Targeting of focal adhesion kinase by small interfering RNAs reduces chondrocyte redifferentiation capacity in alginate beads culture with type II collagen
Article first published online: 12 NOV 2008
Copyright © 2008 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 218, Issue 3, pages 623–630, March 2009
How to Cite
Kim, Y. H. and Lee, J. W. (2009), Targeting of focal adhesion kinase by small interfering RNAs reduces chondrocyte redifferentiation capacity in alginate beads culture with type II collagen. J. Cell. Physiol., 218: 623–630. doi: 10.1002/jcp.21637
- Issue published online: 18 DEC 2008
- Article first published online: 12 NOV 2008
- Manuscript Accepted: 10 OCT 2008
- Manuscript Received: 25 APR 2008
- Stem Cell Research Center of the 21st Century Frontier Research Program, Ministry of Science
Type II collagen is a major protein that maintains biological and mechanical characteristics in articular cartilage. Focal adhesion kinase (FAK) is known to play a central role in integrin signaling of cell–extracellular matrix (ECM) interactions, and chondrocyte–type II collagen interactions are very important for cartilage homeostasis. In this study, we focused on phosphorylation of FAK and MAP kinase in chondrocyte–type II collagen interaction and dedifferentiation, and the effects of FAK knockdown on chondrocyte-specific gene expression and cell proliferation were determined. The addition of exogenous type II collagen to chondrocytes increased levels of tyrosine phosphorylation, p-FAKY397, and p-ERK1/2. In contrast, expression levels of p-FAKY397 and p-ERK1/2, but not p-Smad2/3, were decreased in dedifferentiated chondrocytes with loss of type II collagen expression. Type II collagen expression was significantly increased when dedifferentiated chondrocytes were transferred to alginate beads with TGF-β1 or type II collagen, but transfected cells with small interfering RNA for FAK (FAK-siRNA) inhibited mRNA expression of type II collagen and SOX-6 compared to the control. These FAK-siRNA-transfected cells could not recover type II collagen even in the presence of TGF-β1 or type II collagen in alginate beads culture. We also found that FAK-siRNA-transfected cells decreased cell proliferation rate, but there was no effect on glycosaminoglycans (GAGs) secretion. We suggest that FAK is essentially required in chondrocyte communication with type II collagen by regulating type II collagen expression and cell proliferation. J. Cell. Physiol. 218: 623–630, 2009. © 2008 Wiley-Liss, Inc.