title: Dynamic DNA methylation of matrix metalloproteinase-9 in the development of diabetic retinopathy.
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.
authors.affiliation: Department of Ophthalmology, Kresge Eye Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Renu A
authors.initials: RA
authors.lastname: Kowluru
authors.affiliation: Department of Ophthalmology, Kresge Eye Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Shan
authors.affiliation: Department of Ophthalmology, Kresge Eye Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Manish
authors.initials: M
authors.lastname: Mishra
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D019175:DNA Methylation; D003921:Diabetes Mellitus, Experimental / Q000150:complications; D003930:Diabetic Retinopathy / Q000201:enzymology* / Q000209:etiology; D042783:Endothelial Cells / Q000201:enzymology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D034741:RNA, Small Interfering; D011897:Random Allocation; D012160:Retina / Q000201:enzymology
chemical_list: D034741:RNA, Small Interfering; D020780:Matrix Metalloproteinase 9