role in the epigenetic regulation of gene expression by catalyzing the removal of acetyl groups from histone and non-histone proteins. This deacetylation is a crucial post-translational modification that influences several cellular processes, such as chromatin remodeling, transcriptional repression, and signal transduction. Recent studies have illuminated the significant involvement of HDACs in the pathogenesis of fibrotic diseases, conditions characterized by the excessive accumulation of extracellular matrix components leading to progressive organ dysfunction and failure. These diseases commonly affect the liver, kidney, heart, lung, and colon. The contribution of HDACs to fibrogenesis is multifaceted, involving the modulation of gene expression that governs inflammatory and fibrotic signaling pathways. Therefore, targeting HDACs with specific inhibitors has emerged as a promising therapeutic strategy to mitigate fibrosis in various organs. HDAC inhibitors (HDACi) can potentially reverse the aberrant gene expression profiles associated with fibrotic diseases by restoring acetylation levels, thus attenuating fibrotic responses. Several HDAC inhibitors, such as vorinostat, trichostatin A, and romidepsin, have shown efficacy in preclinical models of fibrosis, demonstrating their potential to suppress fibrogenic signaling pathways and reduce extracellular matrix deposition. In this review, we provide a comprehensive analysis of the current understanding of the roles of HDACs in the regulation of histone and non-histone proteins, and their implications for fibrotic diseases. We compare the molecular mechanisms by which different classes of HDACs contribute to fibrosis in various organs, and highlight the therapeutic potential of HDAC inhibition. This review underscores the importance of further research into HDAC-specific inhibitors as viable treatments for fibrotic diseases, aiming to develop targeted therapies that can effectively ameliorate fibrosis and improve patient outcomes.
bioRxiv. 2025 Jul 03. pii: 2025.07.03.662939. [Epub ahead of print]

Dynamic acetylation of a conserved lysine impacts glycerol kinase activity and abundance in the haloarchaeon Haloferax volcanii.

Karol M Sanchez, Manasa Addagarla, Heather Judd, Xin Wang, Julie Maupin-Furlow.

Haloferax volcanii is a halophilic archaeon that preferentially utilizes glycerol as a carbon source, placing glycerol kinase (GK, glpK ) at the center of its metabolism. In contrast to bacterial GKs, which are often regulated by allosteric inhibition, H. volcanii GK lacks this mode of control, indicating alternative regulatory mechanisms. Here, we show that lysine acetylation of H. volcanii GK enhances its activity and abundance during growth on glycerol, with K153 identified as the primary site of modification. Structural modeling and comparative genomics revealed that K153 resides in a conserved flexible loop common to haloarchaeal GKs. Carbon shifts from glucose to glycerol led to increased activity and enrichment of the K153-acetylated form, as determined by AQUA-MS. GK and the acetylation mimic K153Q supported growth on glycerol, while the non-acetylatable K153R variant did not. Thermal shift analysis showed that the K153R substitution reduced GK stability, while K153Q had no effect. Size exclusion chromatography indicated that GK is predominantly dimeric but forms a tetramer when purified from glycerol-grown cells and assayed with glycerol - coinciding with the highest K153 acetylation levels. Kinetic analysis revealed that K153 acetylation is required to maintain cooperative substrate binding, with the non-acetylatable K153R variant exhibiting a loss of allosteric behavior. The GNAT-family acetyltransferase Pat2 was found to acetylate GK at K153, and Δpat2 mutants exhibited reduced GK protein abundance, linking Pat2 to regulation of GK. These results identify a dynamic, carbon source-responsive lysine acetylation mechanism that modulates GK, highlighting lysine acetylation as a key component of haloarchaeal metabolic regulation.
IMPORTANCE: Post-translational modifications allow microorganisms to rapidly adapt their metabolism to changing environmental conditions. Here, we uncover a carbon source-dependent acetylation mechanism that regulates GK activity and abundance in the halophilic archaeon H. volcanii . Unlike bacterial systems, where allosteric inhibitors control GK, H. volcanii relies on lysine acetylation to fine-tune and enhance enzymatic function based on nutrient availability. Our findings highlight acetylation at a conserved lysine as a key modulator of archaeal carbon metabolism, linking environmental signals directly to enzymatic activity and cellular fitness. This work expands our understanding of extremophile metabolic regulation and reveals how archaea deploy unique strategies to survive and thrive in environments that shift in carbon availability.

DOI: https://doi.org/10.1101/2025.07.03.662939
Proc Biol Sci. 2025 Jul;292(2050): 20251123

Mechanisms of host exploitation by a microsporidian parasite.

Luis M Silva, Armelle Vallat, Jacob C Koella.

  Parasites exploit their hosts to enhance their growth and reproduction, yet the mechanisms underlying host manipulation remain understudied for many taxa. The microsporidian Vavraia culicis, a potential biological control agent for mosquitoes, serves as an excellent model to explore such mechanisms. In this study, we investigate how infection by V. culicis lines that vary in virulence alters resource dynamics within the mosquito host Anopheles gambiae. Using metallomics and quantification of protein, carbohydrate and lipid content, we show that infection alters host resource concentrations in ways that depend on parasite virulence. More virulent parasites led to increased protein levels and greater energy demands, evidenced by higher carbohydrate reserves. Additionally, infection with V. culicis impacted host metal content, particularly zinc and manganese, used by V. culicis independently of its evolutionary background. Iron availability, a key nutrient for parasite growth, enhanced spore production, with selected parasite lines better able to exploit host iron than unselected. These findings provide insight into the mechanisms by which V. culicis manipulates host resources, shedding light on the role of host exploitation in parasite virulence and the potential use of microsporidia as biological control agents in vector biology.

Keywords:  Anopheles gambiae; energy metabolism; host−parasite; iron; life history; metallomics; microsporidia; resource allocation; vector biology; virulence

DOI:  https://doi.org/10.1098/rspb.2025.1123
Front Immunol. 2025 ;16 1582645

Dual single-cell and bulk RNA sequencing reveal transcriptional profiles underlying heterogenous host-parasite interactions in human peripheral blood mononuclear cells.

Praveena Chandrasegaran, Bekir Faydaci, Barbara Shih, Musa A Hassan.

  Toxoplasma gondii, a zoonotic apicomplexan that infects over a billion people worldwide, can cause early death in immunocompromised individuals and defects in foetal brain development. Toxoplasma is also a major cause of abortion in small ruminants. When Toxoplasma encounters host cells, several outcomes are possible. For example, the parasite can enter the host cell or can inject its effector proteins into the cell without entering. These heterogenous outcomes occur simultaneously in the same host and likely determine disease pathogenesis. Yet, current knowledge of host-Toxoplasma interactions is largely based on averaged responses in bulk cell populations. Here, we employed single cell RNA (scRNA) and bulk RNA sequencing to investigate the transcriptional profiles that underpin heterogenous host-Toxoplasma interaction in human peripheral blood mononuclear cells. We observed that Toxoplasma preferentially infects and elicits transcriptional responses in dendritic cells in human blood. Additionally, we observed that monocytes adopt a dendritic cell-like transcriptional profile over the course of infection. Using genes expressed in sorted host cell populations representative of the different heterogenous host-Toxoplasma interaction outcomes as a reference panel, we show that genes expressed in cells infected via phagocytosis are largely expressed in dendritic cells. Thus, by integrating scRNA and bulk RNA sequencing, our study unveils the transcriptional profiles of diverse Toxoplasma-host cell interaction outcomes, providing novel avenues for targeted investigations into host gene functions during Toxoplasma infections.

Keywords:  PBMCs; Toxoplasma gondii; dendritic cells; host-pathogen interactions; monocytes; single-cell RNA sequencing

DOI:  https://doi.org/10.3389/fimmu.2025.1582645
Cell Biol Int. 2025 Jul 05.

Beyond Histones: Unveiling the Functional Roles of Protein Acetylation in Prokaryotes and Eukaryotes.

Bruno Sousa Bonifácio, Ariely Barbosa Leite, Ana Caroline de Castro Nascimento Sousa, Suellen Rodrigues Maran, Antoniel Augusto Severo Gomes, Elton J R Vasconcelos, Nilmar Silvio Moretti.

  Lysine acetylation plays a crucial role in cellular processes and is found across various evolutionary organisms. Recent advancements in proteomic techniques revealed the presence of acetylation in thousands of non-histone proteins. Here, we conducted extensive meta-analysis of 48 acetylomes spanning diverse organisms, including archaea, bacteria, fungi, protozoa, worms, plants, insects, crustacea, fish, and mammals. Our analyzes revealed a predominance of a single acetylation site in a protein detected in all studied organisms, and proteins heavily acetylated, with > 5-10 acetylated-sites, were represented by Hsp70, histone, or transcription GTP-biding domain. Moreover, using gene enrichment approaches we found that ATP metabolic processes, glycolysis, aminoacyl-tRNA synthetase pathways and oxidative stress response are among the most acetylated cellular processes. Finally, to better explore the regulatory function of acetylation in glycolysis and oxidative stress we used aldolase and superoxide dismutase A (SODA) enzymes as model. For aldolase, we found that K147 acetylation, responsible to regulate human enzyme, conserved in all phylogenic clade, suggesting that this acetylation might play the same role in other species; while for SODA, we identified many lysine residues in different species present in the tunnel region, which was demonstrated for human and Trypanosoma cruzi, as negative regulator, also suggesting a conserved regulatory mechanism. In conclusion, this study provides insights into the conservation and functional significance of lysine acetylation in different organisms emphasizing its roles in cellular processes, metabolic pathways, and molecular regulation, shedding light in the extensive function of non-histone lysine acetylation.

Keywords:  acetylation; acetylome; aldolase; glycolysis; superoxide dismutase

DOI:  https://doi.org/10.1002/cbin.70055
Glia. 2025 Jul 09.

Diverse Subpopulations of Reactive Astrocytes Following Chronic Toxoplasma Infection.

Zoe A Figueroa, Jose L Martin, Arzu Ulu, William Agnew-Svoboda, Teresa Ubina, Martin M Riccomagno, Todd A Fiacco, Emma H Wilson.

  Astrocytes provide physical and metabolic support for neurons, regulate the blood-brain barrier, and react to injury, infection, and disease. When astrocytes become reactive, maintenance of the inflammatory state and its functional implications throughout chronic neuroinflammation are all poorly understood. Several models of acute inflammation have revealed astrocyte subpopulations that go beyond a two-activation state model, instead encompassing distinct functional subsets. However, how reactive astrocyte (RA) subsets evolve over time during chronic inflammatory disease or infection has been difficult to address. Here we use a prolific human pathogen, Toxoplasma gondii, that causes lifelong infection in the brain alongside a Lcn2CreERT2 reporter mouse line to examine reactive astrocyte subsets during chronic neuroinflammation. Single-cell RNA sequencing revealed diverse astrocyte populations including transcriptionally unique Lcn2CreERT2+ RAs which change over the course of infection in a subset-dependent manner. In addition to an immune-regulating Lcn2CreERT2+ astrocyte population enriched with gene transcripts encoding chemokines CCL5, CXCL9, CXCL10, and receptors CCR7 and IL7R, a specific subset of Lcn2CreERT2+ astrocytes highly expressed transthyretin (Ttr), a secreted carrier protein involved in glycolytic enzyme activation and potential vasculature regulation and angiogenesis. These findings provide novel information about the evolution and diversity of reactive astrocyte subtypes and functional signatures at different stages of infection, revealing an undocumented role for transthyretin-expressing astrocytes in immune regulation at the central nervous system (CNS) vasculature.

Keywords:   Toxoplasma gondii ; angiogenesis; astrogliosis; glutamate transporters; lipocalin‐2 (Lcn2); neuroinflammation; transthyretin (Ttr)

DOI:  https://doi.org/10.1002/glia.70053
bioRxiv. 2025 Jul 03. pii: 2025.06.30.662456. [Epub ahead of print]

Activation of the impaired NAMPT/SIRT7/SOD2 axis restores alveolar progenitor cell homeostasis in idiopathic pulmonary fibrosis and reverses pulmonary fibrosis in mice.

Xuexi Zhang, Xue Liu, Yujie Qiao, Anas Rabata, Ningshan Liu, Changfu Yao, Tanyalak Parimon, Danica Chen, Peter Chen, Barry Stripp, Stephen J Gardell, Dianhua Jiang, Paul W Noble, Jiurong Liang.

Alveolar type II (AT2) progenitor cell exhaustion and impaired regenerative capacity are key pathogenic hallmarks in idiopathic pulmonary fibrosis (IPF). Nicotinamide adenine dinucleotide (NAD + ) functions as a central regulator of cellular energy metabolism. We have reported that downregulation of NAD + -dependent sirtuin signaling contributes to the impaired progenitor function of IPF AT2s. In this study, we identified that a key NAD + biosynthesis enzyme, nicotinamide phosphoribosyltransferase (NAMPT), is significantly downregulated in IPF AT2s. NAMPT deficiency impairs AT2 renewal and enhances lung fibrosis through downregulation of SIRT7 and SOD2, which results in increased oxidative stress, mitochondrial dysfunction, induction of pathological transitional gene expression and impaired regenerative capacity to generate alveolar type I (AT1) cell required for gas exchange. Mice with deletion of Nampt in AT2s showed severely impaired AT2 renewal and increased susceptibility to bleomycin lung injury and spontaneous fibrois. Activation of NAMPT by small molecule activators promoted AT2 renewal, restored homeostasis, and reversed lung fibrosis. NAMPT activation could be a therapeutic strategy for restoring AT2 progenitor function and halting or reversing progressive pulmonary fibrosis.

DOI: https://doi.org/10.1101/2025.06.30.662456
AMB Express. 2025 Jul 10. 15(1): 102

Comparative evaluation of live attenuated and killed tachyzoites as vaccine candidates for toxoplasmosis.

Eman E El Shanawany, Eman H Abdel-Rahman, Waleed A Nemr, Soad E Hassan, Noha M F Hassan, Hassan M Desouky, Rabab Zalat, Amany Ebrahim Nofal, Raafat M Shaapan, Salwa Sami Younis.



Keywords:   Toxoplasma gondii ; Acute toxoplasmosis; Gamma irradiation; Live attenuated tachhyzoites; Mice; Vaccine

DOI:  https://doi.org/10.1186/s13568-025-01889-3
Arch Pharm (Weinheim). 2025 Jul;358(7): e70045

DCAF16-Based Covalent Molecular Glues for Targeted Protein Degradation of Histone Deacetylases.

Tao Sun, Shiyang Zhai, Stephan Lepper, Beate König, Mateo Malenica, Irina Honin, Finn K Hansen.

  Histone deacetylases (HDACs) are intriguing cancer targets due to their high expression in many tumors. Consequently, inhibition or degradation of HDACs can be beneficial for cancer therapy. Targeted protein degradation using molecular glues represents a promising therapeutic approach, enabling the specific degradation of numerous disease-causing proteins. However, the rational design of molecular glues in a target-based manner remains challenging. A recent study has described the identification of a DCAF16-based covalent linker-less chemical handle for molecular glues. This covalent warhead can be attached to protein of interest ligands to induce the targeted degradation of various protein classes. Inspired by this, we designed and synthesized a new class of DCAF16-based covalent molecular glues utilizing different zinc-binding groups for the targeted degradation of HDACs. This approach led to the discovery of an efficient molecular glue (10a) that reduced HDAC1 levels in multiple myeloma MM.1S cells in a potent and preferential manner.

Keywords:  DCAF16; cancer; histone deacetylases (HDACs); molecular glues; targeted protein degradation (TPD)

DOI:  https://doi.org/10.1002/ardp.70045
Methods Mol Biol. 2025 ;2953 189-203

Identification of Cytosol-Facing Organelle Membrane-Proximal Proteins via Proximity-Dependent Biotinylation.

Xinyue Bao, Xiaoyan Zhang, Huifang Jia, Xiaohong Zhu.

  Organelle membrane (OM)-resident or -proximal proteins that face the cytosol play a critical role in the import and exchange of ions, metabolites, and proteins between subcellular compartments, thereby regulating organelle biogenesis and function. However, the identification and functional characterization of these proteins pose challenges due to their dynamic spatial and temporal nature. We introduce a proximity labeling system using biotin ligase-mediated protein biotinylation in live Arabidopsis thaliana cells. This chapter outlines a detailed step-by-step protocol for identifying cytosol-facing OM-resident or -proximal proteins of mitochondria, chloroplasts, and peroxisomes in plant cells. This protocol can be adapted to identify cytosol-facing OM-resident and/or proximal proteins of any subcellular compartments of interest, as well as to map their spatiotemporal profiles under various stress conditions. The protocol described includes the following key steps: (1) sample preparation; (2) optimization of biotin labeling conditions; (3) enrichment of biotinylated proteins for liquid chromatography-tandem mass spectrometry (LC-MS/MS); (4) validation of identified candidate proteins.

Keywords:  Arabidopsis thaliana; Biotin protein ligase; Organellar quality control; Organelle membrane proximal protein; Organelle membrane proximity labeling; Proximity labeling

DOI:  https://doi.org/10.1007/978-1-0716-4694-6_12
bioRxiv. 2025 Jul 04. pii: 2025.06.30.662412. [Epub ahead of print]

Ulk1(S555) inhibition alters nutrient stress response by prioritizing amino acid metabolism.

Orion S Willoughby, Anna S Nichenko, Matthew H Brisendine, Niloufar Amiri, Shelby N Henry, Daniel S Braxton, John R Brown, Kalyn S Specht, Adele K Addington, Alexey V Zaitsev, Steven T Burrows, Ryan P McMillan, Haiyan Zhang, Spencer A Tye, Charles P Najt, Siobhan M Craige, Timothy W Rhoads, Junco S Warren, Joshua C Drake.

Metabolic flexibility, the capacity to adapt fuel utilization in response to nutrient availability, is essential for maintaining energy homeostasis and preventing metabolic disease. Here, we investigate the role of Ulk1 phosphorylation at serine 555 (S555), a site regulated by AMPK, in coordinating metabolic switching following short-term caloric restriction and fasting. Using Ulk1(S555A) global knock-in mice, we show loss of S555 phosphorylation impairs glucose oxidation in skeletal muscle and liver during short-term CR, despite improved glucose tolerance. Metabolomic, transcriptomic, and mitochondrial respiration analyses reveal a compensatory reliance on glucogenic amino acids, particularly alanine and serine, in Ulk1(S555A) mice, with sustained amino acid oxidation during fasting and blunted mitochondrial response to energetic stress. These findings establish Ulk1(S555) phosphorylation as a critical regulatory event linking nutrient stress to substrate switching and highlights an underappreciated role of Ulk1 in maintaining metabolic flexibility.

DOI: https://doi.org/10.1101/2025.06.30.662412
Inflamm Res. 2025 Jul 10. 74(1): 103

Annexin A1 is crucial during Toxoplasma gondii infection promoting the modulation of inflammation and intestinal and central nervous system barrier functions.

Rayane Aparecida Nonato Rabelo, Rafaela das Dores Pereira, Natalia Fernanda de Melo Oliveira, Samuel Luiz Teixeira Porto, César Luís Nascimento Barbosa, Livia Fernanda Dias Santana, Fernando Bento Rodrigues Oliveira, Mayra Fernanda Ricci, Celso Martins Queiroz-Junior, Cínthia Firmo Teixeira, Vivian Barbosa Santos Alvarenga, Luiza Pinheiro Silva, Viviani Mendes de Almeida, Lirlândia Pires Sousa, Angelica Thomaz Vieira, Mauro Martins Teixeira, Caio Tavares Fagundes, Fabiana Simão Machado.

   BACKGROUND: Toxoplasmosis promotes acute and chronic symptoms ranging from ocular to severe congenital or neurotoxoplasmosis. A proper host immune response and a healthy gut microbiota control the pathophysiology of toxoplasmosis, presenting an opportunity for pro-resolving mediators.
OBJECTIVE: Here, we evaluated the role of the anti-inflammatory/pro-resolving protein annexin (Anx)A1 in Toxoplasma gondii (Tg) infection.
RESULTS: AnxA1 levels increase in the brain during Tg infection, and AnxA1 knockout (KO) mice display higher susceptibility to disease, an increased number of brain cysts, an inflammatory response, severe lesions, and brain permeability, along with lower claudin-5 and occludin expression. Notably, AnxA1 deficiency increased the number of IBA-1+ cells in the brain, macrophages/neutrophils/dendritic cells producing IL-10 and TNF, and Th2 and CD8 T cells producing IL-17 compared to wild-type cells. An increased number of Tregs and innate cells producing TNF has been observed in the spleen. Moreover, the absence of AnxA1 increases gut inflammation, alters microbiota composition, reduces mucus production, increases intestinal permeability, and promotes bacterial translocation from the gut to the liver. Furthermore, imipenem treatment restored animal survival, prevented bacterial translocation into the liver, and reduced brain inflammation. = CONCLUSION: Collectively, our data demonstrate that AnxA1 is critical for regulating the pathogenesis of Tg infection and unveils a possible therapeutic target for this disease.

Keywords:   Toxoplasma gondii ; Annexin A1; Central nervous system; Immune response; Microbiota

DOI:  https://doi.org/10.1007/s00011-025-02065-w
bioRxiv. 2025 Jul 02. pii: 2025.07.01.662652. [Epub ahead of print]

AMPK alters proteasome phosphorylation status and prevents persistent proteasome condensates.

Jianhui Li, Conner Butcher, Kyle VanderVen, Mark Hochstrasser.

Proteasomes are large multiprotein complexes required for selective intracellular protein degradation, regulating numerous cellular processes and maintaining protein homeostasis and organismal health. In the budding yeast Saccharomyces cerevisiae grown under different glucose conditions, proteasomes undergo dynamic phase transitions between free and condensate states concomitant with nucleocytoplasmic translocation. Low glucose-induced cytoplasmic proteasome condensates are usually reversible but become persistent in the absence of AMP-activated protein kinase (AMPK). AMPK is important for proteasome condensate dissolution and proteasome nuclear reimport upon glucose refeeding of quiescent cells. Here we found that AMPK activities and the AMPK signaling pathway affect proteasome subunit phosphorylation, which correlates with the solubility and reversibility of proteasome condensates. Nuclear and cytoplasmic AMPK functions redundantly in proteasome condensate dissolution. AMPK interacts with the proteasome regulatory particle in an AMPK activity-independent manner. At least 50 kinases and phosphatases have been found to associate with the AMPK complex. Therefore, the prevention of persistent proteasome condensate formation by AMPK likely results from regulating the antagonistic effects of downstream kinases and phosphatases on proteasome phosphorylation. A mechanistic understanding of the downstream effector proteins of AMPK that directly regulate proteasome subunit phosphorylation will provide insights into how proteasome phosphorylation is linked to proteasome condensate regulation.
Article summary: Proteasomes undergo dynamic nucleocytoplasmic translocation and phase transitions in response to glucose starvation. AMP-activated protein kinase (AMPK) is important for cytoplasmic proteasome condensate dissolution and proteasome nuclear reentry in budding yeast cells upon glucose refeeding of quiescent cells. This study demonstrates that AMPK interacts with proteasomes, and the AMPK pathway regulates proteasome phosphorylation status and condensate solubility during reversible proteasome condensate formation. AMPK and the PP1 phosphatase dynamically regulate phosphorylation of multiple proteasome subunits. Therefore, the regulation of proteasome phosphorylation by AMPK is likely to be central to proteasome biomolecular condensate formation and dissolution.

DOI: https://doi.org/10.1101/2025.07.01.662652
PLoS Pathog. 2025 Jul 08. 21(7): e1013313

Essential role for PfHSP40 in asexual replication and thermotolerance of malaria parasites.

Brianne Roper, Deepika Kannan, Emily S Mathews, Audrey R Odom John.

Plasmodium falciparum, the parasite responsible for nearly all cases of severe malaria, must survive challenging environments to persist in its human host. Symptomatic malaria is characterized by periodic fevers corresponding to the 48-hour asexual reproduction of P. falciparum in red blood cells. As a result, P. falciparum has evolved a diverse collection of heat shock proteins to mitigate the stresses induced by temperature shifts. Among the assortment of heat shock proteins in P. falciparum, there is only one predicted canonical cytosolic J-domain protein, PfHSP40 (PF3D7_1437900). Here, we generate a PfHSP40 tunable knockdown strain of P. falciparum to investigate the biological function of PfHSP40 during the intraerythrocytic lifecycle. We determine that PfHSP40 is required for malaria parasite asexual replication and survival of febrile temperatures. Previous reports have connected proteotoxic and thermal stress responses in malaria parasites. However, we find PfHSP40 has a specific role in heat shock survival and is not essential for mitigating the proteotoxic stresses induced by artemisinin or proteosome inhibition. Following PfHSP40 knockdown, malaria parasites have a cell cycle progression defect and reduced nuclear replication. Untargeted proteomics reveal PfHSP40 depletion leads to a multifaceted downregulation of DNA replication and repair pathways. Additionally, we find PfHSP40 knockdown sensitizes parasites to DNA replication inhibition. Overall, these studies define the specialized role of the J-domain protein PfHSP40 in malaria parasites during the blood stages of infection.

DOI: https://doi.org/10.1371/journal.ppat.1013313
PLoS Pathog. 2025 Jul;21(7): e1013318

Loss of serine/threonine protein phosphatase 6 severely impairs sexual stage development in malaria parasite Plasmodium berghei.

Yonghui Feng, Wenyan Gao, Chengqi Wang, Shuangrui Shi, Dan Zhou, Lin Sun, Liying Zhu, Liwang Cui, Yaming Cao, Xiaotong Zhu.

Protein phosphorylation plays a critical role during the development of malaria parasites. Here, we performed a functional analysis of the Plasmodium berghei Ser/Thr protein phosphatase 6 (PbPP6), which is associated with the plasma membrane of macrogametes and ookinetes. Compared to wild-type P. berghei, the genetic disruption of pbpp6 (∆pbpp6) resulted in reduced asexual growth of the parasites and prolonged survival of infected mice. The ∆pbpp6 parasites showed impaired gametogenesis, particularly affecting male gametogenesis, which substantially decreased both ookinete formation and mosquito transmission. Transcriptomic analysis revealed an over 11-fold downregulation of nek3, a regulator of MAPK2 within the PKG-Ca2⁺ signaling cascade, foreshadowing pathway dysregulation that was further evidenced by significantly diminished intracellular cGMP levels, decreased cytosolic Ca2⁺ mobilization, and reduced DNA replication in activated Δpbpp6 gametocytes. Phosphoproteomic analysis detected increased phosphorylation at the Ser508 site of guanylyl cyclase alpha (GCα), indicating that PbPP6 regulates cGMP-PKG-Ca2+ signaling through modulation of GCα activity during gametogenesis. Additionally, we observed altered expression of messenger ribonucleoproteins in the Δpbpp6 parasites, which may affect the translational repression of stored mRNAs in female gametocytes and impact post-fertilization development in mosquitoes. Collectively, this study highlights the potential of targeting PP6 to disrupt malaria transmission.

DOI: https://doi.org/10.1371/journal.ppat.1013318
Invest New Drugs. 2025 Jul 10.

Targeting neuroblastoma with hydroxamic acid based HDAC1 and HDAC2 inhibitors: Insights from in vitro and in vivo studies.

Padmini Pai, Yashaswini Reddy, Ipshita Das, Babu Santhi Venkidesh, Poonam Bhandari, Pallavi Rao, Srinivas Oruganti, Keshava Prasad, Manasa Gangadhar Shetty, Kapaettu Satyamoorthy, Babitha Kampa Sundara.

  Histone deacetylases (HDACs) serve a crucial function in transcription regulation, and their dysregulation is linked to numerous diseases, including cancer. Among them, HDAC1 and HDAC2 are particularly significant in neural progenitors and are frequently overexpressed in neural-derived cancers. HDAC inhibitors (HDACis) have shown promise in overcoming chemoresistance by restoring tumor suppressor function in neuroblastoma cells. However, the lack of selectivity in existing HDACis presents challenges, highlighting the need for isoform-selective inhibitors to reduce side effects. This research investigated the anticancer properties of a newly synthesized hydroxamic acid derivative, emphasizing its selective HDAC1 and HDAC2 inhibition and strong antitumor activity. Our findings demonstrated that the newly developed hydroxamic acid analogues, 3A and 3B, effectively inhibited neuroblastoma cells (SH-SY5Y) proliferation, with IC50 values of 8.49 µM and 4.44 µM, respectively, comparable to suberoylanilide hydroxamic acid (SAHA) with IC50 of 0.91 µM. Additionally, compounds 3A and 3B exhibited potent HDAC inhibition. Compound 3A selectively inhibited HDAC2 with an IC50 value of 0.89 μM, while compound 3B showed dual inhibition of HDAC1 and HDAC2, with IC50 values of 0.44 μM and 1.94 μM, respectively. Compound 3B triggered cell cycle arrest in the G2/M phase, reduced colony formation efficiency, and altered cellular architecture upon treatment, further highlighting its anticancer potential. In an in vivo xenograft model, compound 3B significantly decreased tumor growth and tumor weight, highlighting its potential as an effective anticancer agent for neuroblastoma, offering both isoform-selective HDAC inhibition and potent anticancer effects.

Keywords:  Histone deacetylase; Hydroxamic acid; Isoform selective inhibitors; Neuroblastoma; Xenograft model

DOI:  https://doi.org/10.1007/s10637-025-01559-y
Gastroenterology. 2025 Jul 07. pii: S0016-5085(25)05732-4. [Epub ahead of print]

Chemical perturbations impacting histone acetylation govern colorectal cancer differentiation.

Pornlada Likasitwatanakul, Zhixin Li, Paul Doan, Sandor Spisak, Akhouri Kishore Raghawan, Qi Liu, Priscilla Liow, Sunwoo Lee, David Chen, Pratyusha Bala, Pranshu Sahgal, Daulet Aitymbayev, Jennifer S Thalappillil, Malvina Papanastasiou, William Hawkins, Steven A Carr, Haeseong Park, James M Cleary, Jun Qi, Nilay S Sethi.

   BACKGROUND AND AIMS: Aberrant epigenetic programs that suppress differentiation and enhance plasticity drive colorectal cancer (CRC), yet the molecular determinants underlying these processes remain elusive. We aimed to identify and characterize epigenetic regulators of CRC differentiation, uncovering mechanisms that reprogram cancer cell states.
METHODS: A small molecule library targeting epigenetic regulators was screened using an endogenous dual reporter system. We evaluated lead compounds in mouse and human CRC models via histopathology, cellular assays, epigenetic studies, mass-spectrometry-based histone modification profiling, and single cell RNA-sequencing. Integrative analyses of drug-induced chromatin dynamics, gene expression, target engagement, and histone marks elucidated molecular mechanisms. Focused genetic screens were conducted to identify regulators of HDAC1/2-mediated differentiation.
RESULTS: We found that inhibition of histone deacetylase (HDAC) 1/2 catalytic domain promotes CRC differentiation and suppresses tumor growth. Unbiased profiling of histone modifications identified H3K27ac and H3K9ac as critical regulatory marks, with genome-wide analyses demonstrating their enrichment at HDAC1/2-bound regions associated with open chromatin and upregulated differentiation genes. Disrupting H3K27ac by targeted degradation of acetyltransferase EP300 reversed the differentiation phenotype induced by HDAC1/2 inhibition in a patient-derived CRC organoid. Genetic screens revealed that DAPK3 contributes to H3K27ac-mediated CRC differentiation induced by HDAC1/2 inhibition.
CONCLUSIONS: Our findings establish histone acetylation as a chemically targetable mechanism governing CRC cell fate and demonstrate that epigenetic reprogramming can be leveraged as a therapeutic strategy. By identifying HDAC1/2 inhibition as a driver of differentiation and revealing H3K27ac as a key regulatory mark, this study provides a framework for targeting chromatin-modifying enzymes to counteract CRC plasticity and improve treatment outcomes.

Keywords:  colorectal cancer; epigenetic regulation; intestinal differentiation; stem cell

DOI:  https://doi.org/10.1053/j.gastro.2025.07.003
Int J Mol Med. 2025 Sep;pii: 137. [Epub ahead of print]56(3):

Histone deacetylase 6: A new player in oxidative stress‑associated disorders and cancers (Review).

Fei Qu, Qingqing Zhao, Yi Jin.

  Histone deacetylase 6 (HDAC6), a distinctive member of the histone deacetylase family, plays a crucial role in regulating the cellular response to oxidative stress. Unlike other HDACs, HDAC6 primarily deacetylates non‑histone proteins, influencing various cellular functions critical to the pathogenesis of numerous oxidative stress‑related diseases. This review summarizes the latest research on how HDAC6 affects oxidative stress pathways and its impact on diseases such as neurodegeneration, cancer and cardiovascular disorders. Additionally, the therapeutic potential of targeting HDAC6, as evidenced by preclinical trials, was discussed, suggesting that HDAC6 inhibitors can ameliorate symptoms and alter disease progression in numerous disease models. By elucidating the multifaceted roles of HDAC6 in oxidative stress and disease, the review aims to underscore its potential as a therapeutic target. This review enhances the understanding of HDAC6 and presents new opportunities for innovative treatment approaches that can address oxidative stress‑related illnesses.

Keywords:  HDAC6; aggresome‑autophagy pathway; protein homeostasis; reactive oxygen species

DOI:  https://doi.org/10.3892/ijmm.2025.5578
Haematologica. 2025 Jul 10.

The small GTPase ARF6 regulates sphingolipid homeostasis and supports proliferation in acute myeloid leukemia.

Helong Gary Zhao, Nataly Cruz-Rodriguez, Kent C Johnson, Anthony D Pomicter, Briana Bates, Benjamin Bateman, Torsten Haferlach, Tongjun Gu, Jonathan Ahmann, Dongqing Yan, Greg S Lee, Weiquan Zhu, Jenna Bishop, Shannon J Odelberg, Michael W Deininger.

Metabolic dependencies are emerging as promising therapy targets in cancer, including acute myeloid leukemia (AML). Several metabolic vulnerabilities have been identified in AML cells, including a requirement for balanced sphingolipid metabolism to maintain survival and proliferation. Here we describe a novel function of the RAS superfamily small GTPase ARF6 in maintaining sphingolipid homeostasis in AML. Genetic depletion of ARF6 inhibited the proliferation of AML cell lines and reduced colony formation of primary AML CD34+ cells. Mechanistically, ARF6 promotes conversion of ceramide to sphingomyelin by enhancing sphingomyelin synthase (SGMS1/2) expression, thereby preventing accumulation of cytotoxic ceramide levels. Accordingly, higher expression of ARF6 and its effectors SGMS1/2 in AML patient cells correlates with shorter survival in two independent AML cohorts, with ARF6 exhibiting an adverse prognostic effect independent of European Leukemia Net genetic risk. Small molecule inhibitors of ARF6 suppressed colony formation by primary AML CD34+ cells, but not cord blood CD34+ cells and showed activity in xenograft models. The dependency of AML cells on ARF6 to regulate sphingolipid homeostasis may present a therapeutic opportunity.

DOI: https://doi.org/10.3324/haematol.2024.286228
J Cell Commun Signal. 2025 Sep;19(3): e70031

Sirtuin 2 regulates NOD-like receptor protein 3/nuclear factor kappa B axis to promote cartilage repair in osteoarthritis.

Xiaotian Chen, Yining Song, Fan Zhang, Fangyan Hu, Zhenfei Ding, Jianzhong Guan.

  Osteoarthritis (OA) is a prevalent degenerative joint disease driven by inflammation and cartilage degradation. The NOD-like receptor protein 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) pathway are central to OA-associated inflammation. Sirtuin 2 (SIRT2), an NAD+-dependent deacetylase, regulates inflammation and oxidative stress but its role in OA is not fully understood. This study aims to elucidate how SIRT2 modulates the NLRP3/NF-κB signaling axis to promote cartilage repair in OA. In vivo and in vitro experiments were conducted using OA mouse models and chondrocyte cultures. Single-cell RNA sequencing was performed to identify differentially expressed genes, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. SIRT2's impact on NLRP3 and NF-κB was assessed using Western blotting (WB), real-time PCR, co-immunoprecipitation (Co-IP), and chromatin immunoprecipitation (ChIP-qPCR). SIRT2 was found to deacetylate NF-κB p65, inhibiting NLRP3 activation and reducing inflammatory cytokines. SIRT2 overexpression enhanced chondrocyte proliferation, DNA repair, and mitochondrial function while decreasing reactive oxygen species production. In vivo, SIRT2 significantly improved cartilage repair in OA mice with NLRP3 overexpression attenuating its protective effects. SIRT2 promotes cartilage repair in OA by regulating the NF-κB/NLRP3 axis, reducing inflammation and oxidative stress. This highlights SIRT2 as a potential therapeutic target for OA.

Keywords:  NF‐κB; NLRP3; cartilage repair; osteoarthritis; sirtuin 2

DOI:  https://doi.org/10.1002/ccs3.70031
Mol Cancer. 2025 Jul 08. 24(1): 193

Post-translational modifications of cancer immune checkpoints: mechanisms and therapeutic strategies.

Haiqing Jia, Lei Jiang, Xiaoyu Shen, Huinan Ye, Xinguang Li, Liwei Zhang, Yanyan Hu, Dandan Song, Hui Jia, Zhe Wang.

  Immunotherapies, particularly immune checkpoint inhibitors (ICIs), have revolutionized cancer clinical management, but low response rates and treatment resistance remain challenging. Protein post-translational modifications (PTMs) are critical for governing protein expression, localization, functions, and interactions with other cellular molecules, which notably build up the diversity and complexity of the proteome. A growing body of evidence supports that PTMs influence immunotherapy efficacy and outcomes by post-translationally modulating the expression and functions of immune checkpoints. Therefore, understanding the PTM mechanisms that govern immune checkpoints is paramount for developing novel treatment strategies to improve immunotherapy efficacy and overcome resistance. This review provides an overview of the current comprehension of the regulatory mechanisms by which PTMs (glycosylation, phosphorylation, ubiquitination, acetylation, succinylation, palmitoylation, lactylation, O-GlcNAcylation, UFMylation, and neddylation) modulate immune checkpoints to unveil potential therapeutic targets. Moreover, this review discusses the potential of therapeutic strategies targeting PTMs of immune checkpoints, providing insights into the combination treatment with ICIs in maximizing the benefits of immunotherapy and overcoming resistance.

Keywords:  Combination treatment; Immune checkpoints; Immunotherapy; Post-translational modifications; Treatment resistance

DOI:  https://doi.org/10.1186/s12943-025-02397-5