Phosphorylation of CLASP2 by GSK-3beta regulates its interaction with IQGAP1, EB1 and microtubules.
Polarised cell migration is required for various cell behaviours and functions. Actin and microtubules are coupled structurally and distributed asymmetrically along the front-rear axis of migrating cells. CLIP-associating proteins (CLASPs) accumulate near the ends of microtubules at the front of migrating cells to control microtubule dynamics and cytoskeletal coupling. Regional inhibition of GSK-3beta is responsible for this asymmetric distribution of CLASPs. However, it is not known how GSK-3beta regulates the activity of CLASPs for linkage between actin and microtubules. Here we identified IQGAP1, an actin-binding protein, as a novel CLASP-binding protein. GSK-3beta directly phosphorylates CLASP2 at Ser533 and Ser537 within the region responsible for the IQGAP1 binding. Phosphorylation of CLASP2 results in the dissociation of CLASP2 from IQGAP1, EB1 and microtubules. At the leading edges of migrating fibroblasts, CLASP2 near microtubule ends partially colocalises with IQGAP1. Expression of active GSK-3beta abrogates the distribution of CLASP2 on microtubules, but not that of a nonphosphorylatable CLASP2 mutant. The phosphorylated CLASP2 does not accumulate near the ends of microtubules at the leading edges. Thus, phosphorylation of CLASP2 by GSK-3beta appears to control the regional linkage of microtubules to actin filaments through IQGAP1 for cell migration.
Watanabe
Takashi
T
Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, Nagoya, Aichi, Japan.
Noritake
Jun
J
Kakeno
Mai
M
Matsui
Toshinori
T
Harada
Takumi
T
Wang
Shujie
S
Itoh
Norimichi
N
Sato
Kazuhide
K
Matsuzawa
Kenji
K
Iwamatsu
Akihiro
A
Galjart
Niels
N
Kaibuchi
Kozo
K
D000818:Animals; D019556:COS Cells; D002465:Cell Movement; D016764:Cell Polarity; D002522:Chlorocebus aethiops; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D034421:Sus scrofa; D014709:Vero Cells; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000737:chemistry / Q000378:metabolism*
C405804:EB1 microtubule binding proteins; C101203:IQ motif containing GTPase activating protein 1; D008869:Microtubule-Associated Proteins; D020703:ras GTPase-Activating Proteins; D010768:Phosphoserine; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D020830:rac1 GTP-Binding Protein