Contribution of Adipokine Gene Expression in Mesenteric Adipose Tissue to the Pathogenesis of Insulin Resistance in Obese Patients

Mesenteric adipose tissue, being a component of visceral adipose tissue, has a high lipolytic activity. Excessive accumulation of visceral adipose tissue increases the risk of metabolic disorders leading to severe consequences. Therefore, the aim of the presented study was to estimate the production of adipokine and proinflammatory molecules by the adipose tissue of small intestine mesentery evaluating its contribution to the formation of insulin resistance in obesity. The role of the activity of LEP, SERPINA12, RARRES2, and TNFα genes encoding leptin, vaspin, chemerin, and TNFα in adipose tissue of small intestinal mesentery in patients with abdominal obesity with a different state of carbohydrate metabolism was studied. The changes in serum/plasma content of the examined mediators that we detected are closely associated with their production in the adipose tissue of small intestinal mesentery. The revealed interrelations between the production of mediators (adipokines, proinflammatory molecules) studied with the parameters of carbohydrate metabolism indicate an important role of mesenteric adipose tissue in the formation of insulin resistance in obesity.     

Differences in Gene Expression and Cytokine Release Profiles Highlight the Heterogeneity of Distinct Subsets of Adipose Tissue-Derived Stem Cells in the Subcutaneous and Visceral Adipose Tissue in Humans

Differences in the inherent properties of adipose tissue-derived stem cells (ASC) may contribute to the biological specificity of the subcutaneous (Sc) and visceral (V) adipose tissue depots. In this study, three distinct subpopulations of ASC, i.e. ASC_SVF, ASC_Bottom, and ASC_Ceiling, were isolated from Sc and V fat biopsies of non-obese subjects, and their gene expression and functional characteristics were investigated. Genome-wide mRNA expression profiles of ASC_SVF, ASC_Bottom and ASC_Ceiling from Sc fat were significantly different as compared to their homologous subsets of V-ASCs. Furthermore, ASC_SVF, ASC_Ceiling and ASC_Bottom from the same fat depot were also distinct from each other. In this respect, both principal component analysis and hierarchical clusters analysis showed that ASC_Ceiling and ASC_SVF shared a similar pattern of closely related genes, which was highly different when compared to that of ASC_Bottom. However, larger variations in gene expression were found in inter-depot than in intra-depot comparisons. The analysis of connectivity of genes differently expressed in each ASC subset demonstrated that, although there was some overlap, there was also a clear distinction between each Sc-ASC and their corresponding V-ASC subsets, and among ASC_SVF, ASC_Bottom, and ASC_Ceiling of Sc or V fat depots in regard to networks associated with regulation of cell cycle, cell organization and development, inflammation and metabolic responses. Finally, the release of several cytokines and growth factors in the ASC cultured medium also showed both inter- and intra-depot differences. Thus, ASC_Ceiling and ASC_Bottom can be identified as two genetically and functionally heterogeneous ASC populations in addition to the ASC_SVF, with ASC_Bottom showing the highest degree of unmatched gene expression. On the other hand, inter-depot seem to prevail over intra-depot differences in the ASC gene expression assets and network functions, contributing to the high degree of specificity of Sc and V adipose tissue in humans.     

Decrease of the Obese Gene Expression in Bovine Subcutaneous Adipose Tissue by Fasting

The expression of mRNA of leptin, the product of the obese gene, in bovine adipose tissue was analyzed by a lysate RNase protection assay. The mRNA level was significantly decreased by food deprivation for two days and partially recovered after 3 hr of refeeding, indicating that obese gene expression in the ruminant was regulated by feeding.     

布氏田鼠冷暴露中褐色脂肪组织的增补及解偶联蛋白基因表达

布氏田鼠 (Microtusbrandti)随机分组暴露在冷环境 [12L∶12D ,(4± 2 )℃ ]中 12h ,1d ,3d ,7d ,14d ,2 1d和 2 8d ;对照组生活在温暖环境下 [12L∶12D ,(2 5± 2 )℃ ]。与对照组相比 ,布氏田鼠的褐色脂肪组织 (BAT)重量在冷暴露 12h～ 3d时降低 ,7～ 2 1d时则增加。 7～ 2 8d冷暴露组动物的BAT总蛋白和总DNA含量均比对照组明显提高。冷环境中的布氏田鼠解偶联蛋白 (UCP)的mRNA随时间的延长而表达上调 ,在冷暴露 2 1d时达到高峰。结果表明 ,冷暴露能够诱导布氏田鼠BAT细胞增补和UCP基因表达 ,从而使适应性产热增加。     

Partial Genome Scale Analysis of Gene Expression in Human Adipose Tissue Using DNA Array

Objective: Large scale analysis of gene expression in adipose tissue provides a basis for the identification of novel candidate genes involved in the pathophysiology of obesity. Our goal was to explore gene expression in human adipose tissue at a partial genome scale using DNA array. Research Methods and Procedures: Labeled cDNA, derived from human adipose tissue poly(A⁺) RNA, was hybridized to a DNA array containing over 18,000 human expressed sequence‐tagged (EST) clones. The results were analyzed by database searches. Results: Homology searches of the 300 EST clones with highest hybridization signals revealed that 145 contained DNA sequences identical to known genes and 79 could be linked to UniGene clusters. Of the 145 identified genes, 136 were nonredundant and subsequently characterized with respect to function and chromosomal localization by searching MEDLINE, UniGene, GeneMap, OMIM, SWISS‐PROT, the Genome Database, and the Location Data Base. The identified genes were grouped according to their putative functions; cell/organism defense (9.6%), cell division (5.1%), cell signaling/communication (19.8%), cell structure/motility (12.5%), gene/protein expression (16.9%), metabolism (16.2%), and unclassified (19.8%). Less than 50% of these genes have previously been reported to be expressed in adipose tissue. The chromosomal localization of 268 genes strongly expressed in adipose tissue showed that their relative abundance was significantly increased on chromosomes 11, 19, and 22 compared to the expected distribution of the same number of random genes. Discussion: Our study resulted in the identification of numerous genes previously not reported to be expressed in adipose tissue. These results suggest that DNA array is a powerful tool in the search for novel regulatory pathways within adipose tissue on a scale that is not possible using conventional methods.     

Altered Clock Gene Expression in Obese Visceral Adipose Tissue Is Associated with Metabolic Syndrome

Clock gene expression was associated with different components of metabolic syndrome (MS) in human adipose tissue. However, no study has been done to compare the expression of clock genes in visceral adipose tissue (VAT) from lean and obese subjects and its clinical implications. Therefore, we studied in lean and obese women the endogenous 24 h expression of clock genes in isolated adipocytes and its association with MS components. VAT was obtained from lean (BMI 21–25 kg/m²; n = 21) and morbidly obese women (BMI >40 kg/m²; n = 28). The 24 h pattern of clock genes was analyzed every 6 hours using RT-PCR. Correlation of clinical data was studied by Spearman analysis. The 24 h pattern of clock genes showed that obesity alters the expression of CLOCK, BMAL1, PER1, CRY2 and REV-ERB ALPHA in adipocytes with changes found in CRY2 and REV-ERB ALPHA throughout the 24 h period. The same results were confirmed in VAT and stromal cells (SC) showing an upregulation of CRY2 and REV-ERB ALPHA from obese women. A positive correlation was observed for REV-ERB ALPHA gene expression with BMI and waist circumference in the obese population. Expression of ROR ALPHA was correlated with HDL levels and CLOCK with LDL. Obese subjects with MS exhibited positive correlation in the PER2 gene with LDL cholesterol, whereas REV-ERB ALPHA was correlated with waist circumference. We identified CRY2 and REV-ERB ALPHA as the clock genes upregulated in obesity during the 24 h period and that REV-ERB ALPHA is an important gene associated with MS.     

Relationships among Body Condition,Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares

Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT). Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG) or semi-natural grassland (NG) from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT), and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05) and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM); P=0.02), and larger waist circumference (P=0.03) than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04), but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03) during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05) was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ), adiponectin receptor 1 and stearoyl-CoA desaturase (SCD) gene expressions in SAT of both groups during the grazing season (P<0.05). Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01). In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.     

猪脂肪组织和原代脂肪细胞中GPR43基因的转录表达规律

根据GenBank已发表的人、小鼠及大鼠GPR43(G protein-coupled receptor 43)基因序列, 设计并合成一对引物, RT-PCR扩增获得猪GPR43基因cDNA, 并利用PCR技术检测该基因在不同猪种、不同发育阶段、不同部位脂肪组织及原代脂肪细胞中的转录表达规律。结果显示, 成功克隆猪GPR43 cDNA片段, 长度为486 bp (GenBank登陆号为EU122439); 同源性分析发现, 猪GPR43与人、小鼠和大鼠同源性达83%以上; GPR43 mRNA表达量在脂肪型猪种上显著高于瘦肉型猪种, 随月龄增长表达量逐渐上升, 且皮下脂肪表达量较内脏脂肪高; 在猪前体脂肪细胞诱导分化过程中, GPR43 mRNA表达量呈时间依赖性升高。揭示GPR43 mRNA表达与猪肥胖程度、年龄、脂肪沉积部位以及脂肪细胞分化程度密切相关。