Phosphorylation of F-actin-associating G protein gamma12 subunit enhances fibroblast motility.
Eleven isoforms of G protein gamma subunit have been found thus far, but the precise roles of individual gamma subunits are not known. The gamma12 subunit has two unique properties: phosphorylation by protein kinase C and association with F-actin. To elucidate the role of gamma12, we overexpressed gamma12 and other gamma subunits in NIH 3T3 cells together with the beta1 subunit. The overexpressed gamma12 as well as endogenous gamma12, but not gamma2, gamma5, and gamma7 subunits, associated with cytoskeletal components. Expression of gamma12 induced remarkable changes including cell rounding, disruption of stress fibers, and enhancement of cell migration, but expression of other gamma subunits did not induce significant changes. Deletion of the N-terminal region of gamma12 decreased the abilities of gamma12 to associate with cytoskeletal fractions, to induce cell rounding, and to increase cell motility. Replacement by alanine of Ser2 of gamma12 (Ser1 of a mature gamma12 protein), a phosphorylation site for protein kinase C, eliminated these effects of gamma12, whereas a mutant in which Ser2 was replaced with glutamic acid showed effects equivalent to wild-type gamma12. These results indicate that phosphorylation of gamma12 at Ser2 enhances the motility of cells.
Ueda
H
H
Department of Biochemistry, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
Yamauchi
J
J
Itoh
H
H
Morishita
R
R
Kaziro
Y
Y
Kato
K
K
Asano
T
T
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002465:Cell Movement; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid
D000199:Actins; D019204:GTP-Binding Proteins