title: Contribution of calumin to embryogenesis through participation in the endoplasmic reticulum-associated degradation activity.
abstract: Calumin is an endoplasmic reticulum (ER)-transmembrane protein, and little is known about its physiological roles. Here we showed that calumin homozygous mutant embryos die at embryonic days (E) 10.5-11.5. At mid-gestation, calumin was expressed predominantly in the yolk sac. Apoptosis was enhanced in calumin homozygous mutant yolk sacs at E9.5, pointing to a possible link to the embryonic lethality. Calumin co-immunoprecipitated with ERAD components such as p97, BIP, derlin-1, derlin-2 and VIMP, suggesting its involvement in ERAD. Indeed, calumin knockdown in HEK 293 cells resulted in ERAD being less efficient, as demonstrated by attenuation in both degradations of a misfolded α1-antitrypsin variant and the ER-to-cytosol dislocation of cholera toxin A1 subunit. In calumin homozygous mutant yolk sac endoderm cells, ER stress-associated alterations were observed, including lipid droplet accumulation, fragmentation of the ER and dissociation of ribosomes from the ER. In this context, the ER-overload response, assumed to be cytoprotective, was also triggered in the mutant endoderm cells, but seemed to fully counteract the excessive ER stress generated due to defective ERAD. Taken together, our findings suggested that calumin serves to maintain the yolk sac integrity through participation in the ERAD activity, contributing to embryonic development.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan; Department of Molecular Cell Biology and Medicine, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima 770-8505, Japan. Electronic address: yamashin@tokushima-u.ac.jp.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Department of Molecular Cell Biology and Medicine, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima 770-8505, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Yamazaki
authors.affiliation: Saitama Medical University, Saitama 350-0495, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Komazaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Osaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Matsubayashi
authors.affiliation: Department of Signal Transduction, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kidoya
authors.affiliation: Department of Signal Transduction, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takakura
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Daiju
authors.initials: D
authors.lastname: Yamazaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Kakizawa
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002460:Cell Line; D002772:Cholera Toxin / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D004707:Endoderm / Q000166:cytology / Q000473:pathology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress / Q000235:genetics; D060746:Endoplasmic Reticulum-Associated Degradation / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation; D017510:Protein Folding; D034622:RNA Interference; D034741:RNA, Small Interfering; D015017:Yolk Sac / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000378:metabolism
chemical_list: D002772:Cholera Toxin; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D000515:alpha 1-Antitrypsin; C000592843:CCDC47 protein, human; C000592844:CCDC47 protein, mouse
keywords: CCDC47; Calumin; ER stress; ERAD; Embryogenesis; Secretory cells