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High levels of glucose induce apoptosis in cardiomyocyte via epigenetic regulation of the insulin-like growth factor receptor.

Diabetic hyperglycemia result in cardiovascular complications, but the mechanisms by which high levels of glucose (HG) cause diabetic cardiomyopathy are not known. We investigate whether HG-induced repression of insulin-like growth factor 1 receptor (IGF-1R) mediated by epigenetic modifications is one potential mechanism. We found that HG resulted in decreased IGF-1 receptor (IGF-1R) mRNA levels, and IGF-1R protein when compared with H9C2 rat cardiomyocyte cells incubated in normal glucose. HG also induced apoptosis of H9C2 cells. The effects of HG on reduced expression of IGF-1R and increased apoptosis were blocked by silencing p53 with small interference RNA but not by non-targeting scrambled siRNA. Moreover, HG negatively regulated IGF-1R promoter activity as determined by ChIP analysis, which was dependent on p53 since siRNA-p53 attenuated the effects of HG on IGF-1R promoter activity. HG also increased the association of p53 with histone deacetylase 1 (HDAC1), and decreased the association of acetylated histone-4 with the IGF-1R promoter. Furthermore, HDAC inhibitor relieved the repression of IGF-1R following HG state. These results suggest that HG-induced repression of IGF-1R is mediated by the association of p53 with the IGF-1R promoter, and by the subsequent enhanced recruitment of chromatin-modifying proteins, such as HDAC1, to the IGF-1R promoter-p53 complex. In conclusion, our data demonstrate that HG decreases expression of IGF-1R and decreases the association of acetylated histone-4 with the IGF-1R promoter. These studies may help delineate the complex pathways regulating diabetic cardiomyopathy, and have implications for the development of novel therapeutic strategies to prevent diabetic cardiomyopathy by epigenetic regulation of IGF-1R.

Pubmed ID: 20633551

Authors

  • Yu XY
  • Geng YJ
  • Liang JL
  • Lin QX
  • Lin SG
  • Zhang S
  • Li Y

Journal

Experimental cell research

Publication Data

October 15, 2010

Associated Grants

  • Agency: NHLBI NIH HHS, Id: R01HL69509

Mesh Terms

  • Acetylation
  • Animals
  • Apoptosis
  • Blood Glucose
  • Cell Line
  • Diabetic Angiopathies
  • Epigenesis, Genetic
  • Histones
  • Hyperglycemia
  • Myocytes, Cardiac
  • Promoter Regions, Genetic
  • Rats
  • Receptors, Somatomedin
  • Tumor Suppressor Protein p53