YAP and TAZ mediate steroid-induced alterations in the trabecular meshwork cytoskeleton in human trabecular meshwork cells

Abstract

Primary open angle glaucoma is an important type of glaucoma as it is one of the most common causes of blindness. Previous studies have demonstrated that in glaucomatous patients, the human trabecular meshwork (HTM) is markedly stiffened. The purpose of the present study was to determine the regulatory role of Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) in HTM cells. Primary HTM cells were cultured with different concentrations of dexamethasone (DEX), and the expression levels of YAP and TAZ were evaluated using reverse transcription-quantitative polymerase chain reaction and western blotting. The results revealed that DEX increased the expression of YAP and TAZ in a dose-dependent manner. In addition, the western blot analysis of cytoskeleton-associated proteins revealed that the inhibition of YAP and/or TAZ using small interfering RNA resulted in the increased expression of collagen I, and decreased expression of fibronectin, laminin and collagen IV. The expression of β-catenin, a key protein in the Wnt pathway, was also observed to be regulated by YAP and TAZ. A 5-ethynyl-2′-deoxyuridine staining assay indicated that YAP and TAZ induced the proliferation of HTM cells. The investigation of cross-linked actin network formation by the HTM cells demonstrated that the knockdown of YAP and TAZ genes rescued HTM cells from cytoskeletal reorganization. Furthermore, functional evaluation of a HTM cell monolayer using a permeability assay demonstrated that the inhibition of YAP and TAZ attenuated the DEX-induced impairment of permeability. These findings suggest that YAP and TAZ play pivotal roles in the DEX-induced cytoskeletal changes of HTM cells, and reveal novel potential mechanisms for the development and progression of glaucoma.

Lysophosphatidic Acid Induces ECM Production via Activation of the Mechanosensitive YAP/TAZ Transcriptional Pathway in Trabecular Meshwork Cells

“… 7 , 26 Our study also supports previous observations regarding the effects of ECM stiffness, the actin cytoskeleton and dexamethasone on YAP/TAZ activation in TM cells and AH outflow in both normal and glaucomatous eyes. 28 , 29 , 66 Finally, this study provides mechanistic insights into the importance of pharmacologic agents targeting molecules that regulate TM contractile activity, cell-adhesive interactions, YAP/TAZ activation, and fibrogenic activities, to lower IOP in glaucoma patients.…”

The Molecular Processes in the Trabecular Meshwork After Exposure to Corticosteroids and in Corticosteroid-Induced Ocular Hypertension

“…They also found that the average relative protein abundance over all dexamethasone-treated TM cell samples (glaucomatous and nonglaucomatous together) did not show a significant change in fibronectin protein expression. In contrast, Honjo et al., 46 Peng et al., 47 Filla et al., 48 and Zhou et al. 49 reported that the protein expression of fibronectin was significantly increased after exposing human TM cells to dexamethasone.…”

“…They also found that the average relative protein abundance over all dexamethasone-treated TM cell samples (glaucomatous and nonglaucomatous together) did not show a significant change in fibronectin protein expression. In contrast, Honjo et al, 46 Peng et al, 47 Filla et al, 48 Downloaded from iovs.arvojournals.org on 09/06/2020 and Zhou et al 49 reported that the protein expression of fibronectin was significantly increased after exposing human TM cells to dexamethasone. Additionally, Li et al 50 reported the fibronectin protein secretion to be significantly increased in four human TM cell strains but to be decreased in one human TM cell strain after exposure to dexamethasone (both after 1 and 4 weeks of exposure).…”

Integrative transcriptomic and proteomic analysis reveals CD9/ITGA4/PI3K‐Akt axis mediates trabecular meshwork cell apoptosis in human glaucoma

“…High IOP is the major risk factor of glaucoma, and repression of IOP is the important treatment of glaucoma in clinic. 24,25 Maintenance of IOP is depended on the dynamic balance of aqueous humour generation and out-flow. An elevated IOP is caused by excessive resistance to the out-flow of the aqueous humour.…”

“…Thus, it is urgent to uncover the molecular mechanism of glaucoma. High IOP is the major risk factor of glaucoma, and repression of IOP is the important treatment of glaucoma in clinic . Maintenance of IOP is depended on the dynamic balance of aqueous humour generation and out‐flow.…”