丝胶对Ⅱ型糖尿病大鼠肝胰岛素受体和胰岛素受体底物-2的调控作用

目的:研究丝胶对Ⅱ型糖尿病大鼠肝细胞胰岛素受体(IR)及胰岛素受体底物-2 (IRS-2)表达的影响.方法:SD大鼠随机分为5组,分别为正常对照组、糖尿病模型组、丝胶治疗组、阳性对照组、丝胶预防组.采用链脲佐菌素连续腹腔注射法制作Ⅱ型糖尿病大鼠模型.丝胶治疗组大鼠给予丝胶(2.4g·kg-1·d-1)灌胃35 d,阳性对照组大鼠给予二甲双胍(55.33 mg·kg-1·d-1)灌胃35 d,丝胶预防组大鼠于2％链脲佐菌素(25 mg/kg)连续腹腔注射之前给予丝胶(2.4g·kg-1·d-1)灌胃35d.采用葡萄糖氧化酶法检测各组大鼠的空腹血糖;SP免疫组织化学显色、蛋白免疫印迹和RT-PCR检测肝细胞中IR和IRS2的表达.结果:丝胶可明显上调糖尿病大鼠肝胰岛素受体和胰岛素受体底物-2mRNA表达,显著增加IR和IRS-2蛋白的表达.结论:丝胶可通过上调糖尿病肝IR和IRS-2的表达,改善胰岛素抵抗,起到降低血糖的作用.     

胰岛素受体底物与信号转导

胰岛素受体底物 (IRS)家族包括 4种异构体蛋白 ,是多种信号转导受体的共同底物 ,其中通过与胰岛素受体 (IR)及胰岛素样生长因子 1(IGF 1)受体结合而介导的信号转导系统与糖代谢及生长发育 ,胰腺功能密切相关。IRS异构体具有组织特异性及不同亚细胞定位 ,共同介导胰岛素和IGF 1信号转导网络 ,发挥胰岛素和IGF 1的多向性细胞信号转导效应。蛋白激酶C等因素通过抑制IRS的酪氨酸磷酸化影响胰岛素和IGF 1的信号转导效应并与糖尿病的发生有关     

北方汉族2型糖尿病人胰岛素受体底物1基因多态性的研究

目的：研究胰岛素受体底物1（IRS-1）基因变异在中国北方汉族2型糖尿病人发病中的作用。方法： 应用聚合酶链反应-序列特异性引物（PCR-SSP）技术对80例无血缘关系的辽宁地区糖尿病病人和80例正常人IRS-1基因的804、971密码子的核苷酸多态性进行检测。结果： 2型糖尿病人的IRS-1基因第804密码子GCG基因型频率明显高于正常人（分别为0.200和0.062, P<0.01）。第971位密码子AGG基因型在2型糖尿病病人和正常人分别为2例和1例。在2型糖尿病中，第804密码子GCG基因型和第971位密码子AGG基因型的患者胰岛素敏感指数明显下降，但携带不同基因型的患者间体重指数无明显差异。 结论： 2型糖尿病的IRS-1基因变异与胰岛素抵抗密切相关；胰岛素抵抗可能是2型糖尿病发病的重要原因，而IRS-1基因变异是其重要的遗传背景之一。     

自发性2型糖尿病大鼠主动脉形态学改变与胰岛素受体底物1mRNA的表达

目的研究自发性2型糖尿病OLETF大鼠在疾病发展的不同阶段，其主动脉组织形态学改变以及胰岛素受体底物-1（IRS-1）mRNA的表达水平，探讨胰岛素抵抗状态下大血管病变的发生机制。方法10只OLETF大鼠随机分别在16周龄与24周龄检杀，10只同种系非糖尿病LETO大鼠为正常对照组。应用光镜和透射电镜观察大鼠主动脉组织形态学改变，原位杂交技术检测主动脉IRS-1 mRNA表达。结果OLETF大鼠在16周龄时主动脉已出现超微结构异常，至24周时其病变程度加重，表现为典型动脉粥样硬化性早期改变；OLETF大鼠在16周和24周时其主动脉IRS-1 mRNA的表达均明显低于同期LETO对照组，分别减少24．6％（P〈0．01）和25．6％（P〈0．001）。结论血管组织胰岛素受体后信号传递分子在基因转录水平即存在异常，导致内皮细胞胰岛素抵抗，可能是糖尿病早期大血管病变危险性增加的机制之一。     

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。   关键词：肥胖;蛋白酪氨酸磷酸酶1B;胰岛素受体底物2;骨骼肌;胰岛素抵抗 doi:10.3969/j.issn.1673-8225.2012.20.020     

雌激素作用分子机制研究进展

雌激素在体内具有广泛的生物学活性。女性进入绝经期后 ,体内雌激素水平显著下降 ,出现与之相关的绝经期综合症 ,以及心血管疾病如冠心病、动脉粥样硬化和骨质疏松等。使用激素替代疗法能明显减少上述疾病的发生[1 ] 。本文重点在分子机制水平上对雌激素作用研究进展进行综述。     

胰岛素受体与胰岛素样生长因子受体1在阿尔茨海默病中的作用机制

近年来,越来越多的研究岁示阿尔茨海默病（Alzheimer’s disease,AD）与2型糖尿病（Type 2 diabetes mellitus,T2DM）相关,进一步研究表明,胰岛素受体（insulinreceptor,IR）和胰岛素样生长因子受体1（Insulin-like growth factor I receptor,IGF-1R）在AD的发生发展中占有很重要的地位。本文通过对眼和IGF-1R在阿尔茨海默病中的作用机制进行综述,为阿尔茨海默病的研究和治疗提供新的方向。     

多囊卵巢综合征胰岛素抵抗患者Gly972Arg多态性与子宫内膜胰岛素受体底物1表达的关系

目的:研究多囊卵巢综合征(Polycystic ovary syndrome,PCOS)胰岛素抵抗(Insulin resistance,IR)患者胰岛素受体底物1(Insulin receptor substrate,IRS-1)基因Gly972Arg多态性与子宫内膜IRS-1表达的关系。方法:PCOS患者51例,用聚合酶链反应(PCR)技术,检测IRS-1Gly972Arg多态性。于月经周期第1天刮取子宫内膜,合并胰岛素抵抗者28例,非胰岛素抵抗者23例,应用免疫组化技术检测子宫内膜IRS-1,计算机图像分析系统分析子宫内膜IRS-1的表达。结果:Gly972Arg多态性:51例PCOS患者中,基因型GG 49例,基因型GA 2例,IR组与无IR组各1例,两组比较无统计学意义。子宫内膜IRS-1的表达:IR组、非IR组IRS-1表达的灰度值分别为131.94±18.39、78.16±6.87,比较有统计学意义(P<0.01)。结论:IRS-1Gly972Arg的突变率较低,其多态性在PCOS IR组与无IR组比较无统计学意义(P>0.05),不影响子宫内膜IRS-1的表达。     

自发性2型糖尿病大鼠主动脉胰岛素受体底物1与eNOS的蛋白表达

应用免疫组织化学和Western印迹方法，测定16周及24周自发性2型糖尿病OLETF大鼠主动脉胰岛素受体底物1(IRS—1)和内皮型一氧化氯合酶(eNOS)的蛋白表达，以同种系非糖尿病LETO大鼠作为正常对照，以探讨胰岛素受体后信号传递分子IRS—1与胰岛素抵抗状态下大血管病变的关系。结果显示IRS-1和eNOS在主动脉内膜呈阳性表达；OLETF大鼠呈胰岛素抵抗特征，在16周和24周其主动脉组织内IRS—1的蛋白表达水平均明显低于对照组，分别减少28．2％和33．9％(P＜0．01)。eNOS蛋白水平分别减少27．7％和35．8％(P＜0．01)。两者变化方向一致。提示血管组织胰岛素受体后信号传递分子异常，导致内皮细胞胰岛素抵抗及一氧化氯生成障碍，可能是糖尿病患者早期大血管病变危险性增加的机制之一。     

Reduction of insulin signalling pathway IRS-1/IRS-2/AKT/mTOR and decrease of epithelial cell proliferation in the prostate of glucocorticoid-treated rats

Previous studies by our research group using a model of insulin resistance induced by dexamethasone (DEX) showed that in the rat ventral prostate there was epithelial and smooth muscle cell atrophy and there were also alterations in fibroblasts. Proteins of the insulin signalling pathway are known to be very important for cell proliferation and development. Thus, we investigated the insulin signalling pathway and epithelial proliferation in the rat ventral prostate in this model and correlated the findings with expression of glucocorticoid (GR) and androgen (AR) receptors. Insulin resistance was induced in adult male Wistar rats by injection of DEX (1 mg/kg, ip for 5 consecutive days), whereas control (CTL) rats received saline. DEX treatment resulted in a significant decrease in body weight, but not in prostate weight. Reductions in insulin receptor 1 (IRS-1) (CTL 1.11 ± 0.06; DEX 0.85 ± 0.03), IRS-2 (CTL 0.95 ± 0.05; DEX 0.49 ± 0.04), AKT (CTL 0.98 ± 0.03; DEX 0.78 ± 0.02), mammalian target of rapamycin (mTOR; CTL 0.65 ± 0.08; DEX 0.22 ± 0.05), GR (CTL 1.30 ± 0.09; DEX 0.57 ± 0.10) and AR (CTL 1.83 ± 0.16; DEX 0.55 ± 0.08) protein levels were observed in the prostate of DEX-treated rats. The expression of the IRα-subunit, phosphoinositide 3-kinase, p-AKT, p70(S6K) , extracellular signal-regulated kinase (ERK) and p-ERK was not altered. The frequency of AR-positive cells in the epithelium of the prostate decreased in the glucocorticoid-treated group, and the intensity of the reaction for this receptor in the cell nuclei was lower in this group. Furthermore, the treatment with DEX reduced the frequency of proliferating cell nuclear antigen-positive (PCNA) cells 30-fold. This study suggests that the reduction in the insulin signalling pathway proteins IRS-1/IRS-2/AKT/mTOR in the prostate of DEX-treated rats may be associated with the morphological alterations observed previously.     

Increased expression of IRS-1 is associated with lymph node metastasis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor rare throughout most of the world but common in Southeast Asia, especially in Southern China, which is with characteristics of early cervical lymph node metastasis and high incidence rate of distant metastasis. Insulin receptor substrate 1 (IRS-1) is a signaling adapter protein that is encoded by the IRS-1 gene in humans, plays an important role in the development, progression, invasion and metastasis of tumors. The aim of the present study was to investigate the association between the expression of IRS-1 protein and clinicopathological characteristics in NPC by immunohistochemistry. The results showed that the expression level of IRS-1 was significant higher in NPC than that in the control nasopharyngeal epithelia (P = 0.042). The positive percentage of IRS-1 expression in NPC with lymph node metastasis was also significantly higher than those without lymph node metastasis (P = 0.008). Positive expression of IRS-1 was proved to be the independent predicted factor for lymph node metastasis of NPC (P = 0.025) regardless of age, gender, histological type and clinical stages by multivariate logistic regression analysis. In addition, results showed higher sensitivity and agreement rate of IRS-1 for predicting lymph node metastasis of NPC patients. Taken together, high expression of IRS-1 might be closely correlated with lymph node metastasis in NPC and positive expression of IRS-1 could be used as an independent biomarker for predicting lymph node metastasis of NPC.     

Polymorphisms in the insulin receptor substrate-1 (IRS-1) gene and the insulin receptor substrate-2 (IRS-2) gene influence glucose homeostasis and body mass index in women with polycystic ovary syndrome and non-hyperandrogenic controls

BACKGROUND: We aimed to evaluate the influence of the Gly972Arg variant of the insulin receptor substrate-1 gene (IRS-1) and the Gly1057Asp variant in IRS-2 on insulin resistance and glucose tolerance in women with polycystic ovary syndrome (PCOS) and healthy controls. METHODS: Genotypes, allelic frequencies, indexes of insulin resistance, glucose tolerance and hormone profiles were studied in a large sample of Spanish PCOS (n = 103) women compared with a control group (n = 48) of healthy women matched for body mass index. RESULTS: No differences in genotype or allelic frequencies were found between PCOS patients and healthy controls. When considering control subjects and PCOS patients as a whole, IRS-1 Arg972 carriers also presented with increased fasting insulin (133 +/- 60 versus 95 +/- 67 pmol/l, P = 0.008) and insulin resistance measured by homeostasis model assessment (4.3 +/- 2.1 versus 3.1 +/- 2.4, P = 0.009) compared with subjects homozygous for Gly972 alleles. These differences were even higher when restricting the analysis to PCOS patients. Subjects homozygous for the Gly1057 allele of IRS-2 presented with increased 60 and 90 min oral glucose tolerance test (OGTT) glucose levels compared with carriers of one or two Asp1057 alleles (7.9 +/- 2.1 versus 7.1 +/- 2.1 mmol/l, P = 0.042 and 7.0 +/- 2.1 versus 6.0 +/- 1.8 mmol/l, P = 0.014), and a similar tendency was observed for 120 min OGTT glucose levels. CONCLUSIONS: The Gly972Arg in IRS-1 and Gly1057Asp in IRS-2 polymorphisms influence glucose homeostasis in premenopausal women, but are not associated with PCOS.     

Common polymorphisms in the PPARgamma2 and IRS-1 genes and their interaction influence serum adiponectin concentration in young Finnish men

The Gly972Arg substitution of the insulin receptor substrate-1 (IRS-1) gene and the Pro12Pro genotype of the peroxisome proliferator-activated receptor gamma 2 (PPARgamma2) gene have been suggested to be associated with type 2 diabetes mellitus. In this study, the influence of these two polymorphisms on serum adiponectin concentrations was investigated. The Pro12Ala polymorphism of the PPARgamma2 gene and the Gly972Arg polymorphism of the IRS-1 gene were genotyped in 252 young Finnish servicemen. The Ala12Ala genotype of PPARgamma2 was associated with a higher adiponectin level compared to the Pro12Ala genotype (p=0.02) and the Pro12Pro genotype (p=0.02). Total (p=0.02) and low-density lipoprotein (LDL) cholesterol (p=0.03) levels were higher in subjects with the Pro12Pro genotype compared to the Pro12Ala genotype. No difference was observed in serum adiponectin level between the IRS-1 genotype groups. The subjects with X972Arg of this gene had high total and LDL cholesterol levels (p<0.05). The interaction between the PPARgamma2 and IRS-1 genes with respect to their effects on adiponectin levels was statistically significant (p=0.02). Adiponectin was significantly higher (p<0.05) in subjects who simultaneously had the Ala/Ala (PPARgamma2)+Gly/Gly (IRS-1) genotype combination compared to subjects with the Pro/Pro+Gly/Gly and Pro/Ala+Gly/Gly genotype combinations. Total and LDL cholesterol was higher (p<0.05) in subjects with Pro/Pro+X/Arg compared to subjects with the two before mentioned genotype combinations. We conclude that the Ala12Ala genotype of PPARgamma2 is associated with elevated adiponectin level, and that the PPARgamma2 and IRS-1 genes have a possible interaction in their effects on adiponectin concentration.     

苯那普利对糖尿病大鼠肾脏组织细胞膜胰岛素受体及其底物-1蛋白表达的影响

目的:研究血管紧张素转换酶抑制剂苯那普利对糖尿病大鼠肾脏组织细胞膜胰岛素受体(IR)及其底物-1(IRS-1)蛋白表达的影响。方法:实验大鼠随机分3组:对照组(n=6);糖尿病组(n=7)及糖尿病+苯那普利治疗组(n=7)。4周后观察各组体重、肾重及肾重/体重之比的变化,应用荧光分光光度法测定血浆、肾脏组织血管紧张素转换酶(ACE)活性,Western杂交检测肾脏组织细胞膜IR及IRS-1蛋白表达。结果:苯那普利治疗4周后对糖尿病肾脏肥大有显著抑制作用,对血浆、肾脏组织ACE活性抑制分别达92.00%,88.77%。Western杂交显示糖尿病状态下肾脏组织细胞膜IR及IRS-1蛋白表达比对照组分别高2.1与1.5倍,苯那普利治疗4周可使IR及IRS-1蛋白表达分别低45.74%和47.66%。结论:糖尿病状态下肾脏组织细胞膜IR及IRS-1蛋白表达增加可能与肾脏组织糖代谢异常活跃有关,苯那普利下调IR及IRS-1蛋白表达可能是其对糖尿病肾脏保护作用的重要机制之一。     

高糖加高胰岛素对人血管平滑肌细胞增殖及细胞内游离钙水平的影响

目的：了解高糖加高胰岛素对人血管平滑肌细胞（ＨＶＳＭＣ）增殖的影响及其有关机制。方法：用含与不含维拉帕米（Ｖｅｒ）的高糖、高胰岛素、高糖加高胰岛素ＤＭＥＭ培养液分别培养人脐动脉平滑肌细胞３５ｄ；并以正常糖（５６ｍｍｏｌ／Ｌ葡萄糖）ＤＭＥＭ培养液培养为对照。结果：高糖、高胰岛素、高糖加高胰岛素培养液培养的各组ＨＶＳＭＣ计数及细胞内游离钙水平均显著高于对照组和含１μｍｏｌＶｅｒ的高糖、高胰岛素、高糖加高胰岛素培养液培养的各组（Ｐ＜００１）。高糖加高胰岛素培养液培养组ＨＶＳＭＣ计数及细胞内游离钙水平显著高于高糖、高胰岛素培养液培养的各组（Ｐ＜００１）。结论：高糖加高胰岛素具有协同促进ＨＶＳＭＣ增殖的作用，这主要是通过增加细胞膜上钙通道开放而实现的。     

Silibinin improves palmitate-induced insulin resistance in C2C12 myotubes by attenuating IRS-1/PI3K/Akt pathway inhibition

The present study investigated the effect of silibinin, the principal potential anti-inflammatory flavonoid contained in silymarin, a mixture of flavonolignans extracted from Silybum marianum seeds, on palmitate-induced insulin resistance in C2C12 myotubes and its potential molecular mechanisms. Silibinin prevented the decrease of insulin-stimulated 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose) uptake and the downregulation of glutamate transporter type 4 (GLUT4) translocation in C2C12 myotubes induced by palmitate. Meanwhile, silibinin suppressed the palmitate-induced decrease of insulin-stimulated Akt Ser473 phosphorylation, which was reversed by wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K). We also found that palmitate downregulated insulin-stimulated Tyr632 phosphorylation of insulin receptor substrate 1 (IRS-1) and up-regulated IRS-1 Ser307 phosphorylation. These effects were rebalanced by silibinin. Considering several serine/threonine kinases reported to phosphorylate IRS-1 at Ser307, treatment with silibinin downregulated the phosphorylation of both c-Jun N-terminal kinase (JNK) and nuclear factor-κB kinase β (IKKβ), which was increased by palmitate in C2C12 myotubes mediating inflammatory status, whereas the phosphorylation of PKC-θ was not significantly modulated by silibinin. Collectively, the results indicated that silibinin prevented inhibition of the IRS-1/PI3K/Akt pathway, thus ameliorating palmitate-induced insulin resistance in C2C12 myotubes.     

MicroRNA-126 acts as a tumor suppressor in glioma cells by targeting insulin receptor substrate 1 (IRS-1)

MicroRNA (miR-126) was reported to be downregulated and to act as a tumor suppressor in cancers of the lung, cervix, bladder, breast, liver and prostate. However, the precise roles and underling mechanisms of miR-126 in glioma remain largely unknown. This study is aimed to study the role of miR-126 in the progression of glioma and to elucidate underlying miR-126-mediated mechanisms in glioma. Our results revealed that miR-126 was downregulated in the collected glioma specimen, compared with non-cancerous brain tissues. Restored miR-126 expression inhibited cell proliferation, colony formation, migration and invasion, and induced cell cycle arrest at G0/G1 phase and cell apoptosis of U-87 MG glioma cells. Overexpression of miR-126 was also able to suppress the growth of U-87 MG glioma xenografts in mice. Furthermore, insulin receptor substrate 1 (IRS-1) were identified as a target of miR-126, and showed that it was negatively regulated by miR-126 in glioma cells. We also demonstrated that overexpression of miR-126 suppressed PI3K and AKT activation, which contribute to suppress tumor growth of glioma. Taken together, these findings showed that miR-126 functions as a tumor suppressor in glioma cells by targeting IRS-1 expression via the PI3K/AKT signaling pathways, suggesting that miR-126 might be a novel target for therapeutic strategies in glioma.     

Marked suppression of ghrelin concentration by insulin in Prader-willi syndrome

The plasma ghrelin has been reported to be elevated in Prader-Willi syndrome (PWS) and modulated by insulin. It was hypothesized that insulin might have a more pronounced effect on reducing plasma ghrelin in PWS patients, which would influence appetite. This study investigated the degree of ghrelin suppression using an euglycemic hyperinsulinemic clamp in children with PWS (n=6) and normal children (n=6). After a 90-min infusion of insulin, the plasma ghrelin level decreased from a basal value of 0.86+/-0.15 to 0.58+/-0.12 ng/mL in the controls, and from 2.38+/-0.76 to 1.12+/-0.29 ng/mL in children with PWS (p=0.011). The area under the curve below the baseline level over the 90 min insulin infusion was larger in children with PWS than in controls (-92.82+/-44.4 vs. -10.41+/-2.87 ng/mL/90 min) (p=0.011). The insulin sensitivity measured as the glucose infusion rate at steady state was similar in the two groups (p=0.088). The decrease in the ghrelin levels in response to insulin was more pronounced in the children with PWS than in the controls. However, the level of ghrelin was always higher in the children with PWS during the clamp study. This suggests that even though insulin sensitivity to ghrelin is well maintained, an increase in the baseline ghrelin levels is characteristic of PWS.