title: PKD1 haploinsufficiency causes a syndrome of inappropriate antidiuresis in mice.
abstract: Mutations in PKD1 are associated with autosomal dominant polycystic kidney disease. Studies in mouse models suggest that the vasopressin (AVP) V2 receptor (V2R) pathway is involved in renal cyst progression, but potential changes before cystogenesis are unknown. This study used a noncystic mouse model to investigate the effect of Pkd1 haploinsufficiency on water handling and AVP signaling in the collecting duct (CD). In comparison with wild-type littermates, Pkd1(+/-) mice showed inappropriate antidiuresis with higher urine osmolality and lower plasma osmolality at baseline, despite similar renal function and water intake. The Pkd1(+/-) mice had a decreased aquaretic response to both a water load and a selective V2R antagonist, despite similar V2R distribution and affinity. They showed an inappropriate expression of AVP in brain, irrespective of the hypo-osmolality. The cAMP levels in kidney and urine were unchanged, as were the mRNA levels of aquaporin-2 (AQP2), V2R, and cAMP-dependent mediators in kidney. However, the (Ser256) phosphorylated AQP2 was upregulated in Pkd1(+/-) kidneys, with AQP2 recruitment to the apical plasma membrane of CD principal cells. The basal intracellular Ca(2+) concentration was significantly lower in isolated Pkd1(+/-) CD, with downregulated phosphorylated extracellular signal-regulated kinase 1/2 and decreased RhoA activity. Thus, in absence of cystic changes, reduced Pkd1 gene dosage is associated with a syndrome of inappropriate antidiuresis (positive water balance) reflecting decreased intracellular Ca(2+) concentration, decreased activity of RhoA, recruitment of AQP2 in the CD, and inappropriate expression of AVP in the brain. These data give new insights in the potential roles of polycystin-1 in the AVP and Ca(2+) signaling and the trafficking of AQP2 in the CD.
authors.affiliation: Division of Nephrology, UCL Medical School, Université Catholique de Louvain, 10 Avenue Hippocrate, B-1200 Brussels, Belgium.
authors.forename: Ali K
authors.initials: AK
authors.lastname: Ahrabi
authors.forename: Sara
authors.initials: S
authors.lastname: Terryn
authors.forename: Giovanna
authors.initials: G
authors.lastname: Valenti
authors.forename: Nathalie
authors.initials: N
authors.lastname: Caron
authors.forename: Claudine
authors.initials: C
authors.lastname: Serradeil-Le Gal
authors.forename: Danielle
authors.initials: D
authors.lastname: Raufaste
authors.forename: Soren
authors.initials: S
authors.lastname: Nielsen
authors.forename: Shigeo
authors.initials: S
authors.lastname: Horie
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Verbavatz
authors.forename: Olivier
authors.initials: O
authors.lastname: Devuyst
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D051399:Aquaporin 2 / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology; D004195:Disease Models, Animal; D004231:Diuresis / Q000502:physiology; D005260:Female; D006239:Haplotypes; D007177:Inappropriate ADH Syndrome / Q000209:etiology* / Q000235:genetics* / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000502:physiology; D007671:Kidney Concentrating Ability / Q000502:physiology; D007685:Kidney Tubules, Collecting / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009025:Morpholines / Q000494:pharmacology; D009994:Osmolar Concentration; D010766:Phosphorylation; D016891:Polycystic Kidney, Autosomal Dominant / Q000150:complications* / Q000235:genetics* / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013141:Spiro Compounds / Q000494:pharmacology; D050396:TRPP Cation Channels / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D051399:Aquaporin 2; D002118:Calcium; D009025:Morpholines; D017483:Receptors, Vasopressin; D013141:Spiro Compounds; D050396:TRPP Cation Channels; D020742:rhoA GTP-Binding Protein; C496024:Aqp2 protein, mouse; C103281:satavaptan