title: Expression of polycystin-1 C-terminal fragment enhances the ATP-induced Ca2+ release in human kidney cells.
abstract: Polycystin-1 (PC1) is a membrane protein expressed in tubular epithelia of developing kidneys and in other ductal structures. Recent studies indicate this protein to be putatively important in regulating intracellular Ca(2+) levels in various cell types, but little evidence exists for kidney epithelial cells. Here we examined the role of the PC1 cytoplasmic tail on the activity of store operated Ca(2+) channels in human kidney epithelial HEK-293 cell line. Cells were transiently transfected with chimeric proteins containing 1-226 or 26-226 aa of the PC1 cytoplasmic tail fused to the transmembrane domain of the human Trk-A receptor: TrkPC1 wild-type and control Trk truncated peptides were expressed at comparable levels and localized at the plasma membrane. Ca(2+) measurements were performed in cells co-transfected with PC1 chimeras and the cytoplasmic Ca(2+)-sensitive photoprotein aequorin, upon activation of the phosphoinositide pathway by ATP, that, via purinoceptors, is coupled to the release of Ca(2+) from intracellular stores. The expression of TrkPC1 peptide, but not of its truncated form, enhanced the ATP-evoked cytosolic Ca(2+) concentrations. When Ca(2+) assays were performed in HeLa cells characterized by Ca(2+) stores greater than those of HEK-293 cells, the histamine-evoked cytosolic Ca(2+) increase was enhanced by TrkPC1 expression, even in absence of external Ca(2+). These observations indicate that the C-terminal tail of PC1 in kidney and other epithelial cells upregulates a Ca(2+) channel activity also involved in the release of intracellular stores.
authors.affiliation: Department of Biochemistry and Molecular Biology, Section of General Pathology, University of Ferrara, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Aguiari
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Campanella
authors.forename: Elisa
authors.initials: E
authors.lastname: Manzati
authors.forename: Paolo
authors.initials: P
authors.lastname: Pinton
authors.forename: Manuela
authors.initials: M
authors.lastname: Banzi
authors.forename: Sabrina
authors.initials: S
authors.lastname: Moretti
authors.forename: Roberta
authors.initials: R
authors.lastname: Piva
authors.forename: Rosario
authors.initials: R
authors.lastname: Rizzuto
authors.forename: Laura
authors.initials: L
authors.lastname: del Senno
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D003593:Cytoplasm / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D006367:HeLa Cells; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D020917:Receptor, trkA / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000032:analysis; D050396:TRPP Cation Channels
chemical_list: D000255:Adenosine Triphosphate; D002118:Calcium; D006632:Histamine; D010446:Peptide Fragments; D011506:Proteins; D020917:Receptor, trkA; D011993:Recombinant Fusion Proteins; D050396:TRPP Cation Channels