title: Expression level of inositol trisphosphate and inositol tetrakisphosphate receptors and their influence on Ca2+ release in permeabilized HL-60 and T15 cells.
abstract: To try to further define the mechanism of action of the putative second messenger inositol 1,3,4,5-tetrakisphosphate (InsP4), we have studied its effects in permeabilized cells expressing different levels of inositol trisphosphate receptor (InsP3R) types I and III and of the GTPase-activating protein GAP1IP4BP. During the growth curve of human HL-60 cells and mouse T15 cells there was an increase in these proteins, which was further increased by differentiation (HL-60) and, marginally, by transformation (T15). T15 cells entering the stationary phase showed much lower concentrations of these proteins and expression was below detection in apoptotic HL-60 cells. Rasp21 showed a different pattern of expression. The ratios of InsP3R subtypes seem to affect the dose-response curve for inositol 2,4,5-trisphosphate Ins(2,4,5)P3. In permeabilized T15 cells the curve was approximately 5-fold to the right of that obtained using HL-60 cells. However, permeabilized untreated and differentiated HL-60 cells and T15 cells all showed a comparable synergistic effect of InsP4 on Ca2+ release stimulated by a concentration of Ins(2,4,5)P3, releasing approximately 20% of the Ins(1,4,5)P3 sensitive Ca2+ pool. The data indicate that under these conditions InsP4 is acting independently of cell type, of the ratio of inositol trisphosphate receptor subtypes, and of the concentration of GAP1IP4BP.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich, UK. Dreikhausen.Ursula@MH-Hannover.DE
authors.forename: U E
authors.initials: UE
authors.lastname: Dreikhausen
authors.forename: A P
authors.initials: AP
authors.lastname: Dawson
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002454:Cell Differentiation; D002463:Cell Membrane Permeability; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D018922:HL-60 Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D019253:Proto-Oncogene Proteins c-bcl-2; D018160:Receptors, Cytoplasmic and Nuclear; C061107:inositol-1,3,4,5-tetrakisphosphate receptor; C081655:inositol-1,3,4,5-tetrakisphosphate; D014212:Tretinoin; D015544:Inositol 1,4,5-Trisphosphate; D019255:NADPH Oxidases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D002118:Calcium