Regulation of maturation and processing of ENaC subunits in the rat kidney
Regulation of maturation and processing of ENaC subunits in the rat kidney
复制标题
DOI：
10.1152/ajprenal.00422.2005
复制
发表时间：
2006-09-01
影响因子：
4.2
通讯作者：
Palmer, Lawrence G.
中科院分区：
文献类型：
--
作者：
Ergonul, Zuhal;Frindt, Gustavo;Palmer, Lawrence G.
针对上皮钠通道（ENaC）的亚单位的抗体一起使用在皮质集合管的电生理测量，以探讨在钠或钾的摄入量的变化，在大鼠肾脏的蛋白质的处理。当动物保持低钠饮食7-9天，丰富的两种形式的α-亚基，与85和30 kDa的表观质量，增加。盐限制也增加了β-亚基的丰度，并产生了该亚基的糖苷内切酶H（Endo H）抗性库。α-亚基的90-kDa形式的丰度降低，而70-kDa形式的丰度增加，并且该肽还表现出Endo H-抗性糖基化。α-和γ-亚基的这些变化与4小时输注醛固酮引起的钠电导增加相关。所有三个亚基的变化与钠电导下降时，钠剥夺动物喝盐水5小时。我们的结论是，ENaC亚基主要是在一个不成熟的形式在盐充满大鼠。随着Na耗尽，亚基在涉及蛋白水解切割和进一步糖基化的过程中成熟。当动物接受外源性醛固酮治疗时，α-和γ-亚基发生了类似的变化，但β-亚基没有发生变化;当动物喂食高钾饮食时，α-和γ-亚基发生了类似的变化，但β-亚基没有发生变化。通道的加工和成熟的变化发生得足够快，足以参与肾脏对ENaC活性和Na重吸收的日常调节。
Antibodies directed against subunits of the epithelial Na channel ( ENaC) were used together with electrophysiological measurements in the cortical collecting duct to investigate the processing of the proteins in rat kidney with changes in Na or K intake. When animals were maintained on a low-Na diet for 7-9 days, the abundance of two forms of the alpha-subunit, with apparent masses of 85 and 30 kDa, increased. Salt restriction also increased the abundance of the beta-subunit and produced an endoglycosidase H ( Endo H)-resistant pool of this subunit. The abundance of the 90-kDa form of the alpha-subunit decreased, whereas that of a 70-kDa form increased and this peptide also exhibited Endo H-resistant glycosylation. These changes in alpha- and gamma-subunits were correlated with increases in Na conductance elicited by a 4-h infusion with aldosterone. Changes in all three subunits were correlated with decreases in Na conductance when Na-deprived animals drank saline for 5 h. We conclude that ENaC subunits are mainly in an immature form in salt-replete rats. With Na depletion, the subunits mature in a process that involves proteolytic cleavage and further glycosylation. Similar changes occurred in alpha- and gamma- but not beta-subunits when animals were treated with exogenous aldosterone, and in alpha- and gamma- but not beta-subunits when animals were fed a high-K diet. Changes in the processing and maturation of the channels occur rapidly enough to be involved in the daily regulation of ENaC activity and Na reabsorption by the kidney.