Dynamic DNA methylation of matrix metalloproteinase-9 in the development of diabetic retinopathy

Lab Invest. 2016 Oct;96(10):1040-9. doi: 10.1038/labinvest.2016.78. Epub 2016 Jul 25.

Abstract

Diabetes elevates matrix metalloproteinase-9 (MMP-9) in the retina and its capillary cells, and activated MMP-9 damages mitochondria, accelerating retinal capillary cell apoptosis, a phenomenon which precedes the development of retinopathy. Diabetes also favors epigenetic modifications regulating the expression of many genes. DNA methylation is maintained by methylating-hydroxymethylating enzymes, and retinal DNA methyltransferase (Dnmt) is activated in diabetes. Our aim is to investigate the role of DNA methylation in MMP-9 regulation. The effect of high glucose on 5-methylcytosine (5mC) and 5-hydroxymethyl cytosine (5hmC), and binding of Dnmt1 and hydroxymethylating enzyme (Tet2) on MMP-9 promoter were quantified in retinal endothelial cells. Specific role of Tet2 in MMP-9 activation was validated using Tet2-siRNA. The results were confirmed in the retina from streptozotocin-induced diabetic mouse. Although glucose increased Dnmt1 binding at MMP-9 promoter, it decreased 5mC levels. At the same promoter site, Tet2 binding and 5hmC levels were elevated. Tet2-siRNA ameliorated increase in 5hmC and MMP-9 transcription, and protected mitochondrial damage. Diabetic mice also presented similar dynamic DNA methylation changes in the retinal MMP-9 promoter. Thus, in diabetes transcription of retinal MMP-9 is maintained, in part, by an active DNA methylation-hydroxymethylation process, and regulation of this machinery should help maintain mitochondrial homeostasis and inhibit the development/progression of diabetic retinopathy.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cattle
  • Cells, Cultured
  • DNA Methylation*
  • Diabetes Mellitus, Experimental / complications
  • Diabetic Retinopathy / enzymology*
  • Diabetic Retinopathy / etiology
  • Endothelial Cells / enzymology
  • Matrix Metalloproteinase 9 / metabolism*
  • Mice, Inbred C57BL
  • RNA, Small Interfering
  • Random Allocation
  • Retina / enzymology

Substances

  • RNA, Small Interfering
  • Matrix Metalloproteinase 9