title: Differential effect of 1,25-dihydroxycholecalciferol on phosphoinositide turnover in the antipodal plasma membranes of colonic epithelial cells.
abstract: 1,25-dihydroxycholecalciferol stimulates membrane phosphoinositide turnover in colonic epithelial and other cells, but the effects of this hormone on phosphoinositide metabolism in specific antipodal plasma membranes has not been examined. In the present studies, addition of 10(-8)M 1,25-dihydroxycholecalciferol to rat colonic crypts for 90 seconds decreased the phosphatidylinositol-4,5-bisphosphate content and increased the diacylglycerol content of the baso-lateral, but not the brush border plasma membrane. Using Caco-2 cells grown as tight polarized monolayers, 1,25-dihydroxycholecalciferol reduced cellular phosphatidylinositol-4,5-bisphosphate and increased cellular inositol-1,4,5-triphosphate and diacylglycerol when added to the buffer bathing the baso-lateral, but not the brush border membrane surface. These data indicate, therefore, that 1,25-dihydroxycholecalciferol activates the phosphoinositol signal transduction cascade specifically in the baso-lateral cell membrane of colonic cells.
authors.affiliation: Department of Medicine, University of Chicago.
authors.forename: R K
authors.initials: RK
authors.lastname: Wali
authors.forename: M J
authors.initials: MJ
authors.lastname: Bolt
authors.forename: X Y
authors.initials: XY
authors.lastname: Tien
authors.forename: T A
authors.initials: TA
authors.lastname: Brasitus
authors.forename: M D
authors.initials: MD
authors.lastname: Sitrin
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004075:Diglycerides; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D015544:Inositol 1,4,5-Trisphosphate; D002117:Calcitriol