title: Ubiquitin-specific protease 19 regulates the stability of the E3 ubiquitin ligase MARCH6.
abstract: Ubiquitin-specific protease (USP)19 is a recently identified deubiquitinating enzyme (DUB) having multiple splice variants and cellular functions. One variant encodes an endoplasmic reticulum (ER)-anchored DUB that rescues misfolded transmembrane proteins from ER-associated degradation (ERAD), but the underlying mechanism remains to be elucidated. Here, we show that USP19 interacts with the ERAD-associated E3 ubiquitin ligase MARCH6. Overexpression of USP19 delayed the degradation of MARCH6, leading to an increase in its protein level. In contrast, USP19 depletion resulted in decreased expression of MARCH6. We also show that USP19 overexpression reduced ubiquitination of MARCH6, while its knockdown had the opposite effect. In particular, USP19 was found to protect MARCH6 by deubiquitination from the p97-dependent proteasomal degradation. In addition, USP19 knockdown leads to increased expression of mutant ABCB11, an ERAD substrate of MARCH6. Moreover, USP19 is itself subjected to endoproteolytic processing by DUB activity, and the processing cleaves off an N-terminal cytoplasmic region of unknown function. However, elimination of this processing had no evident effect on MARCH6 stabilization. These results suggest that USP19 is involved in the regulation of ERAD by controlling the stability of MARCH6 via deubiquitination.
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan. Electronic address: nnakamur@bio.titech.ac.jp.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakamura
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Kumi
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Kato
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Hirose
mesh_terms: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D011499:Protein Processing, Post-Translational; D055550:Protein Stability; D034741:RNA, Small Interfering / Q000235:genetics; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C093491:ABCB11 protein, human; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D025801:Ubiquitin; C504816:MARCHF6 protein, human; D044767:Ubiquitin-Protein Ligases; D010450:Endopeptidases; C559917:USP19 protein, human
keywords: Deubiquitinating enzyme; E3 ubiquitin ligase; ER-associated degradation; Endoproteolytic processing; Proteasomal degradation