Rho-associated kinase, a novel serine/threonine kinase, as a putative target for small GTP binding protein Rho.

Abstract

The small GTP binding protein Rho is implicated in cytoskeletal responses to extracellular signals such as lysophosphatidic acid to form stress fibers and focal contacts. Here we have purified a Rho‐interacting protein with a molecular mass of approximately 164 kDa (p164) from bovine brain. This protein bound to GTPgammaS (a non‐hydrolyzable GTP analog).RhoA but not to GDP.RhoA or GTPgammaS.RhoA with a mutation in the effector domain (RhoAA37).p164 had a kinase activity which was specifically stimulated by GTPgammaS.RhoA. We obtained the cDNA encoding p164 on the basis of its partial amino acid sequences and named it Rho‐associated kinase (Rho‐kinase). Rho‐kinase has a catalytic domain in the N‐terminal portion, a coiled coil domain in the middle portion and a zinc finger‐like motif in the C‐terminal portion. The catalytic domain shares 72% sequence homology with that of myotonic dystrophy kinase and the coiled coil domain contains a Rho‐interacting interface. When COS7 cells were cotransfected with Rho‐kinase and activated RhoA, some Rho‐kinase was recruited to membranes. Thus it is likely that Rho‐kinase is a putative target serine/threonine kinase for Rho and serves as a mediator of the Rho‐dependent signaling pathway.

Neuropeptide-stimulated cell migration in prostate cancer cells is mediated by RhoA kinase signaling and inhibited by neutral endopeptidase

“…Bombesin (10 nM; panel c) and ET-1 (10 nM; panel e) stimulated actin stress fiber formation in PC-3 cells. The Rho-associated coiled-coil forming protein kinases p160ROCK/ROCK-1 (Ishizaki et al, 1996 and ROCK-a/ROCK-2 (Leung et al, 1996;Matsui et al, 1996) are direct downstream effectors of RhoA that regulate actin stress fiber formation. They are specifically inhibited by the synthetic pyridine derivative, Y-27632 (Uehata et al, 1997;Ishizaki et al, 2000).…”

ROCK‐I and ROCK‐II, two isoforms of Rho‐associated coiled‐coil forming protein serine/threonine kinase in mice

“…ROCK may also be present in related intracellular compartments and be involved in Rho-mediated cytoskeletal regulation. Recently, Leung et al [20] and Matsui et al [21] identified rat and bovine protein kinases as putative Rho targets, which are homologous to human p160 ROCK. The sequences of these protein kinases show much higher homology with mouse ROCK-II than mouse ROCK-I, although the reported rat sequence does not contain the segment corresponding to the amino-terminal region of ROCK-II.…”

Farnesylated RhoB inhibits radiation-induced mitotic cell death and controls radiation-induced centrosome overduplication

“…Among the known downstream effectors of Rho proteins, Rho kinases might be potential candidates for mediating RhoB-F effect on centrosome overduplication and mitotic cell death. Rho kinases have been localized at the cell membrane, 29 at the cleavage furrow in late mitosis, 30 and, more recently, for p160ROCK in centrosomes. 31 Furthermore, p160ROCK is required for centrosomal positioning and centrosome-dependent exit from mitosis.…”