Cataract is the most common cause of blindness in the world today. Surgery is generally very effective in restoring sight;however, a common complication is the development of posterior capsule opacification. This is caused by aberrant growth and differentiation of lens cells that remain in the capsular bag after surgery. Our approach to circumvent this problem is to identify the conditions required for normal growth and differentiation of residual lens cells and apply this new information to promote regeneration of normal lens structure and function. Our previous NEI-funded studies showed that members of the FGF growth factor family could induce fiber differentiation in vitro and subsequent studies by our group and others have now provided compelling evidence that fiber differentiation in vivo depends on FGF signaling. This knowledge is fundamental to devising strategies for lens regeneration after cataract surgery. However, if we are to successfully regenerate transparent lenses with normal focusing abilities, in addition to being able to initiate and promote fiber differentiation, we need to be able to recapitulate the coordinated cell behavior that is required to generate the exquisite three-dimensional organization of fibers (and epithelial cells) that is the central feature of normal lens morphogenesis. In our current NEI-funded project we have identified Wnt/Frizzled signaling through the planar cell polarity (Wnt-Fz/PCP) pathway as critical for promoting the precise alignment/orientation of fibers. We have also shown that epithelial cells provide a polarizing cue that aligns/orients elongating fibers. To exploit these novel findings this renewal application aims to elucidate the mechanism(s) whereby activation of Wnt-Fz/PCP signaling translates into polarized fiber cell behavior and establishes the global alignment/orientation of fibers that is critical for normal lens morphogenesis. In section 1 of the project we will use FGF to induce fiber differentiation in our well- characterized epithelial explant system to identify the mechanism whereby components of the Wnt-Fz/PCP signaling pathway organize the lens cell cytoskeleton and promote coordinated alignment/orientation. In section 2, using epithelial explants and complementary transgenic approaches we will both promote and inhibit Wnt bioavailability and/or Wnt signaling to determine if epithelial-derived Wnt ligand provides a directional cue that draws fibers to poles This project will provide vital new information about mechanisms and molecules that are required to promote the regeneration of lens structure and function and in so doing will address key objectives identified within the Lens and Cataract Program of the NEI.

Public Health Relevance

With approximately 20 million people affected, clouding of the lens (cataract) is the most common cause of blindness in the world today. Although surgery can initially be very effective in restoring sight, in the longer term complications are common and often result in the development of a secondary cataract. A central aim in our laboratory is to devise molecular strategies that (i) prevent the aberrant lens cell behavior that occurs after surgery, and (ii) promote normal patterns of lens cell growth and differentiation so that lens clarity is maintained.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003177-32
Application #
8585848
Study Section
Special Emphasis Panel (ZRG1-BDCN-H (02))
Program Officer
Araj, Houmam H
Project Start
1991-09-30
Project End
2015-11-30
Budget Start
2013-12-01
Budget End
2014-11-30
Support Year
32
Fiscal Year
2014
Total Cost
$177,134
Indirect Cost
$13,121
Name
University of Sydney
Department
Type
DUNS #
752389338
City
Sydney
State
Country
Australia
Zip Code
2006
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McAvoy, J W; Dawes, L J; Sugiyama, Y et al. (2016) Intrinsic and extrinsic regulatory mechanisms are required to form and maintain a lens of the correct size and shape. Exp Eye Res :
Sugiyama, Yuki; Shelley, Elizabeth J; Yoder, Bradley K et al. (2016) Non-essential role for cilia in coordinating precise alignment of lens fibres. Mech Dev 139:10-7
Audette, Dylan S; Anand, Deepti; So, Tammy et al. (2016) Prox1 and fibroblast growth factor receptors form a novel regulatory loop controlling lens fiber differentiation and gene expression. Development 143:318-28
Lovicu, F J; Shin, E H; McAvoy, J W (2016) Fibrosis in the lens. Sprouty regulation of TGFβ-signaling prevents lens EMT leading to cataract. Exp Eye Res 142:92-101
Zhao, Guannan; Wojciechowski, Magdalena C; Jee, Seonah et al. (2015) Negative regulation of TGFβ-induced lens epithelial to mesenchymal transition (EMT) by RTK antagonists. Exp Eye Res 132:9-16
Sugiyama, Yuki; Shelley, Elizabeth J; Badouel, Caroline et al. (2015) Atypical Cadherin Fat1 Is Required for Lens Epithelial Cell Polarity and Proliferation but Not for Fiber Differentiation. Invest Ophthalmol Vis Sci 56:4099-107
Dawes, L J; Sugiyama, Y; Lovicu, F J et al. (2014) Interactions between lens epithelial and fiber cells reveal an intrinsic self-assembly mechanism. Dev Biol 385:291-303
Dawes, Lucy J; Sugiyama, Yuki; Tanedo, Ana S et al. (2013) Wnt-frizzled signaling is part of an FGF-induced cascade that promotes lens fiber differentiation. Invest Ophthalmol Vis Sci 54:1582-90
Wang, Chunxiao; Dawes, Lucy J; Liu, Yizhi et al. (2013) Dexamethasone influences FGF-induced responses in lens epithelial explants and promotes the posterior capsule coverage that is a feature of glucocorticoid-induced cataract. Exp Eye Res 111:79-87

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