Cytoskeletal rearrangements and transcriptional activation of c-fos serum response element by Rho-kinase.
The small GTPase Rho is implicated in cytoskeletal rearrangements including stress fiber and focal adhesion formation and in the transcriptional activation of c-fos serum response element. In vitro, Rho-kinase, which is activated by Rho, phosphorylates not only myosin light chain (MLC) (thereby activating myosin ATPase) but also myosin phosphatase, thus inactivating myosin phosphatase. Rho-kinase is involved in the formation of stress fibers and focal adhesions in fibroblasts. Here we show that the expression of constitutively active Rho-kinase increased the level of MLC phosphorylation. The activity of Rho-kinase was necessary for maintaining the vinculin-containing focal adhesions, whereas organized actin stress fibers were not necessary for this. The microinjection of constitutively active Rho-kinase into fibroblasts induced the formation of focal adhesions to some extent under the conditions where organized actin stress fibers were disrupted. The expression of constitutively active Rho-kinase also stimulated the transcriptional activity of c-fos serum response element. These results suggest that Rho-kinase has distinct roles in divergent pathways downstream of Rho, which include MLC phosphorylation leading to stress fiber formation, focal adhesion formation, and gene expression.
Chihara
K
K
Division of Signal Transduction, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-01, Japan.
Amano
M
M
Nakamura
N
N
Yano
T
T
Shibata
M
M
Tokui
T
T
Ichikawa
H
H
Ikebe
R
R
Ikebe
M
M
Kaibuchi
K
K
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002448:Cell Adhesion; D002460:Cell Line; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D018994:Myosin Light Chains / Q000096:biosynthesis / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D026362:Serum Response Factor; D018411:Spodoptera; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D016596:Vinculin / Q000378:metabolism; D054460:rho-Associated Kinases
D000199:Actins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D026362:Serum Response Factor; D014157:Transcription Factors; D016596:Vinculin; D015638:Cytochalasin D; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009218:Myosins