DNA microarray analysis of whole blood cells and insulin-sensitive tissues reveals the usefulness of blood RNA profiling as a source of markers for predicting type 2 diabetes.

To determine if gene expression profiling of whole blood cells is a useful source of markers for the early diagnosis of the onset of type 2 diabetes, we examined gene expression profiling of whole blood cells and type 2 diabetes-related organs, such as liver, adipose tissue, and skeletal muscle, of Otsuka Long-Evans Tokushima Fatty (OLETF) rats. At the age of 6 weeks, RNA was isolated from tissues of fasted OLETF and control Long-Evans Tokushima Otsuka (LETO) rats. Gene expression was analyzed using the Agilent rat oligo microarray. Gene ontology analysis showed that gene expression of biologically meaningful groups of genes in liver, adipose tissue, and skeletal muscle, which are involved in the pathogenesis of type 2 diabetes, differed between OLETF and LETO rats. Three hundred genes of whole blood cells were differentially expressed. Four out of these 300 genes were related to the insulin-signaling pathway and 57 out of 300 genes were up- or down-regulated in at least one tissues in OLETF rats. These results support our hypothesis that gene expression profiling of whole blood cells might be a useful source of markers to predict the onset of type 2 diabetes.