Subcellular redistribution is involved in acute regulation of the brush border Na+/H+ exchanger isoform 3 in human colon adenocarcinoma cell line Caco-2 -: Protein kinase C-mediated inhibition of the exchanger
Subcellular redistribution is involved in acute regulation of the brush border Na+/H+ exchanger isoform 3 in human colon adenocarcinoma cell line Caco-2 -: Protein kinase C-mediated inhibition of the exchanger
复制标题
DOI：
10.1074/jbc.273.15.8790
复制
发表时间：
1998-04-10
影响因子：
4.8
通讯作者：
Donowitz, M
中科院分区：
文献类型：
--
作者：
Janecki, AJ;Montrose, MH;Donowitz, M
Na+/H+交换器亚型3（NHE 3）是Na+/H+交换器基因家族的上皮刷状缘亚型，在小肠、结肠和肾脏的Na+重吸收中起重要作用。在几种细胞类型中，佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）通过改变V-max来急性抑制NHE 3活性，但这种抑制的机制尚不清楚。我们研究了在PMA诱导的抑制内源性刷状缘NHE 3在模型人结肠腺癌细胞系Caco-2中NHE 3的亚细胞再分布的作用。NHE 3的亚细胞定位通过共聚焦形态测定分析与细胞表面生物素化互补进行检查，并与通过荧光测量细胞内pH值评估的NHE 3活性进行比较。PMA抑制NHE 3活性28%（p < 0.01），这与NHE 3的刷状缘/近顶端细胞质区室的比率从近似4.3降至近似2.4有关。这种易位导致总细胞NHE 3的10-15%从刷状缘池转移到细胞质池。这些作用由蛋白激酶C介导，因为它们被蛋白激酶C抑制剂H7阻断。我们的结论是蛋白激酶C在Caco-2细胞中抑制NHE 3涉及交换器从刷状缘重新分配到根尖下的细胞质室，这种机制有助于类似于50%的整体蛋白激酶C诱导的抑制交换器。
Na+/H+ exchanger isoform 3 (NHE3), an epithelial brush border isoform of the Na+/H+ exchanger gene family, plays an important role in reabsorption of Na+ in the small intestine, the colon, and the kidney. In several cell types, phorbol 12-myristate 13-acetate (PMA) acutely inhibits NHE3 activity by changes in V-max, but the mechanism of this inhibition is unknown. We investigated the role of subcellular redistribution of NHE3 in the PMA-induced inhibition of endogenous brush border NHE3 in a model human colon adenocarcinoma cell line, Caco-2. Subcellular localization of NHE3 was examined by confocal morphometric analysis complemented with cell surface biotinylation and compared with NHE3 activity evaluated by fluorometric measurement of intracellular pH. PMA inhibited NHE3 activity by 28% (p < 0.01), which was associated with a decrease of the ratio of the brush border/subapical cytoplasmic compartment of NHE3 from similar to 4.3 to similar to 2.4. This translocation resulted in 10-15% of the total cell NHE3 being shifted from the brush border pool to the cytoplasmic pool. These effects were mediated by protein kinase C, since they were blocked by the protein kinase C inhibitor H7. We conclude that inhibition of NHE3 by protein kinase C in Caco-2 cells involves redistribution of the exchanger from brush border into a subapical cytoplasmic compartment, and that this mechanism contributes similar to 50% to the overall protein kinase C-induced inhibition of the exchanger.