title: γ-SNAP stimulates disassembly of endosomal SNARE complexes and regulates endocytic trafficking pathways.
abstract: Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) that reside in the target membranes and transport vesicles assemble into specific SNARE complexes to drive membrane fusion. N-ethylmaleimide-sensitive factor (NSF) and its attachment protein, α-SNAP (encoded by NAPA), catalyze disassembly of the SNARE complexes in the secretory and endocytic pathways to recycle them for the next round of fusion events. γ-SNAP (encoded by NAPG) is a SNAP isoform, but its function in SNARE-mediated membrane trafficking remains unknown. Here, we show that γ-SNAP regulates the endosomal trafficking of epidermal growth factor (EGF) receptor (EGFR) and transferrin. Immunoprecipitation and mass spectrometry analyses revealed that γ-SNAP interacts with a limited range of SNAREs, including endosomal ones. γ-SNAP, as well as α-SNAP, mediated the disassembly of endosomal syntaxin-7-containing SNARE complexes. Overexpression and small interfering (si)RNA-mediated depletion of γ-SNAP changed the morphologies and intracellular distributions of endosomes. Moreover, the depletion partially suppressed the exit of EGFR and transferrin from EEA1-positive early endosomes to delay their degradation and uptake. Taken together, our findings suggest that γ-SNAP is a unique SNAP that functions in a limited range of organelles - including endosomes - and their trafficking pathways.
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan hirokii@toyaku.ac.jp tagaya@toyaku.ac.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Inoue
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Matsuzaki
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Hosoi
authors.affiliation: Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ichimura
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Arasaki
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Wakana
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Asano
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okuzaki
authors.affiliation: Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan.
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Katsuko
authors.initials: K
authors.lastname: Tani
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan hirokii@toyaku.ac.jp tagaya@toyaku.ac.jp.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Tagaya
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology; D011485:Protein Binding; D021381:Protein Transport / Q000502:physiology*; D050765:Qa-SNARE Proteins / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000235:genetics*; D014168:Transferrin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D050765:Qa-SNARE Proteins; D034741:RNA, Small Interfering; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D014168:Transferrin; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: Endocytosis; NAPG; STX7; STX8; Syntaxin 8