Identification of differentially expressed genes in skeletal muscle of non-diabetic insulin-resistant and insulin-sensitive Pima Indians by differential display PCR.

AIMS/HYPOTHESIS: Whole body insulin resistance results largely from impaired insulin-stimulated glucose disposal into skeletal muscle. We carried out muscle gene expression profiling to identify differentially expressed genes associated with insulin resistance.

METHODS

Skeletal muscle total RNA samples from six pairs of non-diabetic insulin-resistant and insulin-sensitive Pima Indians matched for percent body fat were analyzed by DDPCR with 90 primer combinations. The mRNA expression concentrations of selected 13 known genes and four expressed sequences tags were measured by quantitative real-time RT-PCR in 50 non-diabetic Pima subjects.

RESULTS

From over 6500 displayed DDPCR cDNA bands, 36 of the most differentially expressed cDNAs were identified, revealing 29 unique sequences: 16 known genes, 10 expressed sequences tags and three unknown transcripts. Multiple regression analyses indicated that whole body insulin-mediated glucose disposal rates of the subjects, independent of age, sex, and percent body fat, were negatively correlated with mRNA concentrations of an EST (DD23; r=-0.38, p=0.007), ATP1A2 (r=-0.27, p=0.05), MAP2K4 (r=-0.34, p=0.02), and PRPSAP1 (r=-0.37, p=0.008). Transcript concentrations of DD23 (r=0.27, p=0.05) and MTND4 (r=-0.29, p=0.05) were correlated with plasma insulin concentration, independent of age, sex, and percent body fat.

CONCLUSION/INTERPRETATION: Altered expression concentrations of these genes might be causes or consequences of insulin resistance, and these genes serve as candidate susceptibility genes for insulin resistance.