Functional characteristics of a cloned epithelial Na+/H+ exchanger (NHE3): resistance to amiloride and inhibition by protein kinase C.
Functional characteristics of a cloned epithelial Na+/H+ exchanger (NHE3): resistance to amiloride and inhibition by protein kinase C.
复制标题
克隆上皮 Na /H 交换器 (NHE3) 的功能特征：对阿米洛利的耐药性和蛋白激酶 C 的抑制。
DOI：
10.1073/pnas.90.19.9110
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发表时间：
1993
影响因子：
11.1
通讯作者：
Donowitz,M
中科院分区：
文献类型：
--
作者：
Tse,CM;Levine,SA;Yun,CH;Brant,SR;Pouyssegur,J;Montrose,MH;Donowitz,M
我们以前克隆了一个亚型Na+/H+交换器（NHE 3），它只在肠，肾和胃中表达。我们通过将NHE 3 cDNA稳定转染到PS120细胞（一种缺乏内源性Na+/H+交换器的成纤维细胞系）中，显示了NHE 3作为Na+/H+交换器的功能特征。NHE 3对阿米洛利和乙基异丙基阿米洛利抑制的抗性分别是管家Na+/H+交换亚型NHE 1的39倍和160倍。虽然这两个交换器被血清刺激，NHE 3被抑制佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA），刺激NHE 1。从机制上讲，血清和PMA刺激NHE 1的表观亲和力的增加交换细胞内的H+。而血清刺激和PMA抑制NHE 3的Vmax变化。当NHE 3在肠上皮细胞系Caco-2细胞中稳定表达时，NHE 3在顶膜中功能性表达。因此，NHE 3是上皮刷状缘Na+/H+交换器的良好候选者。此外，Na+/H+交换器可以通过改变Vmax或对细胞内H+的亲和力的机制来快速调节，这取决于Na+/H+交换器亚型。
We previously cloned an isoform Na+/H+ exchanger (NHE3), which was expressed only in intestine, kidney, and stomach. We show here the functional characteristics of NHE3 as a Na+/H+ exchanger by stably transfecting NHE3 cDNA into PS120 cells, a fibroblast cell line that lacks endogenous Na+/H+ exchangers. NHE3 was 39- and 160-fold more resistant to inhibition by amiloride and ethylisopropyl amiloride, respectively, than NHE1, the housekeeping Na+/H+ exchanger isoform. Although both exchangers were stimulated by serum, NHE3 was inhibited by phorbol 12-myristate 13-acetate (PMA), which stimulated NHE1. Mechanistically, serum and PMA stimulated NHE1 by an increase in the apparent affinity of the exchanger for intracellular H+. In contrast, serum stimulated and PMA inhibited NHE3 by a Vmax change. When NHE3 was stably expressed in Caco-2 cells, an intestinal epithelial cell line, NHE3 was functionally expressed in the apical membrane. Thus, NHE3 is a good candidate to be an epithelial brush border Na+/H+ exchanger. Furthermore, Na+/H+ exchangers can be rapidly regulated by mechanisms that change either the Vmax or the affinity for intracellular H+, depending on the Na+/H+ exchanger subtype.