scholarly journals Alternate Phosphorylation/O-GlcNAc Modification on Human Insulin IRSs: A Road towards Impaired Insulin Signaling in Alzheimer and Diabetes

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Zainab Jahangir ◽  
Waqar Ahmad ◽  
Khadija Shabbiri
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Posttranslational Modifications ◽  
Insulin Signaling ◽  
Insulin Receptors ◽  
Prediction Methods ◽  
Insulin Receptor Substrates ◽  
Impaired Insulin

Impaired insulin signaling has been thought of as important step in both Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM). Posttranslational modifications (PTMs) regulate functions and interaction of insulin with insulin receptors substrates (IRSs) and activate insulin signaling downstream pathways via autophosphorylation on several tyrosine (TYR) residues on IRSs. Two important insulin receptor substrates 1 and 2 are widely expressed in human, and alternative phosphorylation on their serine (Ser) and threonine (Thr) residues has been known to block the Tyr phosphorylation of IRSs, thus inhibiting insulin signaling and promoting insulin resistance. Like phosphorylation, O-glycosylation modification is important PTM and inhibits phosphorylation on same or neighboring Ser/Thr residues, often called Yin Yang sites. Both IRS-1 and IRS-2 have been shown to be O-glycosylated; however exact sites are not determined yet. In this study, by using neuronal network based prediction methods, we found more than 50 Ser/Thr residues that have potential to be O-glycosylated and may act as possible sites as well. Moreover, alternative phosphorylation and O-glycosylation on IRS-1 Ser-312, 984, 1037, and 1101 may act as possible therapeutic targets to minimize the risk of AD and T2DM.

scholarly journals Insulin Resistance and Diabetes Mellitus in Alzheimer’s Disease

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1236
Author(s):  
Jesús Burillo ◽  
Patricia Marqués ◽  
Beatriz Jiménez ◽  
Carlos González-Blanco ◽  
Manuel Benito ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Alzheimer’S Disease ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Alzheimer's Disease ◽  
Type 2 Diabetes Mellitus ◽  
Insulin Signaling ◽  
Molecular Mechanisms ◽  
Progressive Disease

Type 2 diabetes mellitus is a progressive disease that is characterized by the appearance of insulin resistance. The term insulin resistance is very wide and could affect different proteins involved in insulin signaling, as well as other mechanisms. In this review, we have analyzed the main molecular mechanisms that could be involved in the connection between type 2 diabetes and neurodegeneration, in general, and more specifically with the appearance of Alzheimer’s disease. We have studied, in more detail, the different processes involved, such as inflammation, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction.

scholarly journals IRS posttranslational modifications in regulating insulin signaling

2018 ◽  
Vol 60 (1) ◽  
pp. R1-R8 ◽  
Author(s):  
Jinghua Peng ◽  
Ling He
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Posttranslational Modifications ◽  
Insulin Signaling ◽  
Critical Role ◽  
Transferase Activity ◽  
Obese Mice ◽  
Promising Therapeutic Target ◽  
Treatment Of Diabetes

Insulin resistance is the hallmark of type 2 diabetes; however, the mechanism underlying the development of insulin resistance is still not completely understood. Previous reports showed that posttranslational modifications of IRS play a critical role in insulin signaling, especially the phosphorylation of IRS by distinct kinases. While it is known that increasing Sirtuin1 deacetylase activity improves insulin sensitivity in the liver, the identity of its counterpart, an acetyl-transferase, remains unknown. Our recent study shows that elevated endotoxin (LPS) levels in the liver of obese mice lead to the induction of the acetyl-transferase P300 through the IRE1-XBP1s pathway. Subsequently, induced P300 impairs insulin signaling by acetylating IRS1 and IRS2 in the insulin signaling pathway. Therefore, the P300 acetyl-transferase activity appears to be a promising therapeutic target for the treatment of diabetes.

scholarly journals Intervention of Gastrodin in Type 2 Diabetes Mellitus and Its Mechanism

2021 ◽  
Vol 12 ◽  
Author(s):  
Yu Bai ◽  
Ke Mo ◽  
Guirong Wang ◽  
Wanling Chen ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Insulin Receptors ◽  
Control Group ◽  
Sensitivity Index

As a severe metabolic disease, type 2 diabetes mellitus (T2DM) has become a serious threat to human health in recent years. Gastrodin, as a primary chemical constituent in Gastrodia elata Blume, has antidiabetic effects. However, the possible mechanisms are unclear. The aim of the present study was to investigate the effects and possible mechanisms of gastrodin on the treatment of T2DM. In vivo, after treatment with gastrodin for 6 weeks, fasting blood glucose levels, blood lipid metabolism, and insulin sensitivity index values were remarkably reduced compared with those of the diabetic control group. The values of aspartate aminotransferase and alanine aminotransferase also showed that gastrodin alleviates liver toxicity caused by diabetes. Moreover, gastrodin relieved pathological damage to the pancreas in T2DM rats. In vitro, gastrodin alleviated insulin resistance by increasing glucose consumption, glucose uptake, and glycogen content in dexamethasone-induced HepG2 cells. The Western blotting results showed that gastrodin upregulated the expression of insulin receptors and ubiquitin-specific protease 4 (USP4) and increased the phosphorylation of GATA binding protein 1 (GATA1) and protein kinase B (AKT) in vivo and in vitro. Furthermore, gastrodin decreased the ubiquitin level of the insulin receptor via UPS4 and increased the binding of GATA1 to the USP4 promoter. Additionally, administration of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway inhibitors MK-2206 and LY294002 abolished the beneficial effects of gastrodin. Our results indicate that gastrodin promotes the phosphorylation of GATA1 via the PI3K/AKT pathway, enhances the transcriptional activity of GATA1, and then increases the expression level of USP4, thereby reducing the ubiquitination and degradation of insulin receptors and ultimately improving insulin resistance. Our study provides scientific evidence for the beneficial actions and underlying mechanism of gastrodin in the treatment of T2DM.

scholarly journals N1-Methylnicotinamide Improves Hepatic Insulin Sensitivity via Activation of SIRT1 and Inhibition of FOXO1 Acetylation

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jingfan Zhang ◽  
Yu Chen ◽  
Cong Liu ◽  
Ling Li ◽  
Ping Li
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Blood Glucose ◽  
Insulin Sensitivity ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Related Proteins

Objective. To explore the effects of N1-methylnicotinamide (MNAM) on insulin resistance and glucose metabolism in obese type 2 diabetes mellitus (T2DM) mice and regulatory mechanisms of the NAD-dependent deacetylase sirtuin-1 (SIRT1)/forkhead box protein O1 (FOXO1) pathway. Methods. Blood glucose and insulin levels were examined in mice. HE and oil red O staining were used to observe the effects of MNAM on liver lipid deposition in ob/ob mice. Real-time PCR and Western blotting were used to detect expression of gluconeogenesis, insulin signaling-related proteins, and SIRT1/FOXO1 pathway-related proteins. L-O2 cells were cultured as a model of insulin resistance, and MNAM and SIRT1 inhibitors were administered in vivo. Residual glucose and insulin signaling-related proteins were detected and the mechanisms associated with the SIRT1/FOXO1 signaling pathway in insulin resistance explored. Results. MNAM can effectively reduce levels of fasting blood glucose and insulin, improve liver morphology, and reduce lipid accumulation in obese type 2 diabetes mellitus mice. MNAM also downregulates the key proteins in the gluconeogenesis pathway in the liver, upregulates Sirt1 expression, and reduces acetylation of the FOXO1 protein. In vitro, MNAM could promote the glucose uptake capacity of L-O2 cells induced by palmitic acid (PA), a saturated fatty acid that induces IR in various scenarios, including hepatocytes, improving insulin resistance. As Sirt1 expression was inhibited, the reduction of hepatocyte gluconeogenesis and the regulation of the insulin signaling pathway by MNAM were reversed. Conclusion. MNAM activates SIRT1 and inhibits acetylation of FOXO1, which in turn regulates insulin sensitivity in type 2 diabetic mice, leading to a reduction of hepatic glucose output and improvement of insulin resistance.

Mouse models of insulin resistance

2002 ◽  
Vol 282 (5) ◽  
pp. E977-E981 ◽  
Author(s):  
Marta Letizia Hribal ◽  
Francesco Oriente ◽  
Domenico Accili
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Insulin Signaling ◽  
Insulin Action ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Impaired Insulin

The hallmarks of type 2 diabetes are impaired insulin action in peripheral tissues and decreased pancreatic β-cell function. Classically, the two defects have been viewed as separate entities, with insulin resistance arising primarily from impaired insulin-dependent glucose uptake in skeletal muscle, and β-cell dysfunction arising from impaired coupling of glucose sensing to insulin secretion. Targeted mutagenesis and transgenesis involving components of the insulin action pathway have changed our understanding of these phenomena. It appears that the role of insulin signaling in the pathogenesis of type 2 diabetes has been overestimated in classic insulin target tissues, such as skeletal muscle, whereas it has been overlooked in liver, pancreatic β-cells, and brain, which had been thought not to be primary insulin targets. We review recent progress and try to reconcile areas of apparent controversy surrounding insulin signaling in skeletal muscle and pancreatic β-cells.

scholarly journals Vildagliptin: optimal control in type 2 diabetes mellitus treatment

2015 ◽  
Vol 18 (4) ◽  
pp. 125-129
Author(s):  
Alexander Sergeevich Ametov
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Clinical Evidence ◽  
Β Cells ◽  
Postprandial Triglyceride ◽  
Impaired Insulin ◽  
Diabetes Mellitus Treatment

Incretin hormones are important for normal pancreatic islet function and glucose homeostasis. Sensitivity to glucose of the α- and β-cells of the pancreas is diminished in type 2 diabetes mellitus (T2DM), leading to impaired insulin secretion, insulin resistance due to elevated glucagon levels in hyperglycaemia and impaired glucagon counterregulation in hypoglycaemia. In addition, T2DM is associated with increased lipotoxicity-induced insulin resistance. This article is a comprehensive review of the safety and efficacy of vildagliptin in patients with T2DM and evaluates the extra-pancreatic effects of incretin-based therapies. Clinical evidence has proven that vildagliptin effectively decreases HbA1c with a low risk of hypoglycaemia and is weight neutral. Vildagliptin also suppresses postprandial triglyceride (TG)-rich lipoprotein levels after ingestion of fat-rich meals and reduces fasting lipolysis, suggesting inhibition of fat absorption and reduced TG stores in non-fat tissues.

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