Quantitative genetic analysis of glucose transporter 4 mRNA levels in baboon adipose

Glucose transporter 4 (GLUT4) is an insulin-responsive glucose transporter expressed in adipose tissue. A decrease of the mRNA abundance of GLUT4 in adipose tissue has been observed in conditions of insulin resistance. The objective was to conduct quantitative genetic analyses using GLUT4 mRNA levels in omental adipose tissue of baboons as a novel phenotype.

A blood sample and a biopsy of omental adipose tissue were collected from 418 adult, pedigreed baboons. Total RNA was isolated from adipose tissue biopsies, and GLUT4 mRNA abundance was assayed by quantitative, real-time reverse transcription-polymerase chain reaction. Insulin and glucose were determined in fasting plasma by standard methods. Quantitative genetic analyses were conducted using GLUT4 mRNA, insulin, and glucose as quantitative traits.

GLUT4 mRNA expression in omental adipose tissue was heritable (h(2) = 0.23, p = 0.001). Bivariate genetic analyses revealed a significant genetic correlation (rho(G)) between GLUT4 mRNA abundance and both body weight (rho(G) = 0.63, p = 0.007), BMI (rho(G) = 0.59, p = 0.02) and insulin (rho(G) = 0.72, p = 0.04). A genome scan was conducted, and a quantitative trait locus was detected on chromosome 10p12 with a logarithm of the odds ratio score of 1.1.

GLUT4 mRNA abundance in omental adipose tissue has a significant genetic component. These findings suggest that expression of GLUT4 mRNA, plasma insulin levels, and body weight may be regulated by common genes.