title: Rab35 regulates Arf6 activity through centaurin-β2 (ACAP2) during neurite outgrowth.
abstract: Two small GTPases, Rab and Arf, are well-known molecular switches that function in diverse membrane-trafficking routes in a coordinated manner; however, very little is known about the direct crosstalk between Rab and Arf. Although Rab35 and Arf6 were independently reported to regulate the same cellular events, including endocytic recycling, phagocytosis, cytokinesis and neurite outgrowth, the molecular basis that links them remains largely unknown. Here we show that centaurin-β2 (also known as ACAP2) functions both as a Rab35 effector and as an Arf6-GTPase-activating protein (GAP) during neurite outgrowth of PC12 cells. We found that Rab35 accumulates at Arf6-positive endosomes in response to nerve growth factor (NGF) stimulation and that centaurin-β2 is recruited to the same compartment in a Rab35-dependent manner. We further showed by knockdown and rescue experiments that after the Rab35-dependent recruitment of centaurin-β2, the Arf6-GAP activity of centaurin-β2 at the Arf6-positive endosomes was indispensable for NGF-induced neurite outgrowth. These findings suggest a novel mode of crosstalk between Rab and Arf: a Rab effector and Arf-GAP coupling mechanism, in which Arf-GAP is recruited to a specific membrane compartment by its Rab effector function.
authors.affiliation: Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai, Miyagi, Japan.
authors.forename: Hotaka
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D055785:Gene Knockdown Techniques; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D016716:PC12 Cells; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C575760:ACAP2 protein, rat; D000089982:ADP-Ribosylation Factor 6; D020690:GTPase-Activating Proteins; D020932:Nerve Growth Factor; C575759:Rab35 protein, rat; D020727:ADP-Ribosylation Factors; C000715349:Arf6 protein, rat; D020691:rab GTP-Binding Proteins