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Phosphorylation of ERM proteins at filopodia induced by Cdc42
Author(s) -
Nakamura Nao,
Oshiro Noriko,
Fukata Yuko,
Amano Mutsuki,
Fukata Masaki,
Kuroda Shinya,
Matsuura Yoshiharu,
Leung Thomas,
Lim Louis,
Kaibuchi Kozo
Publication year - 2000
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2000.00348.x
Subject(s) - filopodia , phosphorylation , microbiology and biotechnology , cdc42 , ezrin , moesin , biology , radixin , kinase , protein kinase c , cytoskeleton , biochemistry , actin , cell
Background ERM (ezrin, radixin, and moesin) proteins function as membrane‐cytoskeletal linkers, and are known to be localized at filopodia and microvilli‐like structures. We have shown that Rho‐associated kinase (Rho‐kinase)/ROKα/ROCK II phosphorylates moesin at Thr‐558 at the lower stream of Rho, and the phosphorylation is crucial to the formation of microvilli‐like structures (Oshiro, N., Fukata, Y. & Kaibuchi, K. (1998) Phosphorylation of moesin by Rho‐associated kinase (Rho‐kinase) plays a crucial role in the formation of microvilli‐like structures. J. Biol. Chem . 273, 34663– 34666). However, the role of ERM proteins in the formation of filopodia is less well characterized. Results Here we examined the phosphorylation state of ERM during filopodia formation induced by Cdc42 using the antibody recognizing ERM proteins phosphorylated at COOH (C)‐terminal threonine. When NIH 3T3 cells were transfected with constitutively active Cdc42 (Cdc42 V12 ), filopodia formation was induced and phosphorylation of ERM at C‐terminal threonine was observed at the tip of filopodia, while the phosphorylation levels of ERM were lower and phosphorylated ERM was distributed throughout the cytoplasm in the control cells. We also showed that M yotonic dystrophy kinase‐ r elated Cdc42‐binding k inase (MRCK) which has been identified as an effector of Cdc42, phosphorylated moesin at C‐terminal threonine in a cell‐free system. Coexpression of the dominant negative form of MRCK inhibited both the formation of filopodia and accumulation of C‐terminal threonine‐phosphorylated ERM proteins at filopodia induced by Cdc42 V12 . Conclusion The formation of filopodia induced by Cdc42 is accompanied by phosphorylation of ERM proteins, and MRCK is a candidate for the kinase that phosphorylates ERM proteins at filopodia.