TCF7L2 gene expression in human visceral and subcutaneous adipose tissue is differentially regulated but not associated with type 2 diabetes mellitus

Variants in the TCF7L2 gene have been associated with type 2 diabetes mellitus (T2DM), but the causal variant(s) is still unknown. We studied the TCF7L2 messenger RNA (mRNA) expression in paired samples of visceral and subcutaneous adipose tissue from 49 subjects using quantitative real-time polymerase chain reaction and its relation to obesity and T2DM. All subjects were genotyped for the previously described TCF7L2 diabetes risk variants. Independent of age, sex, obesity, and diabetes status, we found >3-fold higher TCF7L2 mRNA expression in subcutaneous compared with visceral adipose tissue. There was no correlation between visceral and subcutaneous TCF7L2 expression. No differences in adipose tissue TCF7L2 mRNA expression levels were found between diabetic and nondiabetic subjects, or between lean and obese subjects (all Ps > .05). In addition, there was no association between TCF7L2 genetic variants and mRNA expression. Based on our data, TCF7L2 mRNA expression is fat-depot specific but does not seem to provide the mechanistic link explaining genetic association with T2DM.