Nucleotides downregulate aquaporin 2 via activation of apical P2 receptors.
Vasopressin regulates water reabsorption in the collecting duct, but extracellular nucleotides modulate this regulation through incompletely understood mechanisms. We investigated these mechanisms using immortalized mouse collecting duct (mpkCCD) cells. Basolateral exposure to dDAVP induced AQP2 localization to the apical membrane, but co-treatment with ATP internalized AQP2. Because plasma membrane-bound P2 receptors (P2R) mediate the effects of extracellular nucleotides, we examined the abundance and localization of P2R in mpkCCD cells. In the absence of dDAVP, P2Y(1) and P2Y(4) receptors localized to the apical membrane, whereas P2X(2), P2X(4), P2X(5), P2X(7), P2Y(2), P2Y(11), and P2Y(12) receptors localized to the cytoplasm. dDAVP induced gene expression of P2X(1), which localized to the apical domain, and led to translocation of P2X(2) and P2Y(2) to the apical and basolateral membranes, respectively. In co-expression experiments, P2R activation decreased membrane AQP2 and AQP2-mediated water permeability in Xenopus oocytes expressing P2X(2), P2Y(2,) or P2Y(4) receptors, but not in oocytes expressing other P2R subtypes. In summary, these data suggest that AQP2-mediated water transport is downregulated not only by basolateral nucleotides, mediated by P2Y(2) receptors, but also by luminal nucleotides, mediated by P2X(2) and/or P2Y(4) receptors.
Urinary System Physiology Unit, Department of Veterinary Basic Sciences, Royal Veterinary College, Camden Campus, Royal College Street, London NW1 0TU, United Kingdom. swildman@rvc.ac.uk
Scott S P
SS
Wildman
Michelle
M
Boone
Claire M
CM
Peppiatt-Wildman
Alberto
A
Contreras-Sanz
Brian F
BF
King
David G
DG
Shirley
Peter M T
PM
Deen
Robert J
RJ
Unwin
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051399:Aquaporin 2 / Q000235:genetics / Q000378:metabolism*; D001127:Arginine Vasopressin; D002460:Cell Line; D015536:Down-Regulation; D005260:Female; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D023421:Models, Animal; D009711:Nucleotides / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D018408:Patch-Clamp Techniques; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058473:Receptors, Purinergic P2Y2; D014982:Xenopus laevis
D051399:Aquaporin 2; D009711:Nucleotides; C546402:P2rx2 protein, mouse; C546386:P2ry2 protein, mouse; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058473:Receptors, Purinergic P2Y2; C104749:purinoceptor P2Y4; D001127:Arginine Vasopressin; D000255:Adenosine Triphosphate