| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Mitochondrial oxidative phosphorylation (OXPHOS) plays an important role in the pathophysiology of type 2 diabetes. Genes for OXPHOS have been reported to be down-regulated in the skeletal muscle from patients with type 2 diabetes; however, hepatic regulation is unknown.
In the present study, I analyzed gene expression for OXPHOS from the livers of 14 patients with type 2 diabetes and 14 subjects with normal glucose tolerance (NGT) using serial analysis of gene expression (SAGE) and DNA chip analysis. I evaluated the correlation between gene expression levels for OXPHOS and clinical parameters of individuals with type 2 diabetes and NGT.
Both gene analyses showed that genes for OXPHOS were significantly up-regulated in the type 2 diabetic liver.
In the SAGE analysis, tag count comparisons of mitochondrial transcripts showed that rRNAs were 3.5-fold over-expressed, and mRNAs were 1.2-fold over-expressed in the type 2 diabetes library. DNA chip analysis revealed that gene expression for OXPHOS, which correlated with several nuclear factors, including estrogen-related receptor-a (ERR-α) or peroxisome proliferator-activated receptor-y (PPAR-y), was a predictor of fasting plasma glucose levels, independent of age, body mass index, insulin resistance, and fasting insulin levels (P=0.04). Surprisingly, genes for OXPHOS did not correlate with either peroxisome proliferator-activated receptor-γ coactivator-la (PGC-1α) or nuclear respiratory factor 1 (NRF-1).
These results indicate that up-regulated genes for OXPHOS in the liver, which are regulated by different mechanisms from genes in the skeletal muscle, are associated with fasting hyperglycemia in patients with type 2 diabetes.
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