The role of focal adhesion kinase in the TGF-β-induced myofibroblast transdifferentiation of human Tenon's fibroblasts

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Authors: Samin Hong ; Jong Bok Lee ; Yoko Iizuka ; Yoo Kyung Song ; Gong Je Seong ; Sueng-Han Han

MeSH: Actins/metabolism ; Analysis of Variance ; Blotting, Western ; Cell Transdifferentiation/drug effects ; Cells, Cultured ; Collagen/metabolism ; Fibroblasts/cytology ; Fibroblasts/drug effects ; Fibroblasts/metabolism ; Focal Adhesion Protein-Tyrosine Kinases/metabolism* ; Humans ; Myofibroblasts ; RNA, Messenger/metabolism ; RNA, Small Interfering/metabolism ; Real-Time Polymerase Chain Reaction ; Transforming Growth Factor beta/pharmacology*

Keywords: Fibroblast ; Focal adhesion protein-tyrosine kinases ; Myofibroblast ; Transforming growth factors

Abstract: PURPOSE: To investigate the role of focal adhesion kinase (FAK) in transforming growth factor (TGF)-β-induced myofibroblast transdifferentiation of human Tenon's fibroblasts.

METHODS: Primary cultured human Tenon's fibroblasts were exposed to TGF-β1 for up to 48 hours. The mRNA levels of FAK, α smooth muscle actin (αSMA), and β-actin were determined by quantitative real time reverse transcription polymerase chain reaction. The protein levels of collagen type I, FAK, phospho-FAK, αSMA, and β-actin were determined by Western immunoblots. After the small interfering RNA targeting FAK (siRNA(FAK)) molecules were delivered into the cells, the expressions of αSMA proteins were determined by Western immunoblots.

RESULTS: In human Tenon's fibroblasts, TGF-β1 significantly increased the mRNA and protein expressions of αSMA. However, when the action of FAK was inhibited using siRNA(FAK), the TGF-β1-induced expression of αSMA was attenuated.

CONCLUSIONS: Our data suggest that FAK may be associated with the TGF-β1-induced transdifferentiation of human Tenon's fibroblasts to myofibroblasts, which is the essential step of subconjunctival fibrosis.