Autophagy

Aphids deplete their host plants of amino acids and other essential nutrients by feeding on phloem sap. Autophagy, a conserved process across eukaryotes, maintains cellular homeostasis during starvation and environmental stress by recycling damaged or excess cellular components. Here, we identified and characterized a previously uninvestigated aphid salivary protein, termed Aphid Autophagy Related Factor 1 (AAF1), that is secreted into plant cells and manipulates plant physiology in a manner that benefits the aphid. We show that AAF1 interacts with four known or putative host autophagy related proteins: RABD1 and RABD2a (plant homologs of Ypt1/RAB1), ATG8, a ubiquitin like protein required for autophagosome formation, and PI3PT, a previously uncharacterized ER localized putative lipid binding or lipid transfer protein annotated as a phosphoinositide 3 phosphate transfer protein. We further demonstrate that the RAB binding domain of AAF1 and its interaction with RABD2a may be specifically required for AAF1 function. In addition, we identified unique, highly mobile compartments containing interacting AAF1 and RABD2a that are associated with the endoplasmic reticulum (ER) and dynamically traffic with autophagosomes. We propose that these compartments may be derived from endosomes or endosome to ER contact sites (EERCSs) and serve as platforms for autophagosome trafficking and/or biogenesis. We further propose that AAF1, RABD2a, and PI3PT function together to regulate the formation or function of these compartments, thereby supporting autophagosome formation and trafficking. Finally, we show that stable expression of AAF1 in plants enhances growth and biomass in an autophagy dependent manner.

We previously discovered that a de novo variant p.R528W in ATAD3A, encoding a mitochondrial membrane-anchored protein, causes a human neurological syndrome. While ATAD3A mutations induce aberrant lysosomal expansion accompanied by undigested material in the lysosomes, how mutant ATAD3A disrupts lysosomal homeostasis and whether this contributes to neurodevelopmental defects remain unknown. Here we show that pathogenic ATAD3A p.R528W expression disrupts the mTORC1-TFEB axis as revealed by dysregulation of mTORC1 substrate phosphorylation, TFEB nuclear localization, and CLEAR gene activation associated with lysosomal biogenesis. ATAD3A binds to lysosome-localized Rag C/D GTPases, which constitute a platform for TFEB recruitment, with pathogenic variants increasing this association and thereby decreasing lysosomal localization of Rag GTPases. Importantly, overexpression of RagC or RagD restores TFEB phosphorylation in human cells expressing p.R528W, and RagC-D overexpression or TFEB/Mitf knockdown rescues lysosomal expansion and neurodevelopmental defects in Drosophila. These data indicate that disrupted Rag GTPase recruitment to lysosomes and subsequent aberrant TFEB/Mitf activation contribute to neurodevelopmental and lysosomal phenotypes caused by pathogenic mutations in ATAD3A. Our work reveals a novel role for the mitochondrial resident protein ATAD3A in modulating lysosomal homeostasis through regulation of the mTORC1-TFEB axis, providing a mechanistic link between impaired mitochondrial and lysosomal homeostasis in a neurodevelopmental disorder.

Autophagy is an intracellular recycling pathway with profound impacts on development, growth, and stress tolerance in eukaryotes. Therefore, unravelling signalling mechanisms that modulate the process has broad applicability. Here, we characterised a small organic molecule as an enhancer of autophagy across diverse plant lineages. Through an in vivo photoaffinity proteomics approach in Arabidopsis thaliana seedlings, we identified Domain of Unknown Function 89 (DUF89) proteins as molecular targets. Hereafter, we refer to these proteins as Reactive Metabolite Damage-Control Phosphatases (RMDPs), which are metabolite-repair phosphatases that clear reactive products. The new autophagy modulator is called RMDP inhbitor-1 (RMDPi-1) due to its demonstrated inhibitory effect on AtRMDP1 activity in vitro. Binding was further confirmed through co-incubation that thermostabilised the protein. Crystal structures of AtRMDP1 were obtained via X-ray diffraction, confirming binding of RMDPi-1 in the catalytic site and revealing a flexible region near the binding pocket that was absent in previous models. Molecular docking predicted two possible binding modes consistent with the observed electron density. RMDPi-1 treatment and the phosphatase gene knockout increased autophagic flux in Arabidopsis and Chlamydomonas reinhardtii, establishing a conserved effect. The observed autophagy response is linked to a spike in reactive oxygen species (ROS). AtRMDP knockout also results in higher ROS tolerance and greater biomass in Arabidopsis seedlings. Targeted and untargeted metabolomic experiments revealed that both pharmacological and genetic suppression of RMDP leads to accumulation of glycating agents and phosphate sugars, associating loss of RMDP activity to the ROS stress that induces alternate ROS-scavenging mechanisms, and autophagy. Taken together, our integrated chemical genetics approach reveals enhanced autophagy via inhibition of RMDP family members, which impacts on plant stress tolerance via conserved metabolite damage-control functions.

Peroxisomes, along with mitochondria, coordinate and compartmentalize oxidative metabolism in eukaryotic cells. Rare genetic disorders caused by mutations in PEX genes impair peroxisome function and cause Peroxisome Biogenesis Disorders, which are characterized by liver and neurological dysfunction, hearing and vision loss, and metabolic abnormalities. The majority of Peroxisome Biogenesis Disorders (PBDs) are caused by mutations in the gene encoding PEX1, which together with PEX6 forms a hetero-hexameric AAA-ATPase complex that drives the import of enzymes into the peroxisome lumen. One particular destabilizing mutation - PEX1G843D - results in almost 30% of all cases. Here we show that deficiencies in PEX1 lead to increased levels of the oxygen-responsive transcription factor HIF1 in normoxia, as well as a HIF1 transcriptional signature. The increase in HIF1 protein was rescued by overexpression of PEX1WT, suggesting PEX1 deficiencies modulate HIF1 signaling. The increased levels of HIF1 were not explained by defects in the oxygen responsive degradation pathway of HIF1 that relies on proline hydroxylase domain enzyme-dependent hydroxylation and von Hippel Lindau tumor suppressor protein-dependent ubiquitination. Instead, we found that PEX1 deficiency alters HIF1 proteostasis by reducing degradation through a hydroxylation- and autophagy- dependent mechanism. Notably, enhancing autophagic capacity by ULK1 agonism was sufficient to reduce HIF1 levels in PEX1 deficient cells. Lastly, we demonstrate that upon hypoxia-reoxygenation, PEX1 deficient cells are slower to reset HIF1 levels. Our results suggest that PBD patients with PEX1 deficiency may be susceptible to dysregulation of the HIF1 pathway, particularly in tissues where oxygen gradients are physiological or developmentally required.

Aims: Premature coronary artery disease (PCAD) lacks specific molecular drivers, and the role of immunosenescence is unclear. We investigated whether aging-related gene dysregulation in T cells contributes to PCAD. Methods: We combined bulk transcriptomics of PBMCs from 12 PCAD patients and 21 controls, single-cell RNA sequencing of PBMCs and human atherosclerotic plaques, weighted gene co-expression network analysis, gene perturbation network analysis, and molecular docking. Results: KRAS was identified as a hub gene intersecting PCAD-associated genes and aging-related genes. Single-cell analysis showed KRAS upregulation predominantly in effector CD8+ T cells, which exhibited the highest senescence scores that were further elevated in disease. Network perturbation of KRAS strongly impacted the cell killing pathway. KRAS-high effector CD8+ T cells were detected in coronary and carotid plaques, displaying enhanced cytotoxicity, exhaustion, and senescence features. Additionally, a candidate small molecule was computationally predicted to bind inactive KRAS. Conclusions: Elevated KRAS expression in senescent, cytotoxic CD8+ T cells is associated with PCAD, bridging immunosenescence and premature atherosclerosis. This finding provides a novel biomarker candidate and potential therapeutic entry point, awaiting further functional validation.

Sporadic disease accounts for about 90% of amyotrophic lateral sclerosis (ALS) cases, and its biological heterogeneity is a major contributor to the failure of trials that enroll patients under a single diagnosis. Because sporadic ALS lacks a shared genetic anchor, identifying biological signals is critical for effective patient stratification. We analyzed induced pluripotent stem cell derived motor neurons from 619 AnswerALS participants using transcriptomics, proteomics, and whole-genome sequencing and identified CCT2 as the first single-gene marker of a molecular state within sporadic ALS, providing a measurable basis for trial enrollment according to biology. We first anchored the analysis in known ALS genotypes. C9orf72 and SOD1 motor neurons did not converge on a common signature but retained genotype-specific differences that bulk postmortem tissue compresses. Scoring 391 sporadic patients along three transcriptomic axes (bioenergetic stress, cell cycle, and inflammation) resolved three states. One state was marked by CCT2, a TRiC chaperonin subunit, which distinguished it from the quiescent state with an area under the curve of 0.892. CCT2 was also elevated at the protein level and associated with the rate of ALSFRS-R decline, although this association weakened after adjustment for culture composition. Upstream regulator analysis placed this state downstream of MYC and mTORC1 activation. No germline test across 360 whole genomes explained these states. Validation using Target ALS data showed that the relationship between CCT2 and the cell cycle program was also present in postmortem cortex enriched for layer 5b projection neurons.

Aims: Cardiac lymphatic endothelial cells (LECs) regulate tissue homeostasis, immune trafficking, and remodeling, but how human cardiac LEC heterogeneity changes with physiological aging and cardiovascular disease remains poorly defined. We sought to define age- and disease-associated LEC states, their regulatory and microenvironmental programs, and the functional relevance of selected pathways. Methods and results: We integrated human cardiac single-nucleus transcriptomic datasets spanning physiological aging, dilated and hypertrophic cardiomyopathy, doxorubicin-associated cardiomyopathy, and heart failure with preserved ejection fraction. Aging redistributed LECs among pre-existing states, with expansion of a homeostatic immune-surveillance state and loss of cytokine-responsive and polarity-associated states. Cardiovascular diseases showed a distinct trajectory, with depletion of a non-failing homeostatic state and expansion of shared and disease-associated remodeling states. SCENIC and NicheNet/MultiNicheNet identified state-specific regulatory programs and disease-dependent signaling networks, with recurrent BMP/TGF-{beta}/activin-family signaling. ACVR2A was prioritized in human doxorubicin-associated cardiomyopathy; endothelial Acvr2a deletion in aged doxorubicin-treated mice was associated with improved cardiac function and increased open cardiac lymphatic vessels. Independent human spatial transcriptomic analyses supported selected aging- and disease-associated programs. Conclusion: Physiological aging and cardiovascular disease remodel cardiac LECs through distinct changes in cellular state, transcriptional regulation, and microenvironmental signaling. Aging is associated with redistribution and reduced representation of specialized LEC programs, whereas cardiovascular diseases redirect LECs through disease-associated signaling environments, highlighting context-dependent remodeling of the cardiac lymphatic endothelium across aging and disease.

Brefeldin A (BFA)-resistant unconventional protein secretion (UPS) is documented in cellular systems across taxa and has roles in disease, but mechanistic details remain sparse. The blast fungus Magnaporthe oryzae uses Golgi-bypass UPS to deploy plant immunity-suppressing cytoplasmic effector proteins into host rice cells to establish infection. However, few M. oryzae UPS components are known, and connections to other cellular processes are undefined. Here, using live-cell imaging of M. oryzae mutant strains, we show that MoGrh1, a resident of the pre-Golgi, BFA-resistant ER-Golgi intermediate compartment (ERGIC), is required for UPS cargo sorting under the autophagy-inducing conditions of early host cell colonization. The loss of MoGRH1 abolished UPS, with cytoplasmic effectors misrouted through a BFA-sensitive secretion pathway instead. Treatment with autophagy-suppressing -ketoglutarate, a preferred carbon source, reconstituted unconventional secretion in {Delta}grh1, restoring fungal growth in host cells. We conclude that MoGrh1 supports UPS cargo sorting under the nutrient-limiting conditions of early host cell infection, linking the ERGIC and autophagy to disease-causing effector secretion in a devastating plant pathogen.

Residual cardiovascular risk persists despite lipid-lowering therapy, independent of LDL and Lp(a), reflecting cholesterol dysregulation. We identify STARD9, a lysosomal cholesterol-sensing kinesin, as a causal gene for divergent familial dyslipidemias and premature atherosclerosis. Its START domain binds cholesterol to govern lysosomal positioning. Rare variants segregate with autosomal dominant hypercholesterolemia and premature coronary disease, while common variants associate with reduced HDL and elevated triglycerides. Both converge on lysosomal cholesterol sequestration, ER depletion, mTORC1 SREBP2 activation, impaired autophagy, and NF-kB inflammation, yet diverge through opposite lysosomal positioning: the rare variant disperses lysosomes peripherally, phenocopying START domain loss across cholesterol sequestration, lysosomal positioning, and TFEB activation, triggering LDLR degradation and CASM/TFEB-dependent efflux that preserves HDL, whereas the common variant causes perinuclear retention that suppresses TFEB dependent lipid-handling transcripts, yielding hypertriglyceridemia and low HDL. In Stard9-knockout mice, enterocyte cholesterol sequestration drives SREBP2 dependent NPC1L1 upregulation and apical localization, increasing intestinal cholesterol absorption. These findings position lysosomal cholesterol trafficking as a targetable node in statin-refractory cardiovascular disease.

Huntington disease (HD) is a fatal, neurodegenerative disorder driven by a CAG trinucleotide repeat expansion in the huntingtin (HTT) gene, resulting in neuronal toxicity and brain atrophy, initially in the most vulnerable brain region striatum and expanding to the cortex and other brain regions along disease progression. While cell-autonomous mechanisms within neurons have been extensively characterized, how brain waste clearance pathways at the brain's borders change during disease progression remains poorly understood. In this study, we investigated the structural and functional adaptations of border-associated macrophages (BAMs) in the zQ175DN knock-in mouse model of HD. Immunohistochemical analysis revealed an age-dependent, selective reduction in the CD206 Lyve1 subset of leptomeningeal BAMs in 16-month-old zQ175DN mice, which tightly correlated with a profound impairment in cerebrospinal fluid (CSF) flow velocity and perivascular influx. To determine whether BAMs actively drives this CSF flow, we selectively depleted these populations of macrophages in 10-month-old zQ175DN mice via intracerebroventricular (i.c.v.) injection of clodronate liposomes (CLO). Chemical ablation of BAMs significantly exacerbated global CSF dynamic impairment, indicted by decreasing CSF fluorescent tracer distribution across perivascular parenchymal channels. Crucially, this CSF flow failure resulted in a marked accumulation of extranuclear mutant huntingtin (mHTT) aggregates in the zQ175DN HD mouse brain, while intranuclear inclusions were not significantly altered. Furthermore, BAMs depletion did not alter microglial or astrocytic gliosis in the brain, demonstrating that the exacerbation of mHTT load is a byproduct of brain waste clearance dysfunction. Together, our results indicate that BAMs are non-redundant regulators of CSF flow dynamics at the brain borders, offering a unique non-neuronal therapeutic target to combat HD.

Genetic regulation of neurodevelopmental disorders that impair brain development and social interaction is complex and poorly understood. Although emerging evidence suggests a link between neurodevelopmental disorders and autophagy deficits, congenital autophagy gene disorders are rare in humans, and underlying molecular mechanisms remain unknown. Here we demonstrate that the autophagy protein BECN1 is a regulator of neuronal and social development in vertebrate species. We identify rare deleterious biallelic BECN1 variants that cause neurodevelopmental disorders in two unrelated families. Becn1 disruption also causes neuronal and social developmental defects in mouse and zebrafish models. BECN1 serves as an adaptor to recruit Arc to the E3 ubiquitin ligase UBE3A for polyubiquitination and degradation, thereby maintaining postsynaptic AMPA receptor (AMPAR) stability, AMPAR-mediated excitatory neurotransmission, and normal social interaction. Thus, our study illustrates new biology and a non-canonical mechanism by which BECN1 regulates neurodevelopment in humans, mice and zebrafish, via a crosstalk with the ubiquitin-proteasomal machinery.

Characterizing temporal dynamics during aging is crucial to understanding the course of aging-related events. The transcriptome is extensively remodeled with age, but the temporal trajectories of these changes, particularly through midlife, remain poorly defined in many tissues. Here, we address this gap in the male mouse colon. Using a dataset of 83 RNA-Seq samples from five time points during adult mouse lifespan, we show that colon aging is characterized by multiple gene-expression trajectories unfolding in parallel, with a major shift occurring during a mid- to late-life transition marked by a collapse of the unfolded protein response (UPR). Moreover, we report widespread non-monotonic trajectories, including genes that peak or dip in midlife and would be missed by comparisons limited to young versus old ages. We further describe age-dependent dynamics of transposable element-containing transcripts and a nonlinear course of transcriptomic entropy across the lifespan. Importantly, we identify a small set of genes that track chronological age and use only three of them to construct a compact transcriptomic clock, which we validate using an independent RNA-seq dataset and qPCR data. Together, our results indicate that nonlinear patterns dominate the aging colon transcriptome and underscore the value of high temporal resolution for identifying key transitions during aging.

Proteomic aging clocks have emerged as biomarkers of aging, but most rely on cross-sectional data. Here, we present a proteomic aging clock based on longitudinal measurements of liquid chromatography-mass spectrometry plasma proteomics at up to three time points in the population-based KORA cohort, comprising 9,105 samples from 4,100 individuals in the final dataset aged 25-88 years. The model predicts chronological age and yields a measure of proteomic age acceleration associated with lifestyle and clinical risk factors. Risk factor-stratified analyses reveal shared proteomic signatures among cardiometabolic exposures and distinct signatures for smoking and physical activity. Within individuals, dyslipidemia and impaired kidney function track transitions to increases in age acceleration, while higher age acceleration is associated with increased all-cause mortality. Mediation analysis suggests that risk factors are linked to mortality indirectly through age acceleration. Affected proteins and pathways highlight extracellular matrix remodeling, complement and coagulation pathways, and liver-derived plasma proteins as key contributors to aging. Mendelian randomization identifies proteins with evidence consistent with a causal role in aging-related traits. Together, these findings are consistent with biological aging being dynamically responsive to changes in modifiable risk factors.

Ether glycerophospholipids (ether lipids) are a subclass of glycerophospholipids that are synthesized at the peroxisome and constitute nearly 20% of the total phospholipid content in metazoans. Biochemically, ether lipids have an alkyl chain attached by an ether bond at the sn-1 position of the glycerol backbone (alkyl-ether) primarily containing choline or ethanolamine head groups. Some ether lipids contain a cis bond adjacent to the ether linkage (alkenyl-ether) and are commonly referred to as plasmalogens. While the importance of ether lipids in humans is clear, highlighted by the severity of inherited peroxisomal disorders caused by ether lipid deficiency, the molecular roles of these lipids remain poorly understood. Here, we identify a link between ether lipid metabolism, peroxisome degradation, and oxygen availability. We find Fatty acyl-CoA-reductase 1 (FAR1), the rate-limiting enzyme in peroxisomal ether lipid metabolism, acts as a peroxisome receptor necessary for peroxisome degradation when oxygen is limiting. Hypoxia increases choline ether lipid abundance, promotes autophagy activation, and peroxisome degradation. Mechanistically, FAR1 binds ATG8-family protein LC3B and is necessary and sufficient to control peroxisome degradation under hypoxia. FAR1s enzymatic function as well as its capacity to bind LC3B is necessary to degrade peroxisomes under hypoxia. Similarly, loss of multiple components of peroxisomal ether lipid metabolism blocks peroxisome degradation under hypoxia in cells and in vivo. In mouse models of chronic HIF activation, Far1 is a direct HIF target gene and is necessary for peroxisome degradation in this setting. Increasing ether lipids using ether lipid precursors activates autophagy and promotes autophagy-dependent cardioprotection against ischemic injury. This work reveals FAR1 as a critical regulator of peroxisome homeostasis in the setting of oxygen limitation.

Chikungunya virus (CHIKV) infection causes acute febrile illness that frequently progresses to chronic arthralgia. Although monocytes are CHIKV targets, whether viral exposure drives their differentiation into macrophages to sustain persistent inflammation remains incompletely understood. To address this, we integrated transcriptomic profiling of pediatric CHIKV patients during acute and convalescent phases, in vitro differentiation of primary human monocytes into macrophages under CHIKV infection, and single-cell RNA-sequencing (scRNA-seq) of joint-associated macrophages from an immunocompetent mouse model of chronic CHIKV arthritis at 28 days post-infection. In acute patients, we observed a marked upregulation of monocyte/macrophage markers alongside robust, IFN-dependent JAK-STAT signaling. In vitro, CHIKV-infected monocytes differentiated into persistently infected macrophages (MDM-CHIKV) that closely aligned with an M1-polarized transcriptional profile. These cells exhibited STAT1/NF-{kappa}B-dependent inflammation, ISG induction, and enhanced antigen presentation capacity. Remarkably, MDM-CHIKV uniquely produced IFN-{pi}/IL-27, revealing an alternative non-canonical axis where JAK-STAT activation persists despite the absence of classical type I IFNs. Functionally, MDM-CHIKV displayed an enhanced respiratory burst upon immune complex uptake, pointing to Fc{gamma}R-mediated pathology, as well as complement activation and T-cell stimulatory capacity. However, upon TLR4 challenge, these cells retained partial regulatory responses via IL-10 and TGF-{beta}; this hybrid immunophenotype offers a potential mechanistic explanation for relapsing arthralgia. Additionally, scRNA-seq of murine joints confirmed that persistent CHIKV replication was restricted to a distinct macrophage subset that resembles MDM-CHIKV, establishing these cells as the primary in vivo viral reservoir. Mirroring our human findings, joint-associated murine macrophage subsets exhibited elevated IFN-{pi}/IL-27 expression alongside robust NF-{kappa}B/STAT1-dependent inflammatory signatures (Tnf, Il1{beta}, Il6, Ccl2, Ccl5, Cxcl9, Cxcl10, Cxcl1-3, and/or Ptgs2), underscoring their critical role in sustaining chronic arthritis. Collectively, our findings demonstrate that CHIKV actively drives monocyte-to-macrophage differentiation into a persistently infected, M1-skewed hybrid phenotype that serves as a viral reservoir and fuels pro-arthritic inflammation. Consequently, macrophage reprogramming, the non-canonical IFN-{pi}/IL-27-STAT1 axis, Fc{gamma}R-mediated phagocytosis, and complement activation emerge as central pathogenic nodes and promising therapeutic targets for mitigating chronic post-CHIKV arthropathy.

Plants perceive pathogenic threats through receptors localized at the plasma membrane and inside cells to initiate pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), respectively. PTI and ETI pathways are interconnected and partially converge on the EDS1-PAD4-ADR1 branch which stimulates anti-pathogen defence. Besides these canonical immune pathways, proteolysis plays a pivotal role in immunity by regulating the abundance and activities of diverse components. We previously identified Arabidopsis papain-like cysteine protease RD19 as a PAD4 interactor and showed that RD19 promotes resistance to host-adapted pathogens. Here, we investigated the contribution of RD19 to bacterial flg22 and nlp20 elicited PTI responses which exhibit, respectively, partial and high PAD4 dependence. We show that although PAD4 and RD19 both promote PTI, they have separate functions. In resting (non-triggered) and nlp20-triggered tissues, RD19 limits RBOHD protein accumulation and consequently ROS production. Using N-terminomic enrichment and protease cleavage site identification methods we identify candidate RD19 substrates in resting and nlp20-responding tissues. Our analysis shows that two immune-related aspartyl proteases AED3 and AED2/ASPG1 are likely direct RD19 targets. This study reveals a role of RD19 in ROS regulation and advances our understanding of proteolysis and dynamic RD19 substrate targeting in plant immunity.

Progressive hepatic fibrosis is the principal determinant of morbidity and mortality in metabolic dysfunction-associated steatotic liver disease and steatohepatitis (MASLD/MASH). Mitochondrial dysfunction is a hallmark of MASH, and the release of mitochondrial damage-associated molecular patterns (mito-DAMPs) from injured hepatocytes can promote fibrosis. However, how mitochondrial dynamics and quality control shape the fibrotic response in MASLD/MASH remains unclear. Here, through large-scale genomic analyses of mitochondrial genes governing mitophagy, fusion and fission in human MASLD, with a power-equivalent sample size of approximately 700,000 individuals, we identify a strong association between hepatic fibrosis and the mitochondrial fusion factor dynamin-like GTPase optic atrophy 1 (OPA1). OPA1 transcripts and protein abundance in the liver epithelium were progressively dysregulated with advancing fibrosis. In mice, hepatocyte-specific OPA1 loss alone was sufficient to induce hepatic stellate cell activation and fibrosis in zone 3, promoted the release of mito-DAMPs into the circulation and exacerbated fibrosis in experimental MASH. These findings identify OPA1 as a central regulator of the hepatic fibrotic response and connect defective mitochondrial homeostasis to mito-DAMP release, hepatic stellate cell activation and fibrosis in MASLD.

Age-related decline in skeletal muscle function, often manifesting as slower gait speed, contributes significantly to frailty and loss of independence. To uncover the molecular basis of this decline, we investigated coordinated changes across the transcriptome, miRNome, and methylome in vastus lateralis muscle from female vervet monkeys (Chlorocebus aethiops sabaeus), contrasting middle-aged animals with normal gait speed versus older animals with declining gait speed. Through multi-omics integration, we identified a molecular signature that sharply distinguishes these two groups. This signature involves key regulatory molecules, including miR-181a-5p, miR-320b and miR-425 control of SYNCRIP, miR-193b-3p regulation of MCL1 and PLAU, as well as a multi-omic regulatory network governing ZNF274 and ANP32E gene expression, and altered levels of mRNAs such as VEZT. Functional annotation implicates miRNA signatures with inverse expression of their mRNA targets operating within systems of skeletal muscle biology, metabolism, and potential immune-inflammation mechanisms. Collectively, these findings reveal an interconnected network of epigenetic, post-transcriptional, and transcriptional alterations associated with impaired muscle function during aging. This molecular signature provides novel insights into potential mechanisms driving sarcopenia and highlights specific molecules as potential targets for interventions aimed at preserving muscle health.

Research has implicated lipid droplets (LDs) and their associated proteins in inflammation and the innate immune response. The key LD protein Perilipin 2 (PLIN2) is tightly correlated with lipid storage and inflammation, but little is known about the mechanisms underlying its proinflammatory effects. Here, we show that PLIN2 is required for the inflammatory response to mitogens and the recruitment of pro-inflammatory proteins to the surface of LDs. PLIN2 directly binds arachidonic acid and interacts with key oxylipin synthetic enzymes such as PLA2 and COX2 to promote LD-localized oxylipin synthesis and propagate inflammatory signaling. Moreover, LPS induces PLIN2 hyperacetylation, and acetylation-dead PLIN2 mutants lose their proinflammatory properties in the presence of an inflammatory stimulus, as if PLIN2 were ablated. Thus, acetylated PLIN2 forms a key metabolon on LDs that is essential for the response and amplification of proinflammatory signaling.

Cells degrade the autophagy receptor p62/sequestosome 1 (SQSTM1) in lysosomes. By knocking the HiBiT peptide into the endogenous SQSTM1 locus, we show that export is a second, quantitatively comparable fate. Specifically, p62 leaves cells continuously inside membrane-enclosed carriers at a rate similar to that of LC3B. Blocking lysosomal degradation amplifies release through an ATG5- and FIP200-dependent route, whereas a basal route persists in autophagy-deficient cells. Thus, p62 exits by at least two parallel pathways. Export requires PB1-mediated self-oligomerization but not LC3 binding, Kelch-like ECH-associated protein 1 (KEAP1) binding, or an intact ubiquitin-associated domain. Hence, oligomerization is the sorting determinant. KEAP1 is also released, and dominant-negative RAB27A retains both proteins inside cells and lowers nuclear factor erythroid 2-related factor 2 transcriptional output. Secretion is therefore a second outlet for the p62-KEAP1 module, and its interruption co-varies with a dampened oxidative stress response.