title: SMAP2 regulates retrograde transport from recycling endosomes to the Golgi.
abstract: Retrograde transport is where proteins and lipids are transported back from the plasma membrane (PM) and endosomes to the Golgi, and crucial for a diverse range of cellular functions. Recycling endosomes (REs) serve as a sorting station for the retrograde transport and we recently identified evection-2, an RE protein with a pleckstrin homology (PH) domain, as an essential factor of this pathway. How evection-2 regulates retrograde transport from REs to the Golgi is not well understood. Here, we report that evection-2 binds to SMAP2, an Arf GTPase-activating protein. Endogenous SMAP2 localized mostly in REs and to a lesser extent, the trans-Golgi network (TGN). SMAP2 binds evection-2, and the RE localization of SMAP2 was abolished in cells depleted of evection-2. Knockdown of SMAP2, like that of evection-2, impaired the retrograde transport of cholera toxin B subunit (CTxB) from REs. These findings suggest that evection-2 recruits SMAP2 to REs, thereby regulating the retrograde transport of CTxB from REs to the Golgi.
authors.affiliation: Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Matsudaira
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Uchida
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanabe
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kon
authors.forename: Toshio
authors.initials: T
authors.lastname: Watanabe
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Taguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D002772:Cholera Toxin / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006056:Golgi Apparatus / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D002772:Cholera Toxin