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The Role of MMPs, Smad3 and Heat Shock Proteins in TGF-β-Induced Anterior Subcapsular Cataract Development

Transforming growth factor beta (TGF-β) has been implicated in anterior subcapsular cataract (ASC) development. In the first section of this thesis, an in-vitro rat lens model was used to determine the role of matrix metalloproteinases during TGF-β-induced ASC. In the second part, an in-vivo TGF-β transgenic and Smad3 knockout model was used to examine the role of Smad3 signaling pathway in TGF-β-induced ASC development. Lastly, an in-vitro rat lens epithelial explant culture model was used to investigate the potential role of heat shock proteins (Hsps) in TGF-β-induced epithelial-mesenchymal transition (EMT). Optical, morphological and molecular changes were analyzed in theses studies.
Results from cultured rat lenses show a significant increase of back vertex distance variability (decrease of sharpness and focus) during ASC development. Inhibition of MMPs eliminated the TGF-β-induced plaque formation. Similarly, the overexpression of TGF-β1 in transgenic mouse lenses leads to ASC formation and a decrease in lens optical quality in comparison to wild-type lenses, while TGF-β1/Smad3-/- (null) lenses show diminished TGF-β-induced effects. The plaques formed in the TGF-β1/Smad3-/- lenses are substantially smaller than in the TGF-β1/Smad3+/+ lenses. The morphological and molecular changes of TGF-β2/FGF-2 treated rat lens epithelial explants are similar to those found in the TGF-β2 treated rat lenses and transgenic TGF-β1 mouse lenses. Heat shock treatment prior to TGF-β treatment significantly reduced the effects of EMT in rat LECs.
In conclusion, MMP inhibition prevented TGF-β-induced ASC formation whereas heat shock treatment and the absence of Smad3 protein expression only reduced the severity of TGF-β-induced effects.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OWTU.10012/3106
Date January 2007
CreatorsBanh, Alice
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeThesis or Dissertation
Format10109029 bytes, application/pdf

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