title: Calcium induces differentiation of primary human salivary acinar cells.
abstract: Cultivation of human parotid glands in serum-free medium (Ca(2+) concentration, 0.2 mM) with growth supplements resulted in isolation of a homogeneous population of epithelial cells without any mesenchymal cells. The isolated cells showed an undifferentiated phenotype with scant cytoplasmic organelles, and low levels of alpha-amylase expression. The cells remained viable and undifferentiated for up to 24 passages when subcultured at 80% confluence in 0.2 mM Ca(2+) medium with a 1:3 split ratios. There was little cell-cell contact. A Ca(2+) switch from 0.2 to 1 mM induced cell-cell contact with translocation of desmosomal proteins from the cytoplasm to the cell membrane, and sequential differentiation of serous acinar cells with a glandular arrangement, well-developed cytoplasmic organelles and an increased level of alpha-amylase expression. These morphological changes and desmosome assembly were blocked by treatment with non-specific PKC inhibitor. Moreover, the addition of PKC activator, tetradecanoylphorbol 13-acetate (TPA), to 0.2 mM Ca(2+) medium caused transient assembly of desmosome-like structure, but did not induce cell-cell contact or morphological differentiation. Cultivation of the cells in 1.5 mM Ca(2+) medium resulted in increased stratification of the cells and reduced alpha-amylase expression. These findings provide the first demonstration that continuous cultivation in 1.0 mM Ca(2+) medium is required for cellular differentiation of salivary gland acinar cells, and maintenance of the differentiated state.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Japan.
authors.forename: Akimitsu
authors.initials: A
authors.lastname: Hiraki
authors.forename: Kanemitsu
authors.initials: K
authors.lastname: Shirasuna
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ikari
authors.forename: Masanori
authors.initials: M
authors.lastname: Shinohara
authors.forename: David R
authors.initials: DR
authors.lastname: Garrod
mesh_terms: D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051180:Desmoplakins; D003896:Desmosomes / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D015388:Organelles / Q000187:drug effects; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects*; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D006133:Growth Substances; D011493:Protein Kinase C; D000516:alpha-Amylases; D002118:Calcium