Off the beaten paths: alternative and crosstalk regulation of Rho GTPases.
Rho proteins are small GTPases of the Ras superfamily that regulate a wide variety of biological processes, ranging from gene expression to cell migration. Mechanistically, the major Rho GTPases function as molecular switches cycling between an inactive GDP-bound and an active GTP-bound conformation, although several Rho proteins spontaneously exchange nucleotides or are simply devoid of GTPase activity. For over a decade, RhoGEFs and RhoGAPs have been established as the mainstream regulators of Rho proteins, respectively flipping the switch on or off. However, regulation by GEFs and GAPs leaves several fundamental questions on the operation of the Rho switch unanswered, indicating that the regulation of Rho proteins does not rely exclusively on RhoGEFs and RhoGAPs. Recent evidence indeed suggests that Rho GTPases are finely tuned by multiple alternative regulatory mechanisms, including post-translational modifications and protein degradation, as well as crosstalk mechanisms between Rho proteins. Here we review these alternative mechanisms and discuss how they alter Rho protein function and signaling. We also envision how the classic binary Rho switch may indeed function more like a switchboard with multiple switches and dials that can all contribute to the regulation of Rho protein function.
Institut National de la Santé et de la Recherche Médicale Avenir Team, Nice Sophia-Antipolis University, Nice, France. boulter@unice.fr
Etienne
E
Boulter
Soline
S
Estrach
Rafael
R
Garcia-Mata
Chloé C
CC
Féral
D000818:Animals; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism; D008954:Models, Biological; D010766:Phosphorylation; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D008563:Membrane Lipids; D017382:Reactive Oxygen Species; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020741:rho GTP-Binding Proteins