title: Circulating aldosterone induces the apical accumulation of the proton pumping V-ATPase and increases proton secretion in clear cells in the caput epididymis.
abstract: Clear cells express the vacuolar proton-pumping H(+)-ATPase (V-ATPase) and acidify the lumen of the epididymis, a process that is essential for male fertility. The renin-angiotensin-aldosterone system (RAAS) regulates fluid and electrolyte balance in the epididymis, and a previous study showed binding of aldosterone exclusively to epididymal clear cells (Hinton BT, Keefer DA. Steroid Biochem 23: 231-233, 1985). We examined here the role of aldosterone in the regulation of V-ATPase in the epididymis. RT-PCR showed expression of the mineralocorticoid receptor [MR; nuclear receptor subfamily 3, group C member 2 (NR3C2)] and 11-β-dehydrogenase isozyme 2 (HSD11β2) mRNAs specifically in clear cells, isolated by fluorescence-activated cell sorting from B1-enhanced green fluorescent protein (EGFP) mice. Tail vein injection of adult rats with aldosterone, 1,2-dioctanoyl-sn-glycerol (DOG), or 8-(4-chlorophenylthio)-cAMP (cpt-cAMP) induced V-ATPase apical membrane accumulation and extension of V-ATPase-labeled microvilli in clear cells in the caput epididymis but not in the cauda. V-ATPase activity was measured in EGFP-expressing clear cells using the intracellular pH (pHi)-sensing dye seminaphthorhodafluor-5F-5-(and 6)-carboxylic acid, acetoxymethyl ester acetate (SNARF-5F). Aldosterone induced a rapid increase in the rate of Na(+)- and bicarbonate-independent pHi recovery following an NH4Cl-induced acid load in clear cells isolated from the caput but not the cauda. This effect was abolished by concanamycin A, spironolactone, and chelerythrine but not myristoylated-protein kinase inhibitor (mPKI) or mifepristone. Thus aldosterone increases V-ATPase-dependent proton secretion in clear cells in the caput epididymis via MR/NR3C2 and PKC activation. This study, therefore, identifies aldosterone as an active member of the RAAS for the regulation of luminal acidification in the proximal epididymis.
authors.affiliation: Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts; and.
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Roy
authors.forename: Eric
authors.initials: E
authors.lastname: Hill
authors.forename: Ye Chun
authors.initials: YC
authors.lastname: Ruan
authors.forename: Luca
authors.initials: L
authors.lastname: Vedovelli
authors.forename: Teodor G
authors.initials: TG
authors.lastname: Păunescu
authors.forename: Dennis
authors.initials: D
authors.lastname: Brown
authors.forename: Sylvie
authors.initials: S
authors.lastname: Breton
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000235:genetics / Q000378:metabolism; D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D002469:Cell Separation / Q000379:methods; D004822:Epididymis / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018161:Receptors, Mineralocorticoid / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000187:drug effects; D015398:Signal Transduction; D013997:Time Factors; D015854:Up-Regulation; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D018161:Receptors, Mineralocorticoid; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D000450:Aldosterone; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D011493:Protein Kinase C; C480628:Atp6v1b1 protein, mouse; D025262:Vacuolar Proton-Translocating ATPases
keywords: V-ATPase pump; aldosterone; clear cell; epididymis; nongenomic