title: The activation of MAP kinase during vertical palatal shelf development in hamster.
abstract: Mitogen-activated protein (MAP) kinase has been implicated in signal transduction pathways that regulate cell cycle progression during the proliferation of eukaryotic cells. Previous studies have shown that a rapid burst of cell proliferation is a major event of the development of mammalian palatal shelves in a vertical direction. The present study analyzed the involvement of MAP kinase during the vertical development of the secondary palate in hamster. Palates were dissected at various times between days 10:00 and 12:00 of gestation, homogenized, centrifuged and fractionated on a Mono Q column by fast protein liquid chromatography. The fractions were assayed for phosphotransferase activity toward myelin basic protein, and also toward a synthetic peptide APRTPGGRR (S5), which was more specifically utilized by MAP kinase. The data showed that MAP kinase activity increased during the initial phase, i.e., between days 10:00 and 11:12, and then decreased during the latter half of vertical palate development, i.e., between days 11:12, and 12:00 of gestation. Western blotting studies, using antibodies raised against the subdomain I ATP binding sequence (GEGA), subdomain III (ERK1-III), and the C-terminus (ERK1-CT) of MAP kinases, demonstrated the presence of both the 42-kDa and 44-kDa MAP kinase isoforms between days 10:12 and 12:12 of gestation. A monoclonal antibody (4G10), which detects phosphotyrosine, demonstrated phosphorylation of both the 42-kDa and 44-kDa isoforms. The amount of protein remained constant during vertical palatal shelf development indicating that the differential activity of MAP kinase was most likely due to post-translational modification (i.e., phosphorylation). There was a good correlation between the temporal expression of MAP kinase activity and the rates of cell proliferation in the developing vertical palate suggesting a possible involvement of MAP kinase in regulation of cell proliferation during secondary palate development.
authors.affiliation: Department of Oral Biology, Faculty of Dentistry, University of British Columbia, Vancouver, Canada.
authors.forename: A V
authors.initials: AV
authors.lastname: Young
authors.forename: B M
authors.initials: BM
authors.lastname: Hehn
authors.forename: J S
authors.initials: JS
authors.lastname: Sanghera
authors.forename: S L
authors.initials: SL
authors.lastname: Pelech
authors.forename: R M
authors.initials: RM
authors.lastname: Shah
mesh_terms: D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000032:analysis / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D002853:Chromatography, Liquid / Q000379:methods; D006224:Cricetinae; D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D004622:Embryo, Mammalian / Q000166:cytology; D004789:Enzyme Activation; D005260:Female; D008297:Male; D008647:Mesocricetus / Q000196:embryology* / Q000378:metabolism* / Q000502:physiology; D010159:Palate / Q000737:chemistry / Q000196:embryology* / Q000201:enzymology*; D010770:Phosphotransferases / Q000032:analysis / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D004247:DNA; D010770:Phosphotransferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases