title: Arf6 regulates AP-1B-dependent sorting in polarized epithelial cells.
abstract: The epithelial cell-specific clathrin adaptor complex AP-1B facilitates the sorting of various transmembrane proteins from recycling endosomes (REs) to the basolateral plasma membrane. Despite AP-1B's clear importance in polarized epithelial cells, we still do not fully understand how AP-1B orchestrates basolateral targeting. Here we identify the ADP-ribosylation factor 6 (Arf6) as an important regulator of AP-1B. We show that activated Arf6 pulled down AP-1B in vitro. Furthermore, interfering with Arf6 function through overexpression of dominant-active Arf6Q67L or dominant-negative Arf6D125N, as well as depletion of Arf6 with short hairpin RNA (shRNA), led to apical missorting of AP-1B-dependent cargos. In agreement with these data, we found that Arf6 colocalized with AP-1B and transferrin receptor (TfnR) in REs. In addition, we observed specific recruitment of AP-1B into Arf6-induced membrane ruffles in nonpolarized cells. We conclude that activated Arf6 directs membrane recruitment of AP-1B, thus regulating AP-1B's functions in polarized epithelial cells.
authors.affiliation: Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Elina
authors.initials: E
authors.lastname: Shteyn
authors.forename: Lucy
authors.initials: L
authors.lastname: Pigati
authors.forename: Heike
authors.initials: H
authors.lastname: Fölsch
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics* / Q000378:metabolism; D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016764:Cell Polarity / Q000502:physiology*; D002478:Cells, Cultured; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism; D013552:Swine
chemical_list: D000089982:ADP-Ribosylation Factor 6; D033961:Adaptor Protein Complex 1; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; C000715727:Arf6 protein, mouse; C000715349:Arf6 protein, rat