Rnd proteins function as RhoA antagonists by activating p190 RhoGAP

TY - JOUR

T1 - Rnd proteins function as RhoA antagonists by activating p190 RhoGAP

AU - Wennerberg, Krister

AU - Forget, Marie-Annick

AU - Ellerbroek, Shawn M

AU - Arthur, William T

AU - Burridge, Keith

AU - Settleman, Jeffrey

AU - Der, Channing J

AU - Hansen, Steen H

PY - 2003/7/1

Y1 - 2003/7/1

N2 - BACKGROUND: The Rnd proteins Rnd1, Rnd2, and Rnd3 (RhoE) comprise a unique branch of Rho-family G-proteins that lack intrinsic GTPase activity and consequently remain constitutively "active." Prior studies have suggested that Rnd proteins play pivotal roles in cell regulation by counteracting the biological functions of the RhoA GTPase, but the molecular basis for this antagonism is unknown. Possible mechanisms by which Rnd proteins could function as RhoA antagonists include sequestration of RhoA effector molecules, inhibition of guanine nucleotide exchange factors, and activation of GTPase-activating proteins (GAPs) for RhoA. However, effector molecules of Rnd proteins with such properties have not been identified.RESULTS: Here we identify p190 RhoGAP (p190), the most abundant GAP for RhoA in cells, as an interactor with Rnd proteins and show that this interaction is mediated by a p190 region that is distinct from the GAP domain. Using Rnd3-RhoA chimeras and Rnd3 mutants defective in p190 binding, as well as p190-deficient cells, we demonstrate that the cellular effects of Rnd expression are mediated by p190. We moreover show that Rnd proteins increase the GAP activity of p190 toward GTP bound RhoA and, finally, demonstrate that expression of Rnd3 leads to reduced cellular levels of RhoA-GTP by a p190-dependent mechanism.CONCLUSIONS: Our results identify p190 RhoGAPs as effectors of Rnd proteins and demonstrate a novel mechanism by which Rnd proteins function as antagonists of RhoA.

AB - BACKGROUND: The Rnd proteins Rnd1, Rnd2, and Rnd3 (RhoE) comprise a unique branch of Rho-family G-proteins that lack intrinsic GTPase activity and consequently remain constitutively "active." Prior studies have suggested that Rnd proteins play pivotal roles in cell regulation by counteracting the biological functions of the RhoA GTPase, but the molecular basis for this antagonism is unknown. Possible mechanisms by which Rnd proteins could function as RhoA antagonists include sequestration of RhoA effector molecules, inhibition of guanine nucleotide exchange factors, and activation of GTPase-activating proteins (GAPs) for RhoA. However, effector molecules of Rnd proteins with such properties have not been identified.RESULTS: Here we identify p190 RhoGAP (p190), the most abundant GAP for RhoA in cells, as an interactor with Rnd proteins and show that this interaction is mediated by a p190 region that is distinct from the GAP domain. Using Rnd3-RhoA chimeras and Rnd3 mutants defective in p190 binding, as well as p190-deficient cells, we demonstrate that the cellular effects of Rnd expression are mediated by p190. We moreover show that Rnd proteins increase the GAP activity of p190 toward GTP bound RhoA and, finally, demonstrate that expression of Rnd3 leads to reduced cellular levels of RhoA-GTP by a p190-dependent mechanism.CONCLUSIONS: Our results identify p190 RhoGAPs as effectors of Rnd proteins and demonstrate a novel mechanism by which Rnd proteins function as antagonists of RhoA.

KW - 3T3 Cells

KW - Animals

KW - COS Cells

KW - Cercopithecus aethiops

KW - DNA-Binding Proteins

KW - GTPase-Activating Proteins/metabolism

KW - Gene Expression

KW - Guanine Nucleotide Exchange Factors/metabolism

KW - Mice

KW - Microscopy, Fluorescence

KW - Nuclear Proteins/metabolism

KW - Precipitin Tests

KW - Repressor Proteins

KW - Signal Transduction

KW - Two-Hybrid System Techniques

KW - rho GTP-Binding Proteins

KW - rhoA GTP-Binding Protein/antagonists & inhibitors

M3 - Journal article

C2 - 12842009

SN - 0960-9822

VL - 13

SP - 1106

EP - 1115

JO - Current Biology

JF - Current Biology

IS - 13

ER -