Regulation of Trabecular Meshwork Cell Contraction and Intraocular Pressure by miR-200c

Abstract

Lowering intraocular pressure (IOP) delays or prevents the loss of vision in primary open-angle glaucoma (POAG) patients with high IOP and in those with normal tension glaucoma showing progression. Abundant evidence demonstrates that inhibition of contractile machinery of the trabecular meshwork cells is an effective method to lower IOP. However, the mechanisms involved in the regulation of trabecular contraction are not well understood. Although microRNAs have been shown to play important roles in the regulation of multiple cellular functions, little is known about their potential involvement in the regulation of IOP. Here, we showed that miR-200c is a direct postranscriptional inhibitor of genes relevant to the physiologic regulation of TM cell contraction including the validated targets Zinc finger E-box binding homeobox 1 and 2 (ZEB1 and ZEB2), and formin homology 2 domain containing 1 (FHOD1), as well as three novel targets: lysophosphatidic acid receptor 1 (LPAR1/EDG2), endothelin A receptor (ETAR), and RhoA kinase (RHOA). Consistently, transfection of TM cells with miR-200c resulted in strong inhibition of contraction in collagen populated gels as well as decreased cell traction forces exerted by individual TM cells. Finally, delivery of miR-200c to the anterior chamber of living rat eyes resulted in a significant decrease in IOP, while inhibition of miR-200c using an adenoviral vector expressing a molecular sponge led to a significant increase in IOP. These results demonstrate for the first time the ability of a miRNA to regulate trabecular contraction and modulate IOP in vivo, making miR-200c a worthy candidate for exploring ways to alter trabecular contractility with therapeutic purposes in glaucoma.

Role of MicroRNAs in the Trabecular Meshwork

“…These results also pointed at miR-200c as an important modulator of the contractile responses in HTM cells. 93 MiR200c is known to regulate epithelial to mesenchymal transitions through repression of the transcription factors ZEB1 and ZEB2 in several cell types. 94 miR-200c also targets the regulator of stress fibers formation FHOD1.…”

“…95 We found that in HTM cells, in addition to regulating the expression of these 3 genes, miR-200c directly inhibits the expression of RhoA kinase and a number of effectors of the Rho-ROCK cascade including endothelin receptor type A (EDNRA) and lysophosphatidic acid (LPA) receptor 1 (LPAR1). 93 Both ET-1 and LPA are present in the aqueous humor and decrease aqueous humor outflow facility by mechanisms dependent on cell contraction mediated by Rho kinase signaling.…”

MicroRNA-483-3p Inhibits Extracellular Matrix Production by Targeting Smad4 in Human Trabecular Meshwork Cells

“…15,16 However, different cells and tissues have different miRNA expression profiles, participating in their own developmental and biological processes. 17,18 More and more studies have focused on the miRNAs regulating the cellular functions of TM 19 and miR-146a contributed to the senescence of TM. 20 Meanwhile, it has been reported that miRNAs could regulate and maintain ECM homeostasis.…”

Bioactive Lysophospholipids: Role in Regulation of Aqueous Humor Outflow and Intraocular Pressure in the Context of Pathobiology and Therapy of Glaucoma

“…80 In human TM cells, expression of one of the GPCR receptors of LPA, LPAR1 has been shown to be regulated by miRNA200c. 88 Most significantly, LPA perfusion has been demonstrated to increase resistance to AH outflow in enucleated porcine eyes, confirming a direct influence of LPA on AH outflow, which is expected to influence IOP. 42 Based on these consistent observations, it is deemed important to evaluate the in vivo effects of LPA and its receptor activation on IOP in live animals.…”

“…87 There is, however, overwhelming evidence that LPA influences cell adhesive, actin cytoskeletal organization, and contractile properties of TM cells derived from different species, including human and porcine. 42,80,84,88 Moreover, both TM cells and TM tissue derived from human eyes have been shown to express various LPA-specific GPCR receptors that are specific to LPA. 42 In serum-starved TM and SC cells, LPA has been shown to induce a robust increase in actin stress fibers, focal adhesions (vinculin and paxillin based), and contraction in association with increased myosin light chain (MLC) phosphorylation.…”