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Tara Tovar-Vidales, Navita Lopez, Abbot F Clark; TGFβ2 Regulation of DNMTs in Optic Nerve Head Astrocytes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5667.
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The profibrotic cytokine transforming growth factor-β2 (TGFβ2) has been implicated in extracellular matrix (ECM) remodeling of the glaucomatous optic nerve head (ONH). Multiple mechanisms have been described in the regulation of ECM genes; however, epigenetic regulation of ECM genes by TGFβ2 is not fully understood. DNA methyltransferases (DNMTs) are enzymes that transfer a methyl group to cytosine residues at CpG dinucleotide islands. To date, five DNMT members have been shown in humans, however, only DNMT1, DNMT3a, and DNMT3b have catalytic methyltransferase activity. DNMT-mediated hypermethylation results in transcriptional gene silencing. The purpose of this study was to determine whether TGFβ2 regulates expression of DNMTs in ONH astrocytes (ONHAs).
Primary human ONHAs (n=3 primary strains) were isolated and characterized as GFAP positive and αSMA negative. ONHAs were grown to 100% confluency and treated with or without 5ng/ml TGFβ2 for 24 hours. RNA was isolated and cDNA synthesis performed and subjected to qPCR for DNMT1, DNMT3a, and DNMT3b expression.
Primary human ONHAs exposed to TGFβ2 showed decreased expression for all 3 DNTMs. There was a statistically significant decrease with both DNTM3a (n=3; p<0.05) and DNTM3b (n=3; p<0.0005) expression.
These data indicate that DNMTs are expressed by human ONHA cells, and their expression is down-regulated by TGFβ2. Thus, lower levels of DNMTs may lead to hypomethylation of ECM genes, which in turn would result in increased ECM gene expression.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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