Phosphorylation and ubiquitylation are opposing processes that regulate endocytosis of the water channel aquaporin-2
Phosphorylation and ubiquitylation are opposing processes that regulate endocytosis of the water channel aquaporin-2
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DOI：
10.1242/jcs.150680
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发表时间：
2014-07-15
影响因子：
4
通讯作者：
Fenton, Robert A.
中科院分区：
文献类型：
--
作者：
Moeller, Hanne B.;Aroankins, Takwa Shaiman;Fenton, Robert A.
翻译后修饰（PTMs）磷酸化和泛素化调节质膜蛋白功能。在这里，我们研究了膜蛋白水通道蛋白-2（AQP 2）的磷酸化和泛素化之间的相互作用，并证明磷酸化可以覆盖先前提出的K63连接的多泛素化的显性内吞信号。在极化上皮细胞中，虽然S256是AQP 2膜定位的重要磷酸化位点，但延长S269特异性磷酸化可降低AQP 2内吞速率。尽管它们非常接近，但S269处的AQP 2磷酸化和K270处的泛素化可以平行发生，当K270多聚泛素化水平最大时，S269磷酸化增加，AQP 2内吞减少。体内研究支持这一数据，最大水平的AQP 2泛素化与最大的S269磷酸化和增强的AQP 2质膜定位平行发生。总之，我们首次证明，虽然K63连接的多泛素化标记AQP 2的内吞作用，位点特异性磷酸化可以抵消多泛素化，以确定其最终定位。其他质膜蛋白可能存在类似的机制。
The post-translational modifications (PTMs) phosphorylation and ubiquitylation regulate plasma membrane protein function. Here, we examine the interplay between phosphorylation and ubiquitylation of the membrane protein aquaporin-2 (AQP2) and demonstrate that phosphorylation can override the previously suggested dominant endocytic signal of K63-linked polyubiquitylation. In polarized epithelial cells, although S256 is an important phosphorylation site for AQP2 membrane localization, the rate of AQP2 endocytosis was reduced by prolonging phosphorylation specifically at S269. Despite their close proximity, AQP2 phosphorylation at S269 and ubiquitylation at K270 can occur in parallel, with increased S269 phosphorylation and decreased AQP2 endocytosis occurring when K270 polyubiquitylation levels are maximal. In vivo studies support this data, with maximal levels of AQP2 ubiquitylation occurring in parallel to maximal S269 phosphorylation and enhanced AQP2 plasma membrane localization. In conclusion, we demonstrate for the first time that although K63-linked polyubiquitylation marks AQP2 for endocytosis, site-specific phosphorylation can counteract polyubiquitylation to determine its final localization. Similar mechanisms might exist for other plasma membrane proteins.