title: The GTP/GDP cycling of rho GTPase TCL is an essential regulator of the early endocytic pathway.
abstract: Rho GTPases are key regulators of actin dynamics. We report that the Rho GTPase TCL, which is closely related to Cdc42 and TC10, localizes to the plasma membrane and the early/sorting endosomes in HeLa cells, suggesting a role in the early endocytic pathway. Receptor-dependent internalization of transferrin (Tf) is unaffected by suppression of endogenous TCL by small interfering RNA treatment. However, Tf accumulates in Rab5-positive uncoated endocytic vesicles and fails to reach the early endosome antigen-1-positive early endosomal compartments and the pericentriolar recycling endosomes. Moreover, Tf release upon TCL knockdown is significantly slower. Conversely, in the presence of dominant active TCL, internalized Tf accumulates in early endosome antigen-1-positive early/sorting endosomes and not in perinuclear recycling endosomes. Tf recycles directly from the early/sorting endosomes and it is normally released by the cells. The same phenotype is generated by replacing the C terminus of dominant active Cdc42 and TC10 with that of TCL, indicating that all three proteins share downstream effector proteins. Thus, TCL is essential for clathrin-dependent endocytosed receptors to enter the early/sorting endosomes. Furthermore, the active GTPase favors direct recycling from early/sorting endosomes without accumulating in the perinuclear recycling endosomes.
authors.affiliation: Centre de Recherches en Biochimie Macromoléculaire, Centre National de la Recherche Scientifique Unité Propre de Recherche 1086, 34293 Montpellier, France.
authors.forename: Marion
authors.initials: M
authors.lastname: de Toledo
authors.forename: Francesca
authors.initials: F
authors.lastname: Senic-Matuglia
authors.forename: Jean
authors.initials: J
authors.lastname: Salamero
authors.forename: Gilles
authors.initials: G
authors.lastname: Uze
authors.forename: Franck
authors.initials: F
authors.lastname: Comunale
authors.forename: Philippe
authors.initials: P
authors.lastname: Fort
authors.forename: Anne
authors.initials: A
authors.lastname: Blangy
mesh_terms: D002462:Cell Membrane / Q000201:enzymology*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000201:enzymology*; D020558:GTP Phosphohydrolases / Q000187:drug effects / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions; D014168:Transferrin / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; D014168:Transferrin; D020558:GTP Phosphohydrolases; C417188:RHOJ protein, human; C503256:RHOQ protein, human; D020764:cdc42 GTP-Binding Protein; D020696:rab5 GTP-Binding Proteins; D020741:rho GTP-Binding Proteins