Insulin resistance occurs early in the disease process, preceding the development of type 2 diabetes. Therefore, the identification of molecules that contribute to insulin resistance and leading up to type 2 diabetes is important to elucidate the molecular pathogenesis of the disease. To this end, we characterized gene expression profiles from insulin-sensitive tissues, including adipose tissue, skeletal muscle, and liver tissue of Zucker diabetic fatty (ZDF) rats, a well characterized type 2 diabetes animal model. Gene expression profiles from ZDF rats at 6 weeks (pre-diabetes), 12 weeks (diabetes), and 20 weeks (late-stage diabetes) were compared with age-and sex-matched Zucker lean control (ZLC) rats using 5000 cDNA chips. Differentially regulated genes demonstrating.1·3-fold change at age were identified and categorized through hierarchical clustering analysis. Our results showed that while expression of lipolytic genes was elevated in adipose tissue of diabetic ZDF rats at 12 weeks of age, expression of lipogenic genes was decreased in liver but increased in skeletal muscle of 12 week old diabetic ZDF rats.These results suggest that impairment of hepatic lipogenesis accompanied with the reduced lipogenesis of adipose tissue may contribute to development of diabetes in ZDF rats by increasing lipogenesis in skeletal muscle. Moreover, expression of antioxidant defense genes was decreased in the liver of 12-week old diabetic ZDF rats as well as in the adipose tissue of ZDF rats both at 6 and 12 weeks of age. Cytochrome P450 (CYP) genes were also significantly reduced in 12 week old diabetic liver of ZDF rats. Genes involved in glucose utilization were downregulated in skeletal muscle of diabetic ZDF rats, and the hepatic gluconeogenic gene was upregulated in diabetic ZDF rats. Genes commonly expressed in all three tissue types were also observed. These profilings might provide better fundamental understanding of insulin resistance and development of type 2 diabetes.

No abstract

Survivin is a new member of the inhibitor of apoptosis protein ( IAP ) family that is implicated in the control of cell proliferation and the regulation of cell life span. This protein is selectively expressed in most human carcinomas but not in normal adult tissues. To down -regulate a human survivin expression as a strategy for cancer gene therapy, we designed two hammerhead ribozymes ( RZ -1, RZ -2 ) targeting human survivin mRNA. RZ -1 and RZ -2 efficiently cleaved the human survivin mRNA at nucleotide positions + 279 and + 289, which was identified by in vitro cleavage assay using in vitro transcribed ribozymes and truncated survivin mRNA substrate. To investigate the function of the ribozymes in cells, the sequences of the ribozymes were cloned into replication -deficient adenoviral vector and transferred to breast cancer cell, MCF -7. The infection with adenovirus encoding the ribozymes resulted in a significant reduction of survivin mRNA ( 74% and 73%, respectively ) and protein. As revealed by nuclear condensation / fragmentation and flow cytometry analysis, inhibition of survivin gene by ribozymes increased apoptosis and sensitivity induced by etoposide or serum starvation. Our results suggest that the designed hammerhead ribozymes against survivin mRNA are good candidates for feasible gene therapy in the treatment of cancer.

No abstract