CELL-SPECIFIC EXPRESSION OF EPITHELIAL SODIUM-CHANNEL ALPHA-SUBUNITS,BETA-SUBUNITS, AND GAMMA-SUBUNITS IN ALDOSTERONE-RESPONSIVE EPITHELIAFROM THE RAT - LOCALIZATION BY IN-SITU HYBRIDIZATION AND IMMUNOCYTOCHEMISTRY

Citation
C. Due et al., CELL-SPECIFIC EXPRESSION OF EPITHELIAL SODIUM-CHANNEL ALPHA-SUBUNITS,BETA-SUBUNITS, AND GAMMA-SUBUNITS IN ALDOSTERONE-RESPONSIVE EPITHELIAFROM THE RAT - LOCALIZATION BY IN-SITU HYBRIDIZATION AND IMMUNOCYTOCHEMISTRY, The Journal of cell biology, 127(6), 1994, pp. 1907-1921
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell Biology
Journal title
ISSN journal
0021-9525
Volume
127
Issue
6
Year of publication
1994
Part
2
Pages
1907 - 1921
Database
ISI
SICI code
0021-9525(1994)127:6<1907:CEOESA>2.0.ZU;2-J
Abstract
A highly selective, amiloride-sensitive, epithelial sodium channel fro m rat colon (rENaC), composed of three homologous subunits termed alph a, beta, and gamma rENaC, has been cloned by functional expression and was proposed to mediate electrogenic sodium reabsorption in aldostero ne-responsive epithelia. To determine whether rENaC could account for sodium absorption in vivo, we studied the cellular localization of the sodium channel messenger RNA subunits by in situ hybridization and th eir cellular and subcellular distribution by immunocytochemistry in th e kidney, colon, salivary, and sweat glands of the rat. In the kidney, we show that the three subunit mRNAs are specifically co-expressed in the renal distal convoluted tubules (DCT), connecting tubules (CNT), cortical collecting ducts (CCD), and outer medullary collecting ducts (OMCD), but not in the inner medullary collecting ducts (IMCD). We dem onstrate co-localization of alpha, beta, and gamma subunit proteins in the apical membrane of a majority of cells of CCD and OMCD. Our data indicate that alpha, beta, and gamma subunit mRNAs and proteins are co -expressed in the distal nephron (excepting IMCD), a localization that correlates with the previously described physiological expression of amiloride-sensitive electrogenic sodium transport. Our data, however, suggest that another sodium transport protein mediates electrogenic am iloride-sensitive sodium reabsorption in IMCD. We also localized rENaC to the surface epithelial cells of the distal colon and to the secret ory ducts of the salivary gland and sweat gland, providing further evi dence consistent with the hypothesis that the highly selective, amilor ide-sensitive sodium channel is physiologically expressed in aldostero ne-responsive cells.