Spatial Control of Proton Pump H,K-ATPase Docking at the Apical Membrane by Phosphorylation-coupled Ezrin-Syntaxin 3 Interaction*
Spatial Control of Proton Pump H,K-ATPase Docking at the Apical Membrane by Phosphorylation-coupled Ezrin-Syntaxin 3 Interaction*
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DOI：
10.1074/jbc.m114.581280
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发表时间：
2014-10
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通讯作者：
Huijuan Yu;Jiajia Zhou;Hirohide Takahashi;William W. Yao;Yuki Suzuki;Xiao Yuan;S. Yoshimura;Yin Zhang;Ya Liu;N. Emmett;V. Bond;Dongmei Wang;Xia Ding;K. Takeyasu;X. Yao
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文献类型：
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作者：
Huijuan Yu;Jiajia Zhou;Hirohide Takahashi;William W. Yao;Yuki Suzuki;Xiao Yuan;S. Yoshimura;Yin Zhang;Ya Liu;N. Emmett;V. Bond;Dongmei Wang;Xia Ding;K. Takeyasu;X. Yao
背景：胃壁细胞的极化酸分泌需要埃兹蛋白及其Ser-66磷酸化。结果：Ser-66的磷酸化诱导ezrin构象变化，这使得ezrin与syntaxin 3相互作用。结论：ezrin的构象变化为H，K-ATP酶的顶端运输提供了空间线索。意义：Ezrin构象协调上皮细胞中极化囊泡的运输。胃的消化功能取决于胃腔的酸化。通过cAMP依赖性蛋白激酶（PKA）级联的激活触发酸分泌到腔中，其最终导致胃H，K-ATP酶插入壁细胞的顶端质膜中。偶联蛋白是ezrin，其通过PKA在Ser-66处的磷酸化是壁细胞活化所需的。然而，关于Ezrin在胃酸分泌中起作用的分子机制知之甚少。在这里，我们表明，丝氨酸-66磷酸化诱导ezrin的构象变化，使其与syntaxin 3（Stx 3）的协会，并提供了一个空间线索H，K-ATP酶贩运。这种构象依赖性的关联是特定的Stx 3，结合界面被映射到N-末端区域。生化分析表明，抑制ezrin在Ser-66磷酸化，防止ezrin-Stx 3协会和插入的H，K-ATP酶到壁细胞的顶端质膜。利用原子力显微镜分析，我们的研究表明，Ser-66的磷酸化诱导ezrin分子的解折叠，使Stx 3结合到其N端。鉴于Stx 3在极化分泌中的重要作用，我们的研究提出了第一个证据，其中磷酸化诱导的ezrin分子的构象重排为上皮细胞中的极化膜运输提供了空间线索。
Background: Polarized acid secretion in gastric parietal cells requires ezrin and its phosphorylation at Ser-66. Results: Phosphorylation of Ser-66 induces ezrin conformational change, which enables ezrin to interact with syntaxin 3. Conclusion: Conformational change of ezrin provides a spatial cue for apical trafficking of H,K-ATPase. Significance: Ezrin conformation orchestrates the polarized vesicle trafficking in epithelial cells. The digestive function of the stomach depends on acidification of the gastric lumen. Acid secretion into the lumen is triggered by activation of a cAMP-dependent protein kinase (PKA) cascade, which ultimately results in the insertion of gastric H,K-ATPases into the apical plasma membranes of parietal cells. A coupling protein is ezrin whose phosphorylation at Ser-66 by PKA is required for parietal cell activation. However, little is known regarding the molecular mechanism(s) by which ezrin operates in gastric acid secretion. Here we show that phosphorylation of Ser-66 induces a conformational change of ezrin that enables its association with syntaxin 3 (Stx3) and provides a spatial cue for H,K-ATPase trafficking. This conformation-dependent association is specific for Stx3, and the binding interface is mapped to the N-terminal region. Biochemical analyses show that inhibition of ezrin phosphorylation at Ser-66 prevents ezrin-Stx3 association and insertion of H,K-ATPase into the apical plasma membrane of parietal cells. Using atomic force microscopic analyses, our study revealed that phosphorylation of Ser-66 induces unfolding of ezrin molecule to allow Stx3 binding to its N terminus. Given the essential role of Stx3 in polarized secretion, our study presents the first evidence in which phosphorylation-induced conformational rearrangement of the ezrin molecule provides a spatial cue for polarized membrane trafficking in epithelial cells.