June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Hic-5, a Focal Adhesion Scaffolding Protein and Co-activator of Glucocorticoid Receptor Induces Actin Cytoskeletal Reorganization, Focal Adhesions, Collagen-1 and Myocilin in Human Trabecular Meshwork Cells
Author Affiliations & Notes
  • Padmanabhan P Pattabiraman
    Ophthalmology, Duke University Medical Center, Durham, NC
  • Vasanth Rao
    Ophthalmology, Duke University Medical Center, Durham, NC
    Pharamacology, Duke University, Durham, NC
  • Footnotes
    Commercial Relationships Padmanabhan Pattabiraman, None; Vasanth Rao, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 3274. doi:
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      Padmanabhan P Pattabiraman, Vasanth Rao, ; Hic-5, a Focal Adhesion Scaffolding Protein and Co-activator of Glucocorticoid Receptor Induces Actin Cytoskeletal Reorganization, Focal Adhesions, Collagen-1 and Myocilin in Human Trabecular Meshwork Cells. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3274.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: To explore the role of Hic-5, a TGF-beta and H2O2 inducible focal adhesion protein and co-activator of glucocorticoid receptor, in regulation of actin cytoskeletal organization, fibrogenic response and myocilin expression in human trabecular meshwork (HTM) cells.

Methods: Expression and distribution of Hic-5 in human aqueous humor (AH) outflow tissues, and regulation of Hic-5 expression and redistribution by RhoA, TGFβ2 and dexamethasone was investigated. The effects of adenovirus-mediated overexpression and siRNA-mediated deficiency of Hic-5, on actin cytoskeletal organization, focal adhesion formation, induction of myocilin, α-smooth muscle actin (α-SMA) and collagen-1A in HTM cells were determined by immunofluorescence and immunoblotting analyses.

Results: Hic-5 is distributed throughout the AH outflow pathway in the human eye including TM, Schlemm’s canal and juxtacanalicular tissues. In HTM cells, Hic-5 co-distributes with vinculin to the tips of actin stress fibers. Constitutively active RhoA (RhoAV14) and TGFβ2 significantly increased Hic-5 expression and led to reorganization of Hic-5 distribution in HTM cells. SMAD2/3 inhibition decreased the effect of TGFβ2-mediated induction of Hic-5 expression. Dexamethasone treatment led to redistribution of Hic-5 predominantly to the focal points of cross linked actin network (CLAN) like structures. Expression of recombinant Hic-5 in HTM cells induced bundling and crosslinking of actin filament and caused significant increase in the levels of myocilin and α-SMA and collagen 1A relative to GFP expressing control cells. Deficiency of Hic-5 led to loss of TGFβ2 and Dexamethasone- induced reorganization of actin as well as significant decreases in protein levels of myocilin, α-SMA and collagen 1A in TM cells.

Conclusions: Taken together, the findings from this study suggest that Hic-5 likely plays a crucial role downstream of Rho GTPase and TGF-β, to influence TM cell actin cytoskeletal organization and focal adhesion formation, and regulate the expression of myocilin, α-SMA and collagen-1. Therefore, Hic-5 dysregulation in TM cells is expected to affect mechanotransduction, cell plasticity and glucocorticoid responses and ultimately drive resistance to AH outflow through the TM.

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