Nongenomic stimulation of vacuolar H+-ATPases in intercalated renal tubule cells by aldosterone.
Nongenomic stimulation of vacuolar H+-ATPases in intercalated renal tubule cells by aldosterone.
复制标题
醛固酮对闰肾小管细胞中液泡 H-ATP 酶的非基因组刺激。
DOI：
10.1073/pnas.0307321101
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发表时间：
2004
影响因子：
11.1
通讯作者：
Wagner,CarstenA
中科院分区：
文献类型：
--
作者：
Winter,Christian;Schulz,Nicole;Giebisch,Gerhard;Geibel,JohnP;Wagner,CarstenA
肾收集管在酸碱平衡中起关键作用，它通过建立陡峭的上皮pH梯度来实现碳酸氢盐的几乎完全重吸收和氨的有效分泌到尿液中。尿液在收集管中酸化的机制包括活跃的、电致氢（H+）分泌，以及不太重要的钾(K+)-氢+交换。紊乱的肾酸化和无法降低尿液pH值是远端小管酸中毒的标志，通常是由先天性代谢错误引起的，涉及集合管中的空泡H+- atp酶亚基。三种因素调节集管嵌入细胞中的H+- atp酶活性：酸碱状态、血管紧张素II和醛固酮。醛固酮的大多数作用涉及矿皮质激素受体的激活和转录和蛋白质合成的基因组变化。在这里，我们证明了分离小鼠外髓集管（OMCD）插层细胞空泡H+- atp酶激活的非基因组途径。体外将分离的外髓集管暴露于醛固酮（10 nM） 15分钟，使空泡H+- atp酶活性≈2- 3倍。无论是抑制矿物皮质激素受体，还是抑制转录和蛋白质合成，都不能阻止醛固酮诱导的H+- atp酶的刺激。然而，秋水仙碱可消除醛固酮的刺激作用，提示微管网络对H+- atp酶的刺激作用。注射醛固酮小鼠肾脏免疫组化显示，omcd插层细胞顶端H+- atp酶染色增加。醛固酮的刺激作用与细胞内Ca2+的短暂升高有关，需要完整的PKC。因此，醛固酮对omcd嵌入细胞空泡H+- atp酶活性的快速非基因组调节可能在激素控制全身酸碱稳态中发挥额外作用。
Renal collecting ducts play a critical role in acid–base homeostasis by establishing steep transepithelial pH gradients necessary for the almost complete reabsorption of bicarbonate and the effective secretion of ammonium into the urine. The mechanisms of urine acidification in collecting ducts involve active, electrogenic hydrogen (H+) secretion and, less importantly, potassium (K+)-H+exchange. Deranged renal acidification and the inability to lower urine pH are hallmarks of distal tubular acidosis and often result from inborn errors of metabolism involving vacuolar H+-ATPase subunits in the collecting ducts. Three factors regulate H+-ATPase activity in intercalated cells of collecting ducts: the acid–base status, angiotensin II, and aldosterone. Most effects of aldosterone involve activation of the mineralocorticoid receptor and genomic changes in transcription and protein synthesis. Here we demonstrate a nongenomic pathway of vacuolar H+-ATPase activation in intercalated cells of isolated mouse outer medullary collecting ducts (OMCD).In vitroexposure of isolated outer medullary collecting ducts to aldosterone (10 nM) for times as short as 15 min increases vacuolar H+-ATPase activity ≈2- to 3-fold. Neither inhibition of mineralocorticoid receptors nor of transcription and protein synthesis prevented aldosterone-induced stimulation of H+-ATPase. Incubation with colchicine, however, abolished the stimulatory effect of aldosterone, suggesting a role of the microtubular network for H+-ATPase stimulation. Immunohistochemistry in kidneys from aldosterone-injected mice showed increased apical H+-ATPase staining in OMCD-intercalated cells. The stimulatory effect of aldosterone was associated with a transient rise in intracellular Ca2+and required intact PKC. Thus, rapid nongenomic modulation of vacuolar H+-ATPase activity in OMCD-intercalated cells by aldosterone may play an additional role in hormonal control of systemic acid–base homeostasis.