Transcription growth factor beta (TGFβ) mediated epithelial to mesenchymal transition (EMT) of lens epithelial cells (LEC) is known to cause posterior capsular opacification (PCO). In this work, I have focused on the TGFβ-induced EMT pathway governed by the cellular actin cytoskeleton dynamics.
This study is the first to report the involvement of transcription co-factor myocardin related transcription factor-A (MRTF-A) in TGFβ-induced EMT in the lens. Using rat lens epithelial explants, I have conclusively established that in LECs, TGFβ induces nuclear migration of MRTF-A leading to induction of αSMA expression. Furthermore, I have manipulated the intracellular translocation of MRTF-A indirectly using actin binding drugs and established that inhibiting nuclear migration of MRTF-A reduces αSMA production by the cells. In addition, direct manipulation of MRTF-A using adenoviral vectors carrying modified gene constructs show that presence of functional MRTF-A construct in the nucleus is necessary to trigger αSMA expression by causing EMT.
In order to understand the involvement of matrix metalloproteinase -9 (MMP-9) in this specific pathway, explants were treated with an MMP2/9 inhibitor and rhMMP9. I have established that rhMMP-9 does not significantly affect the intracellular migration of MRTF-A. Nevertheless, gene expression studies showed that MMP-9 induces the expression of MRTF-A. Taken together, I believe MMP-9 functions through a feedback mechanism controlling MRTF-A expression in the cell. However, the presence of MMP-9 is necessary but not sufficient for induction in MRTF-A nuclear translocation.
Overall, the work presented in this thesis demonstrates for the first time the presence of MRTF-A in LECs and successfully shows that the intracellular translocation of MRTF-A as an integral part of TGFβ induced EMT. Therefore, in the future, MRTF-A may be used as a successful target molecule to inhibit in order to prevent EMT leading to PCO. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16524 |
| Date | 06 1900 |
| Creators | Gupta, Madhuja |
| Contributors | West-Mays, Judith, Biomedical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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