Involvement of the Rho/Rac family member RhoG in caveolar endocytosis.
We show here that the GTPase RhoG is involved in caveolar trafficking. Wild-type RhoG moves sequentially to the plasma membrane, intracellular vesicles, and the Golgi apparatus along markers of this endocytic pathway. Such translocation is associated with changes in RhoG GDP/GTP levels and is highly dependent on lipid raft integrity and on the function of the GTPase dynamin2. In addition, the constitutively active RhoG(Q61L) mutant is preferentially located in endocytic vesicles that can be decorated with markers of the caveola-derived endocytic pathway. RhoG(Q61L), but not the analogous Rac1 mutant protein, affects caveola internalization and the subsequent delivery of endocytic vesicles to the Golgi apparatus. The expression of RhoG/Rac1 chimeric proteins and RhoG(Q61L) effector mutants in cells induces alterations in the internalization of caveolae and severe changes in vesicle structure, respectively. However, the knockdown of endogenous rhoG transcripts using small interfering RNAs does not affect significantly the trafficking of caveola-derived vesicles, suggesting that RhoG function is dispensable for this endocytic process or, alternatively, that its function is compensated by other molecules. Taken together, these observations assign a novel function to RhoG and suggest that caveolar trafficking, as previously shown for other endocytic routes, is modulated by GTPases of the Ras superfamily.
Centro de Investigación del Cáncer, Instituto de Biología Molecular y Celular del Cáncer (IBMCC), and Red Temática Cooperativa de Centros de Cáncer, CSIC-University of Salamanca, Spain.
R M
RM
Prieto-Sánchez
I M
IM
Berenjeno
X R
XR
Bustelo
D000818:Animals; D016466:CHO Cells; D021941:Caveolae / Q000502:physiology*; D022461:Caveolins / Q000032:analysis / Q000502:physiology; D002772:Cholera Toxin / Q000032:analysis; D002966:Clathrin / Q000032:analysis / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D034285:Dynamin II / Q000235:genetics / Q000494:pharmacology; D004705:Endocytosis / Q000502:physiology*; D004789:Enzyme Activation; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000032:analysis; D008856:Microscopy, Fluorescence; D017354:Point Mutation; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013347:Subcellular Fractions / Q000737:chemistry; D014162:Transfection; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*
D022461:Caveolins; D002966:Clathrin; D005456:Fluorescent Dyes; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D002772:Cholera Toxin; D020741:rho GTP-Binding Proteins; D034285:Dynamin II; D016650:Fluorescein-5-isothiocyanate