有氧运动对小鼠骨骼肌结节性硬化复合物蛋白2基因表达及胰岛素受体底物1丝氨酸磷酸化的影响

背景:研究表明,胰岛素受体底物蛋白1(insulin receptor substrate 1,IRS1)的丝氨酸磷酸化和结节性硬化复合物蛋白2的表达及哺乳动物雷帕霉素靶蛋白/核糖体S6激酶1信号通路的异常可诱导机体产生胰岛素抵抗.目的:观察有氧运动对小鼠骨骼肌结节性硬化复合物蛋白2基因表达及IRS1丝氨酸磷酸化的影响.方法:将C57BL/6小鼠随机分为安静组和运动组,运动组进行6周的75%VO2max强度的有氧跑台运动,安静组不做任何干预.采用RT-PCR,Western blot和免疫荧光组织化学染色等方法检测各组大鼠骨骼肌结节性硬化复合物蛋白2,IRS1,pIRS1-Ser307和pIRS1-Ser636/639的表达和定位.结果与结论:运动组结节性硬化复合物蛋白2 mRNA及蛋白表达高于安静组(P < 0.05),两组间胰岛素受体底物蛋白1 mRNA及蛋白表达差异无显著性意义.运动组胰岛素受体底物蛋白1的丝氨酸307和丝氨酸636/639位点的磷酸化明显低于安静组(P < 0.05).结果提示,有氧运动可增强骨骼肌组织结节性硬化复合物蛋白2基因表达,进而抑制胰岛素受体底物蛋白1的丝氨酸磷酸化.     

有氧运动对小鼠骨骼肌结节性硬化复合物蛋白2基因表达及胰岛素受体底物1丝氨酸磷酸化的影响

背景：研究表明,胰岛素受体底物蛋白1（insulin receptor substrate1,IRS1）的丝氨酸磷酸化和结节性硬化复合物蛋白2的表达及哺乳动物雷帕霉素靶蛋白/核糖体S6激酶1信号通路的异常可诱导机体产生胰岛素抵抗。目的：观察有氧运动对小鼠骨骼肌结节性硬化复合物蛋白2基因表达及IRS1丝氨酸磷酸化的影响。方法：将C57BL/6小鼠随机分为安静组和运动组,运动组进行6周的75%VO2max强度的有氧跑台运动,安静组不做任何干预。采用RT-PCR,Western blot和免疫荧光组织化学染色等方法检测各组大鼠骨骼肌结节性硬化复合物蛋白2,IRS1,pIRS1-Ser307和pIRS1-Ser636/639的表达和定位。结果与结论：运动组结节性硬化复合物蛋白2mRNA及蛋白表达高于安静组（P〈0.05）,两组间胰岛素受体底物蛋白1mRNA及蛋白表达差异无显著性意义。运动组胰岛素受体底物蛋白1的丝氨酸307和丝氨酸636/639位点的磷酸化明显低于安静组（P〈0.05）。结果提示,有氧运动可增强骨骼肌组织结节性硬化复合物蛋白2基因表达,进而抑制胰岛素受体底物蛋白1的丝氨酸磷酸化。     

高脂饮食诱导肥胖模型大鼠骨骼肌组织蛋白酪氨酸磷酸酯酶1B和胰岛素受体底物2的表达

背景:外周组织的胰岛素抵抗是2型糖尿病的主要病因。目的:观察高脂饮食诱导的肥胖大鼠骨骼肌中蛋白酪氨酸磷酸酯酶1B和胰岛素受体底物2的表达。方法:将20只SD大鼠随机等分为对照组和高脂组,分别给予常规饲料和高脂饲料喂养12周。结果和结论:与对照组相比,高脂组大鼠胰岛素敏感指数显著降低(P<0.01),大鼠葡萄糖耐量受损,胰岛素释放试验提示葡萄糖刺激的胰岛素第一时相分泌受损,骨骼肌组织中蛋白酪氨酸磷酸酯酶1B蛋白表达水平明显增加(P<0.01),骨骼肌中胰岛素诱导的胰岛素受体底物2磷酸化程度降低(P<0.01)。提示高脂饮食诱导的肥胖大鼠骨骼肌中蛋白酪氨酸磷酸酯酶1B蛋白表达量升高,使胰岛素诱导的胰岛素受体底物2磷酸化程度降低,可能是肥胖导致胰岛素抵抗的机制之一。     

蜕皮甾酮对胰岛素抵抗HepG2细胞胰岛素受体底物表达的影响

目的：探讨蜕皮甾酮对胰岛素抵抗（IR）HepG2细胞胰岛素受体底物（IRS）蛋白表达的影响。方法：胰岛素抵抗HepG2细胞模型建立后,培养液中加入蜕皮甾酮共同孵育,观察蜕皮甾酮及吡格列酮对模型细胞葡萄糖掺入率的影响;应用免疫细胞化学染色法等方法观察蜕皮甾酮对胰岛素抵抗HepG2细胞IRS-1、IRS-2表达的影响。结果：与模型细胞组比较,1×10^-5mol／L蜕皮甾酮可使IR HepG2细胞IRS-1、IRS-2蛋白的表达显著增加。结论：蜕皮甾酮的胰岛素增敏作用可能与胰岛素信号转导分子IRS-1、IRS-2蛋白的表达增强有关。     

桑叶黄酮对胰岛素抵抗HepG2细胞胰岛素受体底物表达的影响

目的 观察桑叶黄酮对胰岛素抵抗HepG2细胞胰岛素受体底物(IRS)蛋白表达的影响,探讨桑叶黄酮时胰岛素敏感性的作用及可能的分子机制.方法 用高胰岛素诱导培养HepG2细胞,建立胰岛素抵抗细胞模型,于培养液中加入桑叶黄酮共同孵育,观察桑叶黄酮对HepG2细胞模型葡萄糖掺入率的影响;应用Western blot等方法观察桑叶黄酮对模型细胞IRS蛋白表达的影响.结果 桑叶黄酮(0.01g/L)可增加胰岛素抵抗HepG2细胞的葡萄糖掺入率[(33.9±1.0)nmol/(mg·h)],与模型组[(27.9±1.1)nmol/(mg·h)]相比,差异有统计学意义(P＜0.01);桑叶黄酮可使模型细胞IRS蛋白的表达显著增加(0.221±0.021),与模型组(0.132±0.014)相比,差异有统计学意义(P＜0.01).结论 桑叶黄酮能提高胰岛素的敏感性,改善胰岛素抵抗,其胰岛素增敏作用可能与胰岛素信号转导分子IRS蛋白的表达增强有关.

Abstract：

Objective To observe the role of mulberry flavone on the expression of insulin receptor substrate(IRS)in HepG2 cells with insulin resistance, and to explore the possible molecular mechanism that mulberry flavone improves insulin resistance. Methods HepG2 cells were cultured to establish insulin-resistance cell model in high concentration of insulin, and then incubated with mulberry flavone. Effect of mulberry flavone on the HepG2 cell model of glucose incorporation rate was observed. Western blot was used to observe the variety of IRS protein expression. Results Mulberry flavone increased the glucose incorporation rate of (33. 9 ± 1.0)higher than that of Conclusions Mulberry flavone can improve insulin resistance. Furthermore, IRS protein expression increasing is the possible molecular mechanism that mulberry flavone improves insulin resistance.     

胰岛素受体信号系统

胰岛素受体酪氨酸蛋白激酶(IRTK)磷酸化/脱磷酸化的信号传递是胰岛素调节细胞物质代谢和细胞生长的中心环节。胰岛素受体底物-1(IRS-1)是胰岛素,IGF-1等受体酪氨酸蛋白激酶(RTK)的专一性内源底物。IRS-1多位点的Tyr磷酸化后可征募下游各种含Src同源区(SH2区)蛋白质相互作用,介导胰岛素信号途径,是胰岛素受体信号偶联的分子开关。糖尿病(NIDDM)出现IRS-1信号系统偶联异常。IRTK被视为Src TK家族成员,参与细胞生长,分化的调控,具有重要的生物学意义。     

Cks1在P27蛋白泛素化降解过程中的作用

在细胞分裂周期中，Cks1蛋白参与并促进P27蛋白泛素化降解，从而解除其对细胞周期蛋白激酶的抑制作用，促使细胞通过G1／S转折期。在大部分肿瘤细胞中Cks1蛋白表达上调，P27蛋白过多泛素化降解，Cks1蛋白参与并促进P27蛋白泛素化降解与细胞周期调控和肿瘤发生发展关系密切。本文综述了Cks1蛋白参与P27蛋白泛素化降解的基础和临床研究进展。     

慢性乙型肝炎患者肝组织胰岛素受体底物2的表达及其酪氨酸磷酸化的研究

目的 观察慢性乙型肝炎(CHB)患者肝组织胰岛素受体底物2(IRS-2)的mRNA和蛋白表达及其酪氨酸磷酸化程度,探讨IRS-2在CHB患者胰岛素抵抗(IR)发生中的作用.方法 选择6例肝功能正常者(对照组)及18例CHB患者,CHB患者再按HOMA模型计算的胰岛素抵抗指数分为CHB非IR(＜2.69)组(10例)和CHB合并IR(＞2.69)组(8例).所有患者于术中及肝穿刺后留取肝组织,采用逆转录-聚合酶链反应检测IRS-2 mRNA表达;采用蛋白质免疫印迹法检测IRS-2蛋白表达;采用免疫沉淀及增强化学发光法检测IRS-2酪氨酸磷酸化程度.结果 CHB非IR组肝组织IRS-2 mRNA(0.38±0.06)、蛋白(0.94±0.18)表达及酪氨酸磷酸化程度(0.78±0.09)较对照组(分别为0.45±0.11、0.99±0.20、1.00±0.23)有所降低,但差异无统计学意义(均P＞0.05);CHB合并IR组IRS-2mRNA(0.26±0.08)、蛋白(0.67±0.11)表达及酪氨酸磷酸化程度(0.63±0.14)均较对照组明显降低,差异有统计学意义(P＜0.05或P＜0.01).结论 CHB合并IR患者肝组织IRS-2的mRNA和蛋白表达及酪氨酸磷酸化程度的降低可能是产生IR的机制之一.     

E3泛素连接酶1对SOX2蛋白稳定性的影响

目的 探讨WW结构域的E3泛素蛋白连接酶1(WWP1)和E3泛素蛋白连接酶2(WWP2)对3种转录因子[八聚体结合转录因子4(OCT4)、性别决定区Y-box蛋白2(SOX2)和NANOG蛋白]水平的影响.方法 通过质粒转染,在HEK 293FT细胞中分别共表达OCT4、SOX2、NANOG和WWP1或WWP2.通过免...     

多囊卵巢综合征大鼠骨骼肌细胞胰岛素受体底物1及其丝氨酸307位点磷酸化的表达

背景：胰岛素受体底物1的丝氨酸307位点磷酸化程度的增加参与了骨骼肌胰岛素抵抗的发生。目的：观察多囊卵巢综合征大鼠骨骼肌细胞胰岛素受体底物1的含量及其丝氨酸307位点磷酸化程度的变化。方法：将大鼠随机分为模型组和对照组,模型组给予人绒毛膜促性腺激素联合胰岛素皮下注射,并配以高脂饮食,构建大鼠多囊卵巢综合征模型;对照组皮下注射生理盐水,正常饲料喂养。结果与结论：干预6周后,Western blot检测结果显示,与对照组相比,模型组大鼠骨骼肌细胞胰岛素受体底物1表达量显著下降（P〈0.05）,而其丝氨酸307位点磷酸化蛋白表达明显升高（P〈0.05）。结果提示,多囊卵巢综合征大鼠骨骼肌细胞中胰岛素受体底物1蛋白表达下调及其丝氨酸307位点磷酸化蛋白表达上调与多囊卵巢综合征大鼠骨骼肌胰岛素抵抗的发生密切相关。     

胰岛素对Reh细胞胰岛素受体和胰岛素样生长因子Ⅰ型受体表达及细胞增殖的影响

本研究探讨胰岛素对Reh细胞胰岛素受体(IR)和胰岛素样生长因子Ⅰ型受体(IGF-ⅠR)表达的影响及对Reh细胞的促增殖作用。用CCK-8法检测Reh细胞的增殖;采用实时PCR法检测Reh细胞IR和IGF-ⅠRmRNA的表达。结果表明,胰岛素对Reh细胞具有浓度和时间依赖性的促增殖作用,当胰岛素浓度为10-9 mol/L时其促增殖作用最强,进一步提高浓度,胰岛素的促增殖作用不再增强。与对照组相比,胰岛素有明显的促增殖作用(P<0.05)。胰岛素10-9mol/L作用24、48及72 h,IR mRNA表达量与对照组相比的比值分别为2.2520±0.7431、1.9956±0.9692和3.9766±1.3189,IGF-ⅠR表达量与对照组相比的比值分别为1.0803±0.2238、1.6026±0.6158和3.1013±0.1008。胰岛素刺激后IR和IGF-ⅠR的mRNA相对表达量与对照组相比均明显增加,差别有统计学显著意义(P=0.022和P=0.00)。结论:胰岛素能促进Reh细胞的增殖,其机制可能与IR和IGF-ⅠR上调有关。IR和IGF-ⅠR的高表达与白血病细胞的生长有着密切关系。     

胰岛素受体底物-2基因1057G/D多态性与妊娠期糖尿病的相关性

目的研究胰岛素受体底物-2(IRS-2)基因1057G/D多态性在南京地区汉族孕妇中的频率分布及其与妊娠期糖尿病(GDM)患者胰岛素抵抗的相关性。方法采用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)检测110例GDM孕妇(GDM组)及100例正常孕妇(NGT组)IRS-2基因1057G/D等位基因分布及基因频率,同时测定所有研究对象的空腹血糖(FPG)、空腹胰岛素(FIns),并计算胰岛素抵抗指数(HOMA-IR)以评价胰岛素抵抗状态。结果①IRS-2基因1057 D等位基因频率在GDM和NGT组中分别为25.91%和31.50%,差异无显著意义(P>0.05);②与NGT组相比,GDM组的FPG、FIns和HOMA-IR明显升高,差异有显著意义(P<0.05)。③GDM组和NGT组中不同基因型孕妇FPG、FIns和HOMA-IR等差异均无显著性(P>0.05)。结论南京地区汉族孕妇中IRS-2基因1057G/D多态性可能与妊娠期糖尿病的发生和胰岛素抵抗状态无关。上述结果尚待进一步通过联合检测和扩大样本量来确认。     

Insulin/IGF‐1 hybrid receptor expression on human platelets: consequences for the effect of insulin on platelet function

Summary. Objectives: As platelets express both insulin and insulin‐like growth factor‐1 (IGF‐1) receptors, their subunits may randomly heterodimerize to form insulin/IGF‐1 receptor hybrids, which avidly bind IGF‐1, but not insulin. This study investigated the possibility that platelets express hybrid receptors, which may affect insulin action on platelet function. Methods: Platelets were incubated with insulin and IGF‐1. Expression and phosphorylation of insulin/IGF‐1 receptors was determined by western blotting of immunoprecipitates, and compared with platelet functional responses. Relative expression of insulin and IGF‐1 receptors was estimated by competitive ligand binding and quantitative polymerase chain reaction. Results: We demonstrated the presence of insulin/IGF‐1 hybrid receptors on human platelets by detecting both insulin and IGF‐1 receptor β subunits in coimmunoprecipitation studies. Stimulation of platelets with insulin (1–100 nm ) resulted in tyrosine phosphorylation of insulin receptors, but not of hybrid receptors. High insulin concentrations (50–100 nm ) stimulated weak phosphorylation of IGF‐1 receptors and protein kinase B (Akt), and correlated with moderately increased aggregation and fibrinogen binding, whereas low insulin concentrations (1–10 nm ) had no effect. In contrast, IGF‐1 (1–100 nm ) induced strong phosphorylation of both hybrid and IGF‐1 receptors, and potentiated platelet aggregation and fibrinogen binding. Specific binding of [¹²⁵I]IGF‐1 (1.08% ± 0.16%) was significantly higher than that of [¹²⁵I]insulin (0.15% ± 0.03%). Accordingly, IGF‐1 receptor mRNA was more abundant than insulin receptor mRNA (IGF‐1 receptor/insulin receptor ratio 69 ± 3.8). Conclusions: Insulin has minimal effects on platelet function, which can be explained by the relatively low insulin receptor expression levels resulting in the majority of insulin receptor subunits being expressed as insulin/IGF‐1 hybrids.     

No association between common Gly972Arg variant of the insulin receptor substrate-1 and polycystic ovary syndrome in Southern Chilean women

BACKGROUND: Previously studies have indicated that the insulin receptor substrate-1 (IRS-1) Gly972Arg (G972R) polymorphism is associated with polycystic ovary syndrome (PCOS). We examined the possible association between G972R common variant of the IRS-1 gene and PCOS in Southern Chilean women with PCOS and controls. METHODS: A total of 50 women with PCOS (29.1+/-8.1 yr) and 75 healthy women (29.3+/-9.3 yr) were included. Serum lipids, glucose and uric acid concentrations were determined by enzymatic-colorimetric methods. The G972R variant of the IRS-1 gene was detected by PCR-RFLP. RESULTS: Women with PCOS exhibited a higher concentrations of total testosterone, glucose, insulin, total cholesterol, triglycerides, LDL-C and uric acid, and lower HDL-C concentrations than controls (P<0.05). The presence of G972R polymorphism in PCOS and control women was not significantly different (16% vs. 6.6%, P=0.276). The OR for PCOS associated to 972R variant was 2.67 (95% CI: 0.82-8.69, P=NS). Moreover, neither association between G972R genotypes and metabolic parameters were observed in PCOS women or controls. CONCLUSION: Our data do not support an association between G972R variant of the IRS-1 with PCOS or its metabolic parameters in Southern Chilean women.     

Safety and efficacy of a glucagon-like peptide-1 receptor agonist added to basal insulin therapy versus basal insulin with or without a rapid-acting insulin in patients with type 2 diabetes: results of a meta-analysis

Objective: To consolidate the evidence from randomized controlled trials evaluating the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) as add-on to basal insulin therapy in type 2 diabetes (T2D) patients.

Research design and methods: We searched the EMBASE® and NCBI PubMed (Medline) databases and relevant congress abstracts for randomized controlled trials evaluating the efficacy and safety of GLP-1 RAs as add-on to basal insulin compared with basal insulin with or without rapid-acting insulin (RAI) through 23 May 2016. The pooled data were analyzed using a random-effects meta-analysis model. A subanalysis was performed for trials investigating basal insulin plus GLP-1 RAs versus basal insulin plus RAI.

Results: Of the 2617 retrieved records, 19 randomized controlled trials enrolling 7,053 patients with T2D were included. Compared with basal insulin ± RAI, reduction in glycated hemoglobin (HbA1c) from baseline (difference in means: –0.48% [95% confidence interval (CI), –0.67 to –0.30]; p < 0.0001) and weight loss (–2.60 kg [95% CI, –3.32 to –1.89]; p < 0.0001) were significantly greater with basal insulin plus GLP-1 RA. The subanalysis similarly showed significant results for change in HbA1c from baseline and for weight loss, as well as a significantly lower risk of symptomatic hypoglycemia in patients treated with basal insulin plus GLP-1 RA versus basal insulin plus RAI (odds ratio, 0.52 [95% CI, 0.42 to 0.64]; p < 0.0001).

Conclusions: Addition of GLP-1 RA to basal insulin provided improved glycemic control, led to weight reduction and similar hypoglycemia rates versus an intensified insulin strategy; however, symptomatic hypoglycemia rates were significantly lower when compared with a basal insulin plus RAI.     

IL-6抗原抗体干预对T2DM大鼠肝脏IL-6 mRNA表达的影响

目的观察IL-6抗原及IL-6抗体对T2DM大鼠的影响,探讨IL-6等炎症因子对糖尿病发病机制的作用。方法 SD T2DM大鼠随机分为四组：糖尿病IL-6抗原组（A组）,糖尿病IL-6抗体组（B组）,糖尿病对照组（C组）,正常对照组（N组）。测定血糖、血清胰岛素、血清IL-6、肝脏胰岛素受体,RT-PCR检测肝脏IL-6mRNA表达量。结果脂肪乳灌胃（高糖高脂饮食）7周加小剂量一次尾静脉注射STZ可以成功诱导SD大鼠的T2DM模型,糖尿病组（A、B、C）较正常对照组出现明显的高胰岛素血症;IL-6抗原干预使T2DM大鼠血清及肝脏的IL-6表达增高;IL-6抗体干预可以降低其胰岛素水平。结论 IL-6作为一种致病因子能够加剧T2DM大鼠慢性低水平炎症,IL-6抗体能够改善其胰岛素抵抗状态。     

妊娠糖尿病子代红细胞膜胰岛素受体与胰岛素抵抗关系的研究

目的探讨妊娠糖尿病（GDM）子代红细胞膜胰岛素受体与胰岛素抵抗之间的关系。方法 32例妊娠糖尿病其儿童,22例正常妊娠其儿童,测定空腹血糖（FBG）、空腹胰岛素（FINS）、餐后2 h血糖（2 hBG）、餐后2 h胰岛素（2 hINS）、胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白（HDL）、低密度脂蛋白（LDL）,并检测高、低亲和力红细胞膜胰岛素受体数目（R1、R2）和亲和力常数（K1、K2）,计算胰岛素抵抗指数（IRI）。结果 GDM组儿童R1、R2低于对照组（P〈0.05）;GDM组儿童体重、BMI、FINS水平高于正常对照组（P〈0.05）。多元线性逐步回归分析结果显示,进入回归方程的因素有BMI（t=3.362,P〈0.05）、R1（t=-2.613,P〈0.05）、R2（t=-2.541,P〈0.05）,提示以上因素是影响GDM组儿童IR的主要危险因素。结论妊娠糖尿病（GDM）子代存在胰岛素抵抗,且与红细胞膜胰岛素受体数目减少、亲和力下降及肥胖有密切关系。     

Glucose tolerance in the elderly: the role of insulin and its receptor

Abstract. Oral glucose tolerance tests were performed in young and elderly subjects with minimal risk factors for diabetes mellitus. Compared to the normal glucose tolerance in the young there was a 45% rate of impaired tolerance in the elderly. Fasting insulin levels were significantly lower in the elderly but post-glucose insulin responses in the first hour were similar in young and elderly subjects. Peripheral insulin action was assessed in terms of the ¹²⁵monoiodoinsulin binding to specific insulin receptor sites on circulating lymphocytes in the young, the elderly and a group of age and sex matched obese maturity-onset diabetics. Specific insulin binding was not significantly different in the elderly than in the young but was significantly lower in the diabetics than the young and the elderly. The results suggest that neither defective insulin secretion nor reduced peripheral insulin binding are major causative factors in the reduced glucose tolerance of the elderly.