Minor intron retention resulting from dysregulation of minor intron splicing factors is an emerging risk factor for the metabolic dysfunction-associated steatotic liver disease (MASLD). However, whether impaired expression of these splicing factors exerts critical roles in MASLD progression independent of their minor intron splicing activity remains largely undefined. Here, we show that hepatic expression of the minor intron splicing factor ZRSR1 (zinc finger CCCH-type, RNA-binding motif, and serine/arginine rich 1) was significantly downregulated in mice fed a high-fat diet (HFD), while canonical minor intron splicing remained unperturbed. Gain- and loss-of-function analyses in liver tissue confirmed that hepatic ZRSR1 negatively modulated HFD-triggered obesity and insulin resistance, indicating that ZRSR1 restrained MASLD progression through a minor intron splicing-independent mechanism. Notably, ZRSR1 cell-autonomously suppressed liver X receptor (LXR) activation-induced de novo lipogenesis in both hepatocyte models and mouse models. Mechanistically, we demonstrate that ZRSR1 directly interacted with LXRα, and this physical interaction suppressed the binding activity of the LXRα/retinoid X receptor α (RXRα) complex toward the promoter regions of its target genes including the sterol regulatory element-binding protein 1c (Srebp1c), consequently repressing the transcription of Srebp1c and its downstream lipogenic genes. Collectively, these findings define a novel, splicing-independent function of the minor intron splicing factor ZRSR1 in mediating hepatic de novo lipogenesis via constraining the LXR-SREBP1c axis, which in turn mitigates MASLD progression. This work expands the functional repertoire of minor intron splicing factors beyond their classical splicing roles, providing new insights into the molecular mechanisms underlying hepatic fatty acid metabolism and MASLD pathogenesis.
Residential greenness has been linked to a reduced risk of type 2 diabetes (T2D), yet whether genetic susceptibility modifies this association remains unclear. Evidence on gene-environment interaction is limited, mainly cross-sectional, and largely from European-ancestry populations. Prospective data from Chinese populations examining the association between residential greenness and incident T2D, as well as glycemic traits, are scarce. In this study, we included 7861 middle-aged and older Chinese adults (aged ≥ 40 years), and assessed residential greenness using the Normalized Difference Vegetation Index (NDVI) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite imagery, linking it to T2D incidence over a median follow-up of 3.8 years. Genetic susceptibility was assessed in 5389 participants with DNA data using a T2D-specific weighted genetic risk score based on 89 genome-wide significant single-nucleotide polymorphisms identified in East Asian populations, weighted by published effect estimates. Our results show that higher residential greenness was associated with a 44% reduction in T2D risk (hazard ratio [HR] = 0.56, 95% confidence interval [CI]: 0.48-0.66), as well as improved insulin sensitivity and β-cell function. Notably, genetic susceptibility significantly modified the association between residential greenness and T2D on both multiplicative (P for interaction = 0.019) and additive scales (relative excess risk due to interaction [RERI] = 0.19), with higher greenness conferring greater relative and absolute risk reductions among individuals at medium and high genetic risk. These findings underscore a protective role of residential greenness against T2D, with stronger effects in those at higher genetic risk, supporting environmental interventions to mitigate genetic predisposition in the prevention of T2D.
Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a central role in regulating low-density lipoprotein cholesterol (LDL-C) levels and has emerged as an attractive target for atherosclerotic cardiovascular disease (ASCVD) therapy. While monoclonal antibodies targeting PCSK9 have demonstrated clinical efficacy, their high cost and need for repeated administration limit widespread use. In this study, we developed a peptide-based vaccine by identifying B-cell epitopes from PCSK9-antibody complexes using the Protein Data Bank (PDB) structural data and AlphaFold3 prediction, and fusing them with a heterologous T-helper epitope. The vaccine induced strong and durable anti-PCSK9 antibody responses in mice, guinea pigs, and rhesus macaques when formulated with the CpG plus alum adjuvant. The vaccine significantly reduced LDL-C levels and attenuated hepatic lipid accumulation in both prophylactic and therapeutic mouse models. Moreover, it mitigated the progression of atherosclerotic plaques. The vaccine also demonstrated no signs of systemic toxicity or autoimmunity in animal models. These findings indicate that the vaccine is a safe, effective, and scalable approach for controlling hypercholesterolemia and preventing ASCVD through active immunization against PCSK9.
The central nervous system is highly sensitive to energy supply, and the hippocampus operates under sustained metabolic load due to continuous synaptic activity and information processing. Lysosomes couple nutrient status to cellular energetics through the mechanistic target of rapamycin complex 1 (mTORC1) and the autophagy–lysosome pathway, yet their subcellular contribution to neuronal metabolic profiles remains unclear. To address this, we established an in vivo AAV-LysoTag/Lyso-IP workflow combined with metabolomics to quantify metabolites within mouse hippocampal lysosomes. An in vitro Lyso-IP platform and immunofluorescence provided cell-based validation. Under every-other-day fasting, hippocampal lysosomes exhibited reprogramming: small-molecule substrates derived from amino acids and fatty acids accumulated; bis(monoacylglycero)phosphate (BMP) was upregulated, indicating enhanced intraluminal vesicle formation and lipid degradation/sorting; sphingolipids and cardiolipin increased, consistent with selective mitophagy. Notably, high basal lysosomal levels of malic acid and α-ketoglutarate (α-KG) suggested additional sources beyond mitochondria. Immunofluorescence further showed lysosomal localization of isocitrate dehydrogenase and fumarate hydratase, suggesting partial residency of these enzymes. The oxoglutarate carrier (OGC, SLC25A11) signals were observed in LAMP1+ compartments, suggesting potential transmembrane exchange of α-KG and malic acid. Together, our data indicate that lysosomal TCA-related metabolites are maintained by three parallel routes: mitochondrial delivery to lysosomes, local production by resident enzymes, and transporter-mediated exchange. These metabolites supplement and reshape neuronal carbon flux and metabolic resilience at the subcellular level. Our findings elevate lysosomes from degradative endpoints to mobilizable metabolic hubs in the brain and provide both methodological and conceptual frameworks for neurometabolic adaptation under energy scarcity.
Type 2 diabetes (T2D) is characterized by pancreatic islet β-cell dysfunction and systemic insulin resistance, with meta-inflammation playing a critical role in disease progression. As the major type of immune cell population in islets, both resident and recruited macrophages are important regulators of the islet immune microenvironment under physiological and T2D conditions. Exercise is an effective strategy for treating T2D, yet its impacts on islet inflammation and β-cell dysfunction remain elusive. Here, we established a mouse model of exercise intervention in obesity-associated T2D by combining high-fat diet (HFD) feeding with treadmill running. Notably, exercise markedly improves glucose tolerance and insulin sensitivity, accompanied by substantial mitigation of HFD-induced β-cell dysfunction, islet hypertrophy, and alterations in β-cell subpopulations. Exercise also reduces intra-islet infiltration of CD45+ immune cells and dampens pro-inflammatory gene expression, indicating robust attenuation of islet inflammation. Using untargeted plasma proteomics, we identified the secreted protein acidic and rich in cysteine (SPARC) as a circulating factor, whose suppression is associated with exercise-linked islet protection under HFD conditions. Mechanistically, our data support a model in which SPARC contributes to β-cell dysfunction, at least in part, through macrophage inflammasome-related signaling. Further analysis of a human cohort demonstrates that circulating SPARC protein levels are markedly elevated in patients with T2D, exhibiting a significant negative correlation with parameters indicative of insulin sensitivity and β-cell function, and a positive correlation with insulin resistance. Together, this work provides a systemic characterization of the effects of exercise intervention on islet homeostasis and β-cell function, and highlights SPARC as a candidate immuno-metabolic node for T2D intervention.
The plasma membrane dynamically organizes into specialized lipid domains to sustain cell proliferative signaling, yet the regulatory mechanisms driving this process, especially during tumor progression, remain poorly understood. Here, we uncover cleft lip and palate transmembrane protein 1-like protein (CLPTM1L), an endoplasmic reticulum-localized lipid scramblase, as a critical regulator of membrane raft formation and the epidermal growth factor receptor (EGFR)-mediated proliferative signaling in cancer. High CLPTM1L expression was significantly associated with poor patient survival in glioblastoma (GBM), the most aggressive brain cancer. Depletion of CLPTM1L disrupts cellular lipid homeostasis and results in a substantial loss of membrane raft components, including glycosphingolipids and glycosylphosphatidylinositol (GPI)-anchored proteins. The cell-surface level of EGFR, which colocalizes with raft marker GM1, is markedly reduced upon CLPTM1L loss. We show that CLPTM1L-mediated raft remodeling promotes EGFR signaling and drives cell proliferation in both cancer and non-cancer cells. In GBM mouse models, CLPTM1L depletion inhibits EGFR signaling and profoundly impairs orthotopic tumor growth. Our work establishes CLPTM1L as a key regulator of membrane raft domain formation and highlights its critical role in cancer proliferative signaling.
Graphical AbstractFor image description, please refer to the figure legend and surrounding text.
Sphingolipids regulate hepatic lipid homeostasis, cell survival, inflammation, and tissue repair. In the healthy liver, balanced de novo sphingolipid synthesis, salvage pathways, and sphingosine-1-phosphate (S1P)-related signals maintain metabolic flexibility, endothelial integrity, and immune quiescence. Dysregulation of sphingolipid metabolism drives the initiation and progression of chronic liver diseases. In metabolic dysfunction-associated steatohepatitis, the acyl chain length-specific remodeling of dihydroceramides and ceramides, together with increased neutral sphingomyelinase activity, triggers lipotoxic stress, abnormal anabolic signal transduction, and hepatic lobule inflammation. Liver fibrosis involves reprogramming of the hepatic stellate cell S1P receptor signaling from regenerative toward profibrotic pathways. In hepatocellular carcinoma, tumor cells utilize sphingolipid metabolism to promote angiogenesis, evade immune surveillance, and develop therapeutic resistance. Sphingolipid remodeling in viral hepatitis links viral persistence to distinct circulating lipid signatures that correlate with disease severity and prognosis. Importantly, multiple nodes in the sphingolipid network and their downstream effectors are emerging as therapeutic targets. Promising preclinical strategies include liver-targeted small interfering RNA against key biosynthetic enzymes, selective modulation of sphingolipid receptors, and nanoliposomal formulations of bioactive ceramides. To enable clinical translation, innovative approaches are being developed to overcome key challenges in delivery, specificity, and safety. Overall, this review integrates recent mechanistic insights, emphasizing that sphingolipids act as central regulators of liver pathophysiology and are also important biomarkers and therapeutic targets in chronic liver diseases.
Intestinal stem cells (ISCs) play critical roles in the self-renewal and regeneration of the intestinal epithelium under physiological conditions and after injury, respectively. However, the underlying mechanisms are not fully understood. In this study, we investigate the role of the G protein-coupled receptor formyl peptide receptor 2 (FPR2) in intestinal epithelium homeostasis and regeneration. In mice, knocking out Fpr2 in either intestinal epithelial cells (IECs) or ISCs significantly reduces villus height and crypt depth by impairing ISC and transit-amplifying (TA) cell proliferation and differentiation, primarily TA cell differentiation. Mechanistic studies using intestinal organoid culture and bulk and single-cell RNA sequencing revealed that activation of FPR2 promotes proliferation and differentiation of ISCs and TA cells by activating the wingless/integrated (Wnt), Notch, and Hippo signaling pathways via protein kinase C (PKC)-extracellular signal-regulated kinase (ERK). Under physiological conditions, the Wnt and Notch signaling pathways mediate the regulation of ISC proliferation and differentiation by FPR2. Fpr2 deficiency in mouse IECs exacerbates X-ray- and 5-fluorouracil-induced villus and crypt injury, and delays intestinal epithelium regeneration by reducing ISC and TA cell proliferation. Administering an FPR2 agonist to mice significantly increases survival rates and accelerates intestinal epithelium regeneration after irradiation. Taken together, these results demonstrate that intestinal epithelial FPR2 plays a key role in intestinal epithelium homeostasis and regeneration by promoting ISC and TA cell proliferation and differentiation. FPR2 is a potential therapeutic target against chemotherapy- and radiotherapy-induced intestinal injury.
The central nervous system is highly sensitive to energy supply, and the hippocampus operates under sustained metabolic load due to continuous synaptic activity and information processing. Lysosomes couple nutrient status to cellular energetics through the mechanistic target of rapamycin complex 1 (mTORC1) and the autophagy-lysosome pathway, yet their -subcellular contribution to neuronal metabolic profiles remains unclear. To address this, we established an in vivo AAV-LysoTag/Lyso-IP workflow combined with metabolomics to quantify metabolites within mouse hippocampal lysosomes. An in vitro Lyso-IP platform and immunofluorescence provided cell-based validation. Under every-other-day fasting, hippocampal lysosomes exhibited reprogramming: small-molecule substrates derived from amino acids and fatty acids accumulated; bis(monoacylglycero)phosphate was upregulated, indicating enhanced intraluminal vesicle formation and lipid degradation/sorting; -sphingolipids and cardiolipin increased, consistent with selective mitophagy. Notably, high basal lysosomal levels of malic acid and α-ketoglutarate (α-KG) suggested additional sources beyond the mitochondria. Immunofluorescence further showed lysosomal localization of isocitrate dehydrogenase and fumarate hydratase, suggesting partial residency of these enzymes. The oxoglutarate carrier (SLC25A11) signals were observed in LAMP1+ compartments, suggesting potential transmembrane exchange of α-KG and malic acid. Together, our data indicate that lysosomal tricarboxylic acid -related metabolites are maintained by three parallel routes: mitochondrial delivery to lysosomes, local production by resident enzymes, and transporter-mediated exchange. These metabolites supplement and reshape neuronal carbon flux and metabolic resilience at the subcellular level. Our findings elevate lysosomes from degradative endpoints to mobilizable metabolic hubs in the brain and provide both methodological and conceptual frameworks for neurometabolic adaptation under energy scarcity.
Optimal control of hemoglobin A1c (HbA1c), blood pressure, and cholesterol (ABC risk factors) is essential for reducing cardiovascular disease (CVD) risk in individuals with diabetes. However, age-specific contributions of these factors remain inadequately characterized. Using data from the China Cardiometabolic Disease and Cancer Cohort study, we assessed the associations between ABC risk factors and incident CVD among Chinese adults with diabetes, stratified by age groups of < 55, 55 to < 65, 65 to < 75, and ≥ 75 years. Cox proportional hazards models and population-attributable fractions (PAFs) were used to quantify the associations between ABC risk factors and incident CVD. During a median follow-up of 10.1 years, 4707 incident cases of CVD were documented. Higher levels of baseline HbA1c, systolic blood pressure (SBP), and low-density lipoprotein cholesterol (LDL-C) were significantly associated with increased CVD risk. Age modified these associations (P interaction < 0.05), with progressively attenuated hazard ratios (HRs) observed in older age groups. Compared with HbA1c < 7.0%, HbA1c ≥ 9.0% showed stronger CVD associations in adults aged < 55 years (HR = 2.42; 95% confidence interval [CI]: 1.98-2.97) than in those aged ≥ 75 years (HR = 1.50; 95% CI: 1.12-2.02), and SBP ≥ 140 mmHg and LDL-C ≥ 4.1 mmol/L were significant only in younger groups. The leading contributor to PAFs for CVD was SBP (28.3%), followed by HbA1c (12.0%) and LDL-C (9.2%), with diminishing impacts across older groups. These results underscore the importance of age-specific management of ABC risk factors in diabetes care, with the benefit of stricter risk factor management in younger adults and the need for a more flexible approach in older populations.
Despite advances in traditional risk factors for cardiovascular diseases (CVDs), significant residual risk of CVDs remains incompletely captured. Integrative analysis incorporating cardiovascular magnetic resonance imaging (CMR) could facilitate to discover novel -therapeutic targets. This study aimed to identify potentially druggable plasma proteins for CVDs by incorporating CMR traits with integrative omics analysis. By integrating protein quantitative trait loci (pQTL) datasets of plasma proteins from Atherosclerosis Risk in Communities (ARIC) study with genome-wide association studies of 19 CVDs and 82 CMR traits, we sequentially used proteome-wide association study (PWAS), Mendelian randomization (MR), and colocalization analysis to identify putatively causal proteins. Replication MR was conducted using deCODE pQTL data, followed by observational association analysis using UK Biobank individual-level data, and multidimensional downstream analyses, as well as phenome-wide MR (Phe-MR). In total, we identified 342 protein-CVD and 115 protein-CMR pairs through PWAS. MR and colocalization ana-lyses revealed 66 protein-CVD and 39 protein-CMR pairs with potential causal relationships, of which 51 protein-CVD and 33 protein-CMR pairs were replicated. Additionally, 26 protein-CVD and 6 protein-CMR pairs showed significantly observational associations. Multidimensional downstream analysis highlighted potential biological pathways and druggability insights. Notably, AGER, CCN3, FER, and SPON1 were identified as proteins associated with both CVDs and CMR traits. Phe-MR analysis suggests potential beneficial and adverse effects of these proteins on other diseases. Our findings highlight potentially druggable plasma proteins for CVDs by incorporating CMR traits, providing novel insights into CVD pathogenesis and therapeutic drug development.
Calorie restriction (CR) is a nutritional intervention known to delay aging and extend lifespan across a wide range of species, raising the possibility of similar benefits in humans. This apparent universality has been questioned by studies reporting shortened lifespan under CR in certain mouse strains. Here, we provide a short perspective on these conflicting findings. Using simple simulation analyses, we explored the apparent strain-specific effects on CR outcomes. Our results illustrate how experimental factors have confounded previous interpretations and led to overemphasis on genotype effects. Reproducible CR studies are crucial for understanding the true potential of CR as a broadly applicable intervention in aging.
Glycine, a non-essential amino acid, has been linked to improved metabolic health and enhanced insulin secretion, yet its mechanistic role in β-cell function remains poorly defined. Here, we identify a glycine-GLRA1-calmodulin signaling axis that regulates endoplasmic reticulum (ER) calcium homeostasis to support insulin biosynthesis and β-cell survival. Dietary glycine deficiency impairs insulin secretion, reduces islet mass, and worsens glucose intolerance, while overexpression of serine hydroxymethyltransferase 2 (Shmt2), a key glycine biosynthetic enzyme, increases circulating glycine, enhances insulin output, and improves glucose control. Conversely, β-cell-specific deletion of Glra1 phenocopies glycine deficiency, disrupting ER calcium dynamics, amplifying ER stress, and impairing insulin gene expression and secretion. Mechanistically, GLRA1 interacts with calmodulin to sustain ER calcium levels and alleviate ER stress, preserving β-cell viability under metabolic stress. Human genetic and transcriptomic analyses reveal that GLRA1 expression and variants are associated with insulin secretion and glycemic traits, underscoring clinical relevance. These findings establish glycine as a signaling metabolite that activates a receptor-calcium axis to maintain β-cell function, offering a mechanistic rationale for targeting GLRA1 or dietary glycine in diabetes therapy.
Alternative splicing (AS) involves production of several different RNA molecules from a single pre-mRNA. Calorie restriction (CR) is a sustained calorie deficit without malnutrition, which extends health and lifespan. AS is dysregulated in aging but less so following CR, suggesting a role for AS in the beneficial effects of CR. To test the hypothesis that AS is involved in the CR response and explore its tissue specificity, male C57BL/6 mice were exposed to 3 months of graded CR (0-40% at 10% increments) and RNA sequencing data from six tissues (epididymal white adipose tissue [eWAT], liver, hypothalamus, gastrocnemius muscle, testes, and stomach) were analyzed to provide a multi-tissue characterization of differential AS (DAS). The number of differentially expressed splicing regulators increased with CR levels in all tissues but primarily the muscle, eWAT, and liver. The total number of DAS genes also increased with increasing CR levels and was largely tissue-specific. Most DAS genes were not differentially expressed. DAS was functionally integrated across tissues with the same processes being overrepresented: namely, mitochondria and oxidative phosphorylation, transcription and translation, and quality checking and degradation of RNA and especially proteins. This study demonstrates that short-term CR evokes a functionally integrated cross-tissue AS response in mice that is largely independent of expression changes.
Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most prevalent chronic liver disease worldwide, affecting both obese and non-obese individuals. While the reduced levels of circulating growth hormone (GH) and insulin-like growth factor 1 (IGF-1) have been consistently observed in patients with hepatic steatosis, the molecular role of hepatic growth hormone receptor (GHR) in MAFLD pathogenesis remains unclear. In this study, we established a liver-specific Ghr knockout (LGHRKO) mouse model that faithfully recapitulates non-obese MAFLD, characterized by hepatomegaly, elevated serum lipids and transaminases, and pronounced hepatic lipid accumulation, all occurring in the absence of obesity or increased adiposity. Mechanistically, LGHRKO livers displayed enhanced lipogenesis, impaired lipolysis, and upregulated cluster of differentiation 36 (CD36) expression, thereby driving hepatic lipid deposition. Single-cell RNA sequencing (scRNA-seq) further revealed hepatocyte-specific transcriptional alterations, including activation of lipid metabolic pathways and dysregulation of autophagy-related processes, providing insights into the cellular mechanisms underlying disease progression. Complementary human genetic analyses, including two-sample Mendelian randomization (MR) and genome-wide association studies (GWASs), demonstrated a causal relationship between impaired GH-IGF signaling and susceptibility to MAFLD, thereby bridging experimental observations with human disease risk. Collectively, our findings identify hepatic GHR deficiency as a key driver of non-obese MAFLD, establish LGHRKO mice as a valuable model for mechanistic and therapeutic studies, and underscore the translational significance of GH-IGF signaling in metabolic liver disease.
