Abstract
Purpose: :
Suppression of tissue inhibitor of matrix metallo proteinase 3 (TIMP3) has been shown to exacerbate retinal neovascularization (RNV). We have previously shown that MicroRNA-21 (MiR-21) is up-regulated in retinal microvascular endothelial cells (RECs) exposed to hypoxia. Because TIMP3 is a potential target of miR-21, in this study we determined whether up-regulation of miR-21resulted in suppression of TIMP3 gene expression in RECs exposed to hypoxia.
Methods: :
RECs of human and bovine origins were exposed to hypoxic conditions (pO2≤ 2%) for 2, 4 and 6 hours. TIMP3 expression was measured at mRNA and protein levels by quantitative PCR (qPCR) and Western blotting analysis, respectively. MiR-21 expression was assessed by qPCR. Inhibition of miR-21 expression in hypoxic RECs was achieved by overexpression of antagomiR-21.
Results: :
The expression of miR-21 was significantly up-regulated in RECs exposed to hypoxia (peak at 2hours), whereas TIMP3 was down-regulated at mRNA and protein level at 4 and 6 hours of hypoxia, respectively. Overexpression of antagomiR-21 blocked hypoxia-induced suppression of TIMP3 gene expression and also restored protein level.
Conclusions: :
Our data show that hypoxia inhibits TIMP3 expression in retinal endothelial cells through a mechanism involving up-regulation of miR-21 expression. Thus, this study suggests that regulation of TIMP3 and neovascularization in the ischemic retina may involve miR-21 up-regulation and function.
Keywords: retinal neovascularization • hypoxia • gene/expression