CRMP-2 binds to tubulin heterodimers to promote microtubule assembly.
Regulated increase in the formation of microtubule arrays is thought to be important for axonal growth. Collapsin response mediator protein-2 (CRMP-2) is a mammalian homologue of UNC-33, mutations in which result in abnormal axon termination. We recently demonstrated that CRMP-2 is critical for axonal differentiation. Here, we identify two activities of CRMP-2: tubulin-heterodimer binding and the promotion of microtubule assembly. CRMP-2 bound tubulin dimers with higher affinity than it bound microtubules. Association of CRMP-2 with microtubules was enhanced by tubulin polymerization in the presence of CRMP-2. The binding property of CRMP-2 with tubulin was apparently distinct from that of Tau, which preferentially bound microtubules. In neurons, overexpression of CRMP-2 promoted axonal growth and branching. A mutant of CRMP-2, lacking the region responsible for microtubule assembly, inhibited axonal growth and branching in a dominant-negative manner. Taken together, our results suggest that CRMP-2 regulates axonal growth and branching as a partner of the tubulin heterodimer, in a different fashion from traditional MAPs.
Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya 466-8550, Japan.
Yuko
Y
Fukata
Tomohiko J
TJ
Itoh
Toshihide
T
Kimura
Céline
C
Ménager
Takashi
T
Nishimura
Takashi
T
Shiromizu
Hiroyasu
H
Watanabe
Naoyuki
N
Inagaki
Akihiro
A
Iwamatsu
Hirokazu
H
Hotani
Kozo
K
Kaibuchi
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D002460:Cell Line; D002522:Chlorocebus aethiops; D019281:Dimerization; D005347:Fibroblasts / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000378:metabolism; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*; D014709:Vero Cells
D036341:Intercellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D014404:Tubulin; C095114:collapsin response mediator protein-2; D049452:Green Fluorescent Proteins