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Cyclic AMP stimulates apical V-ATPase accumulation, microvillar elongation and proton extrusion in kidney collecting duct A-intercalated cells


Paunescu, T G; Ljubojevic, M; Russo, L M; Winter, C; McLaughlin, M M; Wagner, C A; Breton, S; Brown, D (2010). Cyclic AMP stimulates apical V-ATPase accumulation, microvillar elongation and proton extrusion in kidney collecting duct A-intercalated cells. American Journal of Physiology. Renal Physiology, 298(3):F643-F654.

Abstract

Kidney proton-secreting A-intercalated cells (A-IC) respond to systemic acidosis by accumulating the vacuolar ATPase (V-ATPase) in their apical membrane and by increasing the length and number of apical microvilli. We show here that the cell permeant cAMP analog CPT-cAMP, infused in vivo, results in an almost two-fold increase in apical V-ATPase accumulation in AE1-positive A-IC within 15 min, and that these cells develop an extensive array of apical microvilli compared to controls. In contrast, no significant change in V-ATPase distribution could be detected by immunocytochemistry in B-intercalated cells at the acute time point examined. To show a direct effect of cAMP on A-IC, we prepared cell suspensions from the medulla of transgenic mice expressing EGFP in IC (driven by the B1-subunit promoter of the V-ATPase) and exposed them to cAMP analogs in vitro. 3D-reconstructions of confocal images revealed that cAMP induced a time dependent growth of apical microvilli, starting within minutes after addition. This effect was blocked by the PKA inhibitor, myristoylated PKI. These morphological changes were paralleled by increased cAMP-mediated proton extrusion (pHi recovery) by A-IC in outer medullary collecting ducts measured using the ratiometric probe BCECF. These results, and our prior data showing that the bicarbonate-stimulated soluble adenylyl cyclase (sAC) is highly expressed in kidney intercalated cells, support the idea that cAMP generated either by sAC, or by activation of other signaling pathways, is part of the signal transduction mechanism involved in acid-base sensing and V-ATPase membrane trafficking in kidney intercalated cells.

Kidney proton-secreting A-intercalated cells (A-IC) respond to systemic acidosis by accumulating the vacuolar ATPase (V-ATPase) in their apical membrane and by increasing the length and number of apical microvilli. We show here that the cell permeant cAMP analog CPT-cAMP, infused in vivo, results in an almost two-fold increase in apical V-ATPase accumulation in AE1-positive A-IC within 15 min, and that these cells develop an extensive array of apical microvilli compared to controls. In contrast, no significant change in V-ATPase distribution could be detected by immunocytochemistry in B-intercalated cells at the acute time point examined. To show a direct effect of cAMP on A-IC, we prepared cell suspensions from the medulla of transgenic mice expressing EGFP in IC (driven by the B1-subunit promoter of the V-ATPase) and exposed them to cAMP analogs in vitro. 3D-reconstructions of confocal images revealed that cAMP induced a time dependent growth of apical microvilli, starting within minutes after addition. This effect was blocked by the PKA inhibitor, myristoylated PKI. These morphological changes were paralleled by increased cAMP-mediated proton extrusion (pHi recovery) by A-IC in outer medullary collecting ducts measured using the ratiometric probe BCECF. These results, and our prior data showing that the bicarbonate-stimulated soluble adenylyl cyclase (sAC) is highly expressed in kidney intercalated cells, support the idea that cAMP generated either by sAC, or by activation of other signaling pathways, is part of the signal transduction mechanism involved in acid-base sensing and V-ATPase membrane trafficking in kidney intercalated cells.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Integrative Human Physiology
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Uncontrolled Keywords:proton pump, H+ATPase, immunocytochemistry, membrane trafficking
Date:March 2010
Deposited On:15 Mar 2010 10:41
Last Modified:05 Apr 2016 13:59
Publisher:American Physiological Society
ISSN:0363-6127
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1152/ajprenal.00584.2009
PubMed ID:20053793
Permanent URL: https://doi.org/10.5167/uzh-31909

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