Roles of Rho-associated kinase and myosin light chain kinase in morphological and migratory defects of focal adhesion kinase-null cells.
Fibroblasts derived from focal adhesion kinase (FAK)-null mouse embryos have a reduced migration rate and an increase in the number and size of peripherally localized adhesions (Ilic, D., Furuta, Y., Kanazawa, S., Takeda, N., Sobue, K., Nakatsuji, N., Nomura, S., Fujimoto, J., Okada, M., and Yamamoto, T. (1995) Nature 377, 539-544). In this study, we have found that Y27632, a specific inhibitor for Rho-associated kinase (Rho-kinase), dramatically reversed the round cell morphology of FAK(-/-) cells to a spread fibroblast-like shape in 30 min and significantly enhanced their motility. The effects of Y27632 on the FAK(-/-) cell morphology and motility were concomitant with reorganization of the actin cytoskeleton and redistribution of focal adhesions. Conversely, the expression of the constitutively active Rho-kinase in FAK(+/+) cells led to round cell shape and inhibition of cell motility. Furthermore, coincident with the formation of cortical actin filaments, myosin light chain (MLC), Ser-19-phosphorylated MLC, and MLC kinase mainly accumulated at the FAK(-/-) cell periphery. We found that the disruption of actin filaments by cytochalasin D prevented the peripheral accumulation of MLC kinase and that inhibition of myosin-mediated contractility by 2,3-butanedione monoxime induced FAK(-/-) cells to spread. Taken together, our results suggest that Rho-kinase may mediate the formation of cortical actomyosin filaments at the FAK(-/-) cell periphery, which further recruits MLC kinase to the cell periphery and generates a non-polar contractile force surrounding the cell, leading to cell rounding and decreased motility.
Chen
Bor-Huah
BH
Graduate Institute of Biomedical Sciences, National Chung Hsing University, Taichung 40227, Taiwan.
Tzen
Jason T C
JT
Bresnick
Anne R
AR
Chen
Hong-Chen
HC
D000199:Actins / Q000378:metabolism; D000818:Animals; D002465:Cell Movement; D002478:Cells, Cultured; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009219:Myosin-Light-Chain Kinase / Q000502:physiology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D054460:rho-Associated Kinases
D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase