OBJECTIVETo study the expression of insulin receptor substrate-1(IRS-1) and insulin receptor substrate-2 (IRS-2) in pancreas of rats with intrauterine growth retardation (IUGR).

METHODSAn IUGR rat model was prepared by protein malnutrition during pregnancy. The pancreas samples of the IUGR pups were obtained at birth, and 3 weeks and 8 weeks of age. The expression of IRS-1 and IRS-2 mRNA were ascertained by RT-PCR. Western blot was used to measure the protein expression of IRS-1 and IRS-2. The rat pups born from the mother rats who received normal diet during pregnancy severed as the control group.

RESULTSThe expression levels of IRS-2 mRNA and protein in pancreas of the IUGR group were significantly lower than those in the control group at all three time points (P<0.05). There were no significant differences in the expression levels of IRS-1 mRNA and protein in pancreas between the IUGR and the control groups.

CONCLUSIONSThe IRS-2 expression levels in pancreas in IUGR rats decrease significantly at birth, and 3 weeks and 8 weeks of age. This might be one of the molecular mechanisms for the development of metabolic syndrome in later life in IUGR individuals.

Animals ; Fetal Growth Retardation ; metabolism ; Insulin Receptor Substrate Proteins ; RNA, Messenger ; Rats ; Receptor, Insulin

Liver cirrhosis (LC) and insulin resistance (IR) are closely correlated, clinically presenting hyperglycemia, hyperinsulinism, hyperlipidemia and high cytokines levels, however, the underlying mechanism is not completely clear. Recent reports show that insulin receptor substrate-1 (IRS-1) is associated with IR in LC. IRS-1 plays a pivotal role on insulin signal transduction; it changes insulin signaling by up-or down-regulating of protein presentation, post-translational modification and subcellular localization of proteins, particularly in phosphorylation/dephosphorylation of post-translational modification. Furthermore, LC with different etiology may have different mechanism of IRS-1 effect on IR.
Humans ; Insulin ; metabolism ; Insulin Receptor Substrate Proteins ; metabolism ; physiology ; Insulin Resistance ; Liver Cirrhosis ; metabolism

PURPOSE: The insulin-like growth factor (IGF) system performs multiple functions in the regulation of breast cancer cell growth. The IGF system is comprised of a complex network of ligands, receptors and related signaling proteins. Two receptors are recognized, the insulin-like growth factor-I receptor (IGF-IR) and the insulin-like growth factor- II receptor (IGF-IIR), one of which, the IGF-IR, is a transmembrane heterodimer structurally similar to the insulin receptor. The activation of the IGF-IR results in the recruitment of adapter proteins, which adapter proteins used by the insulin-like growth factor-I (IGF-I) to transduce its signal to the insulin receptor substrate-1 (IRS-1). This study investigated the relationship between IGF-IR and IRS-1 by using an immunohistochemical staining technique. METHODS: IGF-IR and IRS-1 expression was detected by immunohistochemical staining using paraffin sections in 123 invasive breast carcinoma cases. The results were evaluated with the survival rate and the clinicopathological prognostic variables such as the patient's age, the clinical stage, the histological grade, the estrogen receptor (ER) and the progesterone receptor (PR). RESULTS: The results showed that IGF-IR and IRS-1 expression positively correlated with the ER and PR, and an inverse relationship was found between the IGF-IR and IRS-1 and histological grades. No association was observed between the IGR-IR and IRS-1 and the patent's age and clinical stage. In survival analysis, there was no definite association between the expressions of IGF-IR and IRS-1 and the disease free survival rate. CONCLUSION: IGF-IR and IRS-1 appear to play a role in the progression and differentiation of breast cancer in association with the ER and the PR.
Breast Neoplasms* ; Breast* ; Disease-Free Survival ; Estrogens ; Insulin Receptor Substrate Proteins* ; Insulin* ; Ligands ; Paraffin ; Receptor, Insulin* ; Receptors, Progesterone ; Survival Rate

OBJECTIVETo investigate the expressions of adipic insulin receptor β(IR-β) and insulin receptor substrate-1 (IRS-1) after gastric bypass (GBP) operation in spontaneous rats with type 2 diabetes mellitus(GK rats) and to elucidate the mechanisms of GBP in improving insulin resistance.

METHODSThirty male GK rats aged 8 weeks were randomly divided into 3 groups according to the table of random number: the operation group (GBP, 10 rats), the sham operation group (the same sites were cut off as GBP and end to end anastomosis was performed in site, 10 rats) and the diet pairing group (the same kind and weight dieting as the operation group, 10 rats), besides 10 male SD rats aged 8 weeks were used as blank control group (free eating and drinking). Four weeks before and after operation, levels of fasting blood glucose(FPG) and fasting insulin(FINS) were measured, HOMA-IR was calculated respectively, and compared among 4 groups. Then rats were decapitated to retrieve the omentum. Expressions of adipic IR-β and IRS-1 protein were detected by Western blot.

RESULTSCompared with the preoperative levels, the FPG and HOMA-IR decreased significantly 4 weeks after surgery in operation group [(5.13±0.22) vs. (11.73±0.37) mmol/L, 2.16±0.18 vs. 5.10±0.29, P<0.05), reaching the level of blank control group(P>0.05). FINS showed no obvious change in these 4 groups after operation(all P>0.05). Expressions of IR-β and IRS-1 were significantly higher in operation group than those in other 3 groups 4 weeks after the operation(all P<0.05).

CONCLUSIONSExpressions of adipic IR-β and IRS-1 in insulin signal transmission of rats with type 2 diabetes mellitus after GBP are up-regulated, meanwhile insulin resistance can be improved and insulin sensibility increases.

Animals ; Body Weight ; Diabetes Mellitus, Type 2 ; Gastric Bypass ; Insulin ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; Male ; Rats ; Receptor, Insulin ; Up-Regulation

More and more evidence suggests that microRNA is widely involved in the regulation of cardiovascular function. Our preliminary experiment showed that miR-494-3p was increased in heart of diabetic rats, and miR-494-3p was reported to be related to metabolism such as obesity and exercise. Therefore, this study was aimed to explore the role of miR-494-3p in diabetic myocardial insulin sensitivity and the related mechanism. The diabetic rat model was induced by high fat diet (45 kcal% fat, 12 weeks) combined with streptozotocin (STZ, 30 mg/kg), and cardiac tissue RNA was extracted for qPCR. The results showed that the level of miR-494-3p was significantly up-regulated in the myocardium of diabetic rats compared with the control (P < 0.05). The level of miR-494-3p in H9c2 cells cultured in high glucose and high fat medium (HGHF) was significantly increased (P < 0.01) with the increase of sodium palmitate concentration, whereas down-regulation of miR-494-3p in HGHF treated cells led to an increase in insulin-stimulated glucose uptake (P < 0.01) and the ratio of p-Akt/Akt (P < 0.05). Over-expression of miR-494-3p in H9c2 cell line significantly inhibited insulin-stimulated glucose uptake and phosphorylation of Akt (P < 0.01). Bioinformatics combined with Western blotting experiments confirmed insulin receptor substrate 1 (IRS1) as a target molecule of miR-494-3p. These results suggest that miR-494-3p reduces insulin sensitivity in diabetic cardiomyocytes by down-regulating IRS1.
Animals ; Diabetes Mellitus, Experimental ; physiopathology ; Down-Regulation ; Insulin ; Insulin Receptor Substrate Proteins ; physiology ; Insulin Resistance ; MicroRNAs ; genetics ; Myocytes, Cardiac ; physiology ; Rats

Insulin resistance,as the main link in the pathogenesis of type 2 diabetes mellitus( T2 DM),runs through the whole process of occurrence and development of T2 DM and is closely related to the insulin receptor signaling pathway. Insulin stimulation causes autophosphorylation of the insulin receptor( IR),which then activates tyrosine phosphorylation of insulin receptor substrate( IRS).Phosphorylation of IRS can induce and activate phosphatidylinositol 3-kinase( PI3 K),subsequently activate downstream 3-phosphoinositide-dependent protease 1( PDK1) and Akt/PKB,and finally promote expression and translocation of glucose transporter 4 to increase glucose uptake of insulin-sensitive tissues and alleviate insulin resistance. Currently,oral hypoglycemic agents for clinical treatment of T2 DM have different side effects on the human body. Traditional Chinese medicine not only has a wide range of sources and abundant types,but also has comprehensive multi-component,multi-link and multi-target effects,showing unique advantages in the treatment of diabetes. In recent years,more and more researchers at home and abroad pay attention to the active ingredients in traditional Chinese medicine for alleviating insulin resistance. In this paper,we would summarize the active hypoglycemic ingredients of traditional Chinese medicine associated with the insulin receptor signaling pathway,which may provide some theoretical guidance for the development of traditional Chinese medicine in the treatment of diabetes.
Diabetes Mellitus, Type 2 ; Humans ; Hypoglycemic Agents/therapeutic use* ; Insulin ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; Medicine, Chinese Traditional ; Phosphatidylinositol 3-Kinases ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; Receptor, Insulin/metabolism* ; Signal Transduction

BACKGROUND: The insulin receptor substrate-1 (IRS-1) is the primary docking molecule for the insulin-like growth factor I receptor (IGF-IR), and is required for activation of the phosphatidylinositol 3'-kinase (PI3K) pathway. IRS-1 activation of the (PI3K) pathway regulates IGF-mediated survival, enhancement of cellular motility and apoptosis. Therefore, we attempted to ascertain whether IRS-1 genetic variations affect an individual's risk for non-small cell lung cancer (NSCLC). METHODS: Two-hundred and eighteen subjects, either diagnosed with NSCLC or control subjects, were matched by age, gender and smoking status. Genomic DNA from each subject was amplified by PCR and analyzed according to the restriction fragment length polymorphism (RFLP) profile to detect the IRS-1 G972R polymorphism. RESULTS: The frequencies of each polymorphic variation, in the control population, were as follows: GG=103 (94.5%) and GR=6 (5.5%); for the NSCLC subjects, the genotypic frequencies were as follows: GG=106 (97.2%) and GR=3 (2.8%). We could not demonstrate statistically significant differences in the genotypic distribution between the NSCLC and the control subjects (p=0.499, Fisher's Exact test). The relative risk of NSCLC, associated with the IRS-1 G972R polymorphic variation, was 1.028 (95% CI; 0.63~9.90). In addition, we found no differences between polymorphic variants with regard to the histological subtype of NSCLC. CONCLUSION: We did not observe any noteworthy differences in the frequency of the IRS-1 G972R polymorphism in NSCLC patients, compared to control subjects. These results suggest suggesting that, in our study population, the IRS-1 G972R polymorphism does may not appear to be associated with an increased risk of NSCLC.
Apoptosis ; Carcinoma, Non-Small-Cell Lung ; DNA ; Genetic Variation ; Humans ; Insulin ; Insulin Receptor Substrate Proteins ; Insulin-Like Growth Factor I ; Phosphatidylinositols ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Receptor, Insulin ; Smoke ; Smoking

OBJECTIVETo investigate the effect of Bushen Tongmai recipe (BSTMR) on the tyrosine phosphorylation of insulin receptor (InsR) and insulin receptor substrate-1 (IRS-1) after insulin stimulation in muscle and fat tissues of insulin resistant (IR) rats induced by high-fat forage.

METHODSMale Wistar rats were randomly divided into normal group (normal forage), model group (high fat forage, in which 61% calories were supplied by fat) and treated group (same forage as model group and treated with BSTMR). All animals were fed for 8 weeks, fasting blood glucose (FBG), blood glucose (BG) levels 1- and 2-hrs after glucose loading were determined routinely, serum fasting insulin (Ins) was determined with radioimmunoassay (RIA) and tyrosine phosphorylation level of InsR and IRS-1 in fatty and muscular tissues was measured by immunoprecipitation and Western blot.

RESULTSCompared with the model group, FBG in the treated group changed insignificantly, but level of Fins decreased markedly (P < 0.01), so the insulin sensitivity index was significantly elevated in the treated group (P < 0.01), levels of BG 1- and 2-hrs after glucose loading in the treated group were greatly improved in comparison with those in the model group (P < 0.05 and P < 0.01 respectively). Meanwhile, the density of electrophoresis bands of tyrosine phosphorylated InsR and IRS-1 proteins in muscular and fatty tissues in the treated group increased obviously.

CONCLUSIONBSTMR could attenuate the insulin resistance in rats, its pharmaceutical mechanisms might be closely related with the elevation of the tyrosine phosphorylation levels of InsR and IRS-1 in muscular and fatty tissues after insulin stimulation, and improvement of insulin signal transduction in target tissues.

Animals ; Blood Glucose ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Insulin ; metabolism ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; physiology ; Male ; Phosphoproteins ; drug effects ; Phosphorylation ; Random Allocation ; Rats ; Rats, Wistar ; Receptor, Insulin ; metabolism ; Signal Transduction ; drug effects ; Tyrosine ; metabolism

Asian Continental Ancestry Group ; China ; Diabetes Mellitus, Type 2 ; ethnology ; genetics ; Genetic Variation ; Genotype ; Humans ; Insulin Receptor Substrate Proteins ; Intracellular Signaling Peptides and Proteins ; Phosphoproteins ; genetics

To study the regulatory effect of acute and chronic insulin treatment on insulin post-receptor signaling transduction pathway in a human hepatoma cell line (Hep G2), Hep G2 cells were incubated in the presence or absence of insulin with different concentrations in serum free media for 16 h and then stimulated with 100 nmol/L insulin for 1 min. Protein levels of insulin receptor beta-subunit (IR beta), insulin receptor substrate-1 (IRS-1) and p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) were determined in total cell lysates by Western-immunoblot. Phosphorylated proteins IR beta, IRS-1 and interaction of PI 3-kinase with IRS-1 were determined by immunoprecipitation. Results showed that 1-min insulin stimulation rapidly induced tyrosine phosphorylation of IR beta and IRS-1, which in turn, resulting in association of PI 3-kinase with IRS-1. 1-100 nmol/L chronic insulin treatment induced a dose-dependent decrease in the protein level of IR beta and a slight decrease in the protein level of IRS-1. There was a more marked reduction in the phosphorylation of IR beta, IRS-1, reaching a nadir of 22% (P < 0.01) and 15% (P < 0.01) of control levels, respectively, after 16 h treatment with 100 nmol/L insulin. The association between IRS-1 and PI 3-kinase was decreased by 66% (P < 0.01). There was no significant change in PI 3-kinase protein levels. These data suggest that chronic insulin treatment can induce alterations of IR beta, IRS-1 and PI 3-kinase three early steps in insulin action, which contributes significantly to insulin resistance, and may account for desensitization of insulin action.
Carcinoma, Hepatocellular ; pathology ; Down-Regulation ; Humans ; Hyperinsulinism ; metabolism ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; Liver Neoplasms ; pathology ; Phosphoproteins ; metabolism ; Phosphorylation ; Receptor, Insulin ; antagonists & inhibitors ; metabolism ; Signal Transduction ; drug effects ; Tumor Cells, Cultured