Abstract
Purpose: :
The microRNA miR-29 inhibits production and deposition of extracellular matrix (ECM) in human trabecular meshwork (HTM) cells. Here, we investigate if miR-29 may play a role on the effects induced by prostaglandin E2 (PGE2), TGFbetas, and the Wnt pathway in HTM cells.
Methods: :
Primary HTM cells were treated with 5µM of PGE2, 1ng/ml of TGFbeta-2 or TGFbeta-1, 20mM LiCl, or 40 picomolar of miR-29b mimic or scramble. Expression of miR-29a/b/c was analyzed by Q-PCR. TGFbeta-1 and TGFbeta-2 proteins were quantified by ELISA. Activity of the TGFbeta-1 promoter was measured using an adenovirus expressing secreted alkaline phosphatase. Effects on the Wnt pathway were evaluated using Wnt Signaling Pathway PCR Arrays (SABiosciences).
Results: :
The three paralogs of miR-29 family (miR-29a/b/c) were significantly up-regulated by PGE2 (>2 fold; p-value 2fold for LiCl and 1.5 fold fold for TGFbeta-2; p-values < 0.01). MiR-29b decreased expression of TGFbeta-1 and TGFbeta-2 proteins (45% for TGbeta-1 and 10% TGbeta-2; p-values <0.05) as well as the activity of the TGFbeta-1 promoter (25%, p-value <0.05). MiR-29b also affected the expression of several genes from the Wnt pathway including FZD1, FZD6, FZD8, WNT3A, WNT5A, WNT7A, WNT8A, WNT9A and WNT16, and leads to decreased expression of beta-catenin target genes such as FOS and JUN.
Conclusions: :
The presence of negative feed-back loops between the miR-29 and the TGFbetas and Wnt pathways might play an important role on the antifibrotic effects of this microRNA in HTM cells. Our results also suggest that changes in expression of miR-29 could play an important role in mediating some of the effects mediated by both prostaglandins and TGFbeta-2 in the outflow pathway not only through direct targeting of ECM genes by miR-29, but also through inhibition of the Wnt and TGFbeta signaling pathways.
Keywords: trabecular meshwork • extracellular matrix • gene/expression