Adrenalectomy reduces alpha 1 and not beta 1 Na(+)-K(+)-ATPase mRNA expression in rat distal nephron

Abstract

The abundance of mRNA of alpha 1-, alpha 2-, alpha 3-, beta 1-, and beta 2-isoforms of Na(+)-K(+)-ATPase was examined in several renal structures of normal and adrenalectomized (ADX) rats. In situ hybridization with 35S-labeled cRNA probes was performed on kidney sections from adult rats. The number of silver grains per unit surface area was quantified over cells of the glomerulus, proximal convoluted tubules (PCT), early distal tubules (EDT), and cortical collecting ducts (CCD). In normal rat kidney, alpha 1- and beta 1-mRNA was detected in PCT, EDT, and CCD, with the following range of magnitude: EDT > CCD > PCT > glomerulus. The amount of alpha 1- and beta 1-mRNA was equivalent. A large abundance of these two mRNA species was also found in the medullary thick ascending limb of the loop of Henle. Expression of alpha 2, alpha 3, and beta 2 was very low and evenly distributed over any cell type. In ADX, a significant decrease in alpha 1-mRNA (30%) was observed in EDT and CCD, with no change in PCT. beta 1-mRNA abundance was unaffected by adrenalectomy. These results indicate that 1) in the rat kidney alpha 1- and beta 1-mRNA are coexpressed at a similar level that varies along the renal tubule according to the cell type, 2) minute expression of alpha 2-, alpha 3-, and beta 2-mRNA is present in the kidney, and 3) corticosteroid depletion reduces the expression of alpha 1- and not beta 1-mRNA in the corticosteroid-sensitive tubular cells.

Differential Effects of Glucocorticoids and Mineralocorticoids on the mRNA Expression of Colon Ion Transporters in Infant Rats

“…In the infant kidney, the transcription rate of Na,K-ATPase is directly increased by G C (6). G C do not regulate Na,K-ATPase mRNA in adults (13,14). In adults, Na,K-ATPase mRNA is regulated by MC, at least in aldosterone-sensitive cells (13).…”

“…The effect of GC is tissue-specific and occurs only in tissues that are rapiclly maturing (9). GC do not seem to be necessary for Na,K-ATI'ase transcription in the adult renal cortex, because adrenalectomy does not affect the abundance of Na,K-ATPase mRNA in proximal tubules (13,14), nor does GC treatment in controll rats alter renal Na,KATPase mRNA (3). In the adult colon, ~t has been reported that GC but not aldosterone increase Na,K.-ATPase mRNA.…”

“…In situ hybridization studies show that in adrenalectomized adult rats the Na,K-ATPase mRNA abundance is reduced in MC-sensitive segments of the nephron-i.e. the distal tubule and the collecting duct (13). The effect of aldosterone on the biosynthesis of Na,K-ATPase has been studied in cultured amphibian A6 renal cells.…”

“…G C do not regulate Na,K-ATPase mRNA in adults (13,14). In adults, Na,K-ATPase mRNA is regulated by MC, at least in aldosterone-sensitive cells (13). The role of aldosterone in the maturation of Na,K-ATPase is less well defined.…”

Multiplicity of expression of Na+,K+–ATPaseα-subunit isoforms in the gill of Atlantic salmon (Salmo salar): cellular localisation and absolute quantification in response to salinity change

“…In addition to differentially regulated rates of transcription, there is evidence that the translational efficiency of the β-subunit may be several-fold higher than the α-subunit, which may account for equal accumulation of the two subunit proteins in those cells and tissues where α-mRNA is more abundant than β-mRNA. There are several examples of differential control of α-and β-subunit genes in cell systems (Corthésy-Theulaz et al, 1991;Farman et al, 1992;Geering et al, 1989) and one remarkable example among teleosts. Deane and Woo cloned both the α-and β-subunit in S. sarba gill and examined the response to various hormones (Deane and Woo, 2005).…”