The omentum of obese girls harbors small adipocytes and browning transcrips
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ABSTRACT: Severe obesity (SO) affects about 6% of youth in US, augmenting the risks for cardiovascular disease and Type 2 diabetes. Herein, we obtained paired omental (omVAT) and abdominal subcutaneous (SAT) adipose tissue biopsies from obese girls with SO, undergoing sleeve gastrectomy (SG), to test whether differences in cellular and transcriptomic profiles between omVAT and SAT depots affect insulin sensitivity differentially. Following weight loss, these analyses were repeated in a subgroup of subjects having a second SAT biopsy. We found that omVAT displayed smaller adipocytes compared to SAT, increased lipolysis through adipose triglyceride lipase (ATGL) phosphorylation, reduced inflammation and increased expression of browning/beige markers. Contrary to omVAT, SAT adipocyte diameter correlated with insulin resistance. Following SG, both weight and insulin sensitivity improved markedly in all subjects. SAT adipocytes size became smaller showing an increased lipolysis through perilipin-1 phosphorylation, decreased inflammation and increased expression in browning/beige markers. In summary, in adolescent girls with SO, both omVAT and SAT depots showed distinct cellular and transcriptomic profiles. Following weight loss, the SAT depot changed its cellular morphology and transcriptomic profiles into a more favorable one. These changes in the SAT depot may play a fundamental role in the resolution of insulin resistance.
Project description:About 20% of youth are obese with higher risk for cardiovascular disease and type 2 diabetes (T2D). We have recently reported that in obese adolescents altered pattern of fat distribution is associated with insulin resistance and T2D. In particular, the high ratio of visceral AT depot (VAT) to abdominal subcutaneous AT depot (SAT) (high VAT/(VAT+SAT)) was associated with a metabolically unhealthy phenotype with high risk for insulin resistance and T2D. CIDEA (Cell death inducing DNA fragmentation factor-alpha-like A) is a member of CIDE family and it is not only involved in the promotion of cell death and DNA fragmentation but it also plays critical roles in the lipid droplets formation and growth. Here we demonstrated in abdominal SAT from adolescent obese girls with high VAT/(VAT+SAT) a significant reduction of CIDEA expression associated with an increase in fasting insulin, serum FFA and consequent insulin resistance. We also demonstrated a direct correlation between CIDEA expression and fraction of large cells and an inverse correlation with small adipocytes number and pre-adipocytes proliferation. After gaining weight, we observed an increase in adipocytes cell diameter but a decrease in CIDEA expression, and the transcriptomic analysis showed a gene profile linked to adipocyte dysfunction. Together, these data suggested that in subjects with high VAT/(VAT+SAT) decreased CIDEA expression is associated with an increase in adipocyte cell sizing and consecutive insulin resistance.
Project description:Objectives Intermittent fasting is an effective dietary intervention to combat metabolic disease. Here, we explore the adipose depot specific response to every-other-day fasting (EODF) in mice to identify mechanisms that underly the beneficial effects. Methods Male C57BL/6J mice were placed on a 12-day EODF or ad libitum diet, after which tissues were harvested including visceral (vWAT) and subcutaneous (scWAT) white adipose tissue, as well as brown adipose tissue (BAT), which was then analysed by unbiased mass spectrometry-based proteomics. Results After EODF treatment, pathway enrichment analysis of our dataset showed that both WAT depots showed increased mitochondrial protein content, with scWAT also showing increased UCP1, but mitochondrial protein content was decreased in BAT. This effect on mitochondria is correlated to the increased abundance of proteins involved in glycolysis, pyruvate metabolism, the TCA cycle and fatty acid synthesis in both WAT depots. Furthermore, EODF-treated mice downregulated the lipolysis pathway in vWAT including a 5-fold decrease in the abundance of the beta3 adrenergic receptor (ADRB3). Enrichment analysis lso revealed that vWAT of EODF treated mice had significantly reduced ECM proteins, which lowers the inflammatory potential of this organ. Our adipose depot proteomic survey also allowed us to identify depot-enriched protein expression, such as the vWAT enrichment for the AKAP12 protein related to PKA signalling that was down-regulated by EODF treatment. Conclusions These findings show how the adipose depots have adapted to the EODF regime to preserve the lipid store, with the most striking changes occurring in the vWAT depot to downregulate the lipolysis pathway and induce expression of pathways needed for fatty acid synthesis. This substrate cycling and reduced inflammatory potential of the adipose tissue may contribute to the improved insulin sensitivity observed in these animals.
Project description:We isolated fat depots from mice, and compared their transcriptome. Hoang, Anh C., Haidong Yu, and Tamás Röszer. 2021. "Transcriptional Landscaping Identifies a Beige Adipocyte Depot in the Newborn Mouse" Cells 10, no. 9: 2368.
Project description:This study seeks to undertake an assessment of the effects of prenatal exposure of female sheep to excess testosterone, the estrogen precursor, in four different adipose depots. The depots investigated are subcutaneous adipose tissue (SAT) - a fat beneath the skin storing >80% of total body fat in the human body, visceral adipose tissue (VAT) - an intra-abdominal fat primarily associated with digestive system organs, and smaller depots such as epicardial adipose tissue (ECAT) and perirenal adipose tissue (PRAT) that serve specialized functions associated with the organs/tissues in their proximity. The goals are to 1) determine gene expression and gene network profiles in the depots; 2) assess prenatal T-treatment induced disruptions in adipose depot-specific gene expression and gene networks; and 3) identify common and divergent gene and gene pathways underlying depot-specific disruption in prenatal T-treated female sheep.
Project description:Cancer cachexia (CC) is a poorly understood cause of morbidity and mortality, which has no efficacious treatment or generally-accepted management strategy. The consensus definition for CC identified skeletal muscle loss as a key marker in the diagnosis and classification of cachexia. The importance of fat wasting however, is less understood. During cachexia, different adipose depots demonstrate differential wasting rates. Studies from animal models have suggested adipose tissue may be a key driver of muscle wasting through fat-muscle crosstalk but human studies in this area are lacking. We performed global gene expression profiling of intra-abdominal (IAAT) and subcutaneous (SAT) adipose from weight stable and cachectic cancer patients and healthy controls. Cachexia was defined as >2% weight loss plus low CT-muscularity. Biopsies of SAT and IAAT were taken from patients undergoing resection for oesophago-gastric cancer, and healthy controls (donor nephrectomy) (n=16 and 8 respectively). RNA was isolated and reverse transcribed. cDNA was hybridised to the Affymetrix Clariom S Microarray and data was analysed using R/Bioconductor. Differential expression of genes was assessed using empirical Bayes and moderated-t-statistic approaches. Category enrichment analysis was used with a tissue-specific background to examine the biological context of differentially expressed genes. Selected differentially regulated genes were validated by qPCR. ELISA for Intelectin-1 was performed on IAAT samples for the corresponding patients. The current cohort plus 12 additional patients from each group also had plasma Intelectin-1 ELISA carried out. In IAAT versus SAT comparisons there were 2101, 1722 and 1659 significantly regulated genes in the cachectic, weight stable and control groups respectively. There were 2200 significantly regulated genes from IAAT in cachectic patients compared to controls and 1253 significantly regulated genes from IAAT in weight stable cancer patients compared to controls. The gene showing the largest difference in expression was Intelectin-1 (Omentin-1) (FDR corrected p=0.0001); a novel adipocytokine associated with weight loss in other groups. Genes involving inflammation were enriched in cancer and control IAAT versus SAT though different groups of genes contributed. Energy metabolism and fat browning genesets were downregulated in cancer IAAT as were key fat browning genes (e.g. UCP1). SAT and IAAT have unique gene expression signatures. IAAT is metabolically active in cancer, and maybe a target for therapeutic manipulation. IAAT may play a fundamental role in cachexia, but the downregulation of energy metabolism genes implies a limited role for fat browning in human cachectic patients, in contrast to pre-clinical models.
Project description:Inappropriate developmental exposure to steroids is linked to metabolic disorders. Prenatal testosterone excess or bisphenol A (BPA, an environmental estrogen mimic) leads to insulin resistance and adipocyte disruptions in female sheep. Adipocytes are key regulators of insulin sensitivity and tissue-specific differences in insulin sensitivity, coupled with adipose depot-specific changes in key mRNAs, were previously observed. We hypothesized that depot-specific changes in the non-coding RNA (ncRNA) regulators of gene expression would prevail to account for the direction of changes seen in mRNAs. Noncoding RNA (lncRNA, miRNA, snoRNA, snRNA) from various adipose depots of prenatal testosterone and BPA-treated animals were sequenced. Adipose depot-specific changes in the ncRNA that are consistent with the depot-specific mRNA expression in terms of directionality of changes and functional implications in insulin resistance, adipocyte differentiation and cardiac hypertrophy were found. Importantly, the adipose depot-specific ncRNA changes were model-specific that were mutually exclusive suggestive of different regulatory entry points in this regulation.
Project description:We applied single-cell ATAC sequencing and lipid profiling to inguinal and epididymal adipose depots from mice that received sham surgery or vertical sleeve gastrectomy (VSG). We observed depot-specific cellular composition and chromatin accessibility patterns that were altered by VSG. Specifically, accessibility at Scd1, a fatty acid desaturase, was substantially reduced after VSG in mature adipocytes of inguinal but not epididymal depots. This was accompanied by reduced accumulation of SCD1-produced unsaturated fatty acids. Given these findings and reports that reductions in Scd1 attenuate obesity and insulin resistance our results suggest VSG exerts its beneficial effects through an inguinal depot-specific reduction of SCD1 activity.
Project description:Factors predicting body weight gain and associated disturbed glucose metabolism remain to be established. Here we assessed the role of subcutaneous adipocyte lipid mobilization (lipolysis) in spontaneous long-term (>10 years) body weight changes. In two independent clinical cohorts we found that low stimulated lipolysis at baseline correlated inversely with body mass index changes over time. Disturbed lipolysis gave odds ratios of ≥4.6 for weight gain and ≥3.2 for development of insulin resistance and impaired fasting glucose/type 2 diabetes. Baseline adipose mRNA expression of a set of established lipolysis-regulating genes was lower in weight gainers.
Project description:Subcutaneous adipose tissue (SAT) is classically viewed as a metabolic buffer for lipid deposition during positive caloric balance, while visceral adipose tissue (VAT) is viewed as the dominant contributor and prime mediator of insulin resistance (IR) and cardiometabolic disease risk. Nevertheless, a growing body of data suggests that similar morphologic and molecular changes may occur in SAT as in VAT during obesity. In addition, while pro-inflammatory immune changes within adipose are thought to drive IR there is increasing data implicating a role for adipocytes and stromal populations especially in humans. Here, we identified a transcriptional landscape of IR in SAT of 220 humans across the spectrum of obesity and IR states, highlighting a broad range of metabolic pathways central to IR. Using single cell and nucleus deconvolution and statistical learning techniques, we identified a 35-gene signature that (1) achieved high predictive accuracy for homeostatic model of IR (HOMA-IR) across BMI; (2) was expressed across a variety of non-immune cell populations (most prominently adipocytes and adipocyte stem and precursor cells [ASPCs]), with primarily “protective” IR associations for adipocyte transcripts and “deleterious” associations for macrophage transcripts; (3) displayed a high concordance between SAT and VAT (greater than non-IR associated genes). Multiple SAT genes exhibited dynamic expression 5-years after weight loss surgery and with insulin stimulation. Finally, using available expression quantitative trait loci in SAT and/or VAT, we demonstrate similar genetic effect sizes of SAT and VAT on type 2 diabetes and BMI, suggesting underlying similarities in genetic determinants of IR between adipose depots. These results implicate a dynamic transcriptional architecture of IR that resides in both immune and non-immune populations in SAT and that is shared with VAT, nuancing the current VAT-centric concept of IR in humans.
Project description:The adipose tissue is a key site regulating energy metabolism. One of the contributing factors behind this is browning of white adipose tissue (WAT), however, knowledge of the intracellular determinants of browning process remains incomplete. By generating adipocyte-specific Senp2 knockout (Senp2-aKO) mice, here we showed that SENP2 negatively regulates browning by de-conjugating SUMO from C/EBPβ. Senp2-aKO mice were resistant to diet-induced obesity and insulin resistance due to increased energy expenditure and heat production. Senp2 knockout promoted beige adipocyte accumulation in inguinal WAT by upregulation of thermogenic gene expression. In addition, SENP2 knockdown promoted thermogenic adipocyte differentiation of precursor cells isolated from inguinal and epididymal WATs. Mechanistically, sumoylated C/EBPβ, a target of SENP2, suppressed expression of HOXC10, a browning inhibitor, by recruiting a transcriptional repressor DAXX. These findings indicate that a SENP2-C/EBPβ-HOXC10 axis operates for the control of beige adipogenesis in inguinal WAT.