cGMP inhibition of Na+/H+ antiporter 3 (NHE3) requires PDZ domain adapter NHERF2, a broad specificity protein kinase G-anchoring protein
cGMP inhibition of Na+/H+ antiporter 3 (NHE3) requires PDZ domain adapter NHERF2, a broad specificity protein kinase G-anchoring protein
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DOI：
10.1074/jbc.m500505200
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发表时间：
2005-04-29
影响因子：
4.8
通讯作者：
Donowitz, M
中科院分区：
文献类型：
--
作者：
Cha, B;Kim, JH;Donowitz, M
Na+/H+ 交换器 3 (NHE3) 介导的电中性 NaCl 吸收对于与水/Na+ 稳态相关的肠道和肾脏功能非常重要。 cGMP 抑制完整上皮细胞中的 NHE3。然而，出乎意料的是，即使在共表达 cGMP 依赖性蛋白激酶 II (cGKII) 时，它也无法抑制 PS120 细胞中稳定转染的 NHE3。 NHERF2（参与 NHE3 的 cAMP 抑制的串联 PDZ 结构域接头蛋白）的额外共表达恢复了 cGMP 以及 cAMP 抑制，而 NHERF1 仅恢复了 cAMP 抑制。确定了 NHERF2 但 NHERF1 不结合 cGKII 的体外条件。 NHERF2 PDZ2 C 末端结合 NHE3，也结合 cGKII。 cGKII 的非肉豆蔻酰化突变体不支持 NHE3 的 cGMP 抑制。尽管 cGKI 在体外也结合 NHERF2，但除非添加肉豆蔻酰化位点，否则它不会引起 NHE3 的抑制。这些结果表明，NHERF2 作为一种新型蛋白激酶 G 锚定蛋白，是 NHE3 的 cGMP 抑制所必需的，并且 cGKII 必须通过其肉豆蔻酰基锚结合到质膜上，并结合到 NHERF2 上才能抑制 NHE3。
Electroneutral NaCl absorption mediated by Na+/H+ exchanger 3 (NHE3) is important in intestinal and renal functions related to water/Na+ homeostasis. cGMP inhibits NHE3 in intact epithelia. However, unexpectedly it failed to inhibit NHE3 stably transfected in PS120 cells, even upon co-expression of cGMP-dependent protein kinase type II (cGKII). Additional co-expression of NHERF2, the tandem PDZ domain adapter protein involved in cAMP inhibition of NHE3, restored cGMP as well as cAMP inhibition, whereas NHERF1 solely restored cAMP inhibition. In vitro conditions were identified in which NHERF2 but not NHERF1 bound cGKII. The NHERF2 PDZ2 C terminus, which binds NHE3, also bound cGKII. A non-myristoylated mutant of cGKII did not support cGMP inhibition of NHE3. Although cGKI also bound NHERF2 in vitro, it did not evoke inhibition of NHE3 unless a myristoylation site was added. These results show that NHERF2, acting as a novel protein kinase G-anchoring protein, is required for cGMP inhibition of NHE3 and that cGKII must be bound both to the plasma membrane by its myristoyl anchor and to NHERF2 to inhibit NHE3.