The E3 ubiquitin-ligase HACE1 catalyzes the ubiquitylation of active Rac1.
Rac1 small GTPase controls essential aspects of cell biology and is a direct target of numerous bacterial virulence factors. The CNF1 toxin of pathogenic Escherichia coli addresses Rac1 to ubiquitin-proteasome system (UPS). We report the essential role of the tumor suppressor HACE1, a HECT-domain containing E3 ubiquitin-ligase, in the targeting of Rac1 to UPS. HACE1 binds preferentially GTP-bound Rac1 and catalyzes its polyubiquitylation. HACE1 expression increases the ubiquitylation of Rac1, when the GTPase is activated by point mutations or by the GEF-domain of Dbl. RNAi-mediated depletion of HACE1 blocks the ubiquitylation of active Rac1 and increases GTP-bound Rac1 cellular levels. HACE1 antagonizes cell isotropic spreading, a hallmark of Rac1 activation, and is required for endothelial cell monolayer invasion by bacteria. Together, these data establish the role of the HACE1 E3 ubiquitin-ligase in controlling Rac1 ubiquitylation and activity.
INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la Relation Hôte Pathogènes, 06204 Cedex 3 Nice, France.
Stéphanie
S
Torrino
Orane
O
Visvikis
Anne
A
Doye
Laurent
L
Boyer
Caroline
C
Stefani
Patrick
P
Munro
Jacques
J
Bertoglio
Gérard
G
Gacon
Amel
A
Mettouchi
Emmanuel
E
Lemichez
D000818:Animals; D055162:Biocatalysis; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D057809:HEK293 Cells; D006801:Humans; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000378:metabolism*; D054875:Ubiquitination; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
C107953:RAC1 protein, human; D025801:Ubiquitin; C497506:HACE1 protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; D020830:rac1 GTP-Binding Protein