Identification of differentially expressed genes in omental adipose tissues of obese patients by suppression subtractive hybridization

To identify differentially expressed genes between obese individuals and normal control, we have undertaken suppression subtractive hybridization （SSH）. Omental adipose tissues were obtained via abdominal surgery for appendicitis in both 13 obese subjects[BMI （body mass index） 〉 30 kg/m（2）] and 13 normal subjects （BMI 〉 18 and 〈 25 kg/m（2））.     

Effect of testosterone on lipolysis in human pre-adipocytes from different fat depots

Aim/hypothesis Regional differences in lipolysis, with higher lipolytic activity in visceral than subcutaneous fat, are important for the development of insulin resistance and might be influenced by testosterone.Methods We studied testosterone-regulated lipolysis and protein expression (by western blot) in fully differentiated pre-adipocytes from visceral (omental) and abdominal subcutaneous adipose tissue from 52 human subjects. These cells were isolated and cultured in a serum-free medium.Results Testosterone caused a specific, time- and concentration-dependent 50% reduction of catecholamine-stimulated lipolysis in the subcutaneous depot. Half of the maximum effect occurred at 10 nmol/l. The inhibitory effect was due to the inability of -adrenoceptors and cyclic AMP to stimulate the protein kinase A, hormone-sensitive lipase complex. Testosterone caused a depot-specific 50% reduction of the protein expression of hormone-sensitive lipase and ₂-adrenoceptors in differentiated subcutaneous pre-adipocytes, but no change in ₁-adrenoceptors, protein kinase A subunits or perilipin expression. In contrast, testosterone had no effect on lipolysis or protein expression in the visceral depot. However, testosterone receptors were present in both depots, and the hormone inhibited adipocyte leptin secretion. Similar effects on lipolysis were observed with dihydrotestosterone.Conclusions/interpretation Testosterone in physiological concentrations causes a depot-specific reduction of catecholamine-stimulated lipolysis in subcutaneous fat cells, probably due to reduced protein expression of ₂-adrenoceptors and hormone-sensitive lipase. This could be an important pathogenic factor underlying regional differences in lipolysis and development of insulin resistance and hyperandrogenic polycystic ovary syndrome.Abbreviations PCOS polycystic ovary syndrome - GPDH glycerol-3-phosphate dehydrogenase - AR adrenergic receptor - HSL hormone-sensitive lipase - PKA protein kinase A - OD optical density - dcAMP dibutyryl cyclic AMP     

二甲双胍抑制高浓度葡萄糖刺激的脂肪分解及机制

目的研究二甲双胍抑制高浓度葡萄糖刺激的脂肪分解及其机制。方法以SD大鼠附睾原代脂肪细胞为研究对象,分为对照A组、对照B组、实验A组和实验B组,每组3个平行管。对照A组予以5 mmol·L^-1葡萄糖,对照B组予以25 mmol·L^-1葡萄糖,实验A组予以5 mmol·L^-1葡萄糖+500μmol·L^-1二甲双胍,实验B组予以25 mmol·L^-1葡萄糖+500μmol·L^-1二甲双胍。细胞孵育24 h后,测定培养基中甘油释放量作为评价脂肪分解的指标,用酶化学法测定脂肪分解酶活性,用Western Blot法检测脂滴包被蛋白表达及其磷酸化水平、脂肪组织三酰甘油水解酶(ATGL)蛋白表达。结果对照B组和实验B组的甘油释放量分别为(1.61±0.08)和(0.50±0.06)μmol·m L^-1packed cell volume,实验B组与对照B组比较明显降低,差异有统计学意义(P<0.001)。这种抑制效应从孵育16 h开始明显并持续到24 h。对照B组和实验B组的脂肪分解酶活性分别为(344.28±65.98)和(200.44±64.25)μmol glycerol·mg protein^-1·h^-1,2组比较,实验B组降低41.78%,差异有统计学意义(P<0.05)。与对照B组相比,实验B组脂滴包被蛋白磷酸化减少,差异有统计学意义(P<0.01),但2组的ATGL蛋白水平与对照A组相比,差异均无统计学意义(均P>0.05)。结论二甲双胍通过抑制脂滴包被蛋白磷酸化和脂肪分解酶活性,从而减少高浓度葡萄糖刺激的脂肪分解,这种效应可以减少糖尿病高血糖状态下游离脂肪酸从脂肪组织向血浆释放,进而减轻胰岛素抵抗。     

Astragaloside IV attenuates lipolysis and improves insulin resistance induced by TNFalpha in 3T3-L1 adipocytes

Increased circulating free fatty acid (FFA) concentrations have been demonstrated to potentially link obesity, insulin resistance and cardiovascular diseases. Astragaloside IV (AS-IV) is a saponin which is widely used in traditional Chinese medicine to treat type 2 diabetes and cardiovascular diseases. The purpose of the present study was to examine the effects of AS-IV on the lipolysis and insulin resistance induced by tumor necrosis factor-alpha (TNFalpha) in cultured 3T3-L1 adipocytes. TNFalpha promotes lipolysis in mammal adipocytes via the mitogen activated protein kinase (MAPK) family resulting in reduced expression/function of perilipin. Application of AS-IV inhibited TNFalpha-induced accelerated lipolysis in a dose-dependent manner, which was compatible with suppressed phosphorylation of ERK1/2 and reversed the downregulation of perilipin. Moreover, TNFalpha induced downregulation of key enzymes in lipogenesis, including LPL, FAS and GPAT, were also attenuated by AS-IV. Further studies showed that AS-IV improved TNFalpha-induced insulin resistance in 3T3-L1 adipocytes. This study provides the first direct evidence of the antilipolytic action of AS-IV in adipocytes, which may allow this agent to decrease the circulating FFA levels, thus increase insulin sensitivity and treat cardiovascular diseases.     

High glucose,insulin and free fatty acid concentrations synergistically enhance perilipin 3 expression and lipid accumulation in macrophages

Objective

Perilipin (PLIN) 3, an intracellular lipid droplet (LD)-associated protein, is implicated in foam cell formation. Since metabolic derangements found in metabolic syndrome, such as high serum levels of glucose, insulin and free fatty acids (FFAs), are major risk factors promoting atherosclerosis, we investigated whether PLIN3 expression is affected by glucose, insulin and oleic acid (OA) using RAW264.7 cells.

Methods

Real-time PCR and Western blotting were performed to detect PLIN3 or PLIN2 expression. Oil-red O staining and Lipid Analysis were employed to measure cellular content of triacylglycerides (TAG) and cholesterol.

Results

PLIN3 mRNA was stimulated by high glucose or insulin concentrations individually, but not by OA. A combination of any two factors did not enhance PLIN3 expression any more than that evoked by glucose alone at 24 h. Interestingly, however, simultaneous addition of all three factors synergistically enhanced the PLIN3 expression. This synergistic effect was not apparent for PLIN2 mRNA expression. Inhibitors of Src family tyrosine kinase and/or phosphatidylinositol 3-kinase, both of which are activated by insulin and FFA signaling, partially suppressed PLIN3 expression induced by the combination of the three factors. While simultaneous addition of glucose, insulin and OA remarkably increased the cellular content of TAG and cholesterol, knocking-down of PLIN3 predominantly reduced TAG content.

Conclusions

These results indicate that PLIN3 expression is synergistically stimulated by high glucose, insulin and FFA concentrations, in parallel with TAG accumulation in macrophages. This finding raises new evidence of PLIN3 involvement in conversion of macrophages into foam cells     

Microarray profiling of gene expression in human adipocytes in response to anthocyanins

Adipocyte dysfunction is strongly associated with the development of obesity and insulin resistance. It is accepted that the regulation of adipocytokine secretion or the adipocyte specific gene expression is one of the most important targets for the prevention of obesity and amelioration of insulin sensitivity. Recently, we demonstrated that anthocyanins, which are pigments widespread in the plant kingdom, have the potency of anti-obesity in mice and the enhancement adipocytokine secretion and its gene expression in adipocytes. In this study, we have shown the gene expression profile in human adipocytes treated with anthocyanins (cyanidin 3-glucoside; C3G or cyanidin; Cy). The human adipocytes were treated with 100 microM C3G, Cy or vehicle for 24 h. The total RNA from the adipocytes was isolated and carried out GeneChip microarray analysis. Based on the gene expression profile, we demonstrated the significant changes of adipocytokine expression (up-regulation of adiponectin and down-regulation of plasminogen activator inhibitor-1 and interleukin-6). Some of lipid metabolism related genes (uncoupling protein2, acylCoA oxidase1 and perilipin) also significantly induced in both common the C3G or Cy treatment groups. These studies have provided an overview of the gene expression profiles in human adipocytes treated with anthocyanins and demonstrated that anthocyanins can regulate adipocytokine gene expression to ameliorate adipocyte function related with obesity and diabetes that merit further investigation.     

吡格列酮、TNF-α对3T3-L1细胞Perilipin mRNA表达影响的研究

目的探讨吡格列酮和TNF-α对3T3-L1细胞中perilipin（周脂素）mRNA表达的影响及其时间效应。方法用吡格列酮（100μmol.L-1）和TNF-α（100μg.L-1）分别处理未分化、分化过程中和分化成熟后的3T3-L1细胞,RT-PCR检测不同干预时间perilipin mRNA的表达水平。结果 （1）未分化3T3-L1细胞中perilipin未见表达,分化过程中细胞perilipin mRNA的表达水平随时间递增。（2）在分化过程中和分化成熟的3T3-L1细胞中,吡格列酮都明显增加perilipin mRNA的表达,TNF-α则明显抑制perilipin mRNA的表达。（3）吡格列酮能抵抗TNF-α对成熟3T3-L1脂肪细胞perilipin mRNA表达的抑制作用。结论随着分化成熟,3T3-L1细胞perilipin mRNA表达量逐渐增加;吡格列酮能明显增加3T3-L1细胞的perilipin mRNA表达,TNF-α则明显抑制其表达;吡格列酮能抵抗TNF-α对3T3-L1脂肪细胞perilipin mRNA表达的抑制作用。     

杨梅素联合围脂滴蛋白对脂肪细胞脂解的影响

目的 研究杨梅素（Myric）与围脂滴蛋白（PLIN1）联合作用对3T3-L1 脂肪细胞脂解的影响。 方法 常规培养及诱导分化3T3-L1 前脂肪细胞,筛选出Myric 最佳干预浓度和时间。Myric 联合sh-RNA 干 扰载体对已诱导分化成熟的3T3-L1 脂肪细胞进行联合干预,实验共分为四组：联合干预组（Myric+sh-RNA）、 转染组（sh-RNA）、杨梅素组（Myric）和空白组。采用油红O 进行脂滴染色,观察脂滴形态;采用酶学方法 检测细胞中三酰甘油（TG）和甘油含量,了解细胞脂解情况;采用Western blot 检测脂肪细胞中PLIN1A、三 酰甘油脂肪酶（ATGL）和激素敏感性脂肪酶（HSL）的表达量。结果 以浓度为100 μmol/L 的Myric 干预 72 h 时,细胞内TG 含量最低,甘油含量最高,脂解效果最佳,与其他浓度和干预24 h 比较,差异有统计学意义 （P <0.05）。联合干预后,与Myric 组和sh-RNA 组比较,Myric+sh-RNA 组细胞内TG 含量下降,甘油含量升 高,脂滴形态变小,数量减少,差异有统计学意义（P <0.05）。同时,Myric+sh-RNA 组PLIN1A 蛋白表达量降低, ATGL 和HSL 蛋白表达量升高,差异有统计学意义（P <0.05）。结论 Myric 联合PLIN1 可以更有效降低PLIN1 表达量,提高ATGL 与HSL 的表达量,从而提高脂解效率。