ROCK I-mediated activation of NF-κB by RhoB

Abstract

RhoB is a short-lived protein whose expression is increased by a variety of extra-cellular stimuli including UV irradiation, epidermal growth factor (EGF) and transforming growth factor β (TGF-β). Whereas most Rho proteins are modified by the covalent attachment of a geranylgeranyl group, RhoB is unique in that it can exist in either a geranylgeranylated (RhoB-GG) or a farnesylated (RhoB-F) form. Although each form is proposed to have different cellular functions, the signaling events that underlie these differences are poorly understood. Here we show that RhoB can activate NF-κB signaling in multiple cell types. Whereas RhoB-F is a potent activator of NF-κB, much weaker activation is observed for RhoB-GG, RhoA, and RhoC. NF-κB activation by RhoB is not associated with increased nuclear translocation of RelA/p65, but rather, by modification of the RelA/p65 transactivation domain. Activation of NF-κB by RhoB is dependent upon ROCK I but not PRK I. Thus, ROCK I cooperates with RhoB to activate NF-κB, and suppression of ROCK I activity by genetic or pharmacological inhibitors blocks NF-κB activation. Suppression of RhoB activity by dominant-inhibitory mutants, or siRNA, blocks NF-κB activation by Bcr, and TSG101, but not by TNFα or oncogenic Ras. Collectively, these observations suggest the existence of an endosomeassociated pathway for NF-κB activation that is preferentially regulated by the farnesylated form of RhoB.

Linking Phenotype to Kinase: Identification of a Novel Benzoxaborole Hinge-Binding Motif for Kinase Inhibition and Development of High-Potency Rho Kinase Inhibitors

“…Our data and that of other researchers have noted that ROCK inhibitors cause the cytokine secretion suppression of TNF-a, IL-6, and IL-1b from human macrophages, PBMCs, and synoviocytes (Doe et al, 2007;Rodriguez et al, 2007;He et al, 2008). The suppression of cytokine secretion by ROCK inhibitors in endothelial cells, leukocytes, and synoviocytes is attributed to the suppression of ROCK-mediated inactivation of IKKb and inhibition of phosphorylation of the RelA/p65 domain and by induction of IkBa phosphorylation, which leads to its degradation (Anwar et al, 2004;Rodriguez et al, 2007;He et al, 2008). As we improved the activity of ROCK, the suppressive activity against cytokine secretion of TNF-a, IL-1b, IL-6, IFN-g, IL-4, and IL-13 did not proportionally increase (Fig.…”

Physical view on migration modes

“…RhoB has been shown to localize to endocytic vesicles (Adamson et al, 1992), where it signals after activation by Vav2 (Gample and Mellor, 2002) through PRK1 to regulate the intracellular epithelial growth factor (EGF) trafficking to the lysosome (Gampel et al, 1999). In addition, RhoB activates NFkB, independently from PRK1, in a ROCK-I dependent fashion (Rodriguez et al, 2007). Moreover, RhoB is involved in the uPA/uPAR-dependent migration and invasion of prostate cancer cells.…”

Rho GTPases

“…Early work on RhoB reported that it localizes to endocytic vesicles 21 where, upon activation by Vav2, 22 it signals through PRK1 to regulate the kinetics of intracellular EGF trafficking to the lysosome 23 . Interestingly, work from Rodriguez et al revealed that RhoB activates NFκB, independently from PRK1, in a ROCK-I dependent manner 24 . More recent work from Ridley’s group has shown that the GTPase RhoB plays a key role in the uPA/uPAR-mediated migration and invasion of prostate cancer cells.…”