ATP and purinergic receptor-dependent membrane traffic in bladder umbrella cells.
The umbrella cells that line the bladder are mechanosensitive, and bladder filling increases the apical surface area of these cells; however, the upstream signals that regulate this process are unknown. Increased pressure stimulated ATP release from the isolated uroepithelium of rabbit bladders, which was blocked by inhibitors of vesicular transport, connexin hemichannels, ABC protein family members, and nucleoside transporters. Pressure-induced increases in membrane capacitance (a measure of apical plasma membrane surface area where 1 microF approximately equals 1 cm2) were inhibited by the serosal, but not mucosal, addition of apyrase or the purinergic receptor antagonist PPADS. Upon addition of purinergic receptor agonists, increased capacitance was observed even in the absence of pressure. Moreover, knockout mice lacking expression of P2X2 and/or P2X3 receptors failed to show increases in apical surface area when exposed to hydrostatic pressure. Treatments that prevented release of Ca2+ from intracellular stores or activation of PKA blocked ATPgammaS-stimulated changes in capacitance. These results indicate that increased hydrostatic pressure stimulates release of ATP from the uroepithelium and that upon binding to P2X and possibly P2Y receptors on the umbrella cell, downstream Ca2+ and PKA second messenger cascades may act to stimulate membrane insertion at the apical pole of these cells.
Wang
Edward C Y
EC
Renal-Electrolyte Division and Laboratory of Epithelial Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Lee
Jey-Myung
JM
Ruiz
Wily G
WG
Balestreire
Elena M
EM
von Bodungen
Maximilian
M
Barrick
Stacey
S
Cockayne
Debra A
DA
Birder
Lori A
LA
Apodaca
Gerard
G
D000255:Adenosine Triphosphate / Q000819:agonists / Q000378:metabolism*; D000818:Animals; D001081:Apyrase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D025802:Electric Capacitance; D004705:Endocytosis / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D058910:Purinergic P2 Receptor Agonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000378:metabolism; D011817:Rabbits; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D015398:Signal Transduction / Q000502:physiology; D001743:Urinary Bladder / Q000166:cytology*; D019459:Urothelium / Q000378:metabolism / Q000648:ultrastructure
C546402:P2rx2 protein, mouse; C546409:P2rx3 protein, mouse; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D001081:Apyrase; D002118:Calcium