Rho and Rho-associated kinase modulate the tyrosine kinase PYK2 in T-cells through regulation of the activity of the integrin LFA-1.
We have examined the role of the small GTPase Rho and its downstream effector, the Rho-associated kinase (ROCK), in the control of the adhesive and signaling function of the lymphocyte function-associated antigen-1 (LFA-1) integrin in human T-lymphocytes. Inhibition of Rho (either by treatment with C3-exoenzyme or transfection with a dominant-negative form of Rho (N19Rho)) or ROCK (by treatment with Y-27632) results in the following: (a) partial disorganization and aggregation of cortical filamentous actin (F-actin); (b) induction of LFA-1-mediated cellular adhesion to the LFA-1 ligand intercellular adhesion molecule-1 (ICAM-1) through a mechanism involving clustering of LFA-1 molecules, rather than alterations in the level of expression or in the affinity state of this integrin; and (c) induction of cellular polarization and activation of the tyrosine kinase PYK2. Transfection of T-cells with a constitutively active form of Rho (V14Rho) blocks the clustering of LFA-1 on the membrane and the LFA-1-mediated activation of PYK2. Importantly, the activation of PYK2 caused by inhibition of Rho or ROCK takes place only when the T-cells are plated onto ICAM-1 but not when they are either prevented from interacting with ICAM-1 with anti-LFA-1 blocking antibodies or when they are plated on the nonspecific poly-l-lysine substrate. These results indicate that the small GTPase Rho regulates the tyrosine kinase PYK2 in T-cells through the F-actin-mediated control of the activity of the integrin LFA-1. These findings represent a novel paradigm for the regulation of the activity of a cytoplasmic tyrosine kinase by the small GTPase Rho.
Rodríguez-Fernández
J L
JL
Instituto de Farmacología y Toxicología CSIC, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
Sánchez-Martín
L
L
Rey
M
M
Vicente-Manzanares
M
M
Narumiya
S
S
Teixidó
J
J
Sánchez-Madrid
F
F
Cabañas
C
C
D002478:Cells, Cultured; D051418:Focal Adhesion Kinase 2; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013601:T-Lymphocytes / Q000201:enzymology*; D014162:Transfection; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D016169:Lymphocyte Function-Associated Antigen-1; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; D020741:rho GTP-Binding Proteins