Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the recessive genetic disease cystic fibrosis, where the chloride transport across the apical membrane of epithelial cells mediated by the CFTR protein is impaired. CFTR protein trafficking to the plasma membrane (PM) is the result of a complex interplay between the secretory and membrane recycling pathways that control the number of channels present at the membrane. In addition, the ion transport activity of CFTR at the PM is modulated through post-translational protein modifications. Previously we described that spleen tyrosine kinase (SYK) phosphorylates a specific tyrosine residue in the nucleotide-binding domain 1 domain and this modification can regulate the PM abundance of CFTR. Here we identified the underlying biochemical mechanism using peptide pull-down assays followed by mass spectrometry. We identified in bronchial epithelial cells that the adaptor protein SHC1 recognizes tyrosine-phosphorylated CFTR through its phosphotyrosine-binding domain and that the formation of a complex between SHC1 and CFTR is induced at the PM in the presence of activated SYK. The depletion of endogenous SHC1 expression was sufficient to promote an increase in CFTR at the PM of these cells. The results identify a SYK/SHC1 pathway that regulates the PM levels of CFTR channels, contributing to a better understanding of how CFTR-mediated chloride secretion is regulated.

囊性纤维化跨膜电导调节因子 ( CFTR ) 基因的突变会导致隐性遗传病囊性纤维化，其中由 CFTR 蛋白介导的氯离子穿过上皮细胞顶膜的转运受到损害。 CFTR 蛋白向质膜 (PM) 的运输是控制膜上通道数量的分泌通路和膜回收通路之间复杂相互作用的结果。此外，CFTR 在 PM 处的离子传输活性通过翻译后蛋白质修饰进行调节。之前我们描述了脾酪氨酸激酶（SYK）磷酸化核苷酸结合域 1 结构域中的特定酪氨酸残基，这种修饰可以调节 CFTR 的 PM 丰度。在这里，我们使用肽下拉分析和质谱分析确定了潜在的生化机制。我们在支气管上皮细胞中发现，接头蛋白 SHC1 通过其磷酸酪氨酸结合域识别酪氨酸磷酸化 CFTR，并且在存在激活的 SYK 的情况下，在 PM 处诱导 SHC1 和 CFTR 之间复合物的形成。内源性 SHC1 表达的减少足以促进这些细胞 PM 时 CFTR 的增加。结果确定了调节 CFTR 通道 PM 水平的 SYK/SHC1 途径，有助于更好地了解 CFTR 介导的氯离子分泌是如何调节的。