Evidence of selection at insulin receptor substrate-1 gene loci

The aim of this study was to investigate the possible effect of the insulin receptor substrate 1 (IRS1) gene (rs1801276) polymorphism on type-2diabetes mellitus risk in Bangladeshi patients. Type-2 diabetes mellitus (T2DM) is a chronic metabolic condition defined by persistent hyperglycemia that is predominantly caused by hereditary and environmental factors. The IRS1 (rs1801276) polymorphism has been linked to changes in the transmission of insulin and glucose metabolism which contribute to the development of type-2 diabetes. A cross-sectional study was carried out on 200 type-2 diabetes patients and 200 healthy controls. Genomic DNA was taken from blood samples, and the rs1801276 polymorphism was detected using PCR-RFLP. Statistical analysis was conducted to determine the relationship between the IRS1 polymorphism and the prevalence of T2DM. To determine how the IRS1 gene has an impact on type-2 diabetes we studied 200 case patients and 200 control individuals. Our investigation indicates that the IRS1 gene polymorphism has no significant effect on the CG genotype [OR = 3.6283, 95% Cl = (0.7443 to 17.6860, P=0.1108], GG genotype [OR = 1.0366, 95% Cl =(0.0205 to 52.5059, P=0.9857] and the CG+GG genotype [OR = 3.6283, 95% Cl = (0.7443 to 17.6860, P=0.1108] compared with wild type CC genotype. The IRS1 (rs1801276) polymorphism is not significantly linked to Type-2 diabetes mellitus in Bangladeshi people. This finding emphasizes its potential for further studies with larger population to identify this polymorphism as a genetic marker for the diagnosis and treatment of T2DM patients in Bangladesh.

Insulin resistance in the brain is a pathological mechanism that is shared between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM). Although aberrant expression and phosphorylation of insulin receptor substrate 1 (IRS-1) contribute to insulin resistance, the underlying mechanism remains elusive. In this study, we used several approaches, including adeno-associated virus-based protein overexpression, immunoblotting, immunoprecipitation, immunohistochemistry, and in situ proximal ligation assays, to investigate the function of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) in IRS-1 regulation and the downstream insulin signaling in neurons. We found that DYRK1A overexpression up-regulated IRS-1 expression by slowing turnover of the IRS-1 protein. We further observed that DYRK1A directly interacted with IRS-1 and phosphorylated IRS-1's multiple serine residues. Of note, DYRK1A and IRS-1 were coordinately up-regulated in the prefrontal cortex of db/db mice brain. Furthermore, DYRK1A overexpression ameliorated chronic high insulin-induced insulin resistance in SH-SY5Y cells as well as in primary rat neurons. These findings suggest that DYRK1A protects against insulin resistance in the brain by elevating IRS-1 expression.

Type 2 diabetes mellitus (T2DM) is highly heritable and exhibits significant variability in prevalence between different populations. Prevalence of T2DM is higher in Asian and African relative to European populations. During evolution, traditional feast-famine cycles likely led to significant natural selection impacting metabolic genes. Human adaptation to environmental changes (food supply, lifestyle, climate, and geography) likely influenced differential selection of T2DM-associated genes. Together, insulin receptor substrate-1 and -2 (IRS1 and IRS2) genes encode the major ligands of insulin and IGF1 receptors. Irs2-deficient mice exhibit a T2DM phenotype with severe insulin resistance, and a common IRS2 polymorphism is associated with T2DM. Therefore, the present study sought evidence of natural selection at IRS2 loci. Data were sourced from the HapMap and 1000 Genomes projects, comprising four different populations with distinct ancestries: European, Yoruba, Han Chinese, and Japanese. A three-step method was applied to detect IRS2 locus selection. The long-range haplotype (LRH) test detected unusual extended haplotypes, the integrated haplotype score (iHS) detected selection, and Wright's F-statistics (particularly Wright's fixation index: FST) were calculated as a measure of population differentiation. The African population exhibited highly significant LRH findings (percentile >99.9, p = 0.005-0.0009), while both the European and African populations exhibited extreme positive iHS test scores ([iHS] >2.5). These findings indicate that genetic selection has occurred at the IRS2 locus, warranting further research into the adaptive evolution of metabolic disorder-associated genes. The online version contains supplementary material available at 10.1007/s40200-021-00745-y.

Type 2 diabetes mellitus (T2DM) is a chronic degenerative disease, phenotypically and genetically heterogeneous, characterized by high levels of glucose and metabolic complications. Insulin receptor substrate 1 (IRS-1) plays a key role in the insulin-stimulated signal transduction pathway. A glycine-to-arginine substitution at codon 972 (G972R) (rs1801278) in the IRS-1 gene has been associated with impaired insulin action. Another SNP rs2943641 in the IRS-1 gene has been found to be associated with T2DM and insulin resistance in genome-wide association studies. The aim of the present study was to evaluate whether rs1801278 and rs2943641 are associated with increased risk of T2DM in the Saudi population. The study included 376 T2DM cases and 380 healthy controls. Genomic DNA was isolated using a commercially available kit supplied by Norgen Biotech Corp. Genotyping was performed by PCR and RFLP analysis. There was a significant difference in the genotypic distribution as well as allelic frequency between the T2DM cases and controls in case of both the polymorphisms for rs1801278 (1.752, 95 % CI 1.002-3.121; p = 0.04), and for rs2943641 (OR = 1.482, 95 % CI 1.176-1.867; p = 0.001). In conclusion, both the (rs1801278 and rs2943641) polymorphisms are associated with T2DM in the Saudi population.

Insulin resistance is recognised as the core factor in the pathogenesis of Type II (non-insulin-dependent) diabetes mellitus, hypertension and atherosclerosis. Several studies indicate the possible role of mutations of the insulin receptor substrate-1 (IRS-1) gene in the pathogenesis of insulin-resistance and suggest a possible interaction between the IRS-1 gene and obesity, either by an effect on the development of obesity or by causing or aggravating the obesity-associated insulin resistance. Therefore, the prevalence of the G972R mutation of the IRS-1 gene was compared in 157 non-diabetic obese subjects (BMI > 30 m/kg2) and in 157 lean subjects (BMI < 28 m/kg2). By investigating the relation between this IRS-1 mutation, measures of obesity and metabolic parameters, we explored the possible influence of this mutation on body fat distribution and insulin resistance. The G972R mutation was detected by PCR amplification and BstN-1 restriction enzyme digestion. Data were analysed by univariate and multivariate analysis. The G972R allele was significantly more frequent in obese subjects than in lean subjects (p < 0.002); however, no difference was found between centrally and peripherally obese subjects. Obese G972R carriers had significantly higher BMI (p < 0.001), fasting insulin (p < 0.001), triglycerides (p < 0.03) and HOMAIR (p < 0.001) than obese non-carriers. No differences were observed between G972R carriers and non-carriers among control subjects. Multivariate analysis confirmed that the IRS-1 G972R mutation was significantly and independently associated with reduced insulin sensitivity (p < 0.009) in the obese group. The G972R mutation of the IRS-1 gene associates with obesity, but not with fat distribution, in this Italian cohort, and within the obese subjects this IRS-1 variant strongly associates with metabolic parameters suggesting greater insulin-resistance. These findings indicate a possible interaction between the IRS-1 variant and obesity in worsening insulin sensitivity.

Double trouble: T2DM genetic risk factors play a causal role in CAD.

BackgroundInsulin receptor substrate (IRS) molecules are key mediators in insulin signaling. Several polymorphisms in the IRS genes have been identified, but only the Gly to Arg 972 substitution of IRS-1 seems to have a pathogenic role in the development of type 2 diabetes mellitus (T2DM). Many polymorphisms described in IRS-1 gene, especially Gly972Arg substitution, are shown to be associated with insulin resistance (IR) in T2DM.Subjects and methodsThis prospective case–control study was performed during the period from November 2014 to May 2015. All patients were selected from the Department of Internal Medicine and were screened for eligibility for this study. Subjects were divided into two groups: first group consisted of 100 T2DM patients; second group consisted of 120 nondiabetic controls. First group was further divided into two subgroups: 66 IR patients and 34 insulin-sensitive (IS) patients (homeostatic model assessment [HOMA] was performed). Restriction fragment length polymorphism (RFLP) was performed using specific primers for scanning single-nucleotide polymorphisms (SNPs) such as Gly972Arg (rs1801278 SNP).ResultsTaking GG genotype and G allele as references, GA, GA+AA genotypes and A allele showed significantly higher frequency in the T2DM group when compared to the control group, with higher risk to develop T2DM in healthy controls. Taking GG as a reference, rs1801278GA+AA genotype and A allele showed significantly higher proportion in IR when compared to IS, with higher risk to develop IR in T2DM patients. Logistic regression analysis showed that higher FBG, fasting plasma insulin (FPI), HOMA-IR, GA+AA genotypes were associated with higher risk to develop IR in univariable analysis.ConclusionIRS-1 genetic factor may be a significant genetic determinant for IR in T2DM patients during severe/acute-phase hyperglycemia.

Sleep apnea syndrome is associated with increased prevalence of diabetes and has recently shown to be associated with insulin resistance. The aim of the present study was to investigate the relationships between insulin resistance, insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2) gene polymorphisms and obstructive sleep apnea syndrome (OSAS). The study population consisted of 56 consecutive patients with OSAS and 26 subjects without OSAS were enrolled in the study. Genotyping of IRS-1 and IRS-2 were amplified by polymerase chain reaction (PCR). Insulin resistance was estimated using the homeostasis model assessment (HOMA). In OSAS patients, 2 (3.6%) had G972R gene polymorphism and 54 (96.4%) had no nucleotide substitution in IRS-1 gene whereas in the control group, there was no nucleotide substitution in IRS-1 gene (p>0.05). Besides, 47 OSAS patients (84.0%) had no nucleotide substitution, 3 (5.3%) had G1057D heterozygous, 1 (1.8%) had P1033P heterozygous, 3 (5.3%) had P1033P homozygous and 2 (3.6%) had P1033P heterozygous/G1057D heterozygous polymorphisms in IRS-2 gene. In the control subjects, 21 (80.8%) had no nucleotide substitution, 3 (11.5%) had P1033P homozygous and 2 (7.7%) had P1033P heterozygous polymorphisms in IRS-2 gene (p>0.05). There was no significant difference between two groups in terms of fasting glucose and HOMA-IR. It was observed that IRS-1 and IRS-2 gene polymorphisms didn’t increase risk for OSAS. Besides, there was no association between IRS-1 and IRS-2 polymorphisms and HOMA in OSAS.

Selective Insulin and Leptin Resistance in Metabolic Disorders

Objective. Type 2 diabetes mellitus (T2DM) is one of diseases that develops in a setting of polymorbid processes or more often promotes their development, forming in this spectrum the phenomenon of comorbidity. The aim of this study was to evaluate changes in the lipid panel data in T2DM patients with comorbid obesity and chronic pancreatitis (CP) taking into account the C/A polymorphism of the insulin receptor substrate 1 (IRS1) gene (rs2943640). Methods. The study involved 34 T2DM patients and 10 healthy individuals. The rs2943640 IRS1 gene polymorphism was genotyped using the TaqMan real-time polymerase chain reaction (PCR) method. Blood serum lipid panel data were determined with commercially available kits on a Cobas 6000 analyzer. Results. In patients with only T2DM and T2DM + comorbid obesity, an association between IRS1 gene polymorphism (rs2943640) and lipid profile abnormalities with maximum changes of the lipid characteristics recorded in C/C genotype carriers was found. Within the C/C genotype of the IRS1 gene (rs2943640) in type 2 diabetic patients with comorbid obesity and CP, significantly lower high-density lipoprotein cholesterol (HDL-C) levels and significantly higher levels of triglycerides (TG), non-HDL-C and remnant cholesterol (RC) in relation to type 2 diabetic patients with comorbid obesity were found. At the same time, within the C/A genotype of the IRS1 gene (rs2943640), significant changes of lipid panel data were found in type 2 diabetic patients with comorbid obesity relative to the control group (p<0.001). Conclusions. Our data indicate that the presence of the C allele of IRS1 gene (rs2943640) in both homozygous and heterozygous states may indicate increased risk of dyslipidemia in type 2 diabetic patients with comorbidities.

Background Globally, 422 million adults have type 2 diabetes mellitus (T2DM), causing 1.5 million deaths per year. Kuwait has one of the highest T2DM prevalence in the world and determining the proportion of patients and relatives who have pre-diabetes (PDM), insulin resistance (IR) and T2DM is crucial to inform preventive activities and curative services. Study objectives: The study describes the prevalence and risk factors of PDM, IR and T2DM, in adult patients attending a primary health care facility in Kuwait and the prevalence and risk factors of the same conditions among the patients’ first-degree relatives. The study also describes the degree of glycaemic control achieved by patients with T2DM and risk factors for poor glycaemic control. Finally, we assessed the agreement of a point of care (POC) device to measure glycated haemoglobin (HbA1c) to monitor T2DM control. Methods We conducted cross-sectional surveys of patients and first-degree relatives attending Nuzha health care facility in Kuwait and case-control studies of participants attending Nuzha’s diabetic clinic. Diabetic participants were consecutively tested by the Quo-test (POC) device to compare its agreement with a reference test. Results The prevalence of T2DM, IR and PDM among patients attending the clinics were 29.6% (95% CI: 25.1%-34.1%), 34.6% (95% CI: 29.1%-40.2%) and 26.0% (95% CI: 21.6%-30.4%), respectively. The proportion of patients with T2DM increased with age (AOR=5.4), with the highest prevalence occurring at 60-69 years of age. T2DM was associated with hypertension (AOR=1.95) and being a widow (AOR=6.11). IR was associated with low HDL (AOR=1.96), overweight (OR=8.25), obesity (OR=18.33) and increased waist circumference (OR= 5.5). Sugar-sweetened beverages were associated with IR. The prevalence of T2DM, IR and PDM among first-degree relatives of T2DM patients were 29.1% (95%CI: 23.7%-34.5%), 32.8% (95%CI: 26.2%-39.4%), 20.4% (95%CI: 15.6%-25.2%). The risk factors for T2DM were similar among patients and first-degree relatives, but IR was associated with manual labour occupations (AOR=3.6). Only 30% of T2DM patients achieved good glycaemic. Poor control was associated with high triglycerides (AOR=2.2), smoking (AOR=4.1) and the number of years since diagnosis (AOR=4). The Quo-Test had comparable performance to the reference test, with a Coefficient of Variation of 2.1% (r2 = 935, Kappa 90% and 87% at HbA1c cut-offs of 7.0 and 9.0% respectively). The POC and the reference tests performed poorly in patients with haemoglobinopathies. Conclusion This study demonstrates that a high proportion of patients and first-degree relatives attending one of the main primary health care centres in Kuwait have T2DM. Many patients and relatives were unaware of their condition. There was also a very high prevalence of IR and PDM suggesting the burden of T2DM will increase further in the future. Major efforts are needed to upscale detection, and preventive programmes for IR, PDM and T2DM and the quality of T2DM management needs to improve. The POC device tested could provide timely information for the management of T2DM.

Since the insulin receptor substrate-1 (IRS-1) is the major substrate of the insulin receptor tyrosine kinase and has been shown to activate phosphatidylinositol (PI) 3-kinase and promote GLUT4 translocation, the IRS-1 gene is a potential candidate for development of non-insulin-dependent diabetes mellitus (NIDDM). In this study, we have identified IRS-1 gene polymorphisms, evaluated their frequencies in Japanese subjects, and analysed the contribution of these polymorphisms to the development of NIDDM. The entire coding region of the IRS-1 gene of 94 subjects (47 NIDDM and 47 control subjects) was screened by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) analysis. Seven SSCP polymorphisms were identified. These corresponded to two previously identified polymorphisms [Gly971 --> Arg (GGG --> AGG) and Ala804 (GCA --> GCG)] as well as five novel polymorphisms [Pro190 --> Arg (CCC --> CGC), Met209 --> Thr (ATG --> ACG), Ser809 --> Phe (TCT --> TTT), Leu142 (CTT --> CTC), and Gly625 (GGC --> GGT)]. Although the prevalence of each of these polymorphisms was not statistically different between NIDDM and control subjects, the prevalence of the four IRS-1 polymorphisms with an amino acid substitution together was significantly higher in NIDDM than in control subjects (23.4 vs 8.5%, p < 0.05), and two substitutions (Met 209 --> Thr and Ser809 --> Phe) were found only in NIDDM patients. Equilibrium glucose infusion rates during a euglycaemic clamp in NIDDM and control subjects with the IRS-1 polymorphisms decreased by 29.5 and 22.0%, respectively on the average when compared to those in comparable groups without polymorphisms, although they were not statistically significant. Thus, IRS-1 polymorphisms may contribute in part to the insulin resistance and development of NIDDM in Japanese subjects; however, they do not account for the major part of the decrease in insulin-stimulated glucose uptake which is observed in subjects with clinically apparent NIDDM.

beta-Cell failure is an essential component of all types of diabetes, and the insulin receptor substrate 2 (IRS2) branch of signaling plays a key role in beta-cell survival and function. We tested the hypothesis that activating transcription factor 3 (ATF3), a stress-inducible proapoptotic gene, downregulates the expression of IRS2 in beta-cells. We used both the gain- and loss-of-function approaches to test the effects of ATF3 on IRS2 gene expression. We also analyzed the binding of ATF3 to the IRS2 promoter by chromatin immunoprecipitation assay and the transcription of the IRS2 gene by polymerase II occupancy assay. Furthermore, we tested the ability of IRS2 to alleviate the proapoptotic effects of ATF3 in cultured beta-cells and in transgenic mice using the rat insulin promoter to drive the transgenes. Expression of ATF3 is sufficient to reduce IRS2 gene expression; in contrast, knockdown or knockout of ATF3 reduces the ability of stress signals to downregulate IRS2 expression. ATF3 binds to the IRS2 promoter in vivo, and the binding of ATF3 correlates with decreased IRS2 gene transcription. Functionally, expression of IRS2 protects beta-cells from ATF3-induced apoptosis. IRS2 is a target gene of ATF3, and its repression by ATF3 contributes, at least partly, to the apoptosis induced by ATF3. Because ATF3 is a stress-inducible gene, our work provides a direct link to explain how environmental stress factors can modulate IRS2 gene transcription.

Common polymorphisms in the PPARγ2 and IRS-1 genes and their interaction influence serum adiponectin concentration in young Finnish men

Background: The polymorphisms of the C–C chemokine receptor type 5 (CCR5) and the insulin receptor substrate 1 (IRS1) have been studied as candidates for the susceptibility to develop type 2 diabetes mellitus (T2DM). CCR5 is a chemokine receptor, and the polymorphisms in the promoter region of this receptor are being studied as candidates for the susceptibility to develop T2DM. Also, IRS1 is a critical factor in the signaling pathway for insulin, and mutations in this gene have been reported, which contribute to the ability to develop T2DM. The aim of the current study was to determine the relationship between CCR5 (59029A/G) and IRS1 (rs10498210) polymorphisms with T2DM in Sanandajian patients.Methods: Genomic DNA was isolated from 200 healthy individuals and 220 Kurdish T2DM patients by salt extraction method and the polymorphisms were examined by restriction fragment length polymorphism (RFLP) method and then the results were analyzed using Chi-square test.Results: The frequency of AA genotype in 220 Kurdish patients for both genes CCR5 (OR=1.9, P=0.02) and IRS1 (OR [95% CI]=2.62, P=0.02) were significantly more than controls. There was no significant association between AG or GG genotypes in with T2DM.Conclusion: The presence of AA homozygote alleles in both loci of IRS1 (rs10498210) and CCR5 (59029A/G) genes increased the risk of T2DM.