The Preliminary Study Of Cytoplasmic Adapter Protein Dok5Susceptibility And Relevant Pathogenesis In Obesity And Type2Diabetes Of Han Chinese Population

Insulin resistance (IR) plays an important role in the pathogenesis ofobesity and type2diabetes. Environmental factors such as obesity andgenetic factors, such as the structural abnormalities of insulin, insulinantibodies, insulin receptor or post receptor and proteins mutationsinvolved in insulin signal transduction pathways can lead to insulinresistance. As a member of insulin receptor substrate (IRS) family thatmediates insulin signaling pathway, Dok5seems to be a strong functionaland positional candidate for obesity and type2diabetes. Moreover, byvarious genome-wide linkage scans20q13is one of the strongest linkedregions for type2diabetes as well as obesity. And, Dok5just locates in20q13region and the highest expression of Dok5has been detected inskeletal muscle which is the major tissue regulating metabolic homeostasis.Dok5is also suggested to be involved in the regulation of immune responseinduced by T cells which are the key modulating pathways in obesity andtype2diabetes. Therefore, we explored Dok5as a potential obesity andtype2diabetes susceptibility gene in Han Chinese population which has ahigh risk of developing obesity and type2diabetes, and also seeked thepossible pathogenesis of obesity and type2diabetes.We extracted genomic deoxyribonucleic acid(DNA) from peripheralbloods of400subjects comprising of200patients with type2diabetes and200controls by blood genomic DNA extraction kit and sequencedpolymerase chain reaction(PCR) products for polymorphisms infunctionally relevant regions of Dok5. Rs2842, rs2841, rs15899and rs2843 total of4single nucleotide polymorphisms(SNPs) which the minor allelefrequency was greater than or equal0.05were identified by sequencing. Wegenotyped SNPs in1,066participants comprising of493patients with type2diabetes and573controls of Han Chinese population. Before adjustmentfor age, sex and body mass index(BMI), there were statistically significantdifferences in allele frequency(A/G) and the distribution of three genotypes(GG, AG, AA) of rs2841SNP between the two groups(P<0.05). Afteradjustment for age, sex and BMI, rs15899and rs2843heterozygousgenotypes were also statistically significant(P<0.05). According to BMI,type2diabetes patients were further divided into the normal weight groupand overweight/obesity group, particularly in overweight/obese patientswith type2diabetes, rs2841in allele and genotype frequency hadsignificant statistical difference(P<0.05). And, the differences in differentgenotypes of rs2841were further analyzed in the clinical features andblood biochemical indexes of type2diabetes patients. The patients for AAgenotype had a higher BMI, homeostasis model assessment of insulinresistance(HOMA-IR) and family history of type2diabetes than GGgenotype(P<0.05), and other clinical features and blood biochemicalindexes also had a tendency of increasing. It suggested that rs2841SNPmay be a potential function and susceptibility SNP in obesity and type2diabetes.Then, rs2841was turned out that it had effects on Dok5transcriptionlevels in vivo in peripheral blood mononuclear cells of type2diabetes. Asthe rs2841SNP is located in3’ untranslated region(3’ UTR), the targetingeffect of microRNA30(miR30) to Dok5was analyzed by using thebiological information website and dual-luciferase reporter activity assay,and the result further confirmed that the targeting effect of miR30related tors2841SNP. It showed that rs2841had effects on miR30ribonucleicacid(RNA) levels in vivo, which was accordance with the above results. Itmeans rs2841SNP adjust the espression of Dok5by the targeting effect of miR30to Dok53’ UTR. That may change the insulin signaling pathway,and lead to obesity and type2diabetes.In a word, we identified Dok5as a novel susceptibility gene forobesity and type2diabetes in Han Chinese subjects. Dok5rs2841SNP andthe targeting effect of miR30to Dok53’ UTR suggested that Dok5mightmodulate obesity and type2diabetes susceptibility through miR30involvement in insulin signaling. This showed that Dok5may have certainrelations with obesity and type2diabetes and may play an importantbiological function in its pathogenesis.