Genetic association of insulin receptor substrate-1 (IRS-1, rs1801278) gene with insulin resistant of type 2 diabetes mellitus in a Pakistani population

Exploring the role of genetic variations in NAFLD: implications for disease pathogenesis and precision medicine approaches

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver diseases, affecting more than one-quarter of people worldwide. Hepatic steatosis can progress to more severe forms of NAFLD, including NASH and cirrhosis. It also may develop secondary diseases such as diabetes and cardiovascular disease. Genetic and environmental factors regulate NAFLD incidence and progression, making it a complex disease. The contribution of various environmental risk factors, such as type 2 diabetes, obesity, hyperlipidemia, diet, and sedentary lifestyle, to the exacerbation of liver injury is highly understood. Nevertheless, the underlying mechanisms of genetic variations in the NAFLD occurrence or its deterioration still need to be clarified. Hence, understanding the genetic susceptibility to NAFLD is essential for controlling the course of the disease. The current review discusses genetics' role in the pathological pathways of NAFLD, including lipid and glucose metabolism, insulin resistance, cellular stresses, and immune responses. Additionally, it explains the role of the genetic components in the induction and progression of NAFLD in lean individuals. Finally, it highlights the utility of genetic knowledge in precision medicine for the early diagnosis and treatment of NAFLD patients.

INSR and ISR‑1 gene polymorphisms and the susceptibility of essential hypertension: A meta‑analysis

INSR and ISR-1 may be candidate genes for essential hypertension (EH). However, the genetic association between the INSR and ISR-1 gene polymorphisms and EH risk remains contradictory. To determine a more precise association of the INSR and ISR-1 gene polymorphisms and EH, the present study performed a meta-analysis. Eligible studies up to Jan 2021 were retrieved from multiple databases including PubMed, Embase, Web of Science and China National Knowledge Infrastructure. The pooled odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the genetic associations between the allele, dominant and recessive models of INSR Nsil, RsaI and ISR-1 G972R polymorphisms and EH susceptibility. A total of 10 case-control studies encompassing 2,782 subjects including 1,289 cases and 1,493 controls were evaluated for the present meta-analysis. Neither of the allele, dominant and recessive models of INSR Nsil and ISR-1 G972R polymorphisms was associated with EH risk (P>0.05). While the allele [P=0.0008, OR=0.58, (95% CI)=(0.42, 0.80)], dominant [P=0.02, OR=0.59, (95% CI)=(0.38, 0.92)] and recessive models [P=0.003, OR=0.38, (95% CI)=(0.20, 0.72)] of INSR Rsal polymorphism were associated with decreased risk of EH. Subgroup analysis according to ethnicity showed that the significant associations between the allele, dominant and recessive models of INSR Rsal polymorphism and EH risk were observed in Caucasian populations, but not in Asian populations (P>0.05). In conclusion, the INSR Rsal polymorphism is probably a protective factor for EH. To identify the result, additional case-control designed research with larger numbers of subjects are required.

Association of IRS-1 and IRS-2 polymorphisms with predisposition to type-2 diabetes (T2D): a meta-analysis and trial sequential analysis

Background: Insulin Receptor Substrate (IRS) molecules play a major role in insulin signalling, and single nucleotide polymorphisms in the IRS-1 (rs1801278) and IRS-2 (rs1805097) gene has been associated with the predisposition to the development of type-2 diabetes (T2D) in some population. However, the observations remain contradictory. Discrepancies in the results have been attributed to several factors, and consideration of a smaller sample size is one of them. To reach a valid conclusion, we performed a meta-analysis of the genetic association between IRS-1 (rs1801278) and IRS-2 (rs1805097) polymorphism with a predisposition to T2D. Materials and Methods: The literature search was performed in different databases such as PubMed, Science Direct, and Scopus. All relevant articles were screened and based in inclusion and exclusion criteria eligible reports were identified. Baseline characteristics, genotype and allele frequencies were extracted from the eligible reports. The meta-analysis was performed by comprehensive meta-analysis software v3.3.070 and odds ratios, 95% confidence interval and probability values were calculated to find out association of IRS-1 and IRS-2 polymorphisms with rhinitis. Results: A total of seven studies comprising 1287 cases and 1638 control were considered for the present meta-analysis for the association of IRS-1 (rs1801278) polymorphism with T2D, and no significant association was observed. For IRS-2 (rs1805097) polymorphism, data from eight cohorts (cases: 1824, controls: 1786) were considered. The heterozygous genetic comparison models revealed a significant protective association against T2D predisposition (p = 0.017, OR = 0.841, 95% CI = 0.729 to 0.970). The trial sequential analysis revealed the requirement of additional case-control studies to draw a definitive conclusion for IRS-1 polymorphism. Conclusions: IRS-2 rs1805097 heterozygotes are protected from T2D development. However, IRS-1 (rs1801278) is not associated with a subject's proclivity for T2D.

Insulin receptor substrate-1 gene polymorphism and lipid panel data in type 2 diabetic patients with comorbid obesity and/or essential hypertension

Objective. The hallmarks of type 2 diabetes mellitus (T2DM) are insulin resistance (IR) and insulin receptor substrate (IRS) proteins essential for the insulin signaling. IRS-1 gene has not only been shown to be associated with T2DM, but also has indicated that it may significantly correlate with diabetic complications, such as coronary heart disease and obesity. The aim of this study was to evaluate changes of the lipid panel data in T2DM patients with comorbid obesity and/or essential hypertension in connection with the IRS-1 (rs2943640) polymorphism. Methods. The study involved 33 T2DM patients and 10 healthy individuals. The IRS-1 (rs2943640) polymorphism was genotyped using a TaqMan real-time polymerase chain reaction method. Blood serum lipid panel data were determined with commercially available kits using a Cobas 6000 analyzer. Results. Analysis of the serum lipid panel data depending on the presence of the C/A alleles of IRS-1 (rs2943640) polymorphism in T2DM patients, regardless of the presence/absence of comorbidities, showed significantly lower level of high-density lipoprotein cholesterol (HDL-C) and significantly higher level of non-HDL-C in the carriers of C allele vs. carriers of A allele. In T2DM patients with comorbid obesity and essential hypertension, proatherogenic lipid changes were found in both C and A alleles carriers. Analysis of the effect of IRS-1 (rs2943640) genotypes on serum lipid panel data in T2DM patients, regardless of the presence/absence of comorbidities, showed that the CC genotype carriers had more pronounced pro-atherogenic changes vs. carriers of СА and АА genotypes. In the comorbid course of T2DM (both in combination with obesity and obesity and essential hypertension), pro-atherogenic changes were found in the carriers of the CA genotype of IRS-1 (rs2943640) polymorphism. Conclusions. The presence of the C allele of IRS-1 (rs2943640) polymorphism in both homo-zygous and heterozygous states indicates increased risk of pro-atherogenic changes in T2DM patients with comorbid obesity and/or essential hypertension.

Association of Insulin Receptor Substrate-1 Gene Polymorphism (rs1801278) with Alzheimer’s Disease

Background: Alzheimer’s disease (AD) is the most common form of dementia. AD is also the leading cause of morbidity and mortality due to dementia worldwide. It has been shown that AD is associated with type 2 diabetes mellitus (T2DM) and brain insulin resistance. Rs1801278 is a polymorphism in insulin receptor substrate-1 (IRS-1) gene which changes the amino acid Arg972. This polymorphism has been found to be associated with susceptibility to AD in some populations. Objective: In the present study, our aim was to investigate the association of Arg972 IRS-1 (rs1801278) gene polymorphism and late-onset Alzheimer’s disease (LOAD) in an Iranian population. Methods: In this case-control study, 150 patients with LOAD and 150 unrelated healthy controls were recruited. Polymerase chain reaction (PCR) was performed to amplify a DNA segment of 263 base-pair (bp) length containing the single nucleotide polymorphism (SNP). The PCR product was then incubated with MvaI restriction enzyme to undergo enzymatic cleavage. Electrophoresis was thereafter carried out using agarose gel and DNA safe stain. The gel was ultimately visualized under a UV trans-illuminator. Allelic and genotypic frequencies were then compared. Results: A allele (mutant) of the gene was significantly associated with the risk of AD after adjustment for sex and age (p = 0.04, adjusted OR:1.77, 95% CI:1.00–3.11). Only AA genotype (mutant homozygote) was significantly associated with the risk of AD after adjustment for sex and age (p = 0.01, adjusted OR:2.39, 95% CI:1.22–4.66). Conclusion: SNP rs1801278 is significantly associated with the risk of developing AD in the studied Iranian population.

Current Studies on Molecular Mechanisms of Insulin Resistance

Diabetes is a metabolic disease that raises the risk of microvascular and neurological disorders. Insensitivity to insulin is a characteristic of type II diabetes, which accounts for 85-90 percent of all diabetic patients. The fundamental molecular factor of insulin resistance may be impaired cell signal transduction mediated by the insulin receptor (IR). Several cell-signaling proteins, including IR, insulin receptor substrate (IRS), and phosphatidylinositol 3-kinase (PI3K), have been recognized as being important in the impaired insulin signaling pathway since they are associated with a large number of proteins that are strictly regulated and interact with other signaling pathways. Many studies have found a correlation between IR alternative splicing, IRS gene polymorphism, the complicated regulatory function of IRS serine/threonine phosphorylation, and the negative regulatory role of p85 in insulin resistance and diabetes mellitus. This review brings up-to-date knowledge of the roles of signaling proteins in insulin resistance in order to aid in the discovery of prospective targets for insulin resistance treatment.

ASSOCIATION OF IRS1 GLY971ARG GENE POLYMORPHISM WITH INSULIN RESISTANCE IN IRANIAN NEWLY DIAGNOSED DIABETIC ADULTS

Context

Insulin receptor substrate-1 (IRS-1) has an important role in insulin signaling and the common Gly971Arg polymorphism is related to type 2 diabetes (T2D). IRS-1 Gly971Arg polymorphism can modify tyrosine phosphorylation at a specific site of IRS-1 and may have a critical role in the development of insulin resistance (IR).

Objective

The purpose of this study was to investigate the association between this polymorphism and IR in Iranian patients with newly-diagnosed type 2 diabetes.

Design

The study was conducted on 114 individuals with newly-diagnosed T2D and 118 healthy matched controls, aged 20-80 years. Fasting blood glucose and insulin were measured by the enzymatic method and enzyme-linked immunosorbent assay, respectively. Insulin-resistance was calculated by homeostasis model assessment estimated-insulin resistance (HOMA-IR). The gene polymorphism was examined by polymerase chain reaction-restriction fragment length polymorphism.

Results

There are significant differences between IRS1 Gly971Arg polymorphism and studied individuals (P<0.0001). The findings showed that the risk of developing T2D in individuals who had R-alleles was 3.74 folds higher than those without R-alleles. However, IRS1 Gly971Arg polymorphism was not associated with high HOMA-IR, high BMI and familial history of diabetes.

Conclusions

Even though there was not a significant relationship between IRS-1 G971R polymorphism with insulin resistance and high BMI, this polymorphism was correlated to newly-diagnosed diabetic patients. Thus, the evaluation of IRS-1 G971R polymorphism may be helpful for predicting T2D new cases.