Phosphorylation of vimentin by Rho-associated kinase at a unique amino-terminal site that is specifically phosphorylated during cytokinesis.
We found that vimentin, the most widely expressed intermediate filament protein, served as an excellent substrate for Rho-associated kinase (Rho-kinase) and that vimentin phosphorylated by Rho-kinase lost its ability to form filaments in vitro. Two amino-terminal sites on vimentin, Ser38 and Ser71, were identified as the major phosphorylation sites for Rho-kinase, and Ser71 was the most favored and unique phosphorylation site for Rho-kinase in vitro. To analyze the vimentin phosphorylation by Rho-kinase in vivo, we prepared an antibody GK71 that specifically recognizes the phosphorylation of vimentin-Ser71. Ectopic expression of constitutively active Rho-kinase in COS-7 cells induced phosphorylation of vimentin at Ser71, followed by the reorganization of vimentin filament networks. During the cell cycle, the phosphorylation of vimentin-Ser71 occurred only at the cleavage furrow in late mitotic cells but not in interphase or early mitotic cells. This cleavage furrow-specific phosphorylation of vimentin-Ser71 was observed in the various types of cells we examined. All these accumulating observations increase the possibility that Rho-kinase may have a definite role in governing regulatory processes in assembly-disassembly and turnover of vimentin filaments at the cleavage furrow during cytokinesis.
Goto
H
H
Laboratory of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Aichi 464, Japan.
Kosako
H
H
Tanabe
K
K
Yanagida
M
M
Sakurai
M
M
Amano
M
M
Kaibuchi
K
K
Inagaki
M
M
D000595:Amino Acid Sequence; D000705:Anaphase; D000818:Animals; D019556:COS Cells; D002417:Cattle; D002455:Cell Division; D019084:Fluorescent Antibody Technique, Indirect; D019204:GTP-Binding Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007158:Immunologic Techniques; D007382:Intermediate Filaments / Q000648:ultrastructure; D047908:Intracellular Signaling Peptides and Proteins; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism*; D020741:rho GTP-Binding Proteins; D054460:rho-Associated Kinases
D047908:Intracellular Signaling Peptides and Proteins; D014746:Vimentin; D010768:Phosphoserine; D006160:Guanosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins