Effect of miR-96-5p targeting IRS1 on apoptosis of PC12 cells induced by aluminum maltol / 中华劳动卫生职业病杂志

Objective: To investigate the effect and mechanism of miR-96-5p on apoptosis of PC12 cells induced by maltol aluminum. Methods: In January 2021, PC12 cells at logarithmic growth phase were divided into blank control group and low, medium and high dose group. Cells in each group were treated with 0, 100, 200 and 400 μmol/L maltol aluminum for 24 hours respectively. Cells were collected and cell apoptosis rates were detected by flow cytometry, miR-96-5p and insulin receptor substrate 1 (IRS1) mRNA expressions were detected by qRT-PCR, and the protein expression levels of cysteine protease 3 (Caspase3) 、activated cysteine protease 3 (Cleaved-caspase3) 、IRS1、phosphorylated protein kinase B (p-AKT) and phosphorylated glucose synthesis kinase 3β (p-GSK3β) were detected by western blotting. The target binding relationship between miR-96-5p and IRS1 was detected by double luciferase reporter gene experiment. The miR-96-5p inhibitor cells and negative control cells were constructed after transfecting PC12 cells with miR-96-5p inhibitor for 24 hours. The cells were divided into blank control group, negative control group, aluminum exposure group, aluminum exposure+negative control group, aluminum exposure+miR-96-5p inhibition group, and miR-96-5p inhibition group. After transfecting PC12 cells with miR-96-5p inhibition and IRS1 siRNA for 24 h, the cells were divided into aluminum exposure+miR-96-5p inhibition+negative control group and aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group. The control group was cultured in complete culture medium, and cells in the aluminum exposure group were treated with 200 μmol/L maltol aluminum for 24 hours. Cells in each group were collected and the apoptosis rate, miR-96-5p and IRS1 mRNA expression levels, as well as protein expression levels of Caspase3, Cleaved-caspase3, IRS1, p-AKT, and p-GSK3β were measured. Results: After 24 hours of exposure, compared with blank control group and low-dose group, the apoptosis rates, relative expressions of Caspase3 and Cleaved-caspase3 proteins, and relative expressions of miR-96-5p in the medium and high-dose groups of PC12 cells were significantly increased, while the relative expression levels of IRS1 mRNA, IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05). Targetscan prediction and double luciferase report experiment both proved that IRS1 was a direct target gene of miR-96-5p. In the transfection experiment, compared with the aluminum exposure group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins, the relative expression of miR-96-5p in the aluminum exposure+miR-96-5p inhibition group were significantly decreased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly increased (P<0.05). In the IRS1 low expression experiment, compared with the aluminum exposure+miR-96-5p inhibition+negative control group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins in the aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group were significantly increased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05) . Conclusion: The increased expression of miR-96-5p and the targeted inhibition of IRS1 may be one of the mechanisms of apoptosis of PC12 cells induced by maltol aluminum exposure.

Effects and mechanisms of total flavones of Abelmoschus manihot in improving insulin resistance and podocyte epithelial-mesenchymal transition in diabetic kidney disease based on IRS1/PI3K/Akt pathway / 中国中药杂志

This study aimed to explore the effects and mechanisms of total flavones of Abelmoschus manihot(TFA), the extracts from traditional Chinese medicine indicated for kidney diseases, on insulin resistance(IR) and podocyte epithelial-mesenchymal transition(EMT) in diabetic kidney disease(DKD), and further to reveal the scientific connotation. Thirty-two rats were randomly divided into a normal group, a model group, a TFA group, and a rosiglitazone(ROS) group. The modified DKD model was induced in rats by methods including high-fat diet feeding, unilateral nephrectomy, and streptozotocin(STZ) intraperitoneal injection. After modeling, the rats in the four groups were given double-distilled water, TFA suspension, and ROS suspension correspondingly by gavage every day. At the end of the 8th week of drug administration, all rats were sacrificed, and the samples of urine, blood, and kidney tissues were collected. The parameters and indicators related to IR and podocyte EMT in the DKD model rats were examined and observed, including the general condition, body weight(BW) and kidney weight(KW), the biochemical parameters and IR indicators, the protein expression levels of the key signaling molecules and structural molecules of slit diaphragm in the renal insulin receptor substrate(IRS) 1/phosphatidylinositol 3-kinase(PI3K)/serine-threonine kinase(Akt) pathway, foot process form and glomerular basement membrane(GBM) thickness, the expression of the marked molecules and structural molecules of slit diaphragm in podocyte EMT, and glomerular histomorphological characteristics. The results showed that for the DKD model rats, both TFA and ROS could improve the general condition, some biochemical parameters, renal appearance, and KW. The ameliorative effects of TFA and ROS were equivalent on BW, urinary albumin(UAlb)/urinary creatinine(UCr), serum creatinine(Scr), triglyceride(TG), and KW. Secondly, they could both improve IR indicators, and ROS was superior to TFA in improving fast insulin(FIN) and homeostasis model assessment of insulin resistance(HOMA-IR). Thirdly, they could both improve the protein expression levels of the key signaling molecules in the IRS1/PI3K/Akt pathway and glomerulosclerosis in varying degrees, and their ameliorative effects were similar. Finally, both could improve podocyte injury and EMT, and TFA was superior to ROS. In conclusion, this study suggested that podocyte EMT and glomerulosclerosis could be induced by IR and the decreased activation of the IRS1/PI3K/Akt pathway in the kidney in DKD. Similar to ROS, the effects of TFA in inhibiting podocyte EMT in DKD were related to inducing the activation of the IRS1/PI3K/Akt pathway and improving IR, which could be one of the scientific connotations of TFA against DKD. This study provides preliminary pharmacological evidence for the development and application of TFA in the field of diabetic complications.

Effect of fucoxanthin on insulin resistance in obese mice induced by high fat diet / 中国中药杂志

The aim of this paper was to study the effect and mechanism of fucoxanthin on insulin resistance of obese mice induced by high-fat diet. Fifty C57 BL/6 J male mice were randomly divided into control group and high-fat diet group. The insulin resistance model was induced with high-fat diet for 12 weeks, and model mice were randomly divided into model group, fucoxanthin-0.2% group, fucoxanthin-0.4% group and metformin group. After dietary treatment for 6 weeks, the body weight and epididymal fat weight in each group were measured. Fasting blood glucose(FBG), fasting insulin(FINS), total cholesterol(TC), triglyceride(TG), low-density lipoprotein(LDL-C) and high-density lipoprotein(HDL-C) were measured, and insulin resistance index(HOMA-IR) was calcula-ted. The pathological morphology in liver was observed by hematoxylin eosin staining, and the expressions of some key proteins in insulin receptor substrate 1(IRS-1)/posphoinositide 3-kinase(PI3 K)/serine-threonine kinase(Akt) and peroxisome proliferators-activated receptor-γ(PPARγ)/sterol regulatory element binding protein-1(SREBP-1)/fatty acid synthetase(FAS) pathways in liver were detected by Western blot. According to the findings, compared with the model group, levels of body weight, epididymal fat weight, FBG, FINS, TC, TG, LDL-C and HOMA-IR, as well as protein expressions of PPARγ, SREBP-1 and FAS in liver were significantly reduced(P<0.05 or P<0.01), while level of HDL-C and protein expressions of p-IRS-1, IRS-1, PI3 K and p-Akt in liver were signi-ficantly increased after treatment with fucoxanthin(P<0.05 or P<0.01). And the pathological changes of liver tissue in fucoxanthin-treated mice were also improved obviously. The results showed that fucoxanthin could improve obesity, hyperglycemia and hyperlipidemia, and alleviate insulin resistance in obese mice, and its mechanism is possibly related to the regulation of IRS-1/PI3 K/Akt and PPARγ/SREBP-1/FAS pathways.

Effect of Baihutang Regulating IRS-1/PI3K/Akt Signal Pathway on Blood Glucose, Blood Lipid Metabolism and Vascular Remodeling in Type 2 Diabetic Rats / 中国实验方剂学杂志

Objective:To study the effect of Baihutang on blood glucose， blood lipid metabolism and vascular remodeling in type 2 diabetic rats and its regulation on insulin receptor substrate-1（IRS-1）/ phosphatidylinositol-3 kinase（PI3K）/ protein kinase B（Akt） signal pathway. Method:The 90 rats were randomly divided into normal group， model group， Baihutang low， middle and high dose groups and metformin group， with 15 rats in each group. Except for normal group， the other rats were injected intraperitoneally with streptozotocin to establish the model of type 2 diabetes. The rats in the low， middle and high dose groups were given Baihutang formula granules of 5， 10， 20 g·kg-1 respectively according to their body weight. The positive control group was given metformin （100 mg·kg-1） by intragastric administration， while those in the control group and model group were given the same amount of normal saline once a day for 12 weeks. The levels of fasting blood glucose， glycosylated hemoglobin， serum tumor necrosis factor-α（TNF-α）， interleukin-6（IL-6）， interleukin-1 β（IL-1β）， total cholesterol（TC）， triglyceride（TG） and low-density lipoprotein cholesterol（LDL-C） were measured after administration. The levels of sterol regulatory element binding protein 1C （SREBP1C）， acetyl CoA carboxylase （ACC）， fatty acid synthase gene （FASN） and carnitine palmitoyl transferase 1A （CPT1A）， acylcoa oxidase 1（ACOX1）， recombinant human acylcoa dehydrogenase （ACADM） mRNA in liver of rats were detected by Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR）， Western blot was used to detect the protein levels of IRS-1， PI3K and Akt in liver of rats. Hematoxylin-eosin（HE） staining was used for histopathological examination of rat thoracic aortic vessels. The migration ability of vascular smooth muscle cells in rat thoracic aorta was detected by scratch test. Result:Compared with the normal group， the fasting blood glucose， glycosylated hemoglobin， serum TNF-α， IL-6，IL-1β， TC，TG and LDL-C levels， liver lipid synthesis gene mRNA level and vascular smooth muscle cell migration ability of thoracic aorta in model group were significantly higher than those in normal group （P<0.05）， while fatty acid oxidation gene mRNA level and IRS-1，PI3K，Akt protein level in liver were significantly decreased in model group （P<0.05）. The vascular wall thickness of thoracic aorta increased significantly in rats （P<0.05）. Compared with model group， the levels of fasting blood glucose， glycosylated hemoglobin， serum TNF-α，IL-6， IL-1β， TC， TG and LDL-C， the level of lipid synthesis gene mRNA in liver and the migration ability of vascular smooth muscle cells in thoracic aorta of rats in all Baihutang groups were significantly lower than those in model group （P<0.05）. The mRNA level of fatty acid oxidation gene and the protein levels of IRS-1， PI3K and Akt in liver were significantly increased（P<0.05）， and the histopathology of thoracic aorta was significantly improved and the vascular wall thickness decreased significantly（P<0.05）. Conclusion:Baihutang can reduce the levels of blood glucose， blood lipid and serum inflammatory factors in type 2 diabetic rats， regulate the expression of genes related to lipid metabolism in liver， and improve the histopathology and vascular remodeling of thoracic aorta. The mechanism may be related to the regulation of IRS-1/PI3K/Akt signal pathway.

Prevalence of Insulin Receptor Substrate-1 Gene (G972R) Polymorphism, Insulin Resistance, and Determination of β-Cell Function among overweight and obese persons with Type 2 Diabetes Mellitus / Journal of the ASEAN Federation of Endocrine Societies

Background@#Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder and its pathogenesis is characterized by a combination of peripheral insulin resistance and impaired insulin secretory capacity of pancreatic β cell. Genetic predisposition interacts with environmental factors including diet, physical activity, and age leading to the development of diabetes.@*Objective@#To determine the proportion of overweight and obese persons with type 2 diabetes and to compare the fasting blood sugar, fasting serum insulin, insulin resistance and β-cell function in G972R carrier and non-carrier overweight and obese persons with type 2 diabetes.@*Methodology@#One hundred overweight and obese patients with T2DM were recruited from persons with diabetes attending the Diabetes Outpatient Department of Yangon General Hospital. History taking and physical examination were done and blood samples were collected. Plasma glucose level was determined by the glucose oxidase method and fasting serum insulin was measured by enzyme linked immunoassay (ELISA) kit method. Polymerase chain reaction and Restriction Fragment Length Polymorphism were done for genetic polymorphism.@*Results@#Among 100 overweight and obese subjects with T2DM, 81 patients were of homozygous (G/G) genotype, 18 patients were of heterozygous (G/A) and only one patient of homozygous (A/A) genotype. There was no statistically significant difference in the proportion of genotypes between overweight and obese subjects with T2DM.There was no significant difference in fasting blood sugar (FBS), fasting serum insulin, HOMA-IR, β-cell function, lipid parameters between IRS-1 (G972R) carriers and non-carriers. There is significant negative correlation between insulin resistance and TG level (r2=0.0529, p=0.01).@*Conclusion@#It was concluded that IRS-1 G972R polymorphism was not important in insulin resistance, β-cell function and lipid parameters in overweight and obese T2DM. There could be a number of candidate genes in the pathophysiology of diabetes mellitus, genetic sequencing of IRS-1 and other genes in the insulin signaling pathway, and finding out the alteration in their genetic patterns would provide clues for the association of the site-specific polymorphisms of these genes with insulin resistance in T2DM.

Bitter gourd extract improves glucose homeostasis and lipid profile via enhancing insulin signaling in the liver and skeletal muscles of diabetic rats

Objective: To investigate the modulatory effects of bitter gourd extract on the insulin signaling pathway in the liver and skeletal muscle tissues of diabetic rats. Methods: The ethanolic extract of bitter gourd was prepared and its contents of total polyphenols and flavonoids were assayed. A neonatal streptozotocin-induced diabetic rat model was established and the diabetic rats were assigned into different groups and were treated with different doses of bitter gourd extract (100, 200, 400, or 600 mg/kg) or with glibenclamide (0.1 mg/kg) for 30 d. Fasting blood glucose, insulin, and lipid profile were evaluated and the insulin signaling pathway in the liver and skeletal muscle of rats was investigated. The correlations between homeostasis model assessment (HOMA) and the components of insulin signaling pathway were also evaluated. Results: Different doses of bitter gourd extract significantly ameliorated fasting blood glucose level and HOMA index for insulin resistance. Moreover, bitter gourd extract increased serum insulin and improved disrupted serum lipid profile. The levels of insulin receptor substrate-1 (IRS-1), p-insulin receptor β (p-IR-β), protein kinase C (PKC), GLUT2, and GLUT4 were improved by treatment with bitter gourd extract. The best results were obtained with 400 mg/kg dose of the extract, the effect of which was equivalent to that of glibenclamide. HOMA in the bitter gourd treated rats was negatively correlated with p-IR-β, IRS-1 and PKC in hepatic and skeletal muscle. HOMA was also negatively correlated with skeletal muscle GLUT4. Conclusions: Bitter gourd extract improves glucose homeostasis and lipid profile in diabetic rats via enhancement of insulin secretion and sensitivity. Therefore, bitter gourd can be used as a potential pharmacological agent for the treatment of type 2 diabetes mellitus.

Effects of Zuogui Jiangtang Jieyu Formulation on insulin resistance in hipppocampus of rats with diabetes-related depression / 中草药

Objective: To investigate the function of Zuogui Jiangtang Jieyu Formulation on hippocampal insulin resistance in rats with diabetes-related depression. Methods: The rat model of diabetes-related depression was established and randomly divided into four groups, including model group, positive drug group (metformin 0.18 g/kg + fluoxetine 1.8 mg/kg), high (20.53 g/kg) and low (10.26 g/kg) doses of Zuogui Jiangtang Jieyu Formulation groups. After 28 d of gavage, fasting blood glucose and peripheral insulin resistance were measured by blood glucose meter and ELISA. The depression-like behaviors of rats were tested by open field experiment and forced swimming test. The expression of p-IR and p-IRS-1 in hippocampus of rats were detected by immunofluorescence and Western blotting, while the levels of p-PI3K and p-Akt were detected by Western blotting. Results: Compared with the normal group, the blood glucose of rats in model group were significantly increased, which accompanied by obvious peripheral insulin resistance. The number of activities in open field experiment was significantly reduced in model group, and the immobility time in forced swimming experiment was significantly prolonged. In addition, it was showed that the levels of p-IR, p-IRS-1, p-PI3K and p-Akt in the brain of model rats were all significantly decreased. Compared with the model group, the blood glucose and insulin levels were significantly decreased in high-dose of Zuogui Jiangtang Jieyu Formulation group. Furthermore, the depression-like behaviors manifested in open field experiment and forced swimming experiment were improves by high dose of Zuogui Jiangtang Jieyu Formulation. More importantly, the expression of p-IR, p-IRS-1, p-PI3K and p-Akt in hippocampus was significantly increased in high dose of Zuogui Jiangtang Jieyu Formulation group compared with model group. Conclusion: Zuogui Jiangtang Jieyu Formulation can effectively regulate the insulin signaling pathway in hippocampus of rats with diabetes-related depression, and then improve the insulin resistance in the brain of model rats.

Study on Hypoglycemic Effect and Mechanism of Zicui Yin on Type Ⅱ Diabetic Rats / 中国药房

OBJECTIVE： To study the hypoglycemic effect and mechanism of Zicui yin on type Ⅱ diabetic rats， and to provide theoretic basis for clinical application. METHODS： Eighty male rats were fed with high fat/sugar diet for 4 weeks， and then given intraperitoneal injected with streptozotocin （35 mg/kg） to induce type 2 diabetic model. Other 10 rats were included in normal group. Model rats were randomly divided into metformin group （positive control， 0.2 g/kg）， model group （constant volume of distilled water）， Zicui yin high-dose， medium-dose， low-dose groups （14.0， 7.0， 3.5 g/kg）， with 10 rats in each group. After 2 weeks of continuous intragastic administration， the fasting blood glucose of rats in each group was measured by automatic blood glucose meter. The serum insulin level was determined by ELISA. mRNA expression of JNK， Akt and IRS-1 were detected by RT-PCR； The phosphorylation of JNK， Akt and IRS-1 proteins in the pancreatic tissue of rats in each group was detected by Western blot method. RESULTS： Compared with normal group， the fasting blood glucose， mRNA expression of JNK， The phosphorylation of JNK and IRS-1 proteins in the pancreatic tissue of the model group were significantly increased （P＜0.05 or P＜0.01）， while the serum insulin content， mRNA expression of Akt and IRS-1， the phosphorylation of Akt protein were significantly decreased （P＜0.01）. Compared with model group， the fasting blood glucose of rats in metformin group and Zicui yin high-dose and middle-dose groups decreased significantly （P＜0.05）， the serum insulin content of rats in both metformin group and Zicui yin high-dose group increased significantly （P＜0.01）， and mRNA expression of JNK in pancreatic tissue of rats in metformin group and Zicui yin groups decreased significantly （P＜0.01）， while mRNA expression of Akt and IRS-1 increased significantly （P＜0.01）. The phosphorylation of JNK and IRS-1 proteins in metformin group and Zicui yin high-dose group decreased significantly （P＜0.01）， while the phosphorylation of        Akt protein were increased significantly （P＜0.01）. CONCLUSIONS： Zicui yin can significantly reduce blood glucose level， the mechanism of which may be related to decreasing the phosphorylation of JNK and IRS-1 proteins and increasing the phosphorylation of Akt proteins in pancreatic islets.

Telmisartan increases hepatic glucose production via protein kinase C ζ-dependent insulin receptor substrate-1 phosphorylation in HepG2 cells and mouse liver / 영남의대학술지

BACKGROUND: Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.METHODS: Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.RESULTS: Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser302) and decreased p-IRS-1-Tyr632 dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr410 which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser302 and -inhibited p-IRS-1-Tyr632. Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser302 and decreased p-IRS-1-Tyr632, which was accompanied by an increase in p-PKCζ-Thr410.CONCLUSION: These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr410 that increases p-IRS-1-Ser302 and decreases p-IRS-1-Tyr632 in a PPARγ-independent manner.

Palmitic acid-induced lipotoxicity promotes a novel interplay between Akt-mTOR, IRS-1, and FFAR1 signaling in pancreatic ß-cells

BACKGROUND: Free fatty acid receptor 1 (FFAR1) is G-protein coupled receptor predominantly expressed in pancreatic ß-cells that is activated by a variety of free fatty acids (FFAs). Once activated, it promotes glucose-stimulated insulin secretion (GSIS). However, increased levels of FFAs lead to lipotoxicity, inducing loss of ß-cell function. FFAR1 plays a key role in the development of type 2 diabetes (T2D), and previous studies have indicated the importance of developing anti-diabetic therapies against FFAR1, although its role in the regulation of ß-cell function remains unclear. The present study investigated the role of FFAR1 under lipotoxic conditions using palmitic acid (PA). The rat insulinoma 1 clone 832/13 (INS-1 832/13) cell line was used as a model as it physiologically resembles native pancreatic ß-cells. Key players of the insulin signaling pathway, such as mTOR, Akt, IRS-1, and the insulin receptor (INSR1ß), were selected as candidates to be analyzed under lipotoxic conditions. RESULTS: We revealed that PA-induced lipotoxicity affected GSIS in INS-1 cells and negatively modulated the activity of both IRS-1 and Akt. Reduced phosphorylation of both IRS-1 S636/639 and Akt S473 was observed, in addition to decreased expression of both INSR1ß and FFAR1. Moreover, transient knockdown of FFAR1 led to a reduction in IRS-1 mRNA expression and an increase in INSR1ß; mRNA. Finally, PA affected localization of FFAR1 from the cytoplasm to the perinucleus. CONCLUSIONS: In conclusion, our study suggests a novel regulatory involvement of FFAR1 in crosstalk with mTOR-Akt and IRS-1 signaling in ß-cells under lipotoxic conditions.

The effect of noise exposure on insulin sensitivity in mice may be mediated by the JNK/IRS1 pathway

BACKGROUND@#Epidemiological studies have suggested that noise exposure may increase the risk of type 2 diabetes mellitus (T2DM), and experimental studies have demonstrated that noise exposure can induce insulin resistance in rodents. The aim of the present study was to explore noise-induced processes underlying impaired insulin sensitivity in mice.@*METHODS@#Male ICR mice were randomly divided into four groups: a control group without noise exposure and three noise groups exposed to white noise at a 95-dB sound pressure level for 4 h/day for 1, 10, or 20 days (N1D, N10D, and N20D, respectively). Systemic insulin sensitivity was evaluated at 1 day, 1 week, and 1 month post-noise exposure (1DPN, 1WPN, and 1MPN) via insulin tolerance tests (ITTs). Several insulin-related processes, including the phosphorylation of Akt, IRS1, and JNK in the animals' skeletal muscles, were examined using standard immunoblots. Biomarkers of inflammation (circulating levels of TNF-α and IL-6) and oxidative stress (SOD and CAT activities and MDA levels in skeletal muscles) were measured via chemical analyses.@*RESULTS@#The data obtained in this study showed the following: (1) The impairment of systemic insulin sensitivity was transient in the N1D group but prolonged in the N10D and N20D groups. (2) Noise exposure led to enhanced JNK phosphorylation and IRS1 serine phosphorylation as well as reduced Akt phosphorylation in skeletal muscles in response to exogenous insulin stimulation. (3) Plasma levels of TNF-α and IL-6, CAT activity, and MDA concentrations in skeletal muscles were elevated after 20 days of noise exposure.@*CONCLUSIONS@#Impaired insulin sensitivity in noise-exposed mice might be mediated by an enhancement of the JNK/IRS1 pathway. Inflammation and oxidative stress might contribute to insulin resistance after chronic noise exposure.

Pathogenesis and treatment of insulin resistance in chronic kidney disease and interventional effects of Chinese herbal medicine / 中国中药杂志

The kidney is the target organ of insulin with abundant insulin receptors. Thereinto,the renal intrinsic cells including glomerular podocytes,endothelial cells,mesangial cells,renal tubular epitheliums and collecting duct epithelial cells are all highly sensitive to insulin as the effector cells. Furthermore,the structural and functional abnormalities of these cells are closely related to insulin and its receptors activity. It is reported that the chronic kidney disease（CKD）patients have systemic or renal insulin resistance（IR）. IR is not only the pathogenic factor of CKD but also one of the mechanisms of CKD progression. The pathogenic factors of IR in the CKD patients include the systemic factors and the local factors in muscles and fat cells. The pathogenesis of IR is related to glomeruli,proximal tubules,collecting ducts and corresponding renal intrinsic cells such as podocytes,mesangial cells,renal tubular epitheliums and collecting duct epithelial cells. IR-related signaling pathways include insulin receptor substrate（IRS）/phosphatidylinositol 3 kinase（PI3K）/serine threonine kinase（Akt）pathway,adenosine monophosphate activated protein kinase（AMPK）pathway,glucose transporter4（GLUT4）pathway,nuclear factor（NF）-κB pathway and mitogen activated protein kinase（MAPK）pathway. Among them,IRS1/PI3K/Akt2 is the main signaling pathway of IR in podocytes of glomeruli, thus intervening its activity can improve podocyte injury. In clinic,some classical oral hypoglycemic agents and diuretic including metformin,rosiglitazone,glibenclamide,thiazolidinedione and spironolactone,as well as some extracts from Chinese herbal medicines including astragalus polysaccharides,quercetin,puerarin,emodin,berberine,curcumin and geniposide can both affect insulin and its receptor activity,and regulate IR-related signaling pathways,thereby ameliorating IR and CKD progression. Overall,the pharmacological studies based on IR-related signaling pathways in the renal intrinsic cells of CKD will become one of the developmental directions in the future.

Effects of Ji Tang Zhi on glucose metabolism and related protein expression in insulin resistance HepG 2 cell line / 药物评价研究

Objective To evaluate the effect of Ji Tang Zhi on glucose metabolism in insulin resistance (IR) HepG 2 cell line,and to explore the related mechanism.Methods The HepG2 cells were incubated in culture medium addition of 10-7 mol/L insulin for 24 h to establish the IR cell model.Effect of Ji Tang Zhi on rate of glucose absorption in HepG2 cell was detected by the method of glucose oxidase-peroxidase (GOD-POD).We performed an MTT assay to determine cytotoxicity effects of Ji Tang Zhi on HepG2 cell line.The expression of p-IRS-1 Ser307,PI3K and GLUT-4 were detected by Western blotting.Results Incubated with 10-7 mol/L insulin for 24 h,the insulin resistance cell model had been built.Compared with model group,the rate of glucose absorption of cell treated with JTZ (30 ～ 120 μg/mL) was significantly improved.According to model cells,the expression of GLUT-4 and PI3K decreased significantly compared to control cells.While the expression of p-IRS-1 Ser 307 was inhibited and GLUT-4 and PI3K expression were increased in IR cells after treated with JTZ (30 ～ 120 μtg/mL).Conclusion JTZ exert beneficial effects on hyperglycosemia in IR cell line possibly through regulating the levels of GLUT-4,p-IRS-1 Ser307 and PI3K in HepG2 cell.

Effect of water extract from Jiangtang Decoction on PI3K/Akt signal pathway of skeletal muscle metabolism in KK-Ay diabetic mice / 药物评价研究

Objective To explore the effects of water extract from Jiangtang Decoction (WEJTD) on PI3K/Akt signal pathway of skeletal muscle metabolism in KK-Ay diabetic mice.Methods Totally 50 KK-Ay mice were randomly divided into five groups:model group,metformin (positive drug,250 mg/kg) group,WEJTD low,medium,and high dose (2,4,and 8 g/kg) group,with 10 C57BL/6J mice as normal group.The relative drugs were ig administered once a day for 12 weeks,and mice in control group and model group were perfused with distilled water of equal volume.After 12 weeks' oral administration,mice were executed to separate serum,serum insulin level was detected by ELISA kit method;RNA was extracted from muscle tissue by Trizol,and real-time PCR were used to detect the level of PI3K,Akt,GLUT-4,GSK-3β,GS and IRS-1 mRNA.Results WEJTD can down-regulate concentration of insulin in serum and GSK-3β mRNA in skeletal muscle (P ＜ 0.05 and 0.001),and down-regulate mRNA of PI3K,Akt,IRS-1,GLUT-4,and GS in skeletal muscle (P ＜ 0.05,0.01,and 0.001).Conclusion WEJTD decreased glycogen deposition and stimulated glucose transport in skeletal muscle through upregulation of PI3K/Akt signaling pathway.

Metformin ameliorates PA-induced skeletal muscle insulin resistance by suppressing SREBP-1c / 中国药理学通报

Aim Metformin has been the first-line oral agent for the treatment of type 2 diabetes. The results from preliminary studies suggested that sterol regulatory element binding protein-1c( SREBP-1c) inhibited the transcription of insulin receptor substrate-1 ( IRS-1), which plays a key role in PA-induced skeletal muscle insulin resistance. In the current study, we investiga-ted the role and mechanism of SREBP-1c in metformin ameliorating PA-induced skeletal muscle insulin resist-ance. Methods L6 cells were treated with metformin (1,10 mmol·L - 1 ) for 24h in 500 μmol·L - 1 PA-in-duced insulin-resistant state and then harvested for pro-tein and glucose uptake assay. Glucose uptake was performed by 2-NBDG method. The protein expression of SREBP-1c, FAS, p-IRS-1 ( Tyr608 / 612), IRS-1, p-AKT ( Ser473 ) and AKT was detected by western blot. The effects of metformin on SREBP-1c and IRS-1 gene transcription were assessed by a dual-luciferase reporter assay. CHIP assay was performed to examine the binding of SREBP-1c protein to the IRS-1 promoter region by metformin treatment. Results PA treatment decreased glucose uptake in L6 myotubes. The protein expression of SREBP-1c and its downstream molecule FAS was increased significantly after exposure to PA. By contrast, the proteins related to insulin signaling pathway including IRS-1, p-IRS-1( Tyr608 / 612) and p-AKT ( Ser473) / AKT were decreased significantly. Metformin increased glucose uptake in a dose-depend-ent manner compared to PA-cultured L6 cells. The SREBP-1c and FAS protein levels were decreased by metformin treatment. Correspondingly, p-IRS-1 (Tyr608 / 612), IRS-1, p-AKT(Ser473) / AKT protein levels were increased significantly. The results from dual-luciferase reporter assay indicated metformin sup-pressed SREBP-1c promoter activity and enhanced IRS-1 promoter. The results from CHIP assay showed that metformin decreased binding of SREBP-1c protein to the IRS-1 promoter region (about 30% ). Conclu-sion Metformin can improve PA-induced muscular in-sulin resistance by suppressing SREBP-1c.

Polimorfismo GLY972ARG del Gen sustrato de receptor de insulina 1 en pre-púberes con riesgo cardiometabólico / GLY972ARG plymorphism in the insulin receptor substrate 1 Gene in prepubertal children with cardiometabolic risk

Introducción: El sustrato del receptor de insulina 1 (IRS1) es un componente importante de la cascada de transducción de señales de la insulina y podría estar relacionado con los trastornos metabólicos asociados al síndrome metabólico. Objetivo: Evaluar el papel del polimorfismo Gly972Arg del gen IRS1 con factores de riesgo cardiometabólicos en niños pre-púberes. Metodología: Se estudiaron 279 niños con edades comprendidas entre 2-12 años, clasificados según los parámetros antropométricos y bioquímicos en: a) niños obesos sin RI (n=135), b) niños obesos con RI (n=80) y c) niños controles sanos (n=64). A cada niño se le realizó una extracción de sangre en ayunas y una postprandial, para determinar glicemia e insulina basal y postprandial, triglicéridos, colesterol total y fraccionado y la frecuencia genotípica del SNP Gly972Arg. Resultados: Se observó que 37,5% de los niños presentó RI; 9,6% hiperglicemia en ayunas; 27,3% hipertrigliceridemia y 50,46% bajos niveles de HDL-c. La frecuencia genotípica fue 89% genotipo Gly/Gly y 11% genotipo Gly/Arg. Se encontró diferencia significativa en la distribución de los diferentes genotipos del gen de IRS1 en los niños con sobrepeso/obesidad sin RI y niños con sobrepeso/obesidad con RI con respecto al grupo control (OR= 4,47; IC 95%=0,96-16,92; p < 0,05) y (OR= 4,43; IC 95%=0,93-21,00; p < 0,05) respectivamente. Conclusión: Se observó una asociación entre la presencia del genotipo Gly/Arg del gen IRS1 con sobrepeso/obesidad (factor de riesgo cardiometabólico) en los niños del estudio, presentando estos niños 4 veces más riesgos a presentar sobrepeso/obesidad que los niños con el genotipo Gly/Gly.

Introduction: Insulin receptor substrate 1 (IRS-1) is an important component of the insulin signal transduction cascade and could be related with metabolic disorders associated with metabolic syndrome (MS). Aim: Evaluate the role of the Gly972Arg polymorphism in the IRS1 gene in prepubertal children with cardiometabolic risk factors. Methods: We studied 279 children between 2-12 years of age, divided in groups 3 groups: a) obese children without insulin resistance (IR) (n=135), b) obese children with IR (n=80) and c) healthy children as controls (n=64). Basal and postprandial glucose, insulin, triglycerides, total and fractionated cholesterol and genotype frequency of the Gly972Arg SNP were determined in fasting and postprandial samples in each child. Results: 37.5% of the children had IR; in the fasting state, 9.6% had hyperglycemia, 27.3% hypertriglyceridemia and 50.46 % low HDL-C. The genotypic frequency was 89% for the Gly / Gly genotype and 11% Gly / Arg genotype. Significant difference was found in the distribution of the different genotypes of the IRS1 gene in children with overweight/obesity without IR and children with overweight/obesity with IR compared to the control group (OR = 4.47;CI 95% = 0.96-16.92; p <0.05) and (OR = 4.43; CI 95%= 0.93 - 21.00, p <0.05) respectively. Conclusion: Association between the presence of Gly/Arg genotype of the IRS1 gene with overweight/obesity (cardiometabolic risk factor) was observed in the studied children. These children were four times more likely to be overweight/obese than children with Gly / Gly genotype.

Expressions and clinical significances of IGF-1R and IRS-1 in squamous cell lung cancer / 实用肿瘤学杂志

Objective The aim of the study is to detect the expression of IGF -1R and IRS-1 in squa-mous cell lung cancer ( SQCLC) and to explore the role in the development of squamous cell lung cancer and clini -cal significance .Methods Specimens from 246 surgical SQCLC and 40 adjacent normal lung tissues were evalu-ated for IGF-1R and IRS-1 expression by immunohistochemistry .We explored the correlation between IGF -1R and IRS-1,their relationship with clinicopathological parameters and their impact on outcome in SQCLC pa -tients.Results SQCLC of IGF -1R positive expression rate was 54.07%,which was higher than in adjacent normal tissue(32.5%),SQCLC of IRS-1 positive expression rate was 38.21%,which was lower than in adja-cent normal tissue(70%),the pairwise difference was statistically significant (P<0.05);Expression of IGF-1R was correlated with lymph node metastasis (P<0.05),IRS-1 expression was related with degree of differentia-tion and lymph node metastasis (P<0.05).Survival of IGF -1R expression group of patients was significantly shorter than the expression of IGF -1R negative patients ,the survival of the IRS-1 expression was significantly longer than patients who negatively expressed IRS -1,the difference was statistically significant (P=<0.001 and=0.021).IGF-1R was negatively correlated with IRS -1 expression in SQCLC(r=-0.125,P<0.001). Conclusion IGF-1R,IRS-1 are involved in the occurrence of SQCLC ,the development .The IGF-1R is an independent prognostic factor in SQCLC .

Rosiglitazone attenuates cognitive function via altering hippocampal IRS-1/Akt signaling pathways in ob/ob mouse / 中国药理学通报

Aim To identify alteration in key molecular components related to memory formation and insulin signaling in the hippocampus after rosiglitazone was in-jected into the ob/ob mice to test whether cognitive dysfunction was pharmacologically reversed by regula-tion of rosiglitazone. Methods The age-matched mice were divided into three groups ( n=18 ): Saline-trea-ted WT mice ( WT-Saline);Saline-treated ob/ob mice ( ob/ob-Saline) and RSG-treated ob/ob mice ( ob/ob-RSG) through intraperitoneal injection of rosiglitazone ( RSG) . The random glucose levels were measured for 10 days during the intraperitoneal injection period. No-vel object recognition was performed before mice were sacrificed. Western blot was implemented to evaluate the following proteins: BACE1, p-Tau, p-IRS1,IRS1, p-Akt and Akt in hippocampal tissues. The Aβ1-40 levels were detected by ELISA Kit. Results The random blood glucose levels were significantly re-duced in ob/ob-RSG compared with ob/ob-saline. RSG treatment led to an increase in hippocampus-de-pendent cognition of ob/ob mice according to the novel object recognition. The proteins levels of BACE1, p-Tau and Aβ were lowered in RSG-treated ob/ob mice. Furthermore, RSG treatment up-regulated hippocampal p-IRS1/IRS1 and p-Akt/Akt ratio. Conclusion Ros-iglitazone ameliorates cognitive deficits in ob/ob mice through up-regulating insulin signaling pathways in the hippocampus.

Generating insulin receptor substrate 1 (Irs1) knockout rat using CRISPR/Cas9 / 中国比较医学杂志

Objective To study the relationship of insulin receptor substrate-1 (Irs1) and metabolic disease, we generated Irs1 gene knockout rat by CRISPR/Cas9 system.Methods Two sgRNA targeting sites were designed for Irs1 targeting.The Cas9 and sgRNAs were transcribed by T7 RNA polymerase in vitro.Cas9 mRNA and sgRNA mixtures were pooled and microinjected into one-cell fertilized eggs of SD rats to generate rats with targeted mutation .Results Five rats with the mutations were detected with the efficiency of 83%.Conclusion The Irs1 gene knockout rats generated in this study can be transmitted by germline .

Variantes polimórficas Ala513Pro y Gly972Arg del gen IRS-1 no se asocian a la diabetes mellitus tipo 2 en un grupo de la población cubana / The Ala513Pro and Gly972ARg polymorphous variants of IRS-1 gen are not associated with type diabetes mellitus in a group of the Cuban population

Introducción: la diabetes mellitus tipo 2 es una enfermedad heterogénea y multifactorial, que está determinada por factores genéticos y no genéticos. El sustrato 1 del receptor de la insulina (IRS-1) cumple una función fundamental en la transmisión de la señal insulínica, por tanto sus variantes génicas constituyen blancos importantes en el estudio de la susceptibilidad genética a esta enfermedad en las diferentes poblaciones. Objetivo: explorar el papel de las variantes polimórficas Gly972Arg y Ala513Pro del gen IRS-1 en la susceptibilidad genética de la diabetes mellitus tipo 2 en un grupo de la población cubana.Métodos: se determinó la frecuencia de los polimorfismos Gly972Arg y Ala513Pro del IRS-1 en 499 ciudadanos cubanos, con un índice de masa corporal entre 22-30, con edades comprendidas entre los 40 y 70 años: de ellos 272 (54,5 por ciento) diabéticos y 227 (45,5 por ciento) no diabéticos.Resultados: la frecuencia del alelo Pro513 fue baja (1,2 por ciento) y similar para ambos grupos (1,1 por ciento vs. 1,3 por ciento para el grupo de diabéticos y el grupo control, respectivamente). La frecuencia del polimorfismo Gly972Arg fue de 16,2 por ciento, superior a la reportada para la mayoría de las poblaciones estudiadas. No se encontraron diferencias significativas en la frecuencia del alelo Arg972 entre el grupo de diabéticos y el grupo control (15,4 por ciento vs. 17,3 por ciento), ni cambios en los niveles de glucemia e insulinemia asociados a la presencia del alelo polimórfico Arg972.Conclusiones: en este grupo de sujetos de la población cubana, las variantes polimórficas Ala513Pro y Gly972Arg del gen IRS-1 no participan en la etiología de la diabetes mellitus tipo 2(AU)

Introduction: the type 2 diabetes mellitus is a heterogeneous and multifactor disease determined by genetic and no-genetic factors. The substrate 1 of insulin receptor (IRS-1) has a fundamental function in transmission of insulin signal, thus its genic variants are significant targets in study of genetic susceptibility to this disease in different populations. Objective: to explore the role of the Gly972Arg and Ala513PRo of IRS-1 gen polymorphous variants in the genetic susceptibility of type 2 diabetes mellitus in Cuban population. Methods: the frequency of above mentioned polymorphous variants in 499 Cuban citizens with a 22-30 body mass index aged between 40 to 70 including 272 diabetics (54,5 por ciento) and 227 non-diabetic (45,5 por ciento). Results: frequency of Pro513 allele was low (1,2 por ciento) and similar en both groups (1,1 por ciento versus 1,3 por ciento for diabetic group and the control one, respectively). Frequency of Gly972Arg polymorphism was of 16,2 por ciento, higher than that reported for most of study populations. There were not significant differences in frequency of Arg972 allele between the diabetic group and the control one (15,4 por ciento versus 17,3 por ciento). Also, there were not changes in glycemia and insulinemia levels associated to presence of polymorphous allele. Conclusions: in present group of Cuban population the above mentioned polymorphous variants are not involved in etiology of type 2 diabetes mellitus(AU)