Adipocyte Gene Research Articles

Black phosphorus quantum dots induce lipid accumulation through PPARγ activation and mitochondrial dysfunction in adipocytes.

Black phosphorus quantum dots (BPQDs) are believed to have broad prospects for application. Obesity has garnered significant attention, but the association between BPQDs and lipid metabolism has not been thoroughly investigated. Mice were orally exposed to BPQDs at doses of 0.1 and 1mg/kg for 28d. The exposed mice exhibited reduced insulin sensitivity, hypertrophy of white adipose tissues, and reduced thermogenic function of brown adipose tissues. In white adipocyte line (3T3-L1), exposure to 5-20μg/mL BPQDs induced lipid accumulation, oxidative stress, and upregulated the expression of PPARγ and genes involved in de novo lipogenesis. Moreover, both a reactive oxygen species (ROS) scavenger and a PPARγ inhibitor were able to attenuate lipid accumulation and downregulate the expression of lipid-associated genes in white adipocytes. In mouse brown adipocytes, BPQDs exposure caused oxidative stress, mitochondrial dysfunction, and downregulation of thermogenic genes such as UCP1. The ROS scavenger attenuated the oxidative stress and improved the mitochondrial thermogenic function in brown adipocytes. In summary, this work demonstrates that oxidative stress induced by BPQDs mediates the lipid accumulation possibly through PPARγ activation and mitochondrial dysfunction of adipose tissues, highlighting the potential obesogenic effect of BPQDs. Our findings provide novel insights into the biosafety of BPQDs and their potential health risks to humans, offering important considerations for the sustainable application of BP materials. ENVIRONMENTAL IMPLICATION: BPQDs are a novel type of nanomaterials with unique physicochemical properties, and have broad applications in various fields, particularly in biomedicine. However, during the production and use of BPQDs as medical materials, they inevitably contact with the human body for long periods of time. Therefore, it is necessary to investigate the effects of BPQDs on organisms under long-term exposure, especially lipid metabolism. This study would be helpful decreasing the environmental health risk of BP materials and promoting their sustainable development of nanotechnology in biomedicine.

Human miR-1 Stimulates Metabolic and Thermogenic-Related Genes in Adipocytes.

MicroRNAs play a pivotal role in the regulation of adipose tissue function and have emerged as promising therapeutic candidates for the management of obesity and associated comorbidities. Among them, miR-1 could be a potential biomarker for metabolic diseases and contribute to metabolic homeostasis. However, thorough research is required to fully elucidate the impact of miR-1 on human adipocyte thermogenesis and metabolism. This study aimed to explore the effect of miR-1 on human adipocyte browning, a process whose activation has been linked to obesity protection and counteraction. Human multipotent adipose-derived stem cells, hMADS cells, were differentiated into white and brown-like adipocytes and transfected with miR-1 mimics for gene expression and western blotting analyses. miR-1 inhibited the expression of its previously validated target PTK9/TWF1 and modulated the expression profile of key genes involved in thermogenesis and adipocyte browning (increased UCP1 at mRNA and protein level, increased CPT1M, decreased HIF3A), adipocyte differentiation and metabolism (decreased PLIN1, FASN, RXRA, PPARG, FABP4, MAPKAPK2), as well as genes related to the cytoskeleton (decreased ACTB) and extracellular matrix (decreased COL1A1). These findings suggest that miR-1 can modulate the expression of adipocyte human genes associated with thermogenesis and metabolism, which could hold value for eventual therapeutic potential in obesity.

Novel role of human epicardial adipocyte-derived SPARCL1 in suppression of postoperative atrial fibrillation in patients undergoing cardiovascular surgery

Abstract Background Postoperative atrial fibrillation (POAF) occurs in 20-50% after cardiovascular surgery and is associated with the short and long-term morbidity/mortality. The epicardial adipose tissue (EAT) may have a potential role to regulate the incidence of POAF. Purpose We explored the possible role of human epicardial adipocyte-derived adipokines in the regulation of the myocardial redox state and POAF. Methods We prospectively evaluated 149 patients without known AF who underwent scheduled open-heart cardiovascular surgery between May 2020 and November 2022. They were divided into POAF or Non-POAF group and followed up after discharge (476.6 ± 290.0 days). POAF was defined as AF lasting more than 30 seconds after the surgery. Human EAT samples were obtained from these patients during surgery and the preadipocytes were isolated. Preadipocytes were terminally differentiated to mature adipocytes and mRNAs were extracted. Genome-wide expression profiling of 6 vs. 6 matched samples of the POAF and Non-POAF groups was performed using Microarray analysis, and the results were validated with qPCR in all the cohort samples. The effects of secreted adipokines on the cardiomyocytes were assessed in terms of oxidative stress. Superoxide and whole reactive oxygen species (ROS) were evaluated with luminometry and live-cell fluorescent probes respectively. As the oxidative stress associated signalling, the phosphorylation of ERK and p38-MAPK were evaluated with western blotting. Angiotensin II (Ang-II) was used to induce oxidative stress and phosphorylation of MAPK. Results POAF was observed in 53 patients (36%). Microarray analysis (n = 6) revealed that there were 132 down- or up-regulated cording genes in epicardial adipocytes of the POAF group compared to the Non-POAF group. Of these genes, 11 genes cording secretable molecules were validated by qPCR (n = 69), showing that only SPARCL1 had significantly downregulated in the POAF group compared to the Non-POAF group (P = 0.005). Superoxide and ROS were induced by Ang II (P < 0.01) and attenuated by SPARCL1 dose-dependent manner (P < 0.01) in neonatal rat cardiomyocytes. The phosphorylation of ERK and p38-MAPK were induced by Ang II (P < 0.01) and attenuated by SPARCL1 (P < 0.01) dose-dependently. Co-culture of human induced pluripotent stem cell-derived atrial cardiomyocytes (iPS-ACM) and human epicardial adipocytes revealed that the adipocytes derived from Non-POAF group suppressed the superoxide (P = 0.002) and ROS (P = 0.02) in iPS-ACM compared to POAF group. Kaplan-Meier survival analysis revealed that the POAF group (P = 0.01) and low SPARCL1 expression in epicardial adipocytes (P = 0.018) were associated with a higher incidence of long-term adverse cardiovascular events after surgery. Conclusion: SPARCL1 derived from epicardial adipocytes may play an important role in the suppression of POAF and long-term cardiovascular events via improving the myocardial redox state.

Effect of gene CRTC2 on the differentiation of subcutaneous precursor adipocytes in goats.

The aim of this study was to obtain goat CRTC2 gene sequence and elucidate its biological properties, and further study the impact of overexpression and interference of CRTC2 on the cell differentiation of goat subcutaneous precursor adipocytes. The sequence of goat CRTC2 was cloned by reverse transcription polymerase chain reaction (RT-PCR) and its molecular characterization was analyzed. The expression of CRTC2 gene in goat tissues and subcutaneous precursor adipocytes differentiated from 0 to 120 h was examined by quantitative real-time PCR (qRT-PCR). The effects of CRTC2 on the subcutaneous precursor adipocyte differentiation were investigated by using liposome transfection, Bodipy, Oil Red O staining and qPCR. The results showed that the cloned goat CRTC2 gene was 2363 bp long (coding sequence [CDS] 2082 bp), encoding 693 amino acids. The relative expression levels of CRTC2 gene were highest in liver and then in kidney (P < 0.05). During differentiation, the highest expression of CRTC2 in subcutaneous precursor adipocytes was observed at 120 of differentiating (P < 0.01). In addition, we found that overexpression of CRTC2 significantly increased the expression of lipid metabolism-related genes (C/EBPα, C/EBPβ, PPARγ, DGAT1, DGAT2, ACC, FASN, SREBP1，AP2，LPL，ATGL) and promoted lipid accumulation. We then chemically synthesized goat CRTC2 small interfering RNA and transfected it into goat subcutaneous precursor adipocytes. The results revealed that SiRNA-mediated interference with CRTC2 significantly inhibited its differentiation and suppressed lipid droplet aggregation. So, this study indicates that CRTC2 is a positive regulator that promoting cell differentiation of subcutaneous adipocyte in goats, which lays the foundation for an in-depth study of the role of CRTC2 in lipid deposition in goats.

Chi-circ_0009659 modulates goat intramuscular adipocyte differentiation through miR-3431-5p/STEAP4 axis.

Circular RNAs (circRNAs) are widely involved in the regulation of lipid deposition in animals, but there are few reports on key circRNAs regulating intramuscular adipocyte differentiation in goats. Therefore, this study took an abundantly expressed in goat adipocytes chi-circ_0009659 as the object. Based on the identification of back splicing site in chi-circ_0009659, its expression level during the goat intramuscular preadipocyte differentiation was detected by qPCR. The chi-circ_0009659 loss-of-function and gain-of-function cell models were obtained by adenovirus and smarter silencer, respectively. and the adipocyte differentiation were explored by Oil Red O staining, Bodipy staining and qPCR. Its major cytoplasmic localization was determined by FISH, nucleocytoplasmic separation and qPCR. The interaction between chi-circ_0009659, miR-3431-5p, and STEAP family member 4 (STEAP4) was verified by bioinformatics, RNA pull down and dual luciferase reporter assay. Silencing chi-circ_0009659 inhibited lipid droplet accumulation and the expression of differentiation-determining genes in goat intramuscular adipocytes, while overexpression of chi-circ_0009659 reversed these results. chi-circ_0009659 was predominantly localized to the cytoplasm and could regulate miR-3431 expression which in turn affects STEAP4. Consistent with expectations, miR-3431-5p acted as a negative regulator of GIMPA differentiation, while STEAP4 promoted differentiation. We demonstrated chi-circ_0009659 positively regulates goat intramuscular preadipocyte differentiation by sponging miR-3431-5p to further regulate the expression of STEAP4. This research provides a new reference for in-depth understanding of the effects of circRNA on adipocyte differentiation.

Screening and analysis of GULP1 downstream target genes based on transcriptomic sequencing.

GULP1 is an engulfment adaptor protein containing a phosphotyrosine-binding (PTB) domain, and existing studies have shown that it can promote glucose uptake in 3T3-L1 adipocytes. To further explore key metabolically related differential genes downstream of GULP1, this study conducted transcriptome analysis on adipocytes and skeletal muscle cells overexpressing GULP1. Subsequently, abnormally expressed genes were subjected to bioinformatic analysis, and real-time fluorescent quantitative PCR (qRT-PCR) was used for mutual validation with transcriptome sequencing. The results indicated that, with a threshold of P < 0.05 and |Log2FoldChange| ≥ 1 for screening differentially expressed genes, compared with control cells, there were 278 upregulated and 263 downregulated genes in adipocytes overexpressing GULP1. Metabolism-related GO (Gene Ontology) terms included cholesterol biosynthetic process, cholesterol metabolic process, response to lipopolysaccharide, lipid metabolic process, etc. A total of 52 metabolically related differentially expressed genes were enriched in 10 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, with lipid metabolism being highly enriched. In skeletal muscle cells overexpressing GULP1, there were 280 upregulated and 302 downregulated genes, with metabolism-related GO terms including hormone metabolic process, response to lipopolysaccharide, one-carbon metabolic process, etc. A total of 86 metabolically related differentially expressed genes were enriched in 10 KEGG pathways, with amino acid metabolism, lipid metabolism, and carbohydrate metabolism being highly enriched. GULP1's biological functions are extensive, including lipid metabolism and oncology. This study, through transcriptomics and bioinformatic analysis, identified key metabolically related differential genes downstream of GULP1, obtained metabolically related differential genes and signaling pathways after GULP1 overexpression, providing important theoretical basis for future research on GULP1 downstream target genes.

Curcuma longa rhizome extract activates brown adipocytes and inhibits lipogenesis in high-fat diet-fed mice

Interactions between the gut, adipose, and liver tissues play important roles in metabolic endotoxemia and gut dysbiosis. This study explored the effectiveness of Curcuma longa rhizome extract (CRE) in improving high-fat diet (HFD)-induced metabolic disorders and modulating gut environments. CRE treatment inhibited lipid accumulation in 3T3-L1 white adipocytes and activated thermogenesis-related genes in T37i brown adipocytes. CRE was administered to HFD-fed mice for 8 weeks, and serum, feces, colon, white adipose, and liver tissue were analyzed. CRE ameliorated the symptoms of metabolic disorders in mice with HFD-induced obesity by suppressing body weight and fat mass gain, adipocyte size, insulin resistance, and hepatic steatosis. CRE regulated gut axis-based mechanisms by inhibiting gut permeability, metabolic endotoxemia, and de novo lipogenesis, and promoting gut barrier integrity. Serum metabolites were negatively correlated with most biomarkers for metabolic disorders. Therefore, CRE could alleviate metabolic disorders by improving the intestinal environment and modulating the gut axis.

Protective effects of menthol against olanzapine-induced metabolic alterations in female mice

AimMetabolic comorbidities such as obesity type 2 diabetes, insulin resistance, glucose intolerance, dyslipidemia are the major contributors for lower life expectancy and reduced patient compliance during antipsychotic therapy in patients with severe mental illnesses such as schizophrenia, bipolar disorder, and depression. TRPM8 activation by menthol is also reported to alleviate high fat diet-induced obesity in mice. Additionally, this TRPM8 activation leads to increase in gene expression of thermogenic genes in white adipocytes and dietary menthol was found to increase browning of WAT along with improved glucose utilization. Therefore, we aimed to evaluate the plausible role of TRPM8 channels in olanzapine-induced metabolic alterations in female balb/c mice. Methods6 weeks olanzapine (6 mg kg−1, per oral) model was used in female balb/c mice. Pharmacological manipulation of TRPM8 channel was done using menthol and N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)-benzamide (AMTB), the agonist and antagonist respectively. Key resultsMenthol co-treatment for six weeks prevented olanzapine-induced metabolic alterations such as weight gain, increased food intake, decreased energy expenditure, adiposity, liver lipid accumulation, systemic inflammation and insulin resistance. Although no significant change in TRPM8 mRNA expression was found in the hypothalamus, however, some of the protective effects of menthol were absent in presence of AMTB indicating possible involvement of TRPM8 channels. ConclusionOur results suggest possible therapeutic implications of menthol in the management of antipsychotic-induced weight gain and other metabolic alterations.

Plant miR6262 Modulates the Expression of Metabolic and Thermogenic Genes in Human Hepatocytes and Adipocytes.

Edible plants have been linked to the mitigation of metabolic disturbances in liver and adipose tissue, including the decrease of lipogenesis and the enhancement of lipolysis and adipocyte browning. In this context, plant microRNAs could be key bioactive molecules underlying the cross-kingdom beneficial effects of plants. This study sought to explore the impact of plant-derived microRNAs on the modulation of adipocyte and hepatocyte genes involved in metabolism and thermogenesis. Plant miR6262 was selected as a candidate from miRBase for the predicted effect on the regulation of human metabolic genes. Functional validation was conducted after transfection with plant miRNA mimics in HepG2 hepatocytes exposed to free fatty acids to mimic liver steatosis and hMADs cells differentiated into brown-like adipocytes. miR6262 decreases the expression of the predicted target RXRA in the fatty acids-treated hepatocytes and in brown-like adipocytes and affects the expression profile of critical genes involved in metabolism and thermogenesis, including PPARA, G6PC, SREBF1 (hepatocytes) and CIDEA, CPT1M and PLIN1 (adipocytes). Nevertheless, plant miR6262 mimic transfections did not decrease hepatocyte lipid accumulation or stimulate adipocyte browning. these findings suggest that plant miR6262 could have a cross-kingdom regulation relevance through the modulation of human genes involved in lipid and glucose metabolism and thermogenesis in adipocytes and hepatocytes.

Adipocyte sphingosine kinase 1 regulates histone modifiers to disrupt circadian function.

Circadian rhythms align biological functions with the 24-hour day-night cycle, but modern artificial light disrupts these patterns, contributing to health issues like obesity and cardiovascular disease. The circadian clock operates through a transcriptional-translational feedback loop involving core components such as BMAL1 and CLOCK. Recent research has shown circadian variations in sphingolipid metabolism, specifically sphingosine-1-phosphate (S1P), which plays crucial signaling roles. This study investigates the sphingolipid enzyme, sphingosine kinase 1 (SphK1), which converts sphingosine to S1P, as a circadian-regulated gene in adipocytes. We find that SphK1 expression and activity follow a circadian rhythm, regulated by BMAL1 and CLOCK binding to its promoter. Adipocyte-specific SphK1 knockout mice exhibit disrupted circadian rhythms, and impaired adipocyte function. Additionally, SphK1 deficiency leads to reduced histone acetylation and altered histone deacetylase (HDAC) localization, affecting gene regulation. These results highlight the critical role of SphK1 in linking lipid metabolism with circadian biology.

Wnt/Wingless signaling promotes lipid mobilization through signal-induced transcriptional repression

The Wnt/Wingless signaling pathway plays critical roles in metazoan development and energy metabolism, but its role in regulating lipid homeostasis remains not fully understood. Here, we report that the activation of canonical Wnt/Wg signaling promotes lipolysis while concurrently inhibiting lipogenesis and fatty acid β-oxidation in both larval and adult adipocytes, as well as cultured S2R+ cells, in Drosophila. Using RNA-sequencing and CUT&RUN (Cleavage Under Targets & Release Using Nuclease) assays, we identified a set of Wnt target genes responsible for intracellular lipid homeostasis. Notably, active Wnt signaling directly represses the transcription of these genes, resulting in decreased de novo lipogenesis and fatty acid β-oxidation, but increased lipolysis. These changes lead to elevated free fatty acids and reduced triglyceride (TG) accumulation in adipocytes with active Wnt signaling. Conversely, downregulation of Wnt signaling in the fat body promotes TG accumulation in both larval and adult adipocytes. The attenuation of Wnt signaling also increases the expression of specific lipid metabolism-related genes in larval adipocytes, wing discs, and adult intestines. Taken together, these findings suggest that Wnt signaling-induced transcriptional repression plays an important role in regulating lipid homeostasis by enhancing lipolysis while simultaneously suppressing lipogenesis and fatty acid β-oxidation.

Pantothenic Acid Alleviates Fat Deposition and Inflammation by Suppressing the JNK/P38 MAPK Signaling Pathway.

Excessive fat deposition leads to obesity and cardiovascular diseases with abnormal metabolism. Pantothenic acid (PA) is a major B vitamin required for energy metabolism. However, the effect of PA on lipid metabolism and obesity has not been explored. We investigated the effects and molecular mechanism of PA on fat accumulation as well as the influence of adipogenic marker genes in both adult male mice and primary adipocytes. First, we demonstrated that PA attenuates weight gain in mice fed high-fat diet (HFD). Besides, PA supplementation substantially improved glucose tolerance and lipid metabolic disorder in obese mice. Furthermore, PA significantly inhibited white adipose tissue (WAT) deposition as well as fat droplets visualized by magnification in both chow and HFD group. More importantly, PA obviously suppressed the mRNA levels of CD36, IL-6, and TNF-α to alleviate inflammation and reduced the levels of PPARγ, aP2, and C/EBPα genes that are related to lipid metabolism in inguinal white adipose tissue (ing-WAT) and epididymal white adipose tissue (ei-WAT). In vitro, PA supplementation showed a lower lipid droplet aggregation as well as reduced expression levels of adipogentic genes. Finally, we identified that PA inhibits the phosphorylation levels of p38 and JNK in murine primary adipocytes. Collectively, our data demonstrated for the first time that PA attenuates lipid metabolic disorder as well as fat deposition by JNK/p38 MAPK signaling pathway.

Circulating plasma fibronectin affects tissue insulin sensitivity, adipocyte differentiation, and transcriptional landscape of adipose tissue in mice.

Plasma fibronectin (pFN) is a hepatocyte-derived circulating extracellular matrix protein that affects cell morphology, adipogenesis, and insulin signaling of adipocytes invitro. In this study, we show pFN accrual to adipose tissue and its contribution to tissue homeostasis in mice. Hepatocyte-specific conditional Fn1 knockout mice (Fn1-/-ALB) show a decrease in adipose tissue FN levels and enhanced insulin sensitivity of subcutaneous (inguinal), visceral (epididymal) adipose tissue on a normal diet. Diet-induced obesity model of the Fn1-/-ALB mouse showed normal weight gain and whole-body fat mass, and normal adipose tissue depot volumes and unaltered circulating leptin and adiponectin levels. However, Fn1-/-ALB adipose depots showed significant alterations in adipocyte size and gene expression profiles. The inguinal adipose tissue on a normal diet, which had alterations in fatty acid metabolism and thermogenesis suggesting browning. The presence of increased beige adipocyte markers Ucp1 and Prdm16 supported this. In the inguinal fat, the obesogenic diet resulted in downregulation of the browning markers and changes in gene expression reflecting development, morphogenesis, and mesenchymal stem cell maintenance. Epididymal adipose tissue showed alterations in developmental and stem cell gene expression on both diets. The data suggests a role for pFN in adipose tissue insulin sensitivity and cell profiles.

Metabolic control by the Bithorax Complex-Wnt signaling crosstalk in Drosophila.

Adipocytes distributed throughout the body play crucial roles in lipid metabolism and energy homeostasis. Regional differences among adipocytes influence normal function and disease susceptibility, but the mechanisms driving this regional heterogeneity remain poorly understood. Here, we report a genetic crosstalk between the Bithorax Complex ( BX-C ) genes and Wnt/Wingless signaling that orchestrates regional differences among adipocytes in Drosophila larvae. Abdominal adipocytes, characterized by the exclusive expression of abdominal A ( abd-A ) and Abdominal B ( Abd-B ), exhibit distinct features compared to thoracic adipocytes, with Wnt signaling further amplifying these disparities. Depletion of BX-C genes in adipocytes reduces fat accumulation, delays larval-pupal transition, and eventually leads to pupal lethality. Depleting Abd-A or Abd-B reduces Wnt target gene expression, thereby attenuating Wnt signaling-induced lipid mobilization. Conversely, Wnt signaling stimulated abd-A transcription, suggesting a feedforward loop that amplifies the interplay between Wnt signaling and BX-C in adipocytes. These findings elucidate how the crosstalk between cell-autonomous BX-C gene expression and Wnt signaling define unique metabolic behaviors in adipocytes in different anatomical regions of fat body, delineating larval adipose tissue domains.

Alternative isoform expression of key thermogenic genes in human beige adipocytes.

The beneficial effect of thermogenic adipocytes in maintaining body weight and protecting against metabolic disorders has raised interest in understanding the regulatory mechanisms defining white and beige adipocyte identity. Although alternative splicing has been shown to propagate adipose browning signals in mice, this has yet to be thoroughly investigated in human adipocytes. We performed parallel white and beige adipogenic differentiation using primary adipose stem cells from 6 unrelated healthy subjects and assessed differential gene and isoform expression in mature adipocytes by RNA sequencing. We find 777 exon junctions with robust differential usage between white and beige adipocytes in all 6 subjects, mapping to 562 genes. Importantly, only 10% of these differentially spliced genes are also differentially expressed, indicating that alternative splicing constitutes an additional layer of gene expression regulation during beige adipocyte differentiation. Functional classification of alternative isoforms points to a gain of function for key thermogenic transcription factors such as PPARG and CITED1, and enzymes such as PEMT, or LPIN1. We find that a large majority of the splice variants arise from differential TSS usage, with beige-specific TSSs being enriched for PPARγ and MED1 binding compared to white-specific TSSs. Finally, we validate beige specific isoform expression at the protein level for two thermogenic regulators, PPARγ and PEMT. These results suggest that differential isoform expression through alternative TSS usage is an important regulatory mechanism for human adipocyte thermogenic specification.

Aging impairs cold-induced beige adipogenesis and adipocyte metabolic reprogramming.

The energy-burning capability of beige adipose tissue is a potential therapeutic tool for reducing obesity and metabolic disease, but this capacity is decreased by aging. Here, we evaluate the impact of aging on the profile and activity of adipocyte stem and progenitor cells (ASPCs) and adipocytes during the beiging process in mice. We found that aging increases the expression of Cd9 and other fibro-inflammatory genes in fibroblastic ASPCs and blocks their differentiation into beige adipocytes. Fibroblastic ASPC populations from young and aged mice were equally competent for beige differentiation in vitro, suggesting that environmental factors suppress adipogenesis in vivo. Examination of adipocytes by single nucleus RNA-sequencing identified compositional and transcriptional differences in adipocyte populations with aging and cold exposure. Notably, cold exposure induced an adipocyte population expressing high levels of de novo lipogenesis (DNL) genes, and this response was severely blunted in aged animals. We further identified Npr3, which encodes the natriuretic peptide clearance receptor, as a marker gene for a subset of white adipocytes and an aging-upregulated gene in adipocytes. In summary, this study indicates that aging blocks beige adipogenesis and dysregulates adipocyte responses to cold exposure and provides a resource for identifying cold and aging-regulated pathways in adipose tissue.

Long noncoding RNA AI504432 upregulates FASN expression by sponging miR-1a-3p to promote lipogenesis in senescent adipocytes

Aging affects lipid metabolism and can cause obesity as it is closely related to the disorder of many lipogenic regulatory factors. LncRNAs have been recognized as pivotal regulators across diverse biological processes, but their effects on lipogenesis in aging remain to be further studied. In this work, using RNA sequencing (RNA-Seq), we found that the expression of lncRNA AI504432 was significantly upregulated in the eWAT (epididymal white adipose tissue) of aging mice, and the knockdown of AI504432 notably reduced the expression of several adipogenic genes (e.g., Cebp/α, Srebp-1c, Fasn, Acaca, and Scd1) in senescent adipocytes. The bioinformatics investigation revealed that AI504432 possessed a binding site for miR-1a-3p, and the discovery was verified by the luciferase reporter assay. The expression of Fasn was increased upon the inhibition of miR-1a-3p but restored upon the simultaneous silencing of AI504432. Taken together, our results suggested that AI504432 controlled lipogenesis through the miR-1a-3p/Fasn signaling pathway. The findings may inspire new therapeutic approaches to target imbalanced lipid homeostasis due to aging.

Abstract 125: The X Chromosome Gene Kdm6a Confers Sex Differences In Mature Adipocyte Function Impacting Cardiometabolic Health

Biological sex impacts cardiovascular disease and other metabolic conditions that increase disease risk, including obesity. Physiological sex differences are determined by two components of sex: gonadal hormones and sex chromosome complement. Using mouse models to dissociate gonadal sex from chromosomal sex, we have identified sex chromosome-dependent regulation of circulating lipoproteins, atherosclerosis, and adiposity. Specifically for adiposity, mice with two X chromosomes had higher body weight gain compared to mice with XY sex chromosomes in the presence of ovaries or testes. In cells with XX chromosome complement, specific X chromosome genes escape X inactivation, which leads to higher expression in XX (female) compared to XY (male) tissues. We identified an X escape gene, Kdm6a , that encodes a histone demethylase enzyme and impacts adiposity by altering the function of mature adipocytes. Mice with mature adipocyte-specific Kdm6a reduction (Ad- Kdm6a -/- ) had lower body weight and adiposity compared to wildtype females. The white adipose triglyceride pool was altered with higher unsaturated and long chain fatty acids in Ad- Kdm6a -/- mice compared to wildtype mice. Furthermore, siRNA knockdown of Kdm6a in cultured adipocytes altered lipid metabolism with reduced lipid droplet size. Given that KDM6A is a histone demethylase, we assessed the Kdm6a dosage effect on adipocyte gene expression and histone modifications across the genome. Differential gene expression associated with lipid homeostasis was identified in Ad- Kdm6a -/- mice and in cultured adipocytes with Kdm6a knockdown compared to controls. KDM6A genomic targets and resultant histone modifications were identified in cultured adipocytes using CUT&amp;RUN. We conclude that differential gene dosage of Kdm6a between female and male tissues is a determinant of adipose sex differences through modulation of histone modifications and gene expression. This leads to effects on adipocyte lipid composition and tissue mass, which impacts susceptibility to obesity and metabolic disease.

Network Meta-Analysis: Effect of Cold Stress on the Gene Expression of Swine Adipocytes ATGL, CIDEA, UCP2, and UCP3.

Cold stress significantly affects gene expression in adipocytes; studying this phenomenon can help reveal the pathogeneses of conditions such as obesity and insulin resistance. Adipocyte triglyceride lipase (ATGL); cell death-inducing deoxyribonucleic acid (DNA) fragmentation factor subunit alpha (DFFA)-like effector (CIDEA); and uncoupling protein genes UCP1, UCP2, and UCP3 are the most studied genes in pig adipose tissues under cold stress. However, contradictory results have been observed in gene expression changes to UCP3 and UCP2 when adipose tissues under cold stress were examined. Therefore, we conducted a meta-analysis of 32 publications in total on the effect of cold stress on the expression of ATGL, CIDEA, UCP2, and UCP3. Our results showed that cold stress affected the expression of swine adipocyte genes; specifically, it was positively correlated with the expression of UCP3 in swine adipocytes. Conversely, expression of ATGL was negatively affected under cold stress conditions. In addition, the loss of functional UCP1 in pigs likely triggered a compensatory increase in UCP3 activity. We also simulated the docking results of UCP2 and UCP3. Our results showed that UCP2 could strongly bind to adenosine triphosphate (ATP), meaning that UCP3 played a more significant role in pig adipocytes.

Prmt6 represses the pro-adipogenic Ppar-gamma–C/ebp-alpha transcription factor loop

The feed-forward loop between the transcription factors Ppar-gamma and C/ebp-alpha is critical for lineage commitment during adipocytic differentiation. Ppar-gamma interacts with epigenetic cofactors to activate C/ebp-alpha and the downstream adipocytic gene expression program. Therefore, knowledge of the epigenetic cofactors associated with Ppar-gamma, is central to understanding adipocyte differentiation in normal differentiation and disease. We found that Prmt6 is present with Ppar-gamma on the Ppar-gamma and C/ebp-alpha promoter. It contributes to the repression of C/ebp-alpha expression, in part through its ability to induce H3R2me2a. During adipocyte differentiation, Prmt6 expression is reduced and the methyltransferase leaves the promoters. As a result, the expression of Ppar-gamma and C/ebp-alpha is upregulated and the adipocytic gene expression program is established. Inhibition of Prmt6 by a small molecule enhances adipogenesis, opening up the possibility of epigenetic manipulation of differentiation. Our data provide detailed information on the molecular mechanism controlling the Ppar-gamma–C/ebp-alpha feed-forward loop. Thus, they advance our understanding of adipogenesis in normal and aberrant adipogenesis.