A collaboration project with Dr. Patrick Brown?s lab is currently underway on differential gene expression of non-diabetic insulin resistant and sensitive groups using cDNA microarray technology. Preliminary experiments using both individual and pooled mRNA from muscle biopsies hybridized to 10,000 cDNA arrays showed 24 reproducibly differentially regulated genes. New cDNA microarrays were constructed to also include candidate genes and Expressed Sequence Tags in the chromosomal regions that have shown suggestive linkage to diabetes and obesity in Pima Indians. Since cultured primary muscle cells have been shown to exhibit biochemical properties that are related to the insulin sensitivity phenotype of the donor, and mRNA from such cultures is more easily extracted than from tissues biopsies, cell cultures from insulin sensitive and resistant Pima Indians are being established. The gene expression profiles of normal cells from each group will be compared using the microarrays. A portion of each cell line will be subjected to either hyperinsulinemic, hyperglycemic or both media for different periods of time and subsequently the extracted mRNA will be hybridized on the microarrays to identify insulin- and/or glucose-regulated genes that may be differentially expressed in cells from insulin resistant and sensitive subjects.
