We also observed a weak interaction of the IGF1R IVS2+46329T>C and IGF2R Ex45+11C>T (L2222L) genotypes with diabetes (P(interaction)=.05) and interaction of IGF2R and IRS1 genotypes with alcohol consumption (P(interaction)=.03 and .019, respectively) on increased pancreatic cancer risk.
We conclude the following: 1) physiological hyperinsulinemia induces sustained activation of insulin-signaling molecules in human skeletal muscle; 2) the more distal insulin-signaling components (Akt, GSK-3) are activated much more rapidly than the proximal signaling molecules (IRTK as well as insulin receptor substrate 1 and phosphatidylinositol 3-kinase [Wojtaszewski et al., Diabetes 46:1775-1781, 1997]); and 3) prior exercise increases insulin stimulation of both glucose uptake and glycogen synthase activity in the absence of an upregulation of signaling events in human skeletal muscle.
The aim of this study was to evaluate the role of the IRS-1 gene G972R variant in 61 subjects with "uncomplicated" obesity [i.e. without diabetes, hypertension, dyslipidemia, coronary artery disease (CAD)], studied by hyperinsulinemic-euglycemic clamp.
We provide such a demonstration here by showing that the hippocampal formation (HF) and, to a lesser degree, the cerebellar cortex in AD cases without diabetes exhibit markedly reduced responses to insulin signaling in the IR→IRS-1→PI3K signaling pathway with greatly reduced responses to IGF-1 in the IGF-1R→IRS-2→PI3K signaling pathway.
Also, the diagnostic test to exclude diabetes amongst control subjects interacted with the association between the IRS-1Gly972Arg variant and Type 2 diabetes (p=0.03).
Although the mechanisms underlying the regulation of IRS-1 in the nutrient-rich conditions associated with diabetes and insulin resistance have been well studied, those under nutrient-poor conditions remain unknown.
Notably, the body-fat-decreasing allele near IRS1 is associated with decreased IRS1 expression and with an impaired metabolic profile, including an increased visceral to subcutaneous fat ratio, insulin resistance, dyslipidemia, risk of diabetes and coronary artery disease and decreased adiponectin levels.
The IRS-1 gene variant was associated with a higher frequency of diabetes mellitus (14.9% among carriers versus 6.5% among noncarriers; P<0.01) and with a 60% increase of plasma total triglycerides (P<0.001).
Our study suggests that HD prevents the development of diabetes and improves renal function in the <i>db/db</i> mice and HD regulation of the IRS1-PI3K-GLUT signaling pathway significantly improves diabetic nephropathy.
Although chronic therapy with metformin fails to achieve recovery from hyperglycemia, a key feature of diabetes in middle-aged diabetic mice, it improves hippocampal-dependent spatial memory functions accompanied by increased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), atypical protein kinase C ζ (aPKC ζ), and insulin receptor substrate 1 (IRS1) at selective serine residues in the hippocampus.
Proliferator-activated receptor gamma Pro12Ala interacts with the insulin receptor substrate 1Gly972Arg and increase the risk of insulin resistance and diabetes in the mixed ancestry population from South Africa.
Investigating the causes of the reduced tyrosine phosphorylation of IRS-1, we found a more than twofold increase in the basal phosphorylation of IRS-1 on serine 636 in myotubes from patients with diabetes.
These studies demonstrate that TF induces cellular insulin resistance in primary murine and human adipocytes through a reduction of IRS-1 expression and protein stability, raising concern about the potential for this fungicide to disrupt metabolism and thereby contribute to the pathogenesis of diabetes.
Erratum to: Metformin treatment ameliorates diabetes-associated decline in hippocampal neurogenesis and memory via phosphorylation of insulin receptor substrate 1.
The ENPP1 121Gln and IRS-1 972Arg polymorphisms were detected in 28.7% and 18.1% of patients and associated with increased body weight/dyslipidaemia and diabetes risk, respectively.
We examined the gene and protein expression of IRS 1 (insulin receptor substrate 1) in adipocytes from two groups of healthy individuals with an increased propensity for non-insulin-dependent diabetes mellitus (NIDDM): those with two first-degree relatives with diabetes and another group with massive obesity.
The decreased hepatic expression of IRS1 and β-catenin in NAFLD is linked to histological progression such as ballooning, and might lead to diabetes as a result of impaired glucose metabolism.
The diabetes risk variant rs7578326 located near the IRS1 locus was associated with both macroscopic (OR = 0.73, p = 0.011) and microscopic (OR = 0.71, p = 0.009) infarct pathology.
Given the documented importance of IRS-1 and -2 in insulin signalling and the implications of distribution of these genes for the pathogenesis of insulin resistance and diabetes, we decided that the most recently identified member of the IRS family, IRS-4, was a relevant candidate to examine for genetic variability which might be associated with subsets of diabetes or insulin resistance.
The GLUT2 and IRS1 amino acid polymorphisms did not show a simple pattern of co-inheritance with NIDDM in the families of these subjects suggesting that neither polymorphism is sufficient to cause NIDDM but may increase diabetes-susceptibility through their interaction with other loci and environmental factors.
The allele frequencies of the Gly972Arg variant of the insulin receptor substrate-1 (IRS-1) gene and the Ala54Thr variant of the fatty acid binding protein 2 (FABP2) gene were compared in 992 normal control subjects and three patient groups: 1) 321 type 2 diabetic individuals, 2) 260 severely obese individuals, and 3) 258 markedly hyperinsulinemic individuals without diabetes.