RNA干扰技术沉默脂肪细胞型脂肪酸结合蛋白基因对脂肪细胞合成甘油三酯及分泌内脂素的影响

目的观察RNA干扰技术沉默脂肪细胞型脂肪酸结合蛋白基因后,脂肪细胞甘油三酯合成及内脂素分泌的变化。方法将3T3-L1前脂肪细胞采用体外诱导分化为脂肪细胞,将脂肪细胞与0～1 mmol/L不同浓度脂肪酸共孵育后,测定其甘油三酯及内脂素的浓度。构建针对脂肪细胞型脂肪酸结合蛋白基因的微小RNA质粒表达载体,将上述载体转染3T3-L1脂肪细胞,用逆转录聚合酶链反应和Western blot检测脂肪细胞型脂肪酸结合蛋白基因及蛋白的表达,将0.5 mmol/L脂肪酸与沉默前后的脂肪细胞共孵育24 h,用逆转录聚合酶链反应检测脂肪细胞型脂肪酸结合蛋白基因沉默前后脂肪细胞内脂素mRNA表达的变化,并测定其甘油三酯及内脂素浓度的变化。结果随着脂肪酸浓度的增高,与其共孵育的脂肪细胞内甘油三酯浓度也随着增加(P<0.05),其分泌的内脂素浓度也随着增加(P<0.05);构建脂肪细胞型脂肪酸结合蛋白微小RNA质粒载体,转染脂肪细胞后,能显著抑制脂肪细胞内脂肪细胞型脂肪酸结合蛋白的mRNA及蛋白表达水平(P<0.05);沉默脂肪细胞型脂肪酸结合蛋白基因后脂肪细胞内甘油三酯浓度明显低于沉默前(P<0.05),其分泌的内脂素浓度也明显低于...     

肿瘤坏死因子α、吡格列酮对3T3-L1脂肪细胞脂联素mRNA表达的影响

目的观察吡格列酮（PIO）和肿瘤坏死因子α（TNF-α）对3T3-L1脂肪细胞脂联素mRNA表达的影响。方法以不同浓度PIO和TNF-α于各时段处理3T3-L1细胞,用RT-PCR技术检测各条件下脂联素mRNA的表达。结果（1）3T3-L1前体脂肪细胞无脂联素mRNA表达。（2）TNF-α抑制分化及成熟的3T3-L1脂肪细胞脂联素mRNA表达。（3）PIO增强分化及成熟的3T3-L1脂肪细胞脂联素mRNA表达。（4）PIO能改善TNF-α对脂联素mRNA表达的抑制。结论在分化及成熟的脂肪细胞中,TNF-α抑制脂联素mRNA表达,而PIO增强其表达;PIO促进前体脂肪细胞分化及激活脂联素表达;PIO改善TNF-α对成熟脂肪细胞脂联素的抑制。     

黄连素对胰岛素抵抗3T3- L1脂肪细胞脂联素、瘦素、TNF-α和IL-6的影响

目的探讨黄连素对胰岛素抵抗(IR)3T3-L1脂肪细胞脂联素、瘦素、肿瘤坏死因子-α(TNF-α)和白细胞介素6(IL-6)蛋白表达的影响,分析黄连素改善IR的分子机制。方法将3T3-L1脂肪细胞随机分为对照组、IR组、黄连素组,应用地塞米松诱导细胞IR,黄连素组同时加入黄连素。采用葡萄糖氧化酶法测定3组细胞上清液葡萄糖消耗量,观察黄连素对脂肪细胞葡萄糖摄取的影响;应用免疫印迹试验测定脂肪细胞脂联素、瘦素蛋白水平变化;应用酶联免疫吸附实验检测脂肪细胞TNF-α和IL-6蛋白水平变化。结果与对照组比较,IR组脂联素蛋白表达水平明显下降(P<0.05),瘦素、TNF-α和IL-6蛋白表达水平升高;经黄连素干预后,脂联素蛋白表达水平有一定升高,瘦素、TNF-α和IL-6蛋白表达水平降低,与对照组比较差异有统计学意义(P<0.05)。结论黄连素可能通过增加脂联素蛋白分泌,减少瘦素、TNF-α和IL-6蛋白水平而改善IR。     

TNF-α对3T3-L1脂肪细胞PPAR-γ2 mRNA表达及脂联素分泌的影响

用肿瘤坏死因子α（TNF-α）分别处理未分化、已分化的3T3-L1细胞，检测培养细胞过氧化物酶体增殖物激活受体γ2（PPAR-γ2）mRNA的表达和脂联素的分泌。结果表明TNF-α可明显抑制3T3-L1脂肪细胞的PPAR-γ2 mRNA表达和脂联素的分泌（P〈0.05或P〈0.01），提示TNF-α可能通过PPAR-γ影响脂联素的分泌。     

重组人白介素6抑制SW872脂肪细胞脂联素及其受体1的表达和脂联素的分泌

油酸诱导体外培养的SW872前脂肪细胞分化为成熟的脂肪细胞，然后加入重组人白细胞介素6（rhIL-6）干预；RT—PCR方法检测脂联素、脂联素受体1和2mRNA水平，ELISA方法检测细胞培养上清中脂联素蛋白的含量。结果显示，rhIL-6以剂量和时间相关的方式抑制SW872脂肪细胞脂联素及其受体1mRNA的表达及脂联素的分泌，对脂联素受体2mRNA的表达无影响。     

未知功能基因JAZF1过表达对3T3-L1脂肪细胞糖脂代谢的影响

目的 观察JAZF1基因(Juxtaposed with another zincfinger gene 1)过表达对3T3-L1脂肪细胞糖脂代谢相关基因的影响.方法 采用实时荧光定量PCR(RT-QPCR)法检测JAZF1 mRNA在健康C57BL/6J小鼠多种组织表达分布情况;构建JAZF1真核表达载体并瞬时转染3T3-L1细胞,RT-QPCR法检测JAZF1、糖脂代谢相关基因mRNA的表达;用Western印迹法测定各组细胞JAZF1蛋白水平;油红O染色比色法检测细胞内脂质积聚的变化.结果 转染48 h后,JAZF1转染组脂肪细胞中,JAZF1 mRNA及蛋白表达明显高于阴性对照和空载组,激素敏感脂肪酶(HSL)mRNA表达水平明显增加(P<0.05),脂肪酸合成酶(FAS)、乙酰辅酶A羧化酶(ACC)、类固醇调节元件结合蛋白1(SREBP1)mRNA相对表达量明显降低(均P<0.01),脂肪细胞甘油三酯酶(ATGL)、葡萄糖转运子1(GLUT1)、GLUT4 mRNA表达并无明显改变;油红O染色显示JAZF1转染组细胞内脂质积聚明显降低(P<0.05).结论 JAZFl在C57BL/6J小鼠多种组织均有表达,提示其可能在维持正常生理功能中起着一定作用.3T3-L1细胞过表达JAZF1可减少脂质合成、增加脂解,并可明显改善脂质积聚,可能是肥胖和糖尿病治疗的一个潜在靶点.     

血清脂肪细胞型脂肪酸结合蛋白及脂联素水平与冠心病的相关性

目的 探讨脂肪细胞型脂肪酸结合蛋白(A-FABP)、脂联素和A-FABP/脂联素比值与冠心病及冠状动脉病变程度的相关性.方法 经冠状动脉造影入选340例患者,分为冠心病组(211例)和非冠心病对照组(129例),用ELISA法测定血清AFABP及脂联素水平,冠状动脉病变程度用病变血管支数和Gensini积分表示.并从上述患者中选取年龄、性别、体质指数相匹配的冠心病及非冠心病者各10例,分离外周血单核细胞,佛波酯刺激为巨噬细胞后取培养上清,用ELISA法测定培养上清液A-FABP及脂联素浓度.结果 (1)冠心病组血清A-FABP水平[18.3(13.2,22.8)μg/L]较非冠心病组[16.4(13.5,20.4)μg/L]高,但差异未达到统计学意义(P=0.088);冠心病组血清脂联素水平低于非冠心病组[13.9(9.8,17.1)mg/L比19.7(14.5,27.6)mg/L,P＜0.05].(2)随着冠状动脉病变支数的增加,血清A-FABP水平呈升高、脂联素水平呈递减趋势;Gensini积分与血清A-FABP呈正相关(r=0.120,P=0.043),与脂联素呈负相关(r=-0.405,P=0.007).(3)冠心病组血清A-FABP/脂联素比值明显高于非冠心病组[(1.51±0.79)μg/mg比(0.89±0.30)μg/mg,P＜0.01];血清A-FABP/脂联素比值与Gensini积分的相关性更明显(r=0.531,P=0.000).(4)冠心病者单核源性巨噬细胞A-FABP/脂联素比值高于非冠心病者[(0.51±0.19)μg/mg比(0.36±0.11)μg/mg,P＜0.05].结论 高A-FABP和低脂联素水平可能是反映严重冠状动脉狭窄的新的血清标记物.A-FABP/脂联素比值较单独A-FABP或脂联素与冠状动脉病变的相关性更好.     

性激素对脂肪细胞瘦素和脂联素分泌的影响

目的 观察性激素对前脂肪细胞增殖与分化及脂肪细胞瘦素脂联素分泌的影响.方法 原代培养人大网膜前脂肪细胞,观察其增殖、分化过程.性激素作用前脂肪细胞增殖和分化过程,检测瘦素、脂联素分泌及mRNA水平.结果 成功地培养出人大网膜前脂肪细胞.雌二醇促进前脂肪细胞增殖(0.823±0.059对0.276±0.032,P＜0.05)、抑制分化(P＜0.05);睾酮对前脂肪细胞增殖无明显作用,但抑制分化(P＜0.05).前脂肪细胞增殖及分化期均分泌瘦素.雌二醇促进瘦素分泌,而睾酮抑制(均P＜0.05).脂联素仅在分化期分泌,且性激素抑制其分泌.雌二醇促进瘦素mRNA表达但抑制脂联素mRNA表达;睾酮抑制瘦素、脂联素mRNA表达(均P＜0.05).结论 雌二醇促进脂肪细胞瘦素分泌及mRNA表达,抑制脂联素分泌及mRNA表达;睾酮抑制二者分泌及mRNA表达.     

JAZF1基因抑制对3T3-L1脂肪细胞糖、脂代谢的影响

目的 探讨JAZF1基因抑制对3T3-L1脂肪细胞糖、脂代谢相关基因的影响.方法 构建JAZF1小发夹RNA (shRNA)表达载体并转染3T3-L1细胞,实时荧光定量PCR(RT-QPCR)和蛋白印迹法检测JAZF1 mRNA和蛋白水平的表达;氢三放射示踪法检测3T3-L1细胞糖摄取率;蛋白印记法检测糖、脂代谢相关基因蛋白水平;油红O染色检测脂肪细胞甘油三酯(TG)含量变化.结果 成功构建JAZF1-shRNA;转染脂肪细胞48 h后,JAZF1 mRNA和蛋白水平明显低于对照组(P＜0.05);氢3放射性示踪法显示转染组葡萄糖摄取率明显降低(P＜0.05);PPAR-γ蛋白表达升高(P＜0.05),激素敏感脂肪酶(HSL)、内脏脂肪素(Visfatin)、胰岛素诱导基囚-2 (Insig-2)蛋白表达降低(均P＜0.05);油红O染色显示JAZF1转染组细胞内脂质积聚明显,比对照组升高约25％(P＜0.05).结论 JAZF1基因抑制可减少基础糖转运,增加脂质与胆固醇合成,减少脂质分解并减少相关脂肪细胞因子的表达.     

罗格列酮对肥胖患者脂肪细胞中脂联素表达的影响

目的:探讨噻唑烷二酮类药物（thiazolidinediones,TZDs）罗格列酮（rosiglitazone,RSG）对肥胖患者脂肪细胞中脂联素表达的影响。方法: 依据检查者的体质量指数(BMI)分为正常体重者和肥胖者,各3例。脂肪组织采用整形外科吸脂手术（供者知情并同意）获得。分离培养6例检查者的前脂肪细胞,用胰岛素、地塞米松、三碘甲状腺原氨酸（T3）及3-异丁基-1-甲基黄嘌呤（IBMX）诱导其分化为成熟的脂肪细胞。实验分为对照组和RSG处理组,前者培养的脂肪细胞不进行处理;后者的脂肪细胞用10 mol/L的RSG分别处理12 h、24 h、48 h和72 h。收集细胞的培养上清液,用ELISA法检测脂联素蛋白分泌的水平。提取细胞的总RNA,用RT-PCR法检测脂联素mRNA表达的水平。结果: 肥胖患者成熟脂肪细胞脂联素mRNA及其蛋白表达的水平较正常体重者明显降低（P<0.05）。与对照组相比较,RSG组成熟脂肪细胞脂联素mRNA和其蛋白表达的水平在处理不同时间（12 h、24 h、48 h和72 h）后均明显增高（P<0.05或P<0.01）,且呈时间依赖性;但肥胖患者脂联素mRNA和其蛋白表达水平增高持续的时间较正常体重者短（P<0.05或P<0.01）。结论: RSG在一定程度上能增加肥胖患者成熟脂肪细胞中脂联素表达的水平。     

Effects of LPS and dietary free fatty acids on MCP-1 in 3T3-L1 adipocytes and macrophages in vitro

Background:

High levels of free fatty acids (FFA) have been suggested to be one of the underlying mechanisms for adipose tissue (AT) inflammation and dysfunction in obesity. Human AT produces several adipokines including monocyte chemoattractant protein-1 (MCP-1), which are involved in the pathogenesis of obesity-mediated inflammation.

Objective:

In this study, we investigated the effects of lipopolysaccharide (LPS) and a panel of dietary FFA on MCP-1 gene and protein expression in adipocytes and macrophages. Furthermore, we investigated whether the effect of LPS and FFA were mediated through the toll-like receptor 4 (TLR4).

Methods:

3T3-L1 adipocytes and THP-1 macrophages were incubated for 24 h with the following FFA: monounsaturated fatty acid (oleic acid), saturated fatty acid (palmitic acid) and trans fatty acid (elaidic acid; 500 μM) with and without LPS (2 ng ml⁻¹), and MCP-1 and TLR4 mRNA expression and MCP-1 protein secretion was determined.

Results:

The results showed that LPS significantly increased MCP-1 and TLR4 expression and MCP-1 secretion in 3T3-L1 adipocytes, and that the MCP-1 expression was blocked by a TLR4 inhibitor (CLI095). The effects of the various FFA on MCP-1 mRNA expression and protein secretion in the adipocytes showed no significant changes either alone or in combination with LPS. In macrophages, palmitic acid increased MCP-1 mRNA expression by 1.8-fold (P<0.05), but oleic acid and elaidic acid had no effects.

Conclusions:

In conclusion, in 3T3-L1 adipocyte, the TLR4-agonist, LPS, stimulates the proinflammatory chemokine MCP-1. The different classes of FFA did not induce MCP-1 mRNA expression or protein secretion in the adipocytes, but the saturated FFA, palmitic acid, induced MCP-1 mRNA expression in macrophages, possibly because of the higher expression level of TLR4 in the macrophages than the adipocytes. Our results indicate that FFA may induce AT inflammation through proinflammatory stimulation of macrophages.     

Reactive oxygen species up-regulates SOCS-3 in 3T3-L1 adipocytes

We investigated the effect of increased intracellular reactive oxygen species(ROS) on SOCS-3 expression in 3T3-L1 adipocytes. Increased intracellular ROS levels in 3T3-L1 adipocytes were achieved by two methods of exposure to H2O2 and the occurrence of oxidative stress in cells was assessed by flow cytometry . Expression of SOCS-3 mRNA and that of some adipokines were measured by real time PCR. The level of SOCS-3 protein was determined by western blot. The effect of the antioxidant alpha-lipoic acid was also investigated. Both the relatively mild increased intracellular ROS and the acute but transient increased ROS elevated the levels of SOCS-3 mRNA and protein in 3T3-L1 adipocytes, acompanied with elevated levels of TNF-α mRNA and resistin mRNA and the decreased levels of adiponectin mRNA and secretory adiponectin in culture medium. α-lipoic acid could attenuate the effects of ROS on 3T3-L1 adipocytes. We hypothesized that in mature 3T3-L1 adipocytes, SOCS-3 could be upregulated directly by the induction of increased intracellular ROS and to some extent which was up-regulated by adipokine modulation.

     

肥胖小鼠脂肪组织缺氧对脂联素表达的转录抑制作用

目的观察缺氧对脂肪细胞脂联素mRNA和蛋白表达的影响,探讨肥胖小鼠脂肪组织缺氧导致脂肪组织脂联素表达下降的机制。方法采用实时定量聚合酶链反应（qRT—PCR）和蛋白免疫印迹法（Western blotting）检测遗传型肥胖小鼠（ob／ob,12周）和高脂饮食肥胖小鼠（HFD,53周）的附睾旁脂肪中脂联素mRNA和蛋白的表达;用小鼠3T3-L1脂肪细胞系为模型,采用RT—PCR和荧光素酶报告基因方法检测缺氧处理后脂联素和过氧化物酶体增殖物激活受体（PPAR）-mRNA的表达和稳定性、脂联素启动子的活性;用Western blotting和荧光素酶报告基因检测缺氧对PPAR-γ在核蛋白中集聚以及PPAR-γ转录因子活性的影响。组间数据比较采用t检验。结果（1）缺氧时两种肥胖小鼠的脂肪组织中脂联素mRNA和蛋白的表达均显著下降（P〈0．01）;333-L1脂肪细胞系在缺氧8h和24h后,脂联素mRNA表达量分别下降至0．65±0．05和0．29±0．05,较对照组（1．00±0．04）明显降低,差异有统计学意义（t=11．548、24．893,均P〈0．01）,但缺氧对脂联素mRNA的稳定性并没有影响;荧光素酶报告基因方法表明,脂联素启动子的活性受到缺氧的抑制。（2）在两种肥胖小鼠的脂肪组织中,PPAR-γmRNA和蛋白的表达均明显下降（P〈0．01）;小鼠333-L1脂肪细胞系在缺氧8h和24h后,PPAR- γmRNA的表达量分别下降至0．72±0．09和0．54±0．07,与对照组（1．00±0．09）相比,差异有统计学意义（t：5．134、9．876,均P〈0．01）;PPAR一1蛋白的核转位以及PPAR一^y转录因子活性也受到缺氧的抑制。结论肥胖小鼠脂肪组织缺氧抑制了脂联素的表达,抑制作用可能发生在转录水平;其机制可能是通过抑制PPAR-γmRNA的表达和PPAR-γ转录因子的活性而实现的。     

抵抗素结合多肽对3T3-L1脂肪细胞分化、脂代谢及葡萄糖转运体4基因表达的影响

目的观察抵抗素结合多肽（RBP）对3T3-L1脂肪细胞分化、脂代谢及葡萄糖转运体4（GLUT-4）基因表达的影响。方法构建大鼠抵抗素真核表达载体并转染3T3-L1前体脂肪细胞，获得稳定表达抵抗素基因细胞株；采用台盼蓝排斥试验，确定理想的RBP干预浓度，于诱导细胞分化第0天加入培养液；采用油红O染色，观察脂肪细胞分化及脂质积聚情况；采用RT-PCR技术检测脂肪细胞分化标志基因及GluT-4基因表达变化；采用全自动生化仪比色法，检测脂肪细胞内TG和游离脂肪酸FFAs含量的变化。结果（1）RBP浓度10^-12mol／L时，脂肪细胞活细胞数比例较高，且细胞形态无明显改变。（2）RBP对正常脂肪细胞分化进程无明显影响，RBP虽未影响抵抗素稳定表达脂肪细胞内脂滴的出现时间，但细胞内脂滴的数目明显减少。（3）RBP对正常脂肪细胞分化标志基因及抵抗素稳定表达细胞分化早期标志基因Pref-1的表达无明显影响，但明显下调抵抗素稳定表达细胞分化中晚期标志基因C/EBPα和FAS的表达水平。（4）RBP对正常脂肪细胞内TG、FFAs含量无影响，但可显著降低抵抗素稳定表达脂肪细胞内的TG、FFAs含量。（5）RBP干预对正常脂肪细胞及抵抗素稳定表达脂肪细胞中GluT-4基因的表达水平均无显著影响。结论RBP对正常3T3-L1脂肪细胞的分化、脂代谢、GluT-4基因表达均无明显影响，但能有效拮抗抵抗素基因，显著促进3T3-L1脂肪细胞分化及脂代谢。     

持续激活的Akt减少了 3T3-L1脂肪细胞脂联素蛋白的表达

目的 研究蛋白激酶B（Akt／PKB）的持续激活与灭活对3T3-L1脂肪细胞内脂联素蛋白表达的影响。方法 通过腺病毒表达系统将持续激活的Akt（myrAkt）和无酶活性的Akt（Akt-AA）导入3T3-L1脂肪细胞内，应用免疫印迹法检测3T3-L1脂肪细胞脂联素蛋白的表达。结果 表达myrAkt的3T3-L1脂肪细胞中脂联素明显减少，表达Akt-AA的3T3-L1脂肪细胞中脂联素无明显变化。结论Akt的激活抑制了3T3-L1脂肪细胞中脂联素蛋白的表达，且Akt的激活是影响脂联素的充分条件，而不是必要条件。     

Heat shock modulates adipokines expression in 3T3-L1 adipocytes

Studies have demonstrated that heat shock is associated with alteration in energy metabolism. In this study, we investigated the effect of heat shock on gene expression and secretion of adiponectin and leptin, and gene expression of Hspa2 and Ppargamma in 3T3-L1 adipocytes. Compared with 37 degrees C, adiponectin mRNA was higher at 39 degrees C, and lower at 41 degrees C. Leptin mRNA was higher when adipocytes were exposed to 41 degrees C compared with 37 and 39 degrees C. Secretion of adiponectin increased at 39 degrees C, and when cells were exposed to 41 degrees C it was not detectable. Leptin secretion increased significantly at 41 degrees C, compared with 37 and 39 degrees C. Hspa2 mRNA was increased at 39 degrees C, and the highest level was reached at 41 degrees C. Ppargamma mRNA exhibited a substantial increase in a temperature-dependent manner. The study provides the first evidence of a possible direct effect of heat shock on adiponectin and leptin gene expression and secretion, and demonstrates that the expression of the two adipokines is differentially regulated at the temperatures tested.     

In vitro aging of 3T3-L1 mouse adipocytes leads to altered metabolism and response to inflammation

We used an in vitro model to evaluate the effects of cellular aging and inflammation on the gene expression and protein secretion profiles of adipocytes. 3T3-L1 mouse preadipocytes were cultured according to standard conditions and analyzed at different time points both at the basal state and after an acute stimulation with LPS. The mRNA levels of CCAAT/enhancer-binding protein (C/EBP)α, peroxisome proliferator-activated receptor (PPAR)γ and S100A1 were maximal during adipocyte differentiation and then significantly decreased. The expression of the GLUT4 and IRS-1 genes peaked during differentiation and then decreased in aged cells. The mRNA levels and secretion of adiponectin, quickly rose as adipocytes matured and then declined. The mRNA levels of IL6, as well as its secretion, increased as preadipocytes matured and became old cells; a similar trend was also found for MCP-1. LPS decreased the mRNA levels of C/EBPα and PPARγ at all time points, as well as those of GLUT4, IRS-1 and adiponectin. LPS significantly increased the mRNA levels of IL-6, as well as its secretion, with a similar trend also observed for MCP-1. These data suggest that aging adipocytes in vitro show a decline in pro-adipogenic signals, in genes involved in glucose metabolism and cytoskeleton maintenance and in adiponectin. These changes are paralleled by an increase in inflammatory cytokines; inflammation seems to mimic and amplify the effects of cellular aging on adipocytes.