School of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3NB, UK.
School of Pharmacy, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Biochem Biophys Res Commun. 2018 Sep 10;503(3):1868-1873. doi: 10.1016/j.bbrc.2018.07.128. Epub 2018 Jul 27.
SPAK and OSR1 are two protein kinases that play important roles in regulating the function of numerous ion co-transporters. They are activated by two distinct mechanisms that involve initial phosphorylation at their T-loops by WNK kinases and subsequent binding to a scaffolding protein termed MO25. To understand this latter SPAK and OSR1 regulation mechanism, we herein show that MO25 binding to these two kinases is enhanced by serine phosphorylation in their highly conserved WEWS motif, which is located in their C-terminal domains. Furthermore, we show that this C-terminal phosphorylation is carried out by WNK kinases in vitro and involves WNK kinases in cells. Mutagenesis studies revealed key MO25 residues that are important for MO25 binding and activation of SPAK and OSR1 kinases. Collectively, this study provides new insights into the MO25-mediated activation of SPAK and OSR1 kinases, which are emerging as important players in regulating ion homeostasis.
SPAK 和 OSR1 是两种蛋白激酶，它们在调节众多离子共转运体的功能方面发挥着重要作用。它们通过两种不同的机制被激活，涉及 WNK 激酶对其 T 环的初始磷酸化，以及随后与一种称为 MO25 的支架蛋白结合。为了理解这种 SPAK 和 OSR1 的调节机制，我们在此表明，MO25 与这两种激酶的结合通过其高度保守的 WEWS 基序中的丝氨酸磷酸化增强，该基序位于它们的 C 末端结构域中。此外，我们表明，这种 C 末端磷酸化是由 WNK 激酶在体外进行的，并且涉及细胞中的 WNK 激酶。突变研究揭示了 MO25 结合和激活 SPAK 和 OSR1 激酶的关键 MO25 残基。总的来说，这项研究为 MO25 介导的 SPAK 和 OSR1 激酶的激活提供了新的见解，这些激酶作为调节离子稳态的重要参与者正在出现。
