title: Expression of a truncated form of inositol 1,4,5-trisphosphate receptor type III in the cytosol of DT40 triple inositol 1,4,5-trisphosphate receptor-knockout cells.
abstract: In non-excitable cells, the inositol 1,4,5-trisphosphate receptor (IP3R) is an intracellular Ca2+ channel playing a major role in Ca2+ signaling. Three isoforms of IP3R have been identified and most cell types express different proportions of each isoform. The DT40 B lymphocyte cell line lacking all three IP3R isoforms (DT40IP3R-KO cells) represents an excellent model to re-express any recombinant IP3R and analyze its specific properties. In the study presented here, we confirmed that DT40IP3R-KO cells do not express any IP3-sensitive Ca2+ release channel. However, with an immunoblot approach and a [3H]IP3 binding approach we demonstrated the presence of a C-terminally truncated form of IP3R type III in the cytosolic fraction of DT40IP3R-KO cells. We further showed that this truncated IP3R retained the ability to couple to the Ca2+ entry channel TRPC6. Therefore, a word of caution is offered about the interpretation of results obtained in using DT40IP3R-KO cells to study the cellular mechanisms of Ca2+ entry.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Que., Canada J1H 5N4.
authors.forename: Joelle
authors.initials: J
authors.lastname: Guillemette
authors.forename: Annabelle Z
authors.initials: AZ
authors.lastname: Caron
authors.forename: Yannik
authors.initials: Y
authors.lastname: Regimbald-Dumas
authors.forename: Guillaume
authors.initials: G
authors.lastname: Arguin
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Mignery
authors.forename: Guylain
authors.initials: G
authors.lastname: Boulay
authors.forename: Gaetan
authors.initials: G
authors.lastname: Guillemette
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D002478:Cells, Cultured; D002645:Chickens / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D050052:TRPC Cation Channels; D014316:Tritium / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels; D018160:Receptors, Cytoplasmic and Nuclear; D050052:TRPC Cation Channels; D014316:Tritium; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium