textThe purpose of this research was to identify the chromosomal regions influencing the
mRNA expression of the hormones resistin and adiponectin, and the glucose transporter
4 (GLUT4) in omental adipose tissue of baboons. These baboon genes were cloned
using a two-step reverse transcription- polymerase chain reaction (RT-PCR) technique.
Real- time, quantitative RT-PCR assays were developed and standardized for
measurement of mRNA levels of each gene. Total RNA was isolated from 460 samples
of adipose tissue from adult pedigreed baboons, and used for the quantification of
adiponectin, resistin and GLUT4 mRNA. Quantitative genetic analyses were conducted
using the mRNA abundance of each gene as a quantitative phenotype applying the
variance decomposition approach. Heritabilities were calculated for resistin (h2
= 0.23, p
= 0.005), adiponectin (h2 = 0.23, p = 0.001) and GLUT4 (h2 = 0.24, p = 0.001). Genome
scan analyses were conducted to locate the chromosomal regions influencing the
expression of the studied genes. The identified regions and corresponding LOD scores
are: 19p13 (LOD score = 3.8) for resistin, 6q13 (LOD score =1.6) for adiponectin mRNA
and same location (LOD score =1.0) for adiponectin protein, and 10q24-26 (LOD score =
1.4) for GLUT4 mRNA. A parallel study in 120 baboons indicated a relationship between
body weight and indicators for insulin sensitivity, and an association between
adiponectin levels and insulin resistance (HOMA-IR index) in baboons. No correlation
between the analyzed phenotypes and resistin expression in monocytes was found. The
relationships between mRNA expression in adipose tissue of resistin, adiponectin and
GLUT4 and circulating levels of selected cytokines (TNFa, IL-6 and IL-1b) and
phenotypes associated to insulin resistance were investigated in a sub-sample of
unrelated baboons (n=40). Resistin expression in adipose tissue was related to insulin
sensitivity, adiponectin mRNA was inversely associated with cytokines in plasma, and
GLUT4 abundance and the HOMA-IR index were correlated. Collectively, these results
revealed novel findings on the genetic component of the endocrine function of adipose
tissue, and confirmed the value of the baboon as a model for the genetic study of
obesity-related conditions.Nutritional Science
