RhoA inhibits the nerve growth factor-induced Rac1 activation through Rho-associated kinase-dependent pathway.
The Rho family of small GTPases has been shown to be involved in the regulation of neuronal morphology, and Rac and Rho exert antagonistic actions in neurite formation. In this study, we have examined the cross-talk between Rac and Rho in relation to the nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. NGF induced a rapid activation of Rac1 and suppression of RhoA activity. Constitutively active RhoA, RhoA(V14), or constitutively active Galpha(12)-induced endogenous RhoA activation inhibited the NGF-induced Rac1 activation without any effect on the NGF-induced extracellular signal-regulated kinase activation. Moreover, Y-27632, an inhibitor of Rho-associated kinase, completely abolished the RhoA-induced down-regulation of the NGF-induced Rac1 activation. We also revealed that NGF induced a rapid recruitment of Rac1 to the cell surface protrusion sites and formed filamentous actin-rich protrusions. Activation of RhoA and Rho-associated kinase formed a thick ringlike structure of cortical actin filaments at the cell periphery and then inhibited the NGF-induced recruitment of Rac1 to protrusions. These results indicate that RhoA down-regulates the NGF- induced Rac1 activation through Rho-associated kinase, inhibiting the neurite formation.
Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Y
Y
Yamaguchi
H
H
Katoh
H
H
Yasui
K
K
Mori
M
M
Negishi
D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000818:Animals; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D000199:Actins; D000577:Amides; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; C108830:Y 27632; D020932:Nerve Growth Factor; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020928:Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein