Wald H, Goldstein O, Asher C, Yagil Y, Garty H
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Am J Physiol. 1996 Aug;271(2 Pt 2):F322-9. doi: 10.1152/ajprenal.1996.271.2.F322.
CHIF is a recently cloned, corticosteroid-induced gene which evokes K+ channel activity in oocytes (B. Attali, H. Latter, N. Rachamim, and H. Garty. Proc. Natl. Acad. Sci. USA 92: 6092-6096, 1995). To further characterize the possible role of this gene in epithelial ion transport, we have studied its epithelial distribution and hormonal induction. Northern hybridizations indicate that the zonal distribution of CHIF mRNA in kidney is: papilla >>medulla>> cortex. High levels of CHIF were also detected in a primary culture from inner medullary collecting duct (IMCD). Perfusing rats with < 20 nM aldosterone through osmotic minipumps evoked a 22.4 +/- 1.9-fold increase in colonic CHIF. A significant increase was observed 3 h after administrating the corticosteroid, but maximal response was detected only after a 72-h incubation. This response appears to be mineralocorticoid specific; perfusing or injecting rats with maximal doses of dexamethasone did not evoke a further increase in CHIF mRNA. In contrast, high levels of CHIF are expressed in kidney papilla and IMCD primary culture, irrespective of corticosteroid treatment. Thus, like the apical Na+ channel and the H(+)-K(+)-adenosinetriphosphatase, CHIF is mineralocorticoid induced in the colon but constitutively expressed in kidney.
CHIF是最近克隆出的一种皮质类固醇诱导基因，它能在卵母细胞中引发钾离子通道活性（B. 阿塔利、H. 拉特尔、N. 拉查米姆和H. 加蒂。《美国国家科学院院刊》92: 6092 - 6096, 1995年）。为了进一步阐明该基因在上皮离子转运中的可能作用，我们研究了其上皮分布及激素诱导情况。Northern杂交显示，CHIF mRNA在肾脏中的区域分布为：乳头>>髓质>>皮质。在内髓集合管（IMCD）的原代培养物中也检测到高水平的CHIF。通过渗透微型泵给大鼠灌注低于20 nM的醛固酮，可使结肠CHIF增加22.4±1.9倍。给予皮质类固醇3小时后观察到显著增加，但仅在孵育72小时后才检测到最大反应。这种反应似乎具有盐皮质激素特异性；给大鼠灌注或注射最大剂量的地塞米松不会使CHIF mRNA进一步增加。相反，无论是否进行皮质类固醇处理，CHIF在肾乳头和IMCD原代培养物中均高水平表达。因此，与顶端钠通道和H(+)-K(+)-三磷酸腺苷酶一样，CHIF在结肠中是盐皮质激素诱导表达，但在肾脏中是组成性表达。
