Cholera toxin inhibits SNX27-retromer-mediated delivery of cargo proteins to the plasma membrane
Cholera toxin inhibits SNX27-retromer-mediated delivery of cargo proteins to the plasma membrane
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DOI：
10.1242/jcs.218610
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发表时间：
2018-08-01
影响因子：
4
通讯作者：
Donowitz, Mark
中科院分区：
文献类型：
--
作者：
Singh, Varsha;Yang, Jianbo;Donowitz, Mark
霍乱毒素(CT)通过增加细胞内cAMP导致依赖PKA的CFTR分泌Cl-增加，并通过抑制Na+/H+交换3(NHE3；也称为SLC9A3)而减少对Na+的吸收，从而导致严重腹泻。CT抑制NHE3的机制(S)尚有部分了解，尽管目前还没有药物治疗能成功逆转这种抑制。我们现在描述CT磷酸化SNX27 PDZ结构域中的一个氨基酸，它抑制SNX27介导的NHE3从早期内吞体膜到质膜(PM)的运输，并通过减少PM表达和减少内胞循环的机制导致NHE3基础活性降低。重要的是，突变研究(从丝氨酸到天冬氨酸)表明，SNX27的这种磷酸化的影响与SNX27功能丧失时看到的效果相似，影响了与SNX27-逆转聚体结合的货物蛋白的PM运输。此外，CT通过减少核心逆转聚体蛋白的数量来破坏逆转聚体功能的稳定。CT的这些效应可以通过使用“药理伴侣”来增强逆转录稳定性来部分挽救。此外，药理伴侣可用于增加基础和霍乱毒素抑制的NHE3活性和肠上皮细胞对液体的吸收。本文对论文的第一作者进行了相关的第一人称采访。
Cholera toxin (CT) causes severe diarrhea by increasing intracellular cAMP leading to a PKA-dependent increase in Cl-secretion through CFTR and decreased Na+ absorption through inhibition of Na+/H+ exchanger 3 (NHE3; also known as SLC9A3). The mechanism(s) by which CT inhibits NHE3 is partially understood, although no drug therapy has been successful at reversing this inhibition. We now describe that CT phosphorylates an amino acid in the PDZ domain of SNX27, which inhibits SNX27-mediated trafficking of NHE3 from the early endosomes to the plasma membrane (PM), and contributes to reduced basal NHE3 activity through a mechanism that involves reduced PM expression and reduced endocytic recycling. Importantly, mutagenesis studies (Ser to Asp) showed that the effect of this phosphorylation of SNX27 phenocopies the effects seen upon loss of SNX27 function, affecting PM trafficking of cargo proteins that bind SNX27-retromer. Additionally, CT destabilizes retromer function by decreasing the amount of core retromer proteins. These effects of CT can be partially rescued by enhancing retromer stability by using 'pharmacological chaperones'. Moreover, pharmacological chaperones canbeused to increase basal and choleratoxin-inhibitedNHE3activity and fluid absorption by intestinal epithelial cells.This article has an associated First Person interview with the first author of the paper.