title: Role of PI 3-kinase and PIP3 in submandibular gland branching morphogenesis.
abstract: The mouse submandibular gland (SMG) epithelium undergoes extensive morphogenetic branching during embryonic development as the first step in the establishment of its glandular structure. However, the specific signaling pathways required for SMG branching morphogenesis are not well understood. Using E13 mouse SMG organ cultures, we showed that inhibitors of phosphatidylinositol 3-kinase (PI 3-kinase), wortmannin and LY294002, substantially inhibited branching morphogenesis in SMG. Branching morphogenesis of epithelial rudiments denuded of mesenchyme was inhibited similarly, indicating that PI 3-kinase inhibitors act directly on the epithelium. Immunostaining and Western analysis demonstrated that the p85 isoform of PI 3-kinase is expressed in epithelium at levels higher than in the mesenchyme. A target of PI 3-kinase, Akt/protein kinase B (PKB), showed decreased phosphorylation at Ser(473) by Western analysis in the presence of PI 3-kinase inhibitors. The major lipid product of PI 3-kinase, phosphatidylinositol 3,4,5-trisphosphate (PIP(3)), was added exogenously to SMG via a membrane-transporting carrier in the presence of PI 3-kinase inhibitors and was found to stimulate cleft formation, the first step of branching morphogenesis. Together, these data indicate that PI 3-kinase plays a role in the regulation of epithelial branching morphogenesis in mouse SMG acting through a PIP(3) pathway.
authors.affiliation: Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4370, USA.
authors.forename: Melinda
authors.initials: M
authors.lastname: Larsen
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Hoffman
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Sakai
authors.forename: Justin C
authors.initials: JC
authors.lastname: Neibaur
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Mitchell
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Yamada
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002867:Chromones / Q000494:pharmacology; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D009024:Morphogenesis; D009025:Morpholines / Q000494:pharmacology; D009924:Organ Culture Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D011247:Pregnancy; D020033:Protein Isoforms / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; C060974:phosphatidylinositol 3,4,5-triphosphate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one