Decreased expression of genes involved in oxidative phosphorylation in human pancreatic islets from patients with type 2 diabetes.

• OBJECTIVE: Gene expression alterations, especially in target tissues of insulin, have been associated with type 2 diabetes (T2D). Here, we examined if genes involved in oxidative phosphorylation (OXPHOS) show differential gene expression and DNA methylation in pancreatic islets from patients with T2D compared with non-diabetic donors. DESIGN AND METHODS: Gene expression was analyzed in human pancreatic islets from 55 non-diabetic donors and 9 T2D donors using microarray. RESULTS: While the expected number of OXPHOS genes with reduced gene expression is 7.21 we identified 21 down-regulated OXPHOS genes in pancreatic islets from patients with T2D using microarray analysis. This gives a ratio of observed over expected OXPHOS genes of 26.37 using a Χ(2)-test with p = 1.52•10-7. The microarray data was validated by qRT-PCR for four selected OXPHOS genes; NDUFA5, NDUFA10, COX11 and ATP6V1H. All four OXPHOS genes were significantly down-regulated in islets from patients with T2D compared with non-diabetic donors using qRT-PCR (p≤0.01). Furthermore, HbA1c levels correlated negatively with gene expression of NDUFA5, COX11 and ATP6V1H (p less than 0.05). Gene expression of NDUFA5, NDUFA10, COX11 and ATP6V1H correlated positively with glucose-stimulated insulin secretion (p less than 0.03). Finally, DNA methylation was analyzed upstream of the transcription start for NDUFA5, COX11 and ATP6V1H. However, none of the analyzed CpG sites in the three genes showed differences in DNA methylation in islets from donors with T2D compared with non-diabetic donors. CONCLUSION: Pancreatic islets from patients with T2D show decreased expression of a set of OXPHOS genes, which may lead to impaired insulin secretion.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

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