bims-toxgon 2026-04-05 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2026–04–05
27 papers selected by
Lakesh Kumar, BITS Pilani

The CLAMP-Linked Invasion Protein (CLIP) plays an essential role in Plasmodium berghei zoites.
A protein disulfide isomerase coordinates redox homeostasis and ER calcium regulation for optimal lytic cycle progression in Toxoplasma gondii.
Global translational and metabolic remodeling during iron deprivation in Toxoplasma gondii.
Translational control of Toxoplasma gondii differentiation.
Pharmacological inhibition of the MST2/Hippo signaling pathway mitigates Toxoplasma gondii-induced apoptosis and immunopathology in macrophage and mice liver.
Kinase inhibitors in organoid media influence Toxoplasma gondii growth and development.
A single-cell atlas of Toxoplasma sexual development in the feline intestinal tract.
Recent advances in Cryptosporidium secreted proteins.
A bridge-like lipid transfer protein is critical for generation of invasive stages in malaria parasites.
Kinetics and experimental parameters of oral Toxoplasma gondii infection in Syrian hamsters.
JmjC Histone Demethylases: Beyond Histone Lysine Demethylation.
Dynamic Lysine Acetylation Disrupts Isocitrate Lyase Function and Enables Metabolic Optimisation.
Lipophilic Pyrimethamine analogs with anti-toxoplasmosis activity.
Expanding Biological Roles of Post-translational Arginylation.
Cytosolic AcCoA: a metabolic signal bridging nutrient sensing and mitophagy.
The inositol pyrophosphate 5-InsP7 regulates mitochondrial polyphosphate synthesis and bioenergetic function.
Synthesis of a HDAC inhibitor-nanogold probe for cryo-EM visualization in class I HDAC co-repressor complexes.
Sex- and skeletal muscle-specific gene expression response of histone 3 lysine 27-modifying enzymes by voluntary running in mice.
Epigenetic insights of microRNAs: Pioneering cancer detection via advanced biosensors.
Epigenetic regulation via histone modifications in ovarian cancer.
Interplay of SLC33A1-dependent and -independent Golgi sialic acid O-acetylation in CASD1 catalysis.
Targeting Plasmodium falciparum with purine antimetabolites as a therapeutic strategy.
Ion Activation Methods for Top-Down Proteomics.
ERN1-dependent regulation of BAG cochaperone 1 expression and the sensitivity to glutamine deprivation in U87MG glioblastoma cells.
The Sirt2-Nur77 axis regulates muscle stem cell quiescence and senescence via epigenetic-metabolic synergy.
Post-transcriptional regulatory networks: The dynamic interplay of RNA-binding proteins.
Protein lactylation: a metabolic signal driving cancer therapy resistance.

bioRxiv. 2026 Mar 23. pii: 2026.03.22.713516. [Epub ahead of print]

The CLAMP-Linked Invasion Protein (CLIP) plays an essential role in Plasmodium berghei zoites.

Tanaya Unhale, Samhita Das, Carine Marinach, Sylvie Briquet, Jean-François Franetich, Lien Boeykens, Yann G-J Sterckx, Olivier Silvie.

Apicomplexan parasites such as Toxoplasma and Plasmodium spp. rely on the sequential secretion of parasite apical organelles, called micronemes and rhoptries, to invade host cells. The claudin-like apicomplexan microneme protein (CLAMP) is a conserved protein that plays an essential role during host cell invasion in Toxoplasma and Plasmodium zoites. Previous studies have shown that CLAMP is essential in Plasmodium merozoites for erythrocyte invasion and also in sporozoites for the invasion of the mosquito vector salivary glands and of mammalian host hepatocytes. In Toxoplasma gondii tachyzoites, CLAMP forms a complex with two other microneme proteins, the Secreted Protein with an Altered Thrombospondin Repeat (SPATR) and the CLAMP-Linked Invasion Protein (CLIP). Both SPATR and CLIP are also expressed in Plasmodium sporozoites, and downregulation of SPATR impacts sporozoite infectivity in P. berghei . In contrast, the role of CLIP in sporozoites remains unknown. To study the function of CLIP, we used a CRISPR-assisted conditional genome editing strategy based on the dimerisable Cre recombinase in the rodent malaria model parasite P. berghei . Deletion of clip in P. berghei blood stages impaired parasite growth and prevented erythrocyte invasion by merozoites. Upon deletion of clip gene in P. berghei transmission stages, sporozoite development in mosquitoes was not affected, but invasion of the mosquito salivary glands was dramatically reduced. In addition, CLIP-deficient sporozoites were impaired in cell traversal and productive invasion of mammalian hepatocytes, associated with a defect in gliding motility, recapitulating the phenotype of CLAMP-deficient parasites. Collectively, our data demonstrate that CLIP plays an essential role in host cell invasion by P. berghei merozoites and sporozoites, and support a conserved role of the CLAMP-CLIP-SPATR complex in invasive stages of apicomplexan parasites.

DOI: https://doi.org/10.64898/2026.03.22.713516
mBio. 2026 Apr 01. e0312425

A protein disulfide isomerase coordinates redox homeostasis and ER calcium regulation for optimal lytic cycle progression in Toxoplasma gondii.

Katherine E Moen, Silvia N J Moreno.

  The endoplasmic reticulum (ER) maintains an oxidative environment that facilitates the formation of disulfide bonds, a critical process for proper protein folding. Protein disulfide isomerases (PDIs) are ER-resident enzymes that facilitate the formation, breakage, and rearrangement of disulfide bonds between cysteine residues, thereby stabilizing protein structures. Although PDIs are functionally diverse, they all contain at least 1 thioredoxin-like domain and most mediate disulfide exchange through their conserved CXXC motifs. The apicomplexan parasite, Toxoplasma gondii, infects approximately one-third of the world population, posing a significant risk to immunosuppressed individuals and unborn fetuses. The fast-replicating tachyzoite form engages in a lytic cycle, causing host tissue damage and contributing to pathogenesis. While approximately 26 PDIs are predicted to be present in T. gondii, their specific roles remain largely unexplored. In this study, we investigate TgPDIA3, a T. gondii PDI localized to the ER, along with several of its interacting protein substrates. We explore its role in ER redox activity and calcium sequestration and assess how these functions contribute to the parasite's lytic cycle.IMPORTANCEThe lytic cycle of Toxoplasma gondii is critical for parasite dissemination and disease progression in the host. Calcium signaling plays a crucial role in driving these processes; however, the molecules that control calcium storage and release remain poorly understood. The endoplasmic reticulum, likely the largest calcium reservoir in T. gondii, has been understudied in the context of calcium signaling. Here, we uncover a direct link between ER redox regulation and calcium homeostasis, showing that ER redox activity can influence calcium signaling events that govern microneme protein maturation and secretion, parasite invasion, and replication. Our findings indicate that redox-dependent calcium regulation in the ER contributes to control of the parasite lytic cycle and reveals a previously unrecognized mechanism that may influence parasite virulence.

Keywords:  SERCA; Toxoplasma gondii; calcium homeostasis; endoplasmic reticulum; protein disulfide isomerase; redox regulation

DOI:  https://doi.org/10.1128/mbio.03124-25
mBio. 2026 Apr 02. e0378825

Global translational and metabolic remodeling during iron deprivation in Toxoplasma gondii.

Jack C Hanna, Shikha Shikha, Megan A Sloan, Clare R Harding.

  Iron is required to support essential cellular processes. Due to diverse and dynamic host environments, the obligate intracellular parasite Toxoplasma gondii must adapt to iron-limited conditions. To investigate the adaptations critical to parasite survival under these conditions, we conducted proteomic and metabolomic profiling of Toxoplasma cultured in iron-depleted conditions. We find that iron depletion results in remodeling of the parasite proteome and triggers swift translational repression, prior to decreases in the key translational factor ABCE1. In the context of repressed translation, we also observe a significant rewiring of energy metabolism. Iron-depleted Toxoplasma have altered mitochondrial morphology and a profound reduction in mitochondrial respiration. Untargeted metabolomics revealed changes in central carbon metabolism, with the accumulation of intermediates of glycolysis and the tricarboxylic acid (TCA) cycle. Stable isotope labeling revealed that iron deprivation leads to a fundamental disconnect between these pathways, with reduced incorporation of glucose-derived carbon into cellular macromolecules and disruption of the TCA cycle. Instead, iron-deprived parasites continued to take up glucose and maintain glycolysis for energy generation. Limiting glucose availability, either in culture media or by genetic ablation of glucose uptake, caused a significant increase in sensitivity to iron restriction. Conversely, the limitation of mitochondrially metabolized glutamine improved parasite fitness in iron-depleted conditions. Together, our results establish iron as a key regulator of parasite translation and metabolic flexibility and demonstrate an increased reliance on glycolysis for energy generation and survival under acute iron deprivation.IMPORTANCEThis study determines the effects of iron deprivation on the parasite Toxoplasma gondii. Using proteomics and metabolomics, we reveal iron as a novel regulator of both protein translation and energy metabolism in Toxoplasma, underpinning the importance of this nutrient for essential cellular processes. We find that iron depletion introduces a metabolic bottleneck, whereby parasites become dependent on glucose as their major carbon source. By modulating the parasite's metabolism by altering carbon source availability, we identify nutrient conditions that improve parasite survival under iron restriction. These data reveal a key role for adaptive plasticity of Toxoplasma central carbon metabolism to drive survival under iron-limited conditions. Understanding the interactions between parasite nutrient availability and metabolism allows us both to map the metabolic flexibility of these parasites and identify potential vulnerabilities.

Keywords:  Toxoplasma gondii; carbon metabolism; iron metabolism; iron regulation; mitochondrial metabolism; proteomics; translation

DOI:  https://doi.org/10.1128/mbio.03788-25
Biosci Rep. 2026 Apr 22. pii: BSR20253672. [Epub ahead of print]46(4):

Translational control of Toxoplasma gondii differentiation.

Fengrong Wang.

  Toxoplasma gondii is a globally prevalent protozoan parasite capable of establishing lifelong infections in its host. While acute infection is often asymptomatic, reactivation of latent bradyzoites can cause severe disease, particularly in immunocompromised individuals. Current therapies are ineffective against chronic infection, underscoring critical gaps in our understanding of bradyzoite biology and the molecular mechanisms governing stage conversion. Recent studies have identified translational control as a central regulator of T. gondii differentiation. This review highlights the roles of canonical translation initiation factors (eIF2α, eIF1.2, and eIF4E1), RNA-binding proteins (RBPs; BFD2/ROCY1, Alba1, and Alba2), and RNA modifications (with pseudouridylation representing the best-characterized modification currently linked to differentiation), as well as alternative splicing and non-coding RNAs in shaping stage-specific translational programs. This review further discusses underexplored mechanisms, including non-canonical initiation pathways, upstream open reading frames, transcript-level RNA modifications, ribosome heterogeneity and rRNA modifications, elongation and termination control, uncharacterized RBPs, and post-translational modifications of translation factors, that may coordinate proteome remodeling during differentiation. Together, established translational regulators and these emerging pathways highlight translational control as a central driver of parasite persistence and a promising therapeutic target for chronic toxoplasmosis.

Keywords:  Alternative splicing; Cell differentiation; Non-coding RNA; RNA editing; RNA-binding proteins; Toxoplasma gondii; Translation; Translation factors

DOI:  https://doi.org/10.1042/BSR20253672
Biochem Pharmacol. 2026 Apr 01. pii: S0006-2952(26)00277-7. [Epub ahead of print] 117944

Pharmacological inhibition of the MST2/Hippo signaling pathway mitigates Toxoplasma gondii-induced apoptosis and immunopathology in macrophage and mice liver.

Kangzhi Xu, Qiangqiang Zheng, Mingyue Zu, Jing Ma, Wentai Xia, Dandan Liu, Yanhong Wang, Xinjun Zhang, Siyang Huang, Jinjun Xu, Jin Yang, Darong Cheng, Zhiming Pan, Jianping Tao, Zhaofeng Hou.

  Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that manipulates host cell apoptosis and inflammation to support its survival and replication. Our previous work demonstrated that T. gondii activates the Hippo signaling pathway through phosphorylation of mammalian STE20-like protein kinase 2 (MST2), thereby promoting host cell apoptosis. However, the impact of Hippo pathway inhibition on apoptosis, inflammation, and host protection during infection remains unclear. Here, we demonstrate that T. gondii infection induces apoptosis in RAW264.7 macrophages and causes acute liver injury in mice, accompanied by increased levels of inflammatory cytokines. These changes were associated with decreased total protein levels of MST2, large tumor suppressor homolog 1 (LATS1), and Yes-associated protein (YAP), but increased phosphorylation of these Hippo components. Treatment with XMU-MP-1, a selective MST1/2 inhibitor, alleviated apoptosis, dampened macrophage-mediated excessive inflammation, reduced liver damage and parasite burden, and prolonged survival in acutely infected mice. These findings provide the first direct evidence that pharmacological inhibition of the Hippo signaling pathway mitigates T. gondii-induced apoptosis and immunopathology. Our results highlight the potential of XMU-MP-1 as a host-directed therapeutic strategy. Its efficacy against T. gondii in combination with antiparasitic agents may have remarkable clinical application value.

Keywords:  Apoptosis; Hippo signaling pathway; Inflammation; Liver damage; Toxoplasma gondii; XMU-MP-1

DOI:  https://doi.org/10.1016/j.bcp.2026.117944
Microbiol Spectr. 2026 Apr 03. e0347225

Kinase inhibitors in organoid media influence Toxoplasma gondii growth and development.

Katie M Cataldo, Nicole M Davis, Laura J Knoll.

  Toxoplasma gondii is a widespread parasite that impacts both human and animal health. Increasing use of organoid model systems has made previously challenging aspects of the T. gondii lifecycle more accessible. The media for these organoid systems are highly complex with many growth factors and pathway inhibitors that promote stem cell retention or differentiation of the cells. We noticed changes in T. gondii growth and development in our intestinal organoid system and wanted to determine if this was driven by cell type or media components. We found that low concentrations of SB202190 (a p38 MAPK inhibitor) and A83-01 (an ALK 4/5/7 receptor inhibitor) are each sufficient to alter T. gondii growth even in fibroblast cells. Further investigation with our qPCR panel of T. gondii stage markers revealed that these compounds promote bradyzoite cyst development and prime parasites for pre-sexual and sexual stage gene expression. As these complex organoid systems become more common in microbiology research, this study highlights the role of organoid media components in controlling pathogen growth and development.
IMPORTANCE: The use of complex cell culture model systems is becoming more common across many fields. Maintenance of these systems often includes growth factors and inhibitors not found in standard media. These added components have the potential to impact pathogen growth and development and can influence how experimental results may be interpreted. This study improves our understanding of the Toxoplasma gondii lifecycle in one of those systems. It also serves as a template for other pathogen researchers to consider influences within their own systems.

Keywords:  Toxoplasma gondii; fibroblast; kinase inhibition; media; organoid

DOI:  https://doi.org/10.1128/spectrum.03472-25
bioRxiv. 2026 Mar 25. pii: 2025.10.31.685900. [Epub ahead of print]

A single-cell atlas of Toxoplasma sexual development in the feline intestinal tract.

Hisham S Alrubaye, Sarah M Reilly, Rafaela da Silva, NyJaee Washington, Jon P Boyle.

Toxoplasma gondii undergoes sexual development exclusively in the feline intestine, a process critical for genetic diversity and population expansion. Recent studies have identified genes critical in suppressing presexual development and metabolic differences in felines that may promote sexual development, but to date the gene regulatory networks driving development in the cat are unknown. To investigate this, we performed single-cell transcriptomics on parasites isolated from cat intestines, using fluorescent reporter strains and flow cytometry. From 15,068 cells across two experiments, we identified rare populations, including cells that bear all of the hallmarks of gametes. Candidate genes emerging from this study were tested via CRISPR-Cas9 Perturb-seq, identifying AP2X6 as a regulator of macrogametocyte development. Our single-cell data extends what is known about gene expression changes throughout sexual development and should be useful to those in the field working towards inducing gametogenesis, mating, and oocyst production in vitro .

DOI: https://doi.org/10.1101/2025.10.31.685900
Curr Opin Microbiol. 2026 Mar 31. pii: S1369-5274(26)00040-8. [Epub ahead of print]91 102746

Recent advances in Cryptosporidium secreted proteins.

Annet Puthenpurackal, Amandine Guérin.

As an apicomplexan parasite, Cryptosporidium possesses the conserved secretory organelles, micronemes, rhoptry and dense granules in addition to the unique small granules. These specialized organelles house various effectors that are secreted upon invasion, helping to establish cryptosporidiosis, a leading cause of severe diarrhea among children. Only recently has its proteome been defined, laying the foundation to unravel host-parasite interactions that are poorly understood in Cryptosporidium. Recent technical advances in genetic manipulation have helped elucidate the role of a few secreted effectors, highlighting the possibility of exploiting them in our journey to fight the disease.

DOI: https://doi.org/10.1016/j.mib.2026.102746
Nat Commun. 2026 Mar 28. pii: 3030. [Epub ahead of print]17(1):

A bridge-like lipid transfer protein is critical for generation of invasive stages in malaria parasites.

Andrés Guillén-Samander, Nika Perepelkina, Vendula Horáčková, Hannah M Behrens, Hely O Rodriguez Cruz, Joëlle Paolo Mesén-Ramírez, Ana Ribeiro-Holbein, Per Haberkant, Frank Stein, Tobias Spielmann.

Malaria blood stages build and maintain an intricate system of membranes during their cycle of rapid growth and schizogony (daughter-cell formation), requiring precise mechanisms of lipid synthesis and trafficking. Lipid transfer proteins (LTPs) at ER membrane contact sites (MCSs) have emerged as key for lipid distribution processes but remain largely unexplored in protozoans. Here we use the ER adapter VAP to identify essential mechanisms of lipid transfer at ER-MCSs in P. falciparum. One PfVAP-interacting LTP is the bridge-like PfVPS13L1, which allows bulk flow of lipids between two apposed membranes. PfVPS13L1 bridges the ER with the nascent inner membrane complex (IMC), a de novo-generated organelle required for schizogony. Its loss-of-function reduces IMC growth and leads to smaller anucleated progeny, impairing schizogony. Our data supports a model in which VPS13L1 is critical for the formation of apicomplexan invasive stages by mediating bulk transfer of lipids from the ER to the growing IMC.

DOI: https://doi.org/10.1038/s41467-026-70887-1
Vet Parasitol. 2026 Mar 30. pii: S0304-4017(26)00076-2. [Epub ahead of print]344 110757

Kinetics and experimental parameters of oral Toxoplasma gondii infection in Syrian hamsters.

Talita Rodrigues Dos Santos, Jorge Lucas Nascimento Souza, Luis Fernando Viana Furtado, Maira do Santos Carneiro Lacerda, Letícia Pereira Lopes, Mike Dos Santos, Roselene Ecco, Érica Dos Santos Martins-Duarte, Élida Mara Leite Rabelo.

  Toxoplasma gondii is a globally prevalent intracellular parasite. Although mice are widely used as experimental models for toxoplasmosis, reliance on a single host species may limit the understanding of host-parasite interactions across different biological contexts. The Syrian hamster (Mesocricetus auratus) presents physiological and immunological characteristics that warrant evaluation as an alternative experimental model. This study aimed to characterize the kinetics of oral T. gondii infection in Syrian hamsters and to define experimental parameters, including host age and inoculum size, under controlled conditions. Hamsters aged 6-8 and 20 weeks were orally infected with sublethal doses (5, 10, or 20 cysts) of either the Brazilian atypical strain CTBr5 (ToxoDB#8) or the clonal ME49 strain (ToxoDB#1) to assess dose- and age-related susceptibility. Based on survival and parasite detectability, 6-8-week-old hamsters infected with 20 cysts were selected for kinetic analyses. Parasite dissemination was monitored in the lungs, spleen, liver, brain, and eyes at 3, 7, 15, and 30 days post-infection using quantitative PCR and histopathology. Both strains established infection without mortality under the tested conditions. CTBr5 infection was associated with prolonged parasite persistence in peripheral tissues and a delayed increase in brain parasite load, whereas ME49 showed earlier detection in neural tissue. By 30 days post-infection, brain parasite burdens were comparable between strains. Histopathological analysis confirmed cyst presence and inflammatory alterations during early chronic infection. These findings define reproducible experimental parameters and describe the temporal dynamics of oral T. gondii infection in Syrian hamsters under the tested strains and conditions, providing reference data for future studies using this species.

Keywords:  Oral infection; Parasite dissemination; Syrian hamster; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.vetpar.2026.110757
Chimia (Aarau). 2026 Mar 25. 80(3): 138-144

JmjC Histone Demethylases: Beyond Histone Lysine Demethylation.

Joanna Bonnici, Christopher J Schofield, Akane Kawamura.

  Jumonji C histone lysine demethylases (JmjC-KDMs) are key chromatin regulators best known for catalysing histone lysine demethylation. There is growing evidence that JmjC-KDMs have a broader catalytic scope. This review summarises recent advances on JmjC-KDM activities beyond histone lysine demethylation, including arginine demethylation and arginine hydroxylation. We discuss how emerging insights into sequence-reactivity and inter-domain relationships, combinatorial post-translational modifications (PTMs), and cellular context shape substrate selectivity and enzymatic outcomes. These findings highlight substantial mechanistic flexibility within the JmjC-KDM family and may help prompt reconsideration of how their biochemistry is connected to physiological roles. We discuss implications for JmjC-KDM inhibitor development and outline outstanding questions, guiding future research concerning their roles in epigenetic regulation.

Keywords:  2-oxoglutarate (2OG) dependent oxygenases; Argine demethylation / hydroxylation; Cancer metabolism; Epigenetics; JmjC histone demethylases; JmjC-KDMs

DOI:  https://doi.org/10.2533/chimia.2026.138
Microb Biotechnol. 2026 Apr;19(4): e70334

Dynamic Lysine Acetylation Disrupts Isocitrate Lyase Function and Enables Metabolic Optimisation.

Adrián Martínez-Vivancos, Beatriz Gomariz-Turpin, Gema Lozano-Terol, Rosa Alba Sola-Martínez, Álvaro Ortega, Julia Gallego-Jara, Teresa de Diego Puente.

  Proteomic studies have suggested that Escherichia coli isocitrate lyase (ICL) undergoes multiple acetylation events, partially inhibiting its activity. However, the molecular basis of this regulation and the contribution of individual lysine residues had not been defined. This study demonstrates that acetylation of ICL in E. coli is acetyl-phosphate-dependent and reversible by the CobB deacetylase, establishing a key post-translational regulatory mechanism within the glyoxylate shunt. Site-specific acetylation at K13 and K308 inhibits ICL activity by destabilising the tetrameric assembly and rendering the protein more prone to degradation, whereas lysine-to-arginine substitutions at these positions alleviate this inhibition, enhancing carbon flux distribution, metabolic flexibility and biomass yield without the burden of plasmid-based overexpression. Leveraging this regulatory insight, a KR mutant bearing lysine-to-arginine substitutions at residues 13 and 308, engineered directly into the chromosomal aceA gene, maintained wild-type growth rates while reducing acetate overflow and improving metabolic balance during glucose depletion and acetate assimilation, leading to a 61% increase in lycopene production. These findings highlight regulatory-based metabolic engineering as a powerful strategy to optimise bioproduction and pave the way for extending this approach to other central metabolic enzymes to develop robust microbial cell factories for the sustainable synthesis of biofuels, biochemicals and high-value compounds.

Keywords:  genetic code expansion; glyoxylate cycle; isocitrate lyase; lysine acetylation; post‐translational modification

DOI:  https://doi.org/10.1111/1751-7915.70334
Infect Genet Evol. 2026 Mar 28. pii: S1567-1348(26)00059-6. [Epub ahead of print]140 105935

Lipophilic Pyrimethamine analogs with anti-toxoplasmosis activity.

Darin Kongkasuriyachai, Khuanchai Koompapong, Nongnaput Tuyapala, Marie Hoarau, Tararat Jantra, Jutharat Pengon, Yuwadee Talawanich, Lokachet Tanasugarn, Sasithorn Decharuangsilp, Uthai Arwon, Jarunee Vanichtanankul, Yongyuth Yuthavong, Sumalee Kamchonwongpaisan, Aongart Mahittikorn.

  Toxoplasmosis remains a threat for neonates and immuno-compromised populations, against which only broad spectrum antiparasitic drugs are currently available. Here, a virtual screen was conducted on a Plasmodium falciparum dihydrofolate reductase (DHFR) inhibitor library to identify novel Toxoplasma gondii DHFR inhibitors. Three hit compounds were identified, showing nM-range in vitro activity against T. gondii and high selectivity compared to mammalian cells. All compounds are highly lipophilic. However, the most promising compounds, P12 and P33, did not exhibit significantly lower parasite burden of RH-T. gondii from infected mice in a 4-day suppressive test. Although P33-treated mice appeared to have longer median survival time compared to vehicle control group, the survival time was still shorter than the survival time in the pyrimethamine-treated group. Nonetheless, the promising activity of our compounds can guide further anti-toxoplasmosis drug development.

Keywords:  DHFR inhibitor; Drug development; Drug screening; Infectious diseases; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.meegid.2026.105935
Chimia (Aarau). 2026 Mar 25. 80(3): 130-137

Expanding Biological Roles of Post-translational Arginylation.

Dominic Scopelliti, Changfeng Deng, Benjamin A Garcia, Zongtao Lin.

  Protein arginylation is a conserved post-translational modification in eukaryotes, involving the conjugation of arginine residues to proteins by the enzyme arginyl-tRNA transferase. Historically associated with targeted degradation, recent studies have expanded this view by uncovering its broader regulatory influence across diverse cellular functions. This review first examines the established roles of arginylation in protein degradation through the Ubiquitin-Proteasome System and Autophagy-Lysosome System. It then highlights its non-degradative functions, including the modulation of protein-protein interactions, complex assembly, protein stability, and crosstalk with other post-translational modifications. Emerging evidence supports the notion that arginylation functions in a context dependent manner, simultaneously affecting both the stability and functional behaviour of proteins. Together, these works reveal arginylation as a dynamic and versatile mechanism that extends well beyond proteolysis, positioning it as a key global regulator of cellular functioning.

Keywords:  Arginylation; Biology; Degradation; Non-degradative functions; Post-translational modification

DOI:  https://doi.org/10.2533/chimia.2026.130
Trends Biochem Sci. 2026 Mar 28. pii: S0968-0004(26)00007-1. [Epub ahead of print]

Cytosolic AcCoA: a metabolic signal bridging nutrient sensing and mitophagy.

Jiayi Chen, Xin Pan.

  How cells sense energy status to precisely regulate organelle fate is a central question in life sciences. Recent work by Zhang et al. reframes cytosolic acetyl-coenzyme A (AcCoA) from a metabolic substrate into a signaling metabolite that directly regulates mitophagy, thereby establishing a molecular link between nutrient sensing and mitochondrial homeostasis.

Keywords:  NLRX1; cytosolic AcCoA; mitophagy

DOI:  https://doi.org/10.1016/j.tibs.2026.01.007
J Biol Chem. 2026 Mar 31. pii: S0021-9258(26)00283-8. [Epub ahead of print] 111413

The inositol pyrophosphate 5-InsP7 regulates mitochondrial polyphosphate synthesis and bioenergetic function.

Jayashree S Ladke, Azmi Khan, Anshit Singh, Henning J Jessen, Ullas Kolthur-Seetharam, Manish Jaiswal, Rashna Bhandari.

  Inorganic polyphosphate (polyP) is a linear polymer of phosphate residues linked by phosphoanhydride bonds. PolyP remains poorly understood in mammals due to its low abundance and lack of information on its metabolism. We developed a DAPI fluorescence-based assay to quantify the low levels of polyP present in mammalian cell lines and tissues, detecting an enrichment of polyP in the mitochondria compared with the nucleus and post-mitochondrial fraction. Mitochondrial polyP synthesis was found to depend on active FoF1 ATP synthase and an intact proton gradient across the inner mitochondrial membrane. Additionally, orthophosphate (Pi) is essential for mitochondrial polyP production, and ATP enhances Pi-driven polyP synthesis in isolated mitochondria. We discovered that the inositol pyrophosphate 5-InsP7, synthesized by IP6K1, regulates mitochondrial polyP levels. Mice and cells deficient in IP6K1 showed a significant reduction in mitochondrial polyP synthesis compared with wild type controls. Cells lacking IP6K1 also showed impaired mitochondrial respiration. The expression of active IP6K1, but not its catalytically inactive form, restored mitochondrial polyP synthesis in IP6K1 deficient cells, but mitochondrial respiration was rescued by expression of either active or inactive IP6K1. These data show that IP6K1 regulates mitochondrial function and polyP production both through the synthesis of 5-InsP7 and via a catalytic activity-independent mechanism. Our findings uncover a link between 5-InsP7, an energy sensor, and polyP, an energy store, in the regulation of mammalian mitochondrial homeostasis.

Keywords:  ATP synthase; cell metabolism; inorganic polyphosphate; inositol phosphate; inositol pyrophosphates; mitochondria; mitochondrial membrane potential; mitochondrial respiration

DOI:  https://doi.org/10.1016/j.jbc.2026.111413
Beilstein J Org Chem. 2026 ;22 480-485

Synthesis of a HDAC inhibitor-nanogold probe for cryo-EM visualization in class I HDAC co-repressor complexes.

Wiktoria A Pytel, John W R Schwabe, James T Hodgkinson.

  Class I histone deacetylases (HDACs 1-3) serve as catalytic subunits within seven multiprotein co-repressor complexes, each of which has distinct functions in the cell. We report the synthesis of a HDAC inhibitor-nanogold probe, derived from the class I HDAC inhibitor CI-994, for cryo-electron microscopy (cryo-EM) visualization of the HDAC catalytic domain within class I HDAC co-repressor complexes. The nanogold probe retained HDAC inhibitory activity comparable to CI-994 against the HDAC1-LSD1-CoREST complex in vitro. In cryo-EM studies, 2D class averages revealed the bi-lobed architecture of the CoREST complex and partial localization of the gold nanoparticle probe to the CoREST complex. However, the probe was not observed in classes showing the side-view of the CoREST complex, limiting unambiguous identification and positioning of the HDAC catalytic domain within the CoREST complex.

Keywords:  CI-994; CoREST; HDAC; co-repressor complex; cryo-EM; gold nanoparticle

DOI:  https://doi.org/10.3762/bjoc.22.35
Physiol Rep. 2026 Apr;14(7): e70853

Sex- and skeletal muscle-specific gene expression response of histone 3 lysine 27-modifying enzymes by voluntary running in mice.

Daniel Gamu, Makenna Cameron, Yasmeen Jalil, Imen Zouaoui, Jada Sangha, Jonathan Kim.

  Skeletal muscle is highly plastic and capable of remodeling its contractile and metabolic properties depending on physical demands. Such remodeling requires modification of chromatin structure to support transcriptional activation and repression of gene programs. Chromatin dynamics depend, in part, on the acetylation and methylation of histone 3 lysine 27 (H3K27), which is controlled by several enzymes that add and remove these histone marks. Several histone post-translational modifications in muscle have been shown to be modulated by exercise. Here, we sought to examine whether major H3K27 regulators themselves are altered by endurance training. Male and female C57BL/6J mice were provided with voluntary running wheels for 6 weeks and compared to sex-matched sedentary controls with locked running wheels. We found that exercise altered gene expression of epigenetic machinery responsible for regulating acetylation and methylation enrichment in both a muscle- and sex-specific manner, including major H3K27 acetyltransferases and core components of the polycomb repressive complex-2. Our findings add to a growing body of evidence implicating H3K27 post-translational modifications, and thereby chromatin dynamics, as a mechanistic component of exercise-induced muscle remodeling.

Keywords:  exercise; histone acetylation/methylation; muscle adaptation; skeletal muscle

DOI:  https://doi.org/10.14814/phy2.70853
Int Rev Cell Mol Biol. 2026 ;pii: S1937-6448(25)00021-8. [Epub ahead of print]400 31-62

Epigenetic insights of microRNAs: Pioneering cancer detection via advanced biosensors.

P P Ashikha Shirin Usman, Durairaj Sekar.

  The epigenetic landscape of cancer reveals how microRNAs (miRNAs) regulate gene expression through epigenetic mechanisms, alongside advancements in miRNA-based biosensor technology for early detection. Epigenetics, which studies heritable gene function changes without altering DNA sequences, has transformed our understanding of cancer by highlighting the complex interaction between genetics and environment. Key mechanisms such as DNA methylation, histone modification, and chromatin remodelling shape gene expression and cellular identity, with dysregulation in these processes often marking cancer development. Within this framework, miRNAs act as crucial epigenetic regulators, influencing gene expression post-transcriptionally and functioning as either oncogenes (oncomiRs) or tumour suppressors. miRNAs interact with epigenetic modifiers like histone deacetylases (HDACs) and DNA methyltransferases (DNMTs), creating regulatory networks that affect cancer cell behaviours such as proliferation, differentiation, and apoptosis. To apply these molecular insights, the chapter reviews innovations in miRNA-targeting biosensors. Electrochemical and photoelectrochemical biosensors, enhanced with nanotechnology, are designed to detect miRNAs at ultra-low concentrations in biological fluids, addressing limitations of conventional cancer diagnostics. These biosensors offer high sensitivity, specificity, and point-of-care potential, with benefits such as rapid response, cost-efficiency, and miniaturization. Case studies showcase miRNA-based biosensors targeting cancer-related miRNAs, underscoring their promise in early cancer detection and monitoring. By bridging epigenetics, miRNA regulation, and biosensor technology, these emerging diagnostic tools offer new possibilities for improving cancer diagnosis and patient outcomes.

Keywords:  RISC; mRNA; miRNA; pre-miRNA; pri-miRNA

DOI:  https://doi.org/10.1016/bs.ircmb.2025.01.008
Int Rev Cell Mol Biol. 2026 ;pii: S1937-6448(25)00109-1. [Epub ahead of print]400 107-134

Epigenetic regulation via histone modifications in ovarian cancer.

Junzui Li, Hao Huang.

  Ovarian cancer is a highly heterogeneous and lethal gynecological malignancy, with its progression tightly regulated by both genetic and epigenetic mechanisms. Among the epigenetic regulators, histone modifications-including acetylation, methylation, phosphorylation, ubiquitination, and SUMOylation-have emerged as pivotal modulators of chromatin architecture and gene transcription. These post-translational modifications, governed by specific histone-modifying enzymes, shape the transcriptional landscape of tumor cells and influence key oncogenic processes such as cellular proliferation, invasion, stemness, DNA repair, and chemotherapy resistance. Dysregulation of enzymes such as histone acetyltransferases (HATs), deacetylases (HDACs), methyltransferases (HMTs), demethylases (HDMs), ubiquitin ligases, and SUMO ligases has been implicated in the pathogenesis of ovarian cancer and is associated with adverse clinical outcomes. Importantly, these modifications are reversible, rendering them tractable therapeutic targets. This review provides a comprehensive synthesis of the major classes of histone modifications and their biological functions in ovarian cancer, highlights recent insights into the interplay between different modifications (crosstalk), and evaluates ongoing therapeutic strategies that aim to reverse epigenetic dysregulation. By elucidating the complex epigenetic landscape, this review supports the development of next-generation diagnostic, prognostic, and therapeutic approaches in ovarian cancer.

Keywords:  Histone modification; Ovarian cancer

DOI:  https://doi.org/10.1016/bs.ircmb.2025.08.003
Nat Commun. 2026 Apr 01. pii: 3156. [Epub ahead of print]17(1):

Interplay of SLC33A1-dependent and -independent Golgi sialic acid O-acetylation in CASD1 catalysis.

Malena Albers, Lydia Bosse, Larissa Schröter, Anna-Maria T Junemann, Charlotte Rossdam, Maike Hartmann, Melanie Grove, Thomas Litfin, Anna-Sophia Egger, Marcel Kwiatkowski, Kathrin Thedieck, Georg Zocher, Falk F R Buettner, Alpeshkumar K Malde, Mark von Itzstein, Martina Mühlenhoff.

Sialic acid O-acetylation is implicated in the modulation of sialoglycan recognition and ganglioside biology. The sugar modification is catalyzed by CASD1, a Golgi membrane protein that encompasses a luminal catalytic domain and a multipass transmembrane domain. The mechanism of how acetyl-CoA is provided to the Golgi remains poorly understood. Here, we show that the acetyl-CoA transporter SLC33A1 provides acetyl-CoA to the luminal domain of CASD1 and that patient-derived SLC33A1 variants linked to inherited neurodevelopmental and neurodegenerative disorders impair ganglioside 9-O-acetylation. Under conditions that enable the formation of 7,9-di-O-acetylated sialoglycans, genetic inactivation of SLC33A1 impaired di-O-acetylation, but unexpectedly, still enabled mono-O-acetylation. Structure prediction and site-directed mutagenesis revealed a second active site in CASD1 that shares striking similarities with the catalytic acetyl-CoA binding transmembrane tunnel of the lysosomal acetyltransferase HGSNAT. Together, our data provide strong evidence that CASD1 has dual functionalities and catalyzes 7,9-di-O-acetylation through SLC33A1-dependent luminal acetylation and SLC33A1-independent transmembrane acetylation.

DOI: https://doi.org/10.1038/s41467-026-71333-y
Front Microbiol. 2026 ;17 1773050

Targeting Plasmodium falciparum with purine antimetabolites as a therapeutic strategy.

Worlanyo Tashie, Harry P de Koning, Nancy O Duah-Quashie, Neils B Quashie.

  Plasmodium falciparum lacks the de novo purine biosynthesis pathway and relies exclusively on salvaging free purines from the host to meet its metabolic requirements. This absolute dependence on the purine salvage pathway provides a compelling opportunity for antimalarial drug development, particularly in the face of rising resistance to current therapies. Although the purine salvage system has been extensively studied as a potential drug target in P. falciparum, no purine-based antimalarial drug has yet reached clinical use. In this review, we summarize the potential of targeting the purine salvage pathway in antimalarial drug development, with a focus on strategies that leverage P. falciparum Equilibrative Nucleoside Transporters (Pf ENTs) as conduits for therapeutic agents. Purine analogs that efficiently enter P. falciparum-infected erythrocytes, reach Pf ENTs, and undergo selective activation within the parasite can disrupt purine metabolism and nucleic acid synthesis, ultimately leading to parasite death. The Pf ENTs therefore offer a unique and viable route for delivering purine-based analogs into the parasite. Such approaches provide a framework for target-based design of purine-analog-based antimalarial therapies.

Keywords:  Pf ENT; drug discovery; drug transporter; nucleotide metabolism; plasmodium falciparum; purine antimetabolites

DOI:  https://doi.org/10.3389/fmicb.2026.1773050
Mass Spectrom Rev. 2026 Mar 31.

Ion Activation Methods for Top-Down Proteomics.

Jada N Walker, Jennifer S Brodbelt.

  Mass spectrometry (MS) has emerged as a premier method used to characterize the sequences of proteins. Top-down proteomics aims to capture the multiple sources of structural diversity reflected in proteins, such as those that arise from alternative RNA splicing events or the addition of post-translational modifications. Tandem MS (i.e., MS/MS) represents a critical component of a top-down proteomics experiment, as the resulting fragmentation patterns unveil various structural features associated with protein function. This review spotlights recent developments and applications of ion activation methods used to decipher the structural properties of intact proteins, including collisional activation and those based on the use of electrons and photons. The analysis of fragment ions generated by these MS/MS methods are also discussed, along with an outlook on future developments in the field related to instrumentation and burgeoning approaches to top-down proteomics, such as single-cell methods.

Keywords:  collision induced dissociation; collisional activation; electron activation; intact proteins; photodissociation

DOI:  https://doi.org/10.1002/mas.70023
Endocr Regul. 2026 Jan 01. 60(1): 37-47

ERN1-dependent regulation of BAG cochaperone 1 expression and the sensitivity to glutamine deprivation in U87MG glioblastoma cells.

Yuliia M Viletska, Oleksandr H Minchenko, Olena O Khita, Daria O Tsymbal, Myroslava Y Sliusar, Oleh V Halkin, Halyna E Kozynkevych, Dmytro O Minchenko.

  Objective. The BAG cochaperone 1 (BAG1) binds to oncogene BCL2 and markedly enhances its anti-apoptotic effects. This cochaperone represents a link between growth factor receptors and anti-apoptotic mechanisms mediated by endoplasmic reticulum stress. BAG1 interacts with the glucocorticoid receptor and modulates its transcription activity. As a cochaperone for several HSP70 proteins, it participates in control of protein folding. The present study aims to investigate the regulation of the BAG1 mRNA expression in U87MG glioblastoma cells by hypoxia and glucose or glutamine deprivation, depending on the inhibition of ERN1 (endoplasmic reticulum to nucleus signaling 1) with the intent to reveal the role of ERN1 signaling in the regulation of this gene expression and function in oncogenesis. Methods. The U87MG glioblastoma cells (transfected by an empty vector; control) and cells with inhibited ERN1 endoribonuclease and protein kinase (dnERN1) or only ERN1 endoribonuclease (dnrERN1) were used. Silencing of ERN1 and XBP1 mRNAs for suppression of ERN1 function was also used. A hypoxic condition was created by dimethyloxalylglycine (4 h). DMEM medium without glucose or glutamine was used for glucose and glutamine deprivation (16 h). The expression level of the BAG1 mRNA was studied by real-time qPCR and normalized to the beta-actin mRNA. Results. Inhibition of the endoribonuclease activity of ERN1 significantly decreased BAG1 mRNA expression. However, a lesser suppression of this mRNA expression was observed in dnERN1 cells (with inhibited ERN1 endoribonuclease and protein kinase) indicating the involvement of protein kinase in controlling BAG1 expression. The silencing of ERN1 and XBP1 mRNAs also reduced the expression of BAG1 mRNA demonstrating the involvement of XBP1s in this regulation. The expression of the BAG1 gene was resistant to glutamine deprivation and upregulated in response to glucose deprivation in control glioblastoma cells. However, the inhibition of ERN1 increased the sensitivity of BAG1 gene expression to both glucose and glutamine deprivation. Furthermore, the expression of the BAG1 gene was increased under hypoxia in control U87MG cells; however, a greater induction was observed in dnERN1 cells. Conclusion. The results of this study demonstrated that ERN1 inhibition reduces BAG1 mRNA expression through the endoribonuclease activity of ERN1 and that protein kinase activity counteracts endoribonuclease in regulating the expression of BAG1 mRNA. Moreover, ERN1 inhibition also enhances the sensitivity of BAG1 mRNA expression to nutrient supply and hypoxia resulting in reduced resistance of glioblastoma cells.

Keywords:  BAG1; ERN1 and XBP1 silencing; ERN1 endoribonuclease; ERN1 inhibition; ERN1 protein kinase; gene expression; glioblastoma cells; glutamine and glucose deprivation; hypoxia

DOI:  https://doi.org/10.2478/enr-2026-0005
Cell Death Dis. 2026 Mar 28.

The Sirt2-Nur77 axis regulates muscle stem cell quiescence and senescence via epigenetic-metabolic synergy.

Yanteng Wang, Yichen Yang, Wan Yu, Yue Liu, Wenwei Guan, Yingxi Wang, Na Li, Liu Cao, Difei Wang.

Nur77 expression decreases with age in multiple organs, including the liver, brain, heart, and kidney, whereas Sirt2 increases with age in the mouse cerebral cortex and hippocampus. We identified the central role of the Sirt2-P300/Nur77/K310 acetylation axis in regulating muscle homeostasis and regeneration and its age-related alterations. Consistently, we observed reduced Nur77 and elevated Sirt2 expression in aging skeletal muscle, particularly the anterior tibialis, which is enriched in type IIB and IIA fast-twitch fibers. Mechanistically, Sirt2 promoted Nur77 degradation via K310-specific deacetylation, weakening Myf5 transcriptional activity and altering satellite cell metabolic heterogeneity. Functional tests showed that Sirt2 inhibition (AGK2) or Nur77 activation (CSNB) improved muscle function in aged mice, whereas the K310R mutation led to muscle atrophy and impaired regeneration. These findings suggest the Sirt2-P300/Nur77 axis as a potential therapeutic target for skeletal muscle aging and anti-sarcopenia drug development.

DOI: https://doi.org/10.1038/s41419-026-08645-w
FEBS J. 2026 Apr 01.

Post-transcriptional regulatory networks: The dynamic interplay of RNA-binding proteins.

Lena A Street, Marko Jovanovic, Eugenio F Fornasiero.

  Post-transcriptional regulation of gene expression is orchestrated by RNA-binding proteins (RBPs), which regulate key aspects of the RNA life cycle including splicing, localization, translation, and decay. Although RBPs have been initially considered as isolated regulators, it is becoming clear that RNA molecules are commonly bound by several RBPs whose coordination directs their fate. These combinatorial interactions produce complex, context-dependent post-transcriptional regulatory networks (PTRNs) whose outcomes are difficult to predict. RBPs may also switch function depending on cell state, subcellular localization, or post-translational modification, adding further complexity to RNA regulation. This review focuses on recent technological advances expanding our ability to map and interpret PTRNs. Multiplexed methods allow profiling of the RNA-binding patterns of several RBPs in parallel, whereas deeper interaction proteomics studies reveal protein-protein connections and changes in distinct biological settings. Complementary RNA-targeting pulldown and single-molecule imaging strategies enable real-time and single-cell-resolution visualization of ribonucleoprotein assembly and dynamics, while functional high-throughput screens allow assignment of first order functions for these RBPs. Overall, these approaches set the stage for comprehensive decoding of the spatiotemporal structure of PTRNs and reveal how RBP interactions coordinate sets of RNAs to collectively regulate them in response to physiological demands. In addition to describing these systems-level approaches, we outline key future analytical and experimental innovations that could transform our understanding of RBP function. We believe that a systems-level understanding of RBPs as dynamic, integrated components of multiscale regulatory regimes is required to fully understand the complexity of gene expression control and its disruption in disease.

Keywords:  RNA‐binding proteins; RNA–protein interactions; RNP complex dynamics; post‐transcriptional regulation; systems biology of RNA regulation

DOI:  https://doi.org/10.1111/febs.70524
Cell Death Discov. 2026 Mar 31.

Protein lactylation: a metabolic signal driving cancer therapy resistance.

Silvia D'amico, Sara Giovannini, Gerry Melino, Angelo Peschiaroli, Francesca Bernassola.

Unlike normal cells, which primarily rely on oxidative phosphorylation, cancer cells reprogram their metabolism by preferentially utilizing glycolysis even in the presence of oxygen to generate ATP. As a result, cancer cells and the tumor microenvironment typically accumulate high levels of lactate. Although initially considered a mere byproduct of glucose metabolism, lactate has recently emerged as an important metabolic intermediate involved in many intracellular pathways and protein modifications. Lysine lactylation is indeed a newly identified, metabolism-linked post-translational modification in which lactate is covalently bound to specific lysine residues. This review provides an overview of the current understanding of how lysine lactylation mechanistically contributes to therapeutic resistance in tumor cells. Remarkably, protein lactylation is emerging as a promising druggable approach for overcoming therapy resistance. Hence, here, we also highlight new strategies that target lactylation with pharmacological inhibitors to counteract drug resistance in cancer.

DOI: https://doi.org/10.1038/s41420-026-03050-w