title: Intracellular calcium release modulates polycystin-2 trafficking.
abstract: BACKGROUND
  Polycystin-2 (PC2), encoded by the gene that is mutated in autosomal dominant polycystic kidney disease (ADPKD), functions as a calcium (Ca(2+)) permeable ion channel. Considerable controversy remains regarding the subcellular localization and signaling function of PC2 in kidney cells.
  
  
  METHODS
  We investigated the subcellular PC2 localization by immunocytochemistry and confocal microscopy in primary cultures of human and rat proximal tubule cells after stimulating cytosolic Ca(2+) signaling. Plasma membrane (PM) Ca(2+) permeability was evaluated by Fura-2 manganese quenching using time-lapse fluorescence microscopy.
  
  
  RESULTS
  We demonstrated that PC2 exhibits a dynamic subcellular localization pattern. In unstimulated human or rat proximal tubule cells, PC2 exhibited a cytosolic/reticular distribution. Treatments with agents that in various ways affect the Ca(2+) signaling machinery, those being ATP, bradykinin, ionomycin, CPA or thapsigargin, resulted in increased PC2 immunostaining in the PM. Exposing cells to the steroid hormone ouabain, known to trigger Ca(2+) oscillations in kidney cells, caused increased PC2 in the PM and increased PM Ca(2+) permeability. Intracellular Ca(2+) buffering with BAPTA, inositol 1,4,5-trisphosphate receptor (InsP3R) inhibition with 2-aminoethoxydiphenyl borate (2-APB) or Ca(2+)/Calmodulin-dependent kinase inhibition with KN-93 completely abolished ouabain-stimulated PC2 translocation to the PM.
  
  
  CONCLUSIONS
  These novel findings demonstrate intracellular Ca(2+)-dependent PC2 trafficking in human and rat kidney cells, which may provide new insight into cyst formations in ADPKD.
authors: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
authors: Ayako
authors: A
authors: Miyakawa
authors: Cristián
authors: C
authors: Ibarra
authors: Seth
authors: S
authors: Malmersjö
authors: Anita
authors: A
authors: Aperia
authors: Peter
authors: P
authors: Wiklund
authors: Per
authors: P
authors: Uhlén
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D051381:Rats
chemical_list: D002118:Calcium
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