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Coralia Catalina Luna, Jianming Qiu, David L Epstein, Pedro Gonzalez; Role of miR-146a in the Regulation of Gene Expression Changes Induced by Mechanical Stress in Trabecular Meshwork Cells. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4516.
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To investigate the involvement of miR-146a in the regulation of responses induced by cyclic mechanical stress (CMS) in human trabecular meshwork (HTM) cells and its effects on intraocular pressure in vivo.
Effects of miR-146a on the responses to CMS were evaluated in cells transfected with miR-146a mimic or controls transfected with scrambled microRNA. Two primary HTM cell culture lines were incubated in triplicate on flexible bottom plates and subjected to cyclic mechanical stress (20% stretching, 1 cycle per second, during 3 hours). Non-stress parallel control cultures were incubated in similar plates under identical conditions. The effects of miR-146 inhibitor were tested in one primary HTM culture. Changes in expression for miR-146a, IL6, IL8, IL1beta, BMP2, MMP3, HSP70, IRAK1, Serpin, COX1 and COX2 were analyzed by quantitative real time PCR. Three Sprague-dawley rats were injected into the anterior chamber with influenza virus (IAV) expressing miR-146a and the intraocular pressure was measured using a Tonolab rebound tonometer.
HTM cells transfected with miR-146 significantly down regulated the expression of IL6, IL8, IL1beta, BMP2, MMP3, IRAK1, Serpin, COX1 and COX2 in both primary cell lines and the inhibition of miR-146 up-regulated significantly all these genes. CMS induced (p ≤ 0.05) the expression of miR-146a (2.03 fold), COX2 (1.68), IL6 (1.65), HSP70 (1.3), serpin (1.6), IL8 (1.45) and BMP2 (1.4). These genes were also induced by CMS in cells transfected with miR-146a but the basal expression levels were lower than the stressed controls and in most cases even lower than the non-stressed controls. Preliminary data from injections of rat anterior chamber with IAV-miR146a showed a transient increase in intraocular pressure of 17% (p= 0.03).
The observed up-regulation of miR-146a in response to CMS may act as a negative modulator to multiple other responses induced by CMS in HTM cells. Alterations in expression of miR-146a, such as those observed in senescent HTM cells, could contribute to pathological elevation of IOP by altering the normostatic responses in the trabecular meshwork to the cycles of stretching and relaxation associated with the ocular pulse.
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