Alpha2-chimaerin, cyclin-dependent Kinase 5/p35, and its target collapsin response mediator protein-2 are essential components in semaphorin 3A-induced growth-cone collapse.
Neurite outgrowth is influenced by positive and negative signals that include the semaphorins, an important family of axonal outgrowth inhibitors. Here we report that the Rac GTPase activating protein (GAP)alpha2-chimaerin is involved in Semaphorin 3A (Sema 3A) signaling. In dorsal root ganglion neurons, Sema 3A-induced growth cone collapse was inhibited by alpha2-chimaerin mutated to eliminate GAP activity or interaction with phosphotyrosine. Activation of alpha2-chimaerin by phorbol ester caused growth cone collapse. Active alpha2-chimaerin interacts with collapsin response mediator protein-2 (CRMP-2) and cyclin-dependent kinase (Cdk) 5/p35 kinase through its SH2 and GAP domains, respectively. Cdk5 phosphorylates CRMP-2 at serine 522, possibly facilitating phosphorylation of serine 518 and threonine 514 by glycogen synthase kinase 3beta (GSK3beta), a kinase previously implicated in Sema 3A signaling. Phosphorylation of CRMP-2 serine 522 was essential for Sema 3A-induced growth cone collapse, which is dependent on Cdk5 but not Rho kinase activity. alpha2-chimaerin, like CRMP-2, can associate with the Sema 3A receptor. These results indicate that active alpha2-chimaerin Rac GAP, Cdk5/p35, and its substrate CRMP-2, are implicated in the dynamics of growth cone guidance initiated through Sema 3A signaling.
Department of Molecular Neuroscience, Institute of Neurology, University College London, London WC1N 1PJ, United Kingdom.
Matthew
M
Brown
Tom
T
Jacobs
Britta
B
Eickholt
Giovanna
G
Ferrari
Mabel
M
Teo
Clinton
C
Monfries
Robert Z
RZ
Qi
Thomas
T
Leung
Louis
L
Lim
Christine
C
Hall
D000818:Animals; D000831:Animals, Newborn; D001923:Brain Chemistry; D002478:Cells, Cultured; D020848:Chimerin 1 / Q000187:drug effects / Q000378:metabolism*; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D020536:Enzyme Activators / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010703:Phorbol Esters / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D040121:Semaphorin-3A / Q000378:metabolism / Q000493:pharmacokinetics / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D018909:src Homology Domains / Q000502:physiology
D020848:Chimerin 1; D020536:Enzyme Activators; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D010703:Phorbol Esters; D040121:Semaphorin-3A; C095114:collapsin response mediator protein-2; C089495:neuronal Cdk5 activator (p25-p35); D051360:Cyclin-Dependent Kinase 5; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; C495907:Cdk5 protein, rat; D018844:Cyclin-Dependent Kinases; D038362:Glycogen Synthase Kinase 3