Cross-talk between miR-29 and Transforming Growth Factor-Betas in Trabecular Meshwork Cells

PURPOSE. To investigate the interactions between microRNA-29 (miR-29), a negative regulator of extracellular matrix (ECM), and transforming growth factors (TGF)beta-1 and TGF beta-2. METHODS. Changes in expression of the miR-29 family were analyzed by quantitative-PCR (Q-PCR) after treatment with TGF beta 1 and TGF beta 2 (1 ng/mL). TGF beta 1 and TGF beta 2 were evaluated at gene expression and protein levels by Q-PCR and ELISA, respectively, in human trabecular meshwork (HTM) cells transfected with miR-29b or scramble control. TGF beta 1 promoter activity was analyzed using an adenovirus with the reporter SEAP. The effects of miR-29b and TGF beta 2 on ECM gene expression were evaluated in cells transfected with miR-29b or scramble control and treated with TGF beta 2, and the expression of ECM genes was analyzed by Q-PCR. RESULTS. TGF beta 2 but not TGF beta 1, downregulated the three members of the miR-29 family. Overexpression of miR-29b antagonized the effects of TGF beta 2 on the expression of several ECM components. MiR-29b decreased the expression of TGF beta 1 at the promoter, transcript, and protein levels but had only a minor effect on the expression of active TGF beta 2. The inhibition of TGF beta 1 by miR-29b was partially recovered after co-transfection with a plasmid-expressing bone morphogenetic protein 1. CONCLUSIONS. Results showed some level of crosstalk between TGF beta s and miR-29. Specifically, the downregulation of miR-29 by TGF beta 2 contributed to the induction of several ECM components by this cytokine in TM cells. This observation, together with the inhibitory effects of miR-29b on the expression of TGF beta 1, suggests that the miR-29 family could play an important role in modulating TGF beta s on the outflow pathway. (Invest Ophthalmol Vis Sci. 2011;52:3567-3572) DOI: 10.1167/iovs.10-6448