title: Localization and function in endoplasmic reticulum stress tolerance of ERdj3, a new member of Hsp40 family protein.
abstract: Heat shock protein 40 (Hsp40) family proteins are known to bind to Hsp70 through their J-domain and regulate the function of Hsp70 by stimulating its adenosine triphosphatase activity. In the endoplasmic reticulum (ER), there are 5 Hsp40 family proteins known so far, 3 of which were recently identified. In this report, one of the novel Hsp40 cochaperones, ERdj3, was characterized in terms of its subcellular localization, stress response, and stress tolerance of cells. By using ERdj3-specific polyclonal antibody, endogenous ERdj3 protein was shown to reside in the ER as gene transfer-mediated exogenous ERdj3. Analysis of the expression level of endogenous ERdj3 protein revealed its moderate induction in response to various ER stressors, indicating its possible action as a stress protein in the ER. Subsequently, we analyzed whether this molecule was involved in ER stress tolerance of cells, as was the case with the ER-resident Hsp70 family protein BiP. Although overexpression of ERdj3 by gene transfection could not strengthen ER stress tolerance of neuroblastoma cells, reduction of ERdj3 expression by small interfering ribonucleic acid decreased the tolerance of cells, indicating that ERdj3 might have just a marginal role in the ER stress resistance of neuroblastoma cells. In contrast, overexpression of ERdj3 notably suppressed vero toxin-induced cell death. These data suggest that ERdj3 might have diverse roles in the ER, including that of the molecular cochaperone of BiP and an as yet unknown protective action against vero toxin.
authors.affiliation: Department of Pathology, Sapporo Medical University School of Medicine, S-1, W-17, Chuo-ku, Sapporo 060-8556, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kamiguchi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Torigoe
authors.forename: Chika
authors.initials: C
authors.lastname: Nabeta
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Hirohashi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Asanuma
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Tobioka
authors.forename: Norie
authors.initials: N
authors.lastname: Koge
authors.forename: Oi
authors.initials: O
authors.lastname: Harada
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tamura
authors.forename: Hideki
authors.initials: H
authors.lastname: Nagano
authors.forename: Shoki
authors.initials: S
authors.lastname: Yano
authors.forename: Susumu
authors.initials: S
authors.lastname: Chiba
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D050956:HSP40 Heat-Shock Proteins; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D034622:RNA Interference; D022603:Shiga Toxins / Q000494:pharmacology; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: C494647:DNAJB1 protein, human; C494648:DNAJB11 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D022603:Shiga Toxins; D014415:Tunicamycin; D019284:Thapsigargin