Regulation of the association of adducin with actin filaments by Rho-associated kinase (Rho-kinase) and myosin phosphatase.
The small GTPase Rho is believed to regulate the actin cytoskeleton and cell adhesion through its specific targets. We previously identified the Rho targets: protein kinase N, Rho-associated kinase (Rho-kinase), and the myosin-binding subunit (MBS) of myosin phosphatase. Here we purified MBS-interacting proteins, identified them as adducin, and found that MBS specifically interacted with adducin in vitro and in vivo. Adducin is a membrane-skeletal protein that promotes the binding of spectrin to actin filaments and is concentrated at the cell-cell contact sites in epithelial cells. We also found that Rho-kinase phosphorylated alpha-adducin in vitro and in vivo and that the phosphorylation of alpha-adducin by Rho-kinase enhanced the interaction of alpha-adducin with actin filaments in vitro. Myosin phosphatase composed of the catalytic subunit and MBS showed phosphatase activity toward alpha-adducin, which was phosphorylated by Rho-kinase. This phosphatase activity was inhibited by the phosphorylation of MBS by Rho-kinase. These results suggest that Rho-kinase and myosin phosphatase regulate the phosphorylation state of adducin downstream of Rho and that the increased phosphorylation of adducin by Rho-kinase causes the interaction of adducin with actin filaments.
Kimura
K
K
Department of Anatomy and Neurobiology, Graduate School of Medicine, Kyoto University, Konoe-Yoshida, Sakyo-ku, Kyoto 606, Japan.
Fukata
Y
Y
Matsuoka
Y
Y
Bennett
V
V
Matsuura
Y
Y
Okawa
K
K
Iwamatsu
A
A
Kaibuchi
K
K
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D017487:Ankyrins / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002460:Cell Line; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D043263:Myosin-Light-Chain Phosphatase; D010748:Phosphopeptides / Q000032:analysis; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054460:rho-Associated Kinases; D000099291:Adducins
D000199:Actins; D017487:Ankyrins; D002148:Calmodulin-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D043263:Myosin-Light-Chain Phosphatase; D010748:Phosphopeptides; D010749:Phosphoprotein Phosphatases; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins; D054460:rho-Associated Kinases; D000099291:Adducins