Determining Mechanisms by which Pathological Extracellular Matrix induces Ocular Hypertensive Phenotypes in Human Trabecular Meshwork Cells

Purpose: Aberrant extracellular matrix (ECM) remodeling is prevalent in several sight-threatening diseases; in the trabecular meshwork (TM), it is implicated in elevated intraocular pressure (IOP), the only treatable risk factor for glaucoma. Herein, two different glaucoma-relevant cell-derived matrices (CDMs) were used to dissect the specific mechanisms by which diseased ECMs may precipitate ocular hypertensive phenotypes in human TM (hTM) cells. Methods: (1) To determine whether dexamethasone (DEX)/glucocorticoid-induced matrix (GIM) temporally modulate mechanoreceptors / contractility / stiffness in hTM cells, hTM cells were treated with DEX/vehicle or cultured on GIM/VehM for 1/3/5/7 days. (2) To determine whether GIM modulates transforming growth factor beta-2 (TGFβ2) signaling in hTM cells, hTM cells were cultured on GIM/VehM for 24h or 7d in the presence/absence of TGFβ2, with/without type I TGFβ receptor inhibitor (TGFβRi). (3) To determine whether genipin-induced crosslinked CDM (XCDM) stiffens hTM cells via dysregulating β-catenin and Yes-associated protein (YAP)/Transcriptional co-activator with a PDZ-binding motif (TAZ) signaling pathways, hTM cells were seeded on CDMs/XCDMs for 24h. Where applicable, immunocytochemistry, RT-qPCR, Western blotting, enzymatic assays, transmission/scanning electron and atomic force microscopies were performed. Results: (1) Whereas DEX temporally overexpressed αV, β3 and β5 integrins, integrin linked kinase, α-Smooth muscle actin(α-SMA) and RhoA in hTM cells, GIM temporally upregulated αV integrin, Cavin1, and RhoA; and increased α-SMA and cell stiffness independent of time. (2) GIM triggered non-Smad/TGFβ2 signaling in hTM cells, correlated with overexpression of key ECM structural/matricellular/crosslinking/turnover genes/enzymes; whereas GIM+TGFβ2 activated Smad and non-Smad/TGFβ2 signaling, associated with increased cell contractility and heightened upregulation of aforementioned and new ECM genes/enzymes. TGFβRi abrogated GIM-/GIM+TGFβ-mediated increased contractility or ECM deposition. (3) At the highest genipin concentration (10%XCDM), XCDM had increased crosslinks, appeared morphologically fused, and was stiffer (5.3-fold, p<0.001). On 10%XCDM, hTM cells were 7.8-fold (p<0.001) stiffer, associated with impaired nucleocytoplasmic shuttling of inactive β-catenin, reduced Cadherin-11, and key Wnt target genes/proteins; and increased cytoplasmic TAZ levels, reduced YAP levels in the nucleus and critical YAP/TAZ target genes/proteins. Wnt activation rescued hTM cells from 10%XCDM-induced stiffening correlated with increased nuclear β-catenin. Conclusions: These data highlight critical signaling pathways/mediators that may instruct design of novel therapeutics in ameliorating pathological ECM-mediated fibrotic phenotypes in hTM cells associated with elevated IOP.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physiological Optics and Vision Science

Grantor

University of Houston

Year dc:date.issued

2020

Author dc:creator

• Yemanyi, Felix

Advisor dc:contributor.advisor

• Raghunathan, Vijaykrishna

Committee members dc:contributor.committeemember

• Patel, Nimesh B.
• Frishman, Laura J.
• Vranka, Janice A.

• Extracellular matrix
• Trabecular meshwork
• Mechanotransduction
• Fibrotic phenotypes
• Ocular hypertension
• Glaucoma

Statement dc:rights

• The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/10657/7767

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/7767