title: Cgr11 encodes a secretory protein involved in cell adhesion.
abstract: We performed comparative proteomic analyses of pituitary tumor-derived cell lines, and found a new protein, preliminarily called hydrophobestin, which was produced only in somatotrophic cells, MtT/S, but not in non-hormone-producing cells, MtT/E. Hydrophobestin is encoded by the cell growth regulatory gene, Cgr11, which is known to have growth-suppressive potential in several cell lines. We have now sought to investigate the underlying events responsible for cell growth inhibition by hydrophobestin. Immunocytochemisty revealed that hydrophobestin is localized in the Golgi apparatus of MtT/S cells and Cgr11-transfected MtT/E cells. The apparent molecular mass of the protein was determined by Westerm blot analysis of conditioned culture medium of MtT/S cells. Our data show that hydrophobestin is a secretory protein localized in the pituitary gland, adrenal gland, digestive tract, reproductive organs, and kidney. We also found that hydrophobestin promotes compact monolayer cell aggregates in PC12 cells transfected with Cgr11, however, non-transfected, vector- or EF-hand motif-deleted (DeltaEF) Cgr11-transfected PC12 cells cannot form compact cell colonies. An antibody recognizing EF-hand motifs showed strong staining in the intercellular space of both Cgr11-transfected PC12 cells and MtT/S cells (Cgr11-expressing cells). Our data suggest that hydrophobestin-mediated cell adhesion may regulate cell growth through compact cell attachment.
authors.affiliation: Department of Regulatory Biology, Graduate School of Science and Engineering, Saitama University, Sakura-ku, Saitama, Japan.
authors.forename: Sukumar
authors.initials: S
authors.lastname: Devnath
authors.forename: Taro
authors.initials: T
authors.lastname: Kataoka
authors.forename: Kaoru
authors.initials: K
authors.lastname: Miura
authors.forename: Mie
authors.initials: M
authors.lastname: Kusuda
authors.forename: Kunio
authors.initials: K
authors.lastname: Kitamura
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kumada
authors.forename: Akikazu
authors.initials: A
authors.lastname: Mochiduki
authors.forename: Kei
authors.initials: K
authors.lastname: Kaneko
authors.forename: Akihito
authors.initials: A
authors.lastname: Adachi
authors.forename: Kinji
authors.initials: K
authors.lastname: Inoue
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007150:Immunohistochemistry; D016716:PC12 Cells; D051381:Rats; D014162:Transfection
chemical_list: D015815:Cell Adhesion Molecules; C545513:Cgref1 protein, rat