Lipid Droplets Research Articles

Jordans’ anomaly in Chanarin-Dorfman syndrome

Abstract Objectives Chanarin-Dorfman syndrome is a rare disease inherited in an autosomal recessive pattern whose prevalence does not exceed 130 cases worldwide. Case presentation A 4-year-old patient with generalized erythematous-desquamative ichthyosiform syndrome since birth. The main laboratory finding was persistent hypertransaminasemia. Supplementary studies included peripheral blood smear (PBS), which revealed the presence of multiple cytoplasmatic vacuoles in polymorphonuclear leukocytes (PMN) and platelets. Ichthyosiform lesions concomitant to the presence of lipid vacuoles in peripheral blood PMNs are signs of Chanarin-Dorfman syndrome. Diagnostic suspicion was confirmed by genetic sequencing. Conclusions Chanarin-Dorfman syndrome is characterized by a mutation in the CGI-58 gene. This gene is involved in the catabolism of long-chain triglycerides stored in cytoplasmic lipid droplets. Jordans’ anomaly is a congenital alteration characterized by the presence of multiple vacuoles in the granulocytic series due to defective lipid metabolism. In this syndrome, long-chain triglycerides build up in tissues, thereby causing dermatological manifestations that are controllable through diet.

The acyltransferase transmembrane protein 68 regulates breast cancer cell proliferation by modulating triacylglycerol metabolism.

Cellular carcinogenesis is often marked by the accumulation of lipid droplets (LDs) due to reprogrammed lipid metabolism. LDs are dynamic organelles that primarily store intracellular triacylglycerol (TAG) and cholesteryl esters (CEs). Transmembrane protein 68 (TMEM68), a potential modifier of human breast cancer risk and outcomes, functions as a diacylglycerol acyltransferase, synthesizing TAG. However, the specific roles of TMEM68 in breast cancer cells remain unclear. Gene expression profiling interactive analysis and survival analysis were conducted. TMEM68 was overexpressed or knockdown in breast cancer cells to assess its impact on cell proliferation, migration and invasion. Targeted quantitative lipidomic analysis and quantitative polymerase chain reaction were used to profile lipid alterations and examine gene expression related to lipid metabolism following changes in TMEM68 levels. TMEM68 gene was upregulated in breast cancer patients and higher TMEM68 levels were associated with poorer survival outcomes. Overexpression of TMEM68 increased breast cancer cell proliferation and invasion, whereas knockdown had minimal or no impact on reducing proliferation and invasion. Altering TMEM68 levels resulted in corresponding changes in TAG levels and cytoplasmic LDs, with overexpression increasing both and knockdown decreasing them. Lipidomic analysis revealed that TMEM68 regulated TAG levels and altered diacylglycerol content in breast cancer cells. Additionally, TMEM68 influenced the metabolism of glycerophospholipids, CEs and acylcarnitines. TMEM68 also modified the expression of key genes encoding enzymes related to neutral lipid metabolism, including TAG and CEs. TMEM68 is highly expressed in breast cancer and negatively correlated with survival. Its overexpression promotes breast cancer cell proliferation while knockdown has varied effects depending on TMEM68 levels. TMEM68 regulates intracellular TAG and LDs contents along with alterations in glycerophospholipids. These findings suggest that TMEM68 may drive breast cancer cells proliferation by modulating TAG and LD content.

Treating metabolic dysfunction-associated steatohepatitis: The fat-trimming FGF21 approach.

Metabolic dysfunction-associated steatohepatitis (MASH) is a condition characterized by hepatosteatosis, inflammation, and tissue damage, with steatosis as the initial stage, which involves chronic, excess deposition of lipids in hepatic lipid droplets. Despite the growing prevalence and serious risks it poses, including liver decompensation, the need for transplantation, and increased patient mortality, MASH currently faces no approved pharmacotherapy. Several promising treatment candidates have emerged from recent clinical trials, including analogs of FGF21 and agonists of the associated FGFR1-KLB complex. These agents were well-tolerated in trials and have demonstrated significant improvements in both histological and biochemical markers of liver fat content, inflammation, injury, and fibrosis in patients with MASH. Endocrine FGF21 plays a vital role in maintaining homeostasis of lipid, glucose, and energy metabolism. It achieves this through pathways that target lipids or lipid droplets in adipocytes and hepatocytes. Mechanistically, pharmacological FGF21 acts as a potent catabolic factor to promote lipid or lipid droplet lipolysis, fatty acid oxidation, mitochondrial catabolic flux, and heat-dissipating energy expenditure, leading to effective clearance of hepatic and systemic gluco-lipotoxicity and inflammatory stress, thereby preventing obesity, diabetes, and MASH pathologies. In this review, we aim to provide an update on the outcomes of clinical trials for several FGF21 mimetics. We compare these outcomes with preclinical studies and offer a lipid-centric perspective on the mechanisms underlying the clinical benefits of these agents for MASH.

Ethanol extract of cassia seed alleviates metabolic dysfunction-associated steatotic liver disease by acting on multiple lipid metabolism-related pathways

Abstract Background and objective In northern China’s cold regions, the prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) exceeds 50%, significantly higher than the national and global rates. MASLD is an important risk factor for cardiovascular and cerebrovascular diseases, including coronary heart disease, stroke, and tumors, with no specific therapeutic drugs currently available. The ethanol extract of cassia seed (CSEE) has shown promise in lowering blood lipids and improving hepatic steatosis, but its mechanism in treating MASLD remains underexplored. This study aims to investigate the therapeutic effects and mechanisms of CSEE. Methods MASLD models were established in male Wistar rats and golden hamsters using a high fat diet (HFD). CSEE (10, 50, 250 mg/kg) was administered via gavage for six weeks. Serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), as well as liver TC and TG, were measured using biochemical kits. Histopathological changes in the liver were evaluated using Oil Red O staining, Hematoxylin-eosin (H&E) staining, and transmission electron microscopy (TEM). HepG2 cell viability was assessed using the cell counting kit-8 (CCK8) and Calcein-AM/PI staining. Network pharmacology was used to analyze drug-disease targets, and western blotting was used to confirm these predictions. Results CSEE treatment significantly reduced serum levels of TC, TG, LDL-C, ALT, and AST, and improved liver weight, liver index, and hepatic lipid deposition in rats and golden hamsters. In addition, CSEE alleviated free fatty acid (FFA)-induced lipid deposition in HepG2 cells. Molecular biology experiments demonstrated that CSEE increased the protein levels of p-AMPK, p-ACC, PPARα, CPT1A, PI3K P110 and p-AKT, while decreasing the protein levels of SREBP1, FASN, C/EBPα, and PPARγ, thus improving hepatic lipid metabolism and reducing lipid deposition. The beneficial effects of CSEE were reversed by small molecule inhibitors of the signaling pathways in vitro. Conclusion CSEE improves liver lipid metabolism and reduces lipid droplet deposition in Wistar rats and golden hamsters with MASLD by activating hepatic AMPK, PPARα, and PI3K/AKT signaling pathways.

Inhibiting lipid droplet biogenesis enhances host protection against hypervirulent Klebsiella pneumoniae infections.

Hypervirulent Klebsiella pneumoniae (hvKp), an emerging Kp subtype, has become a serious global pathogen. However, the information regarding host interactions and innate immune responses during hvKp infection is limited. Here, we found that hvKp clinical strains increased triacylglycerol synthesis, resulting in lipid droplets (LDs) formation via the mammalian target of rapamycin signaling pathway in RAW264.7 cells. Treatment with rapamycin, an inhibitor of this pathway, affected LDs formation and antimicrobial responses against clinical hvKp infections. In accordance with the role of LDs in modulating inflammation, the pharmacological inhibition of lipogenesis reduced proinflammatory cytokine expression during hvKp infections. In addition, inhibition of LDs formation using pharmacological inhibitors and knockdown of lipogenesis regulators decreased the intracellular survival of hvKp in macrophages. Moreover, inhibiting LDs biogenesis reduced mortality, weight loss, and bacterial loads in hvKp-infected mice. Collectively, these data suggest that LDs biogenesis is crucial in linking host immune responses to clinical hvKp infections.

Stearoyl-CoA desaturase in CD4+ T cells suppresses tumor growth through activation of the CXCR3/CXCL11 axis in CD8+ T cells.

Within the tumor microenvironment, altered lipid metabolism promotes cancer cell malignancy by activating oncogenic cascades; however, impact of lipid metabolism in CD4+ tumor-infiltrating lymphocytes (TILs) remains poorly understood. Here, we elucidated that role of stearoyl-CoA desaturase (SCD) increased by treatment with cancer-associated fibroblast (CAF) supernatant in CD4+ T cells on their subset differentiation and activity of CD8+ T cells. In our study, we observed that CD4+ TILs had higher lipid droplet content than CD4+ splenic T cells. In tumor tissue, CAF-derived supernatant provided fatty acids to CD4+ TILs, which increased the expression of SCD and oleic acid (OA) content. Increased SCD expression by OA treatment enhanced the levels of Th1 cell markers TBX21, interleukin-2, and interferon-γ. However, SCD inhibition upregulated the expression of regulatory T (Treg) cell markers, FOXP3 and transforming growth factor-β. Comparative fatty acid analysis of genetically engineered Jurkat cells revealed that OA level was significantly higher in SCD-overexpressing cells. Overexpression of SCD increased expression of Th1 cell markers, while treatment with OA enhanced the transcriptional level of TBX21 in Jurkat cells. In contrast, palmitic acid which is higher in SCD-KO cells than other subclones enhanced the expression of Treg cell markers through upregulation of mitochondrial superoxide. Furthermore, SCD increased the secretion of the C-X-C motif chemokine ligand 11 (CXCL11) from CD4+ T cells. The binding of CXCL11 to CXCR3 on CD8+ T cells augmented their cytotoxic activity. In a mouse tumor model, the suppressive effect of CD8+ T cells on tumor growth was dependent on CXCR3 expression. These findings illustrate that SCD not only orchestrates the differentiation of T helper cells, but also promotes the antitumor activity of CD8+ T cells, suggesting its function in adverse tumor microenvironments.

Up-regulated succinylation modifications induce a senescence phenotype in microglia by altering mitochondrial energy metabolism.

The aging of the central nervous system(CNS) is a primary contributor to neurodegenerative diseases in older individuals and significantly impacts their quality of life. Neuroinflammation, characterized by activation of microglia(MG) and release of cytokines, is closely associated with the onset of these neurodegenerative diseases. The activated status of MG is modulated by specifically programmed metabolic changes under various conditions. Succinylation, a novel post-translational modification(PTM) mainly involved in regulating mitochondrial energy metabolism pathways, remains unknown in its role in MG activation and aging. In the present study, we found that succinylation levels were significantly increased both during aging and upon lipopolysaccharide-induced(LPS-induced) MG activation undergoing metabolic reprogramming. Up-regulated succinylation induced by sirtuin 5 knockdown(Sirt5 KD) in microglial cell line BV2 resulted in significant up-regulation of aging-related genes, accompanied by impaired mitochondrial adaptability and a shift towards glycolysis as a major metabolic pathway. Furthermore, after LPS treatment, Sirt5 KD BV2 cells exhibited increased generation of reactive oxygen species(ROS), accumulation of lipid droplets, and elevated levels of lipid peroxidation. By employing immunoprecipitation, introducing point mutation to critical succinylation sites, and conducting enzyme activity assays for succinate dehydrogenase(SDH) and trifunctional enzyme subunit alpha(ECHA), we demonstrated that succinylation plays a regulatory role in modulating the activities of these mitochondrial enzymes. Finally, down-regulation the succinylation levels achieved through administration of succinyl phosphonate(SP) led to amelioration of MG senescence in vitro and neuroinflammation in vivo. To our knowledge, our data provide preliminary evidence indicating that up-regulated succinylation modifications elicit a senescence phenotype in MG through alterations in energy metabolism. Moreover, these findings suggest that manipulation of succinylation levels may offer valuable insights into the treatment of aging-related neuroinflammation.

Cannabinoid Receptor type 2 agonist GP1a attenuates macrophage activation induced by M. bovis-BCG by inhibiting NF-ĸB signaling.

Tuberculosis (TB) is one of the leading causes of death worldwide and a major public health problem. Immune evasion mechanisms and antibiotic resistance highlight the need to better understand this disease and explore alternative treatment approaches. Mycobacterial infection modulates the macrophage response and metabolism to persist and proliferate inside the cell. Cannabinoid receptor type 2 (CB2) is expressed mainly in leukocytes and modulates the course of inflammatory diseases. Therefore, our study aimed to evaluate the effects of the CB2-selective agonist GP1a on irradiated M. bovis-BCG (iBCG)-induced J774A.1 macrophage activation. We observed increased expression of CB2 in macrophages after iBCG stimulation. The pretreatment with CB2-agonists, GP1a, JWH-133, and GW-833972A (10 µM), reduced iBCG-induced TNF-α and IL-6 release by these cells. Moreover, the CB2-antagonist AM630 (200nM) treatment confirmed the activity of GP1a on CB2 by scale down its effect on cytokine production. GP1a pretreatment (10 µM) also inhibited the iBCG-induced production of inflammatory mediators as prostaglandin (PG)E2 and nitric oxide (NO) by macrophages. Additionally, GP1a pretreatment also reduced the transcription of proinflammatory genes (inos, il1b, cox2) and genes related to lipid metabolism (dgat1, acat1, plin2, atgl, cd36). Indeed, lipid droplet accumulation was reduced by GP1a treatment which was partially blockade by AM630 pretreatment. Finally, GP1a pretreatment reduced the activation of the NF-κB signaling pathway. In conclusion, the activation of CB2 by GP1a modulated the macrophage response to iBCG by reducing inflammatory mediator levels and metabolic reprogramming.

Complex‐mediated nucleophilic aromatic substitution with aryl nitriles to realize intramolecular flapping‐restricted D‐A AIEgens for bioimaging

AbstractDonor‐acceptor (D‐A) compounds are particularly important in optoelectronic and biological applications. However, they are normally synthesized in the presence of transition metal catalysts. Herein, we report a metal‐free method by a complex‐mediated nucleophilic aromatic substitution of aryl nitriles with amines. The method can lead to rich D‐A type aggregation‐induced emission luminogens (AIEgens) with tunable properties. They emit from deep‐blue to yellow‐green and possess high photoluminescence quantum yields up to 70.5% in the aggregate state. Interestingly, the suppression of intramolecular flapping is proved to play an indispensable role in the AIE behavior, which is different from the mechanism met in other AIEgens. Moreover, the biocompatible AIEgens possess specific staining of lipid droplets in HeLa cells and the superiority of identifying fatty liver over traditional Oil Red O staining is exhibited.

Extracts ofHylotelephiumerythrostictum (miq.) H. Ohba ameliorate intestinal injury by scavenging ROS and inhibiting multiple signaling pathways in Drosophila.

The intestinal epithelial barrier is the first line of defense against pathogens and noxious substances entering the body from the outside world. Through proliferation and differentiation, intestinal stem cells play vital roles in tissue regeneration, repair, and the maintenance of intestinal homeostasis. Inflammatory bowel disease (IBD) is caused by the disruption of intestinal homeostasis through the invasion of toxic compounds and pathogenic microorganisms. Hylotelephium erythrostictum (Miq.) H. Ohba (H. erythrostictum) is a plant with diverse pharmacological properties, including antioxidant, anti-inflammatory, antidiabetic, and antirheumatic properties. However, the roles of H. erythrostictum and its bioactive compounds in the treatment of intestinal injury are unknown. We examined the protective effects of H. erythrostictum water extract (HEWE) and H. erythrostictum butanol extract (HEBE) on Drosophila intestinal injury caused by dextran sodium sulfate (DSS) or Erwinia carotovoracarotovora 15 (Ecc15). Our findings demonstrated that both HEWE and HEBE significantly prolonged the lifespan of flies fed toxic compounds, reduced cell mortality, and maintained intestinal integrity and gut acid‒base homeostasis. Furthermore, both HEWE and HEBE eliminated DSS-induced ROS accumulation, alleviated the increases in antimicrobial peptides(AMPs) and intestinal lipid droplets caused by Ecc15 infection, and prevented excessive ISC proliferation and differentiation by inhibiting the JNK, EGFR, and JAK/STAT pathways. In addition, they reversed the significant changes in the proportions of the gut microbiota induced by DSS. The bioactive compounds contained in H. erythrostictum extracts have sufficient potential for use as natural therapeutic agents for the treatment of IBD in humans. Our results suggest that HEWE and HEBE are highly effective in reducing intestinal inflammation and thus have the potential to be viable therapeutic agents for the treatment of gut inflammation. Not applicable.

Effects of different water temperatures on the ovarian development and biochemical composition of Portunus trituberculatus after mating (Decapoda, Portunidae)

Abstract This study investigated the effects of different water temperatures (20, 23, 26 and 29°C) on the ovarian development and biochemical composition of Portunus trituberculatus (a swimming crab) after mating. The results showed that the higher the water temperature was, the faster the ovarian development, especially the GSI in the 29°C group was significantly higher than that in the 20°C and 23°C groups (). The hepatosomatic index (HSI) decreased with increasing water temperature, but there was no significant difference between the groups at different water temperatures (). The muscle yield (MY) was basically maintained at approximately 34%. The condition factor (CF) of the crab reached 0.62 in the 29°C group, which was significantly higher than that in the 20°C and 23°C groups (). Histological observation revealed that the number of lipid droplets and the degree of homogenization of yolk granules in ovarian oocytes gradually increased with the increase of the water temperature. From the perspective of conventional biochemical composition, the moisture and crude protein contents in muscle and the crude fat content in hepatopancreas did not change much among the groups, but the crude protein content in the ovary of the 29°C group was as high as 24.65%, which was significantly higher than that in the other three groups (). In terms of fatty acid composition, there was little difference in the fatty acid content in the ovaries of the different water temperature groups. The contents of C22 : 2n6 and C18 : 3n3 in polyunsaturated fatty acids were significantly higher in the 29°C group than in the other three groups (). In the hepatopancreas, the contents of C22 : 5n3 (DPA) and C22 : 6n3 (DHA) in the 20°C group were the lowest, 0.07% and 0.15%, respectively, which were significantly lower values than in the 29°C group (). The change of amino acid content is mainly reflected in ovarian tissues, showing a gradual upward trend as a whole. Furthermore, the essential amino acid score (EAAS) and average score of the two tissues in the 20°C and 23°C groups were relatively close, and both reached the highest score in the 29°C group. Overall, with increasing water temperature, the rate of ovarian development significantly accelerated, and the nutritional quality of the tissues improved in these swimming crabs.

Distinct peroxisome populations differentially respond to alcohol-associated hepatic injury.

Although peroxisomes are known to oxidize ethanol, metabolize lipids, and regulate oxidative stress, they remain understudied in the context of ethanol-induced liver injury. We examined peroxisome early responses to alcohol-induced oxidative stress and lipid overload. Analysis of peroxisomes labeled with catalase, an ethanol oxidizing enzyme, or ABCD3, a fatty acid transporter, revealed that distinct peroxisome populations differentially respond to ethanol. We determined that ethanol exposure induced a reversible, time-dependent, saturable increase in functional peroxisomes labeled with either marker. This increase was due to ethanol-induced oxidative stress. In cells treated with oleic acid (to mimic fatty liver), only ABCD3-positive peroxisomes proliferated, and preferentially colocalized with lipid droplets in cells treated with oleic acid alone and/or with ethanol. In cells overexpressing the tubulin-specific acetyltransferase, αTAT1, we determined that peroxisome-lipid droplet contacts were mediated by acetylated microtubules. Peroxisome proliferation was also observed in ethanol-fed mouse and rat livers, but was absent in fibrotic mouse models of liver injury and in samples from individuals with alcohol-induced cirrhosis suggesting that alcohol exposure promotes an early hepatoprotective rise in peroxisomes that is lost as the condition progresses to fibrosis. Our studies further suggest that PPAR agonists may be an effective intervention for early ethanol-associated liver disease.

PunctaFinder: an algorithm for automated spot detection in fluorescence microscopy images.

Fluorescence microscopy has revolutionised biological research by enabling the visualisation of subcellular structures at high resolution. With the increasing complexity and volume of microscopy data, there is a growing need for automated image analysis to ensure efficient and consistent interpretation. In this study, we introduce PunctaFinder, a novel Python-based algorithm designed to detect puncta, small bright spots, in raw fluorescence microscopy images without image denoising or signal enhancement steps. Furthermore, unlike other available spot detectors, PunctaFinder not only detects puncta, but also defines the cytoplasmic region, making it a valuable tool to quantify target molecule localisation in cellular contexts. PunctaFinder is a widely applicable punctum detector and size estimator, as evidenced by its successful detection of Atg9-positive vesicles, lipid droplets, aggregates of a destabilised luciferase mutant, and the nuclear pore complex. Notably, PunctaFinder excels in detecting puncta in images with a relatively low resolution and signal-to-noise ratio, demonstrating its capability to identify dim puncta and puncta of dynamic target molecules. PunctaFinder reliably detects puncta in fluorescence microscopy images where automated analysis was not possible before, providing researchers with an efficient and robust method for punctum quantification in fluorescence microscopy images.

Abstract 4140191: ChREBP Drives Brown Adipocyte Differentiation and Lipid Utilization for Excess Energy Expenditure

Introduction: Although several anti-obesity drugs have become recently available, they reduce patients’ appetite, which might worsen cardiovascular disease (CVD) prognosis by malnutrition/cachexia. Brown adipose tissue (BAT) oxidizes glucose and lipids for thermogenesis, a process that requires excess energy expenditure provided by uncoupling protein 1 (UCP1) + cells. Recently, critical roles of BAT in cardio-protection have been discovered. Taken together, boosting BAT activity can be a novel anti-obesity treatment suitable for CVD patients. In this study, we aimed to establish anti-obesity strategy by manipulation of the glucose-sensing lipid-storage transcription factor, ChREBP, with unexpected function of boosting lipid utilization in BAT. Methods and Results: Through mouse/human single-cell/nucleus RNA sequencing analyses, we identified ChREBP as specifically expressed in highly thermogenic UCP1 + brown adipocytes ( Fig.A ). To investigate the role of ChREBP in BAT formation, we generated human brown adipocyte-like model from induced pluripotent stem cells (iPSC-BAT, Fig.B ). The iPSC-BAT exhibited high UCP1 and ChREBP expression, multi-locular lipid droplets, and vigorous oxygen consumption. Knocking down ChREBP strongly blocked iPSC-BAT differentiation ( Fig.C ) and impaired lipid utilization ( Fig.D ). Consistently, in vitro deletion of ChREBP in mouse BAT progenitors impeded differentiation, lipid droplet accumulation, and oxygen consumption ( Fig.E-F ). In vivo, BAT-specific deletion of all ChREBP isoforms reduced lipid accumulation and BAT characteristics. Conversely, using a new mouse model for Cre-mediated ChREBPβ overexpression, we showed that ChREBPβ overexpression in BAT (Chβ BATOX) increased BAT cellularity and activated lipogenic machineries, with paradoxical decreased lipid content, suggesting excessively activated lipid consumption in BAT ( Fig.G ). More importantly, Chβ BATOX maintained UCP1 expression and reduced fat volume ( Fig.H ) even after strongly inhibiting BAT activity. Conclusion: In summary, ChREBP is essential for BAT development and thermogenic capacity by affecting lipid utilization. Our results suggest that ChREBPβ activation may be a novel anti-obesity avenue for CVD patients.

Abstract 4136511: Targeting ATP Citrate Lyase: A Novel Therapeutic Strategy for Vascular Remodeling in Pulmonary Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by a progressive obliteration of distal pulmonary arteries (PA), which is driven by a cancer-like pro-proliferative phenotype of smooth muscle cells (SMCs). A metabolic shift towards glycolysis and changes in the epigenetic landscape contribute to this abnormal phenotype. ATP Citrate Lyase (ACLY) is an enzyme that plays a role in promoting the Warburg effect, lipid synthesis, and chromatin remodeling in cancer. However, its role in PAH remains unknown. We hypothesized that ACLY is upregulated in PAH and supports the abnormal phenotype of PAH-PASMCs . Methods/Results: To investigate this hypothesis, we measured ACLY expression in human distal pulmonary arteries and isolated PASMCs from PAH patients (immunoblot/Immunofluorescence). We found increased expression and activation of ACLY in PAH-PASMCs, with preferential localization in the nucleus. Inhibition of ACLY using BMS-303141 or siACLY decreased PAH-PASMCs proliferation (Ki67/MCM2, PLK1, PCNA) and survival (Annexin V/SURVIVIN). ACLY inhibition also reduced glycolysis markers and increased mitochondrial respiration. Additionally, the inhibition of ACLY lowered cholesterol levels and lipid droplet accumulation in PAH-PASMCs. Further analysis showed that ACLY promotes nuclear acetyl-CoA production, leading to acetylation of specific histone proteins and GCN5-mediated transcriptional activation of genes involved in cell cycle progression. The transcription factor FOXM1 appeared to mediate this genetic signature. In vivo , pharmacological inhibition of ACLY using BMS-303141 significantly improved pulmonary vascular remodeling (Elastica Van Gieson staining, EVG) and right ventricular function (RVSP, mPAP, TAPSE, S-Wave, SV by echocardiography and right heart catheterization) in Su/Hx-challenged rats with established PAH. SMC-specific Acly K.O mice were protected against Su/Hx-induced PAH. Consistently, tamoxifen-induced SMC-specific Acly deletion improved hemodynamics parameters in Su/Hx mice. These therapeutic effects were associated with a reduced acetylation of H3K27 and H3K9 (IF). Ex vivo , inhibition of ACLY attenuated vascular remodeling (EVG) in human precision cut lung slices exposed to a growth factor cocktail. Conclusion: Our study reveals that ACLY plays a critical role in vascular remodeling in PAH and its pharmacological inhibition may represent a novel and attractive avenue as therapeutic treatment.

Analysis of Lipid Metabolism in Adipose Tissue and Liver of Chinese Soft-Shelled Turtle Pelodiscus sinensis During Hibernation

Hibernation serves as an energy-conserving strategy that enables animals to withstand harsh environments by reducing their metabolic rate significantly. However, the mechanisms underlying energy adaptation in hibernating ectotherms, such as Pelodiscus sinensis, remain contentious. This paper first reports the decrease in lipid levels and the expression of metabolism-related genes in P. sinensis during hibernation. The results of physiological and biochemical analysis showed that adipocyte cell size was reduced and liver lipid droplet (LD) contents were decreased during hibernation in P. sinensis. Concurrently, serum levels of triglycerides (TGs), total cholesterol (TC), non-esterified fatty acids (NEFAs), high-density lipoprotein cholesterol (HDLC), and low-density lipoprotein cholesterol (LDLC) were diminished (n = 8, p < 0.01), while an increase in serum glucose (Glu) (n = 8, p < 0.01) was noted among hibernating P. sinensis. These observations suggest a shift in energy metabolism during hibernation. To gain insights into the molecular mechanisms, we performed integrated transcriptomic and lipidomic analyses of adipose tissue and livers from summer-active versus overwintering P. sinensis, which revealed downregulation of free fatty acids (FFAs), triglycerides (TGs), diglycerides (DGs), and ceramides (Cers) during hibernation. The results of GSEA analysis showed that metabolic pathways associated with lipid metabolism, including glycerolipid metabolism and regulation of lipolysis in adipocytes, were suppressed significantly. Notably, acute cold exposure induced significant downregulation of genes related to lipolysis such as PNPLA2, ABHD5, LPL, CPT1A, and PPARα. The results indicate that lipolysis is suppressed during hibernation in P. sinensis. Collectively, these findings deepen our understanding of survival mechanisms and elucidate the unique energy adaptation strategies employed by hibernating ectotherms. Future research should explore the implications of these findings for the conservation of ectotherms and the applications for artificially inducing hibernation.

Abstract 4138745: Blockade of Mineralocorticoid Receptor by Esaxerenone Improves Insulin Sensitivity in Obese Mice

Background: Aldosterone regulates blood pressure and electrolyte balance. However, overactivation of the mineralocorticoid receptor (MR) and elevated aldosterone levels are implicated in the pathogenesis of cardiometabolic disorders, though the underlying mechanisms are not fully understood. In this study, we investigated whether a novel, non-steroidal selective MR blocker, esaxerenone, ameliorates the development of metabolic disorders in obese mice models and examined the underlying mechanism. Methods: Esaxerenone (3 mg/kg/day) was orally administered to high-fat diet (HFD)-fed C57BL/6J or normal chow-fed db/db mice. Metabolic parameters, tissue morphology, and effects of esaxerenone on insulin sensitivity were assessed. Gene expression and insulin signaling, determined by Akt phosphorylation, were examined using quantitative RT-PCR and western blotting, respectively. In in-vitro experiments, insulin targets cell lines such as 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes were used. Insulin-responsive cells were treated with 10 nM or 100 nM esaxerenone or eplerenone for 30 minutes before 4-hour 1000 nM aldosterone stimulation. Insulin signaling was assessed 15 minutes after stimulation with 17 nM insulin. Results: Esaxerenone improved insulin sensitivity (P<0.05) without altering metabolic parameters in HFD-induced obese and db/db mice. Esaxerenone suppressed fat accumulation, adipocyte size, and liver lipid droplets compared with the vehicle-treated group (P<0.01). In adipose tissue, esaxerenone reduced macrophage infiltration (P<0.01) and the expression of inflammatory molecules (P<0.05). In in-vitro experiments, aldosterone significantly decreased the expression levels of PPARγ and adiponectin in 3T3-L1 adipocytes. Moreover, aldosterone attenuated insulin-induced Akt phosphorylation in 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes in a dose-dependent manner (P<0.01). Pretreatment with esaxerenone reversed the effect of aldosterone, whereas eplerenone, an MR antagonist, did not show a similar effect at the same dose. Conclusion: Inhibition of MR by esaxerenone improved insulin sensitivity in HFD-induced obese and genetically diabetic mice. The reduction of inflammation and fat accumulation and enhancement of insulin signaling were suggested to be underlying mechanisms. Esaxerenone might be a beneficial therapeutic approach for managing metabolic disorders.

Molecular mechanisms of lipid droplets-mitochondria coupling in obesity and metabolic syndrome: insights and pharmacological implications

Abnormal lipid accumulation is a fundamental contributor to obesity and metabolic disorders. Lipid droplets (LDs) and mitochondria (MT) serve as organelle chaperones in lipid metabolism and energy balance. LDs play a crucial role in lipid storage and mobilization, working in conjunction with MT to regulate lipid metabolism within the liver, brown adipose tissue, and skeletal muscle, thereby maintaining metabolic homeostasis. The novelty of our review is the comprehensive description of LD and MT interaction mechanisms. We also focus on the current drugs that target this metabolism, which provide novel approaches for obesity and related metabolism disorder treatment.

Global impacts of peroxisome and pexophagy dysfunction revealed through multi-omics analyses of lon2 and atg2 mutants.

Peroxisomes house diverse metabolic pathways that are essential for plant and animal survival, including enzymes that produce or inactivate toxic byproducts. Despite the importance of peroxisomes and their collaborations with other organelles, the mechanisms that trigger or prevent peroxisome turnover and the cellular impacts of impaired peroxisomes are incompletely understood. When Arabidopsis thaliana LON2, a peroxisomal protein with chaperone and protease capacity, is disrupted, metabolic dysfunction and protein instability in peroxisomes ensue. Paradoxically, preventing autophagy in lon2 mutants appears to normalize peroxisomal metabolism and stabilize peroxisomal proteins-hinting at a role for autophagy in causing the peroxisomal defects observed in lon2 seedlings. Using a combination of transcriptomics, proteomics, and in silico investigations, we compared wild type to lon2 and autophagy null mutants and double mutants. Through this analysis, we found that impeding autophagy via an atg2 null mutation alleviated several of the global defects observed when LON2 is absent. Moreover, we revealed processes influenced by LON2 that are independent of autophagy, including impacts on lipid droplet and chloroplast protein levels. Finally, we identified and classified potential LON2 substrates, which include proteins that might provide signal(s) for pexophagy.

TMIC-19. EXCESSIVE LIPID PRODUCTION SHAPES GLIOMA TUMOR MICROENVIRONMENT

Abstract Disrupted lipid metabolism is a characteristic of gliomas. This study utilizes an ultrastructural approach to characterize the prevalence and distribution of lipids within gliomas. This study made use of tissue from IDH1 wild type (IDH1-wt) glioblastoma (n=18) and IDH1 mutant (IDH1-mt) astrocytoma (n=12) tumors. We uncover a prevalent and intriguing surplus of lipids. The bulk of the lipids manifested as sizable cytoplasmic inclusions and extracellular deposits in the tumor microenvironment (TME); in some tumors the lipids were stored in the classical membraneless spheroidal lipid droplets (LDs). Frequently, lipids accumulated inside mitochondria, suggesting possible dysfunction of the beta-oxidation pathway. Additionally, the tumor vasculature has lipid deposits in their lumen and vessel walls; this lipid could have shifted in from the tumor microenvironment or have been produced by the vessel-invading tumor cells. Lipid excess in gliomas stems from disrupted beta-oxidation and dysfunctional oxidative phosphorylation pathways. The implications of this lipid-driven environment include structural support for the tumor cells and protection against immune responses, non-lipophilic drugs, and free radicals.