eLife: latest articles by subject

Polo-like kinase phosphorylation of the orphan kinesin KIN-G negatively regulates centrin arm biogenesis in Trypanosoma brucei

Ziyin.Li@uth.tmc.edu (Huiqing Hu) — Fri, 04 Sep 2026 00:00:00 +0000

The unicellular parasite Trypanosoma brucei assembles a motile flagellum that is required for locomotion, cell division plane placement, and cell-cell communication. Inheritance of the flagellum during the cell cycle relies on the faithful duplication/segregation of multiple flagellum-associated cytoskeletal structures, including a centrin-marked, bar-shaped structure termed centrin arm, which also determines the site for Golgi assembly. Biogenesis of the centrin arm requires the Polo-like kinase homolog TbPLK and the orphan kinesin KIN-G, but the mechanistic role of TbPLK in centrin arm biogenesis remains elusive. Here, we report that TbPLK phosphorylates KIN-G, disrupts its microtubule-binding activity, and negatively regulates its function. TbPLK phosphorylates KIN-G in vitro at multiple residues, two of which are in vivo TbPLK phosphosites, including the Thr301 residue within one of the microtubule-binding motifs of the kinesin motor domain. Phosphorylation of Thr301 by TbPLK inhibits the microtubule-binding activity of KIN-G in vitro, and expression of a Thr301 phospho-mimic mutant in T. brucei disrupts centrin arm integrity, Golgi duplication, flagellum attachment zone elongation, flagellum positioning, and cell division plane placement. In wild-type T. brucei cells, Thr301 phosphorylation occurs on a small portion of the KIN-G population, suggesting that KIN-G undergoes phosphorylation/dephosphorylation cycles to regulate its activity. Together, these findings uncover a negative role of TbPLK-mediated phosphorylation of KIN-G in regulating centrin arm biogenesis in trypanosomes.

The insulin/IGF axis is critically important for controlling gene transcription in the podocyte

Richard.Coward@bristol.ac.uk (Aaron R Jeffries) — Fri, 04 Sep 2026 00:00:00 +0000

Podocyte integrity depends critically on signalling through the insulin receptor and IGF1 receptor, and this study defines their combined importance using dual-receptor knockdown in mice and cultured podocytes. Podocyte-specific reduction of both receptors in transgenic mice caused kidney disease characterised by albuminuria and glomerulosclerosis, with premature death occurring in some animals between 4 and 24 weeks. Receptor-deficient cultured podocytes exhibited >50% cell loss within 7 days. Integrated proteomic and transcriptomic analyses revealed marked depletion of spliceosome-associated proteins and widespread intron retention with premature termination codons, indicating profound disruption of RNA processing. Phospho-proteomic profiling further showed that insulin/IGF1 stimulation induces dynamic post-translational modifications across spliceosomal components and regulatory kinases. Together, these findings uncover a previously unrecognised role for podocyte insulin/IGF1 signalling in maintaining spliceosomal integrity and transcriptional fidelity, establishing this hormonal axis as a key extrinsic regulator of podocyte gene expression.

A biochemical mechanism for Stu2/XMAP215-family microtubule polymerases

Luke.Rice@UTSouthwestern.edu (Binnu Gangadharan) — Thu, 03 Sep 2026 00:00:00 +0000

Defining quantitative biochemical mechanisms of microtubule dynamics and regulation is a current challenge. Stu2/XMAP215-family polymerases use tubulin-binding TOG domains to catalyze microtubule growth, but how polymerase activity results from the number and tubulin-binding properties of TOGs is not understood. We tested whether an enzyme-like biochemical model for the unrelated actin polymerase Ena/VASP could be applied to quantitatively relate Stu2 microtubule polymerase activity to the number of its TOGs, and the rate constants governing their interactions with tubulin. Stu2 activity displayed enzyme-like characteristics consistent with the biochemical model: Stu2 stimulated microtubule growth rates with hyperbolic dependence on tubulin concentration, and the amount of Stu2 on the microtubule end did not vary with tubulin concentration (microtubule growth rate). Complementary measurements of TOG:tubulin binding revealed high affinity (10 nM) and slow dissociation (0.03 s^–1). The polymerase and binding measurements can be unified within the biochemical model: Stu2 operates with high efficiency, acting as a tubulin-shuttling antenna on the microtubule end that is primarily limited by the rate of tubulin:TOG association. Our work thus provides a quantitative biochemical mechanism for TOG-based polymerases. That unrelated microtubule and actin polymerases use the same enzyme-like mechanism provides an example of convergent evolution in the cytoskeleton.

Cardiolipin deficiency disrupts electron transport chain and drives steatohepatitis

kfunai@utah.edu (Alek D Peterlin) — Wed, 02 Sep 2026 00:00:00 +0000

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to metabolic dysfunction-associated steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress. Specifically, mitochondrial cardiolipin (CL) was downregulated with MASLD/MASH in humans and in mice. Hepatocyte-specific CL synthase knockout (CLS-LKO) led to spontaneous and robust MASH with extensive steatotic and fibrotic phenotype. Loss of CL paradoxically increased mitochondrial respiratory capacity but also promoted electron leak primarily at sites III_QO and II_F of the electron transport chain (ETC), reduced the formation of I + III₂ + IV respiratory supercomplex, and disrupted the propensity of coenzyme Q to become reduced. Thus, low mitochondrial CL disrupts the ETC to promote oxidative stress and contributes to the pathogenesis of MASH.

SETD6-mediated methylation of PPARγ establishes a transcriptional feedback circuit promoting lipid accumulation in liver-derived cells

ledan@post.bgu.ac.il (Anand Chopra) — Fri, 28 Aug 2026 00:00:00 +0000

Peroxisome proliferator-activated receptor gamma (PPARγ) is a key transcriptional regulator of genes mediating adipogenesis (fat-cell differentiation), and lipid storage in several cell types like hepatocytes. As such, its regulation is crucial for cell and organismal physiology. Indeed, PPARγ’s activity is regulated by multiple mechanisms, including post-transcriptional modifications, which, when dys-coordinated, may contribute to the pathogenesis of various states, including obesity, insulin resistance, and fatty liver disease. Here, we demonstrate that SETD6 binds to and methylates PPARγ at lysine 170 (K170) both in vitro and in liver-derived cells. This methylation event, in turn, is required for PPARγ-mediated activation of SETD6 transcription via promoter binding, forming a positive feedback regulatory loop. RNA-sequencing revealed that both SETD6 and PPARγ methylation at K170 are required for full induction of lipid metabolism genes’ expression, manifesting functionally in lipid droplet biogenesis in liver-derived cells. Together, our findings uncover a novel role for lysine methylation of PPARγ in the regulation of lipid synthesis and lipid droplet biogenesis, thereby identifying putative new therapeutic targets for lipid overproduction diseases, including metabolic dysfunction-associated fatty liver disease and obesity.

Zasp52’s differentially expressed intrinsically disordered region confers thin filament stability at the Z-disc

frieder.schoeck@mcgill.ca (Frieder Schöck) — Thu, 27 Aug 2026 00:00:00 +0000

The Drosophila scaffolding protein Zasp52 is required to maintain structure at the muscle Z-disc, which experiences strong forces during contraction. It is alternatively spliced into many isoforms, some of which contain a long intrinsically disordered region (IDR). We show that this region is primarily expressed in the indirect flight muscle (IFM) and is required for maintaining the integrity of the Z-disc. Deleting the IDR-encoding exon 15e results in flightlessness and structural IFM defects, including sarcomere bending at the Z-disc and an inability to de-contract. These defects are indicative of a lack of proper thin filament anchoring to the Z-disc. This is further supported by a genetic interaction between exon 15e and actin. Fluorescence recovery after photobleaching of an isoform lacking exon 15e shows that the IDR is required for maintaining Zasp52 at the Z-disc and thereby stabilizing Z-discs. Lastly, we can rescue these phenotypes by restricting IFM use. Together, these results suggest that Zasp52’s IDR confers thin filament stability at the Z-disc of IFM.

Disruption of sphingolipid metabolism promotes tau seeding through endolysosomal membrane rigidification and rupture

carmen.nussbaum@med.uni-muenchen.de (Carl Alexander Sandhof) — Thu, 27 Aug 2026 00:00:00 +0000

Endolysosomal dysfunction is a hallmark of Alzheimer’s disease and related tauopathies, yet underlying mechanisms remain poorly understood. This study investigates the role of sphingolipid metabolism in maintaining endolysosomal membrane integrity and its impact on tau aggregation and toxicity in Caenorhabditis elegans and human cell culture models. Fluorescence recovery after photobleaching and C-Laurdan dye imaging revealed that silencing sphingolipid metabolism genes reduced endolysosomal vesicle membrane fluidity, increasing their rupture. The accumulation of aggregated tau in endolysosomal vesicles further aggravated endomembrane rigidification and damage, and promoted seeded tau aggregation, potentially by facilitating the escape of tau seeds from the endolysosomal system. Supplementation with unsaturated fatty acids improved membrane fluidity, suppressing endolysosomal rupture and seeded tau aggregation in cell models, and alleviating tau-associated neurotoxicity in C. elegans. Together, this study provides mechanistic insight into how perturbation of sphingolipid metabolism promotes endolysosomal membrane damage and contributes to the escape of aggregated tau from this compartment, suggesting that restoration of membrane fluidity may represent a strategy to limit tau propagation and toxicity.

MOTS-c is a mitochondrial-encoded interferon-linked host defense peptide

berenice.benayoun@usc.edu (Bérénice A Benayoun) — Tue, 18 Aug 2026 00:00:00 +0000

The mitochondrial DNA (mtDNA) can trigger immune responses and directly entrap pathogens, but it is not known to encode active immune factors. The immune system is traditionally thought to be exclusively nuclear-encoded. Here, we report the identification of a host defense peptide (HDP) encoded in the human mitochondrial genome that presumably derives from the primordial proto-mitochondrial bacteria. We demonstrate that MOTS-c (mitochondrial open reading frame from the 12 S rRNA type-c) is a mitochondrial-encoded amphipathic and cationic peptide with direct antibacterial and immunomodulatory functions, consistent with the peptide chemistry and functions of known HDPs. MOTS-c targeted Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), in part, by targeting their membranes using its hydrophobic and cationic domains. In a mouse model of acute peritonitis, MOTS-c fully neutralized MRSA infectivity. In human monocytes, interferon gamma (IFNγ), lipopolysaccharides (LPS), and differentiation signals each induced the expression of endogenous MOTS-c. Notably, exogenous MOTS-c, applied during primary mouse monocyte differentiation, reprogrammed the cells into macrophages with distinct transcriptomic signatures related to antigen presentation and IFN signaling. MOTS-c-programmed macrophages exhibited enhanced bacterial clearance and shifted metabolism. Our findings support MOTS-c as a first-in-class mitochondrial-encoded HDP and indicate that our immune system is not only encoded by the nuclear genome but also by the co-evolved mitochondrial genome.

How to give cells an identity crisis

hollien@biology.utah.edu (Julie Hollien) — Thu, 13 Aug 2026 00:00:00 +0000

The transcription factor CHOP helps cells switch from an emergency stress response to a chronic one, where cells survive but lose some of the functions that define their identity.

Aging-associated increase of GATA4 levels in articular cartilage is linked to impaired regenerative capacity of chondrocytes and osteoarthritis

hal46@pitt.edu (Alyssa Aguglia) — Wed, 12 Aug 2026 00:00:00 +0000

Although the causal association between aging and osteoarthritis (OA) has been documented, our understanding of the underlying mechanism remains incomplete. To define the regulatory molecules governing chondrocyte aging, we performed transcriptomic analysis of young and old human chondrocytes from healthy donors. The data predicted that GATA-binding protein 4 (GATA4) may play a key role in mediating the difference between young and old chondrocytes. Results from immunostaining and western blot showed significantly higher GATA4 levels in old human or mouse chondrocytes when compared to young cells. Moreover, overexpressing GATA4 in young chondrocytes remarkably reduced their cartilage-forming capacity in vitro and induced the upregulation of proinflammatory cytokines. Conversely, suppressing GATA4 expression in old chondrocytes, through either siRNA or a small-molecule inhibitor NSC140905, increased the production of aggrecan and collagen type II, and also decreased levels of matrix-degrading enzymes. In OA mice induced by surgical destabilization of the medial meniscus, intra-articular injection of lentiviral vectors carrying mouse Gata4 resulted in a higher OA severity, synovial inflammation, and pain level when compared to control vectors. Mechanistically, we found that overexpressing GATA4 significantly increased the phosphorylation of SMAD1/5. Our work demonstrates that the aging-associated increase of GATA4 in chondrocytes plays a vital role in OA progression, which may also serve as a target to reduce OA in the older population.

A tool to pulse-label yeast nuclear pore complexes in imaging and biochemical experiments

l.m.veenhoff@rug.nl (Annemiek C Veldsink) — Mon, 10 Aug 2026 00:00:00 +0000

Nuclear pore complexes (NPCs) are key gateways to the nucleus and major organizers of genome architecture. Despite their importance, it is still not fully understood how NPCs are formed and degraded. Tools to track specific NPCs over time or under stress could unlock critical insights into these questions. Here, we demonstrate that a brief pulse of expression of a previously developed nanobody against baker’s yeast nucleoporin Nup84 (Nordeen et al., 2020) enables a robust, rapid, and straightforward method for pulse-labeling NPCs in both imaging and affinity purification experiments. This approach offers an alternative to permanent, yet less rapid, genetic fluorophore- or tag-switching techniques, and provides a powerful tool for studying NPC inheritance and turnover through both microscopy and biochemical methods.

Analysis of cancer mutations introduced into the Drosophila melanogaster Notch negative regulatory region uncovers a diversity of regulatory outcomes

martin.baron@manchester.ac.uk (Hideyuki Shimizu) — Tue, 04 Aug 2026 00:00:00 +0000

Activating mutations of Notch are drivers of the blood cell cancer, T-ALL, and some solid tumours. The negative regulatory region (NRR) of the extracellular domain (ECD) and the PEST region of the intracellular domain (ICD) are mutation hot spots which can act synergistically in T-ALL. The NRR, comprised of a heterodimerisation domain (HD) and three Lin12/Notch repeats (LNR A-C), masks the S2 cleavage site, normally only exposed following ligand binding and cleaved as the first step that ultimately leads to ICD release. Drosophila mutants have played a key role in analysing Notch structure/function, but there have been few mutational studies of the NRR. Here, we expressed, in S2 cells, over 20 cancer mutations located in the HD, LNR and LNR/HD interface, introduced into Drosophila Notch. Mutations in the HD domain core did not activate, likely due to absence in Drosophila of an S1 cleavage within the HD required for mammalian Notch activity. In contrast, mutations in the LNR/HD interface behaved similarly to T-ALL, activating constitutively with no further ligand induction and were synergistic with PEST deletion. Mutations of surface-exposed residues of LNR-C also activated constitutively but remained inducible both by ligand and by an intracellular endocytic regulator, Deltex, and were not synergistic with PEST deletions. These mutations caused elevated Notch levels and decreased turnover, suggesting a novel regulatory mechanism. Our results, therefore, uncover a variety of outcomes arising from perturbations of the NRR and will facilitate the establishment of Drosophila cancer models and the development of mutant-specific approaches to effective therapies.

Following your heart as it takes shape

nicole.dubois@mssm.edu (Alexandra Trouilloud) — Fri, 31 Jul 2026 00:00:00 +0000

A novel computational pipeline reveals patterns of tissue movement and growth in early heart formation and advances virtual modeling of development.

Decoupling AMPK from fatty acid synthesis allows maintenance of fitness late in life

jon.houseley@babraham.ac.uk (Dorottya Horkai) — Fri, 31 Jul 2026 00:00:00 +0000

Although lifespan has long been the focus of ageing research, preventing functional decline late in life is a more pressing societal need. Here, we investigate the basis of senescence and declining fitness during replicative ageing in budding yeast, and describe a metabolic perturbation that preserves late-life fitness even on an unrestricted glucose diet. We show that senescence can be prevented by constitutive activation of AMPK, though only for approximately half the ageing population, and use genetic and functional assays to link this heterogeneous response with differences in cytosolic acetyl coenzyme A (Acetyl-CoA) metabolism. In one class of ageing cell, AMPK activity maintains fitness late in life through pathways that transport cytosolic Acetyl-CoA into mitochondria, but AMPK also inhibits fatty acid synthesis which leads to lipid starvation in the other class of ageing cell. Therefore, AMPK activity has both positive and negative effects, but we show that constitutive AMPK activity uncoupled from fatty acid synthesis inhibition (the A2A mutant) suppresses senescence and maintains fitness in both classes of ageing cell. Our findings support a model in which lipid starvation and excess Acetyl-CoA availability are major drivers of senescence in replicatively aged wild-type yeast. This work shows that ageing is not intrinsically associated with declining fitness, at least in yeast, and that re-engineering highly conserved metabolic pathways allows fitness to be preserved very late in life.

The titin N2A-MARP signalosome constrains muscle longitudinal hypertrophy in response to stretch

coeno@arizona.edu (Coen Ottenheijm) — Thu, 30 Jul 2026 00:00:00 +0000

Titin-based mechanosensing is a key driver of trophic signaling in muscle, yet the downstream pathways linking titin sensing to muscle remodeling remain poorly understood. To investigate these signaling mechanisms, we utilized unilateral diaphragm denervation (UDD), an in vivo model that induces titin-stiffness-dependent hypertrophy via mechanical stretch. Using UDD in rats and mice, we characterized the longitudinal hypertrophic response and distinguished stretch-induced signaling from denervation effects by performing global transcriptomic and proteomic analyses following UDD and bilateral diaphragm denervation (BDD) in rats. Our findings identified upregulation of titin-associated muscle ankyrin repeat proteins (MARPs). Subsequent phosphorylation enrichment mass spectrometry in mouse diaphragm highlighted the involvement of the N2A-element. UDD in MARP knockout (KO) mice resulted in enhanced longitudinal hypertrophy, with Western blot analysis revealing activation of the mTOR pathway. Furthermore, pharmacological inhibition of mTORC1 with rapamycin suppressed longitudinal hypertrophy, demonstrating that mTOR signaling regulates titin-mediated hypertrophic growth in a MARP-dependent manner. These findings establish MARPs as key modulators of titin-based mechanotransduction and highlight mTORC1 as a central regulator of longitudinal muscle hypertrophy.

Correction: Differential regulation of hair cell actin cytoskeleton mediated by SRF and MRTFB

Mon, 27 Jul 2026 00:00:00 +0000

Stable excitatory-inhibitory synapse balance despite dynamic turnover

richard.sando@vanderbilt.edu (Cassandra M Smith) — Mon, 27 Jul 2026 00:00:00 +0000

Diverse synaptic connections self-organize into neural circuits during brain development. A balance between excitatory and inhibitory synaptic function is required for information processing by these neural circuits. Despite the importance of this balance, the interplay between excitatory and inhibitory synaptic assembly during circuit establishment remains unclear due to a lack of means to monitor both processes simultaneously. Here, we develop imaging and analysis methods to visualize and track excitatory and inhibitory synapses. By applying these approaches, we find that despite continual dynamics, excitatory and inhibitory synaptic density remain at steady-state levels during synapse maturation. These results indicate balanced excitatory and inhibitory synapse assembly, despite continual synaptic turnover.

CROP2, a Retriever–PROPPIN complex mediating protein export from endosomes to the plasma membrane in human cells

andreas.mayer@unil.ch (Andreas Mayer) — Fri, 24 Jul 2026 00:00:00 +0000

Endosomes generate tubulo-vesicular carriers to redistribute proteins between plasma membrane, Golgi, and lysosomes. These transport routes employ distinct combinations of sorting nexins with complexes such as Retromer or Retriever. We now show that, while Retromer associates with the PROPPIN WIPI1 to form the previously described CROP complex, Retriever associates with WIPI2, forming CROP2. WIPI2 integrates into Retriever-dependent coat complexes since it interacts both with the Commander subunit CCDC93 and its cognate sorting nexin SNX17. CROP and CROP2 are exclusive in their physical associations and pathway selective. Whereas CROP2 is required for endosomal exit of Integrin β1, it does not affect CROP-dependent cargos such as EGFR or GLUT1. Vice versa, CROP is not required for Integrin β1 trafficking. WIPI1 and WIPI2 rely on similar molecular features. Their activity depends on the same FSSS motif to integrate into Retromer and Retriever complexes, respectively, and on an amphipathic membrane-inserting α-helix, which conveys membrane fission activity to PROPPINs. This suggests that Retromer and Retriever coats integrate distinct PROPPIN isoforms to promote fission of the respective endosomal carriers formed by them.

Enteropathogenic Escherichia coli-mediated fast and coordinated Ca^²+ responses regulate NF-κB activation

guy.tranvannhieu@i2bc.paris-saclay.fr (Fangrui Guo) — Wed, 22 Jul 2026 00:00:00 +0000

Enteropathogenic Escherichia coli (EPEC) is a major bacterial enteropathogen causing infectious diarrhea among children in developing countries. Here, we found that EPEC induced isolated Ca²⁺ responses in epithelial cells, triggered by extracellular ATP (eATP). These responses were dependent on type III secretion (T3S) and down-regulated by the bacterial secreted protease EspC, consistent with eATP released by the T3S translocon pore-forming activity in host membranes. By performing high-speed Ca²⁺ imaging, we uncovered that at the onset of infection, low eATP levels triggered Ca²⁺-responses involving the whole cell but showing small amplitude and fast kinetics usually associated with local Ca²⁺ responses. The findings, supported by theoretical modeling, evoke a conceptual shift whereby low amounts of inositol 1, 4, 5-trisphosphate (IP₃) induced by low eATP levels and subsequent moderate Ca²⁺ release enable the fast coordination of IP₃ receptor cluster activation throughout the cell. Importantly, these yet undescribed coordinated fast responses occurred over prolonged time periods and defined a cell state with dampened activation of the pro-inflammatory transcriptional activator NF-kB associated with a decrease in its Ca²⁺-dependent O-linked β-N-acetylglucosamine modification.

DNA tensiometer reveals catch-bond detachment kinetics of kinesin-1, -2, and -3

woh1@psu.edu (Crystal R Noell) — Mon, 20 Jul 2026 00:00:00 +0000

Bidirectional cargo transport by kinesin and dynein is essential for cell viability, and defects are linked to neurodegenerative disease. Computational models predict that load-dependent motor detachment strongly determines the outcome of kinesin–dynein tug-of-war, with kinesin-3 and kinesin-2 more load-sensitive than kinesin-1. Yet reconstituted assays show that all three kinesin families compete similarly well against dynein. Previous work demonstrated that vertical forces from optical trapping assays can enhance kinesin-1 dissociation, suggesting that motor behavior may depend strongly on cargo geometry. To measure kinesin detachment and reattachment kinetics under forces applied parallel to the microtubule, we developed a DNA-based tensiometer using an entropic DNA spring linking motors to microtubules. For kinesin-1, –2, and –3, dissociation rates at stall were slower than during unloaded motion, and reattachment kinetics were consistent with a weakly bound slip state preceding detachment. Kinesin-3 behavior further suggested that long KIF1A run lengths arise from multiple short runs connected by diffusive episodes. Stochastic simulations reproduced the measured load-dependent kinetics and enabled direct comparison of transition rates among kinesin families. These results provide insight into how kinesin-1, –2, and –3 transport cargo in complex cellular geometries and compete against dynein during bidirectional transport.

DuoHexaBody-CD37 induces direct cytotoxic signaling in diffuse large B-cell lymphoma

Annemiek.vanSpriel@radboudumc.nl (Annemiek B van Spriel) — Mon, 20 Jul 2026 00:00:00 +0000

Diffuse large B-cell lymphoma (DLBCL) is a common aggressive form of non-Hodgkin lymphoma. Tetraspanin CD37 is highly expressed on mature B cells and being studied as a therapeutic target for NHL, including DLBCL. DuoHexaBody-CD37 is a biparatopic antibody with an E430G hexamerization-enhancing mutation targeting two non-overlapping CD37 epitopes shown to promote complement-dependent cytotoxicity. However, the impact of DuoHexaBody-CD37 on direct cytotoxic signaling has not yet been studied. Here, we demonstrate that DuoHexaBody-CD37 induces direct cytotoxicity in DLBCL-derived tumor cell lines independent of the subtype. DuoHexaBody-CD37 induced significant CD37 clustering and was retained at the cell surface in contrast to rituximab, which was internalized. Unbiased screening identified the modulation of 26 (phospho)proteins upon DuoHexaBody-CD37 treatment of primary B cells or DLBCL cells. Whereas DLBCL cells predominantly upregulated p-SHP1(Y564) upon DuoHexaBody-CD37 treatment, primary B cells showed significantly increased p-AKT(S473) and MAPK signaling which is linked to cell survival. Studies using CD37-mutants identified the N-terminus to be involved in DuoHexaBody-CD37-induced signaling. Finally, DuoHexaBody-CD37 treatment inhibited cytokine pro-survival signaling in DLBCL cells. These findings provide novel insights into the signaling functions of CD37 upon DuoHexaBody-CD37 treatment, and open up opportunities for developing CD37-targeted immunotherapy in combination with small molecule inhibitors to maximize tumor cell death.

FMRP regulates neuronal RNA granules containing stalled ribosomes, not where ribosomes stall

wayne.sossin@mcgill.ca (Jewel T-Y Li) — Mon, 20 Jul 2026 00:00:00 +0000

Local protein synthesis is a crucial process that maintains local proteostasis in neurons. A large percentage of mRNAs translated in developing neurons are associated with stalled ribosomes. FMRP, the protein lost in Fragile X syndrome, is highly enriched in RNA granules that contain stalled ribosomes. Previous examination of ribosome-protected fragments (RPFs) from stalled neuronal ribosomes identified sequences that match those found in mRNAs associated with FMRP. To investigate whether FMRP recognition of these sequences is important for determining where ribosomes stall on mRNAs, we examined RPFs isolated from P5 mice of both sexes that lack the FMRP protein. The loss of FMRP had no significant effect on the proteins associated with neuronal stalled ribosomes, on ribosome structure, or the stalling sites (locations where RPFs accumulated). There was a small, but significant decrease in the number of RPFs from mRNAs previously shown to be associated with FMRP by CLIP. Additionally, the number of neuronal RNA granules containing stalled ribosomes, as assayed by ribopuromycylation, decreased. These results suggest a role of FMRP in neuronal RNA granules that contain stalled ribosomes, though loss of FMRP does not influence where ribosomes are stalled or the formation of stalled ribosome.

Cytoplasmic circular dsDNA is a key constituent of stress granules

natalia.demeshkina@nih.gov (Adrian R Ferré-D'Amaré) — Mon, 13 Jul 2026 00:00:00 +0000

Stress granules are large cytoplasmic bodies formed in response to environmental insults by eukaryotic cells. Stress granule formation is key for post-stress recovery, and many diseases and infections are characterized by dysregulation of these membraneless organelles. How specific and non-specific macromolecular interactions drive the formation of stress granules and other large assemblies is an area of active research. Stress granules are comprised of dense, ~200 nm cores, and these are known to contain numerous RNAs and proteins. Now, we have discovered that more than half of the nucleic acid content of stress granule cores is circular, double-stranded DNA. We demonstrate cytologically that these extrachromosomal circular DNAs (eccDNAs) colocalize cytoplasmically with canonical stress granule marker proteins in HEK293T cells, and through CRISPR targeting in budding yeast, that they are required for stress granule formation upon stress. This discovery thus reveals a key function for eccDNA in the eukaryotic stress response.

Canonical and phosphoribosyl ubiquitination coordinate to stabilize a proteinaceous structure surrounding the Legionella-containing vacuole

Shaeri.Mukherjee@ucsf.edu (Adriana Steinbach) — Wed, 08 Jul 2026 00:00:00 +0000

Legionella pneumophila (L.p.), an intracellular bacterial pathogen, hijacks the ubiquitin signaling network of its eukaryotic host cells to establish infection. Two families of L.p. secreted ubiquitin ligases are instrumental in the maturation of the Legionella-containing vacuole (LCV): the SidC/SdcA family, which catalyzes canonical ubiquitination, and the SidE family, which bypasses the E1-E2-E3 enzymatic cascade and directly conjugates ubiquitin to a target through a phosphoribosyl (PR) linkage. Here, we demonstrate that the coordinated activities of these two effector families generate a hyperstable, ubiquitin-rich structure surrounding the LCV. We propose a model in which an initial wave of SidC/SdcA-mediated canonical ubiquitination around the LCV is further modified by SidE family-driven PR-ubiquitination, resulting in a detergent-resistant ‘cloud’. The ‘cloud’ is transient, breaking down as infection progresses, suggesting that L.p. reshapes the properties of the proteinaceous shell surrounding the vacuole to meet changing needs throughout its intracellular lifecycle. This unusual structure likely stabilizes and protects the LCV, shielding it from host defense mechanisms during early infection. Our findings reveal cellular consequences of effector interplay during infection and provide a foundation for future studies into the structure and function of the proteinaceous ‘cloud’ surrounding the LCV.

Proteomic composition and mutual assembly of the C2a projection in vertebrate motile cilia

623056@sdnu.edu.cn (Chunyu Liu) — Wed, 08 Jul 2026 00:00:00 +0000

The central apparatus of motile cilia, consisting of central microtubules and various protein projections, is essential for dictating the ciliary movement. Although three proteins (FAP65, FAP147, and FAP70) have been localized to the C2a projection in Chlamydomonas reinhardtii, the full protein composition and functional roles of the vertebrate C2a remain inadequately defined. Here, we use three knockout mouse models corresponding to their respective homologs (Ccdc108, Mycbpap, and Cfap70) to systematically investigate their functions in vertebrates. Notably, all three knockout strains exhibit distinct phenotypes related to primary ciliary dyskinesia (PCD), including hydrocephalus and sinusitis. The ciliary incorporation of CCDC108, MYCBPAP, and CFAP70 is essential for one another’s stability, with the loss of any single component triggering C2a collapse, which destabilizes the central pair microtubules, and ultimately alters the ciliary movement pattern. Furthermore, we significantly expand the vertebrate C2a proteome by identifying ARMC3 and MYCBP as additional C2a components. Collectively, our findings illuminate the proteomic composition and strict physiological requirements of the vertebrate C2a projection, providing new insights into the molecular pathogenesis of PCD.

Activity-dependent CO₂ production in the axon triggers opening of Connexin32 in the Schwann cell paranode

n.e.dale@warwick.ac.uk (Amol Bhandare) — Mon, 06 Jul 2026 00:00:00 +0000

Loss of function mutations of Cx32, which is expressed in Schwann cells, cause X-linked Charcot-Marie-Tooth disease, a slowly progressive peripheral neuropathy. Action potential propagation causes Cx32 hemichannels in the Schwann cell paranode to open. As Cx32 hemichannels are directly sensitive to CO₂, we have tested whether CO₂ produced in the axon, as a consequence of the energetic demands of action potential propagation, might gate Cx32 hemichannels. Using isolated sciatic nerve from the mouse, we found that the critical components required for intercellular CO₂ signaling are present (nodal mitochondria, the source of CO₂; a CO₂-permeable aquaporin, AQP1; paranodal Cx32; and carbonic anhydrase). We have used a membrane impermeant fluorescent dye, FITC, to demonstrate the opening of Cx32 in Schwann cells in response to an external CO₂ stimulus or during action potential propagation in the isolated nerve. Pharmacological manipulations of AQP1 or carbonic anhydrase activity altered Cx32 gating during action potential firing. Expression of a modified Cx32 subunit, Cx32^DN, that coassembles with Cx32^WT, revealed that the activity-dependent dye loading of Schwann cells depended upon CO₂ binding to Cx32. CO₂ can, therefore, mediate neuron-to-glia signaling via connexins. CO₂ permeable aquaporins and carbonic anhydrase are key components of this signaling mechanism.

Lipid packing contributes to the confinement of caveolae to the plasma membrane

richard.lundmark@umu.se (Aleksei Kabedev) — Mon, 06 Jul 2026 00:00:00 +0000

Lipid packing is a fundamental characteristic of bilayer membranes. Yet, we lack detailed mechanistic understanding of how lipid packing directly affects membrane-associated cellular processes. Here, we address this by focusing on caveolae, small Ω-shaped invaginations of the plasma membrane, which serve as key regulators of cellular lipid sorting and mechano-responses. In addition to caveolae coat proteins, the lipid membrane is a core component of caveolae that critically impacts their biogenesis, morphology, and stability. We show that the small compound Dyngo-4a adsorbs and inserts into the membrane, resulting in a dramatic dynamin-independent inhibition of caveola dynamics. Analysis of model membranes in combination with molecular dynamics simulations revealed that a substantial amount of Dyngo-4a was inserted and positioned at the level of cholesterol in the bilayer, affecting lipid order in a cholesterol-dependent manner. Dyngo-4a treatment resulted in decreased lipid packing of the plasma membrane. This prevented caveolae internalization and lateral diffusion without affecting their morphology, associated proteins, or the overall cell stiffness. Artificially increasing plasma membrane cholesterol levels was found to counteract the block in caveola dynamics caused by Dyngo-4a. Therefore, we propose that the outer leaflet lipid packing of cholesterol in the plasma membrane critically contributes to the confinement of caveolae to the plasma membrane.

Mechanistic insights into transcriptional regulation of ARHGAP36 expression identify a factor predictive of neuroblastoma survival

olehmann@ualberta.ca (Armin M Gamper) — Mon, 06 Jul 2026 00:00:00 +0000

Cancer repeatedly exploits attributes fundamental for morphogenesis to advance malignancy and metastasis. This is illustrated by lineage-specific transcription factors that regulate neural crest migration, representing frequent drivers of malignancy. One such example is the forkhead transcription factor FOXC1, where gain of function is a feature of diverse cancers that is associated with an unfavorable prognosis. Using RNA-, ChIP-sequencing and CRISPR interference, we show that Foxc1 binds a locus in a region of closed chromatin to induce expression of Arhgap36, a tissue-specific inhibitor of protein kinase A. Because PKA is a core Hedgehog (Hh) pathway inhibitor, Foxc1’s induction of Arhgap36 expression increases Hh activity. The function of Sufu, a PKA substrate, and a second essential Hh pathway inhibitor, is likewise impaired. The resulting increased Hh pathway output is resistant to pharmacological inhibition of Smoothened, a phenotype of more aggressive cancers. The Foxc1–Arhgap36 relationship identified in murine cells was further evaluated in neuroblastoma, a neural crest-derived pediatric malignancy. This demonstrated in a cohort of 1348 patients that high levels of ARHGAP36 are predictive of improved 5-year survival. Accordingly, this study has identified as a novel transcription factor which enhances ARHGAP36 expression, one that induces Hh activity in multiple tissues during development. It also establishes a model by which increased levels of FOXC1 via ARHGAP36 and PKA inhibition dysregulate multiple facets of Hh signaling and provides evidence demonstrating relevance to a common neural-crest-derived malignancy.