title: Interaction between the G1057D variant of IRS-2 and overweight in the pathogenesis of type 2 diabetes.
abstract: The insulin receptor substrate-2 (IRS-2) is a major insulin signalling molecule. IRS-2 inactivation in mice induces a form of diabetes characterized by peripheral insulin resistance and reduced beta cell mass. We tested the hypothesis that a common non-conservative amino acid substitution of IRS-2 (G1057D) might interact with overweight in the pathogenesis of type 2 diabetes. The variant was genotyped in 193 Italian patients with type 2 diabetes and 206 control subjects. In the absence of overweight, the risk of type 2 diabetes decreased according to the dosage of the D1057 allele (odds ratio for GD genotype 0.46 [95% CI 0.25-0.86]; DD genotype 0.18 [0.04-0.68]; P for trend = 0.0012). Conversely, the interaction between overweight and genotype increased the risk of type 2 diabetes according to the dosage of the D1057 allele (odds ratio for GD genotype 2.50 [1.11-5.65]; DD genotype 5.74 [1.11-29. 78]; P for trend = 0.0047). Among controls, fasting C-peptide levels, after adjustment for plasma glucose, were inversely related to the dosage of the D1057 allele (P = 0.020). This finding suggested that carriers of the D1057 allele may have higher insulin sensitivity and supported the protective effect of this allele. Conversely, among overweight patients there was a parallel increase in fasting plasma glucose (P for trend = 0.037) and fasting C-peptide according to the dosage of the D1057 allele, suggesting that higher insulin resistance and relative beta cell failure contributed to the increased risk of type 2 diabetes in overweight carriers of this allele. These data provide evidence for a strong association between type 2 diabetes and the G1057D common genetic variant of IRS-2, which appears to be protective against type 2 diabetes in a codominant fashion. Overweight appears to modify the effect of this polymorphism toward a higher risk of type 2 diabetes. Carriers of this polymorphism may represent an elective target for prevention of type 2 diabetes through preventing or treating excessive weight.
authors.affiliation: Department of Oncology and Neurosciences, Section of Molecular Pathology, University Gabriele D'Annunzio, Chieti, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Mammarella
authors.forename: F
authors.initials: F
authors.lastname: Romano
authors.forename: A
authors.initials: A
authors.lastname: Di Valerio
authors.forename: B
authors.initials: B
authors.lastname: Creati
authors.forename: D L
authors.initials: DL
authors.lastname: Esposito
authors.forename: R
authors.initials: R
authors.lastname: Palmirotta
authors.forename: F
authors.initials: F
authors.lastname: Capani
authors.forename: P
authors.initials: P
authors.lastname: Vitullo
authors.forename: G
authors.initials: G
authors.lastname: Volpe
authors.forename: P
authors.initials: P
authors.lastname: Battista
authors.forename: F
authors.initials: F
authors.lastname: Della Loggia
authors.forename: R
authors.initials: R
authors.lastname: Mariani-Costantini
authors.forename: A
authors.initials: A
authors.lastname: Cama
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology* / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D010750:Phosphoproteins / Q000235:genetics*; D011110:Polymorphism, Genetic; D012044:Regression Analysis
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526298:Irs2 protein, mouse; D010750:Phosphoproteins