LeMaire Sophia M, Raghuram Viswanathan, Grady Cameron R, Pickering Christina M, Chou Chung-Lin, Umejiego Ezigbobiara N, Knepper Mark A
Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
Howard University College of Medicine, Washington, District of Columbia.
Am J Physiol Renal Physiol. 2017 Jan 1;312(1):F84-F95. doi: 10.1152/ajprenal.00455.2016. Epub 2016 Oct 26.
Phosphorylation of the aquaporin-2 (AQP2) water channel at four COOH-terminal serines plays a central role in the regulation of water permeability of the renal collecting duct. The level of phosphorylation at these sites is determined by a balance between phosphorylation by protein kinases and dephosphorylation by phosphatases. The phosphatases that dephosphorylate AQP2 have not been identified. Here, we use large-scale data integration techniques to identify serine-threonine phosphatases likely to interact with AQP2 in renal collecting duct principal cells. As a first step, we have created a comprehensive list of 38 S/T phosphatase catalytic subunits present in the mammalian genome. Then we used Bayes' theorem to integrate available information from large-scale data sets from proteomic and transcriptomic studies to rank the known S/T phosphatases with regard to the likelihood that they interact with AQP2 in renal collecting duct cells. To broaden the analysis, we have generated new proteomic data (LC-MS/MS) identifying 4538 distinct proteins including 22 S/T phosphatases in cytoplasmic fractions from native inner medullary collecting duct cells from rats. The official gene symbols corresponding to the top-ranked phosphatases (common names in parentheses) were: Ppp1cb (PP1-β), Ppm1g (PP2C), Ppp1ca (PP1-α), Ppp3ca (PP2-B or calcineurin), Ppp2ca (PP2A-α), Ppp1cc (PP1-γ), Ppp2cb (PP2A-β), Ppp6c (PP6C), and Ppp5c (PP5). This ranking correlates well with results of prior reductionist studies of ion and water channels in renal collecting duct cells.
水通道蛋白2（AQP2）水通道在四个COOH末端丝氨酸处的磷酸化在肾集合管水通透性调节中起核心作用。这些位点的磷酸化水平由蛋白激酶的磷酸化和磷酸酶的去磷酸化之间的平衡决定。使AQP2去磷酸化的磷酸酶尚未被鉴定出来。在此，我们使用大规模数据整合技术来鉴定可能在肾集合管主细胞中与AQP2相互作用的丝氨酸 - 苏氨酸磷酸酶。第一步，我们创建了一份包含哺乳动物基因组中存在的38种S/T磷酸酶催化亚基的综合列表。然后我们使用贝叶斯定理整合来自蛋白质组学和转录组学研究的大规模数据集的可用信息，以对已知的S/T磷酸酶与它们在肾集合管细胞中与AQP2相互作用的可能性进行排名。为了拓宽分析范围，我们生成了新的蛋白质组学数据（LC-MS/MS），鉴定了4538种不同的蛋白质，包括来自大鼠天然内髓集合管细胞胞质部分的22种S/T磷酸酶。排名靠前的磷酸酶对应的官方基因符号（括号内为常用名称）为：Ppp1cb（PP1-β）、Ppm1g（PP2C）、Ppp1ca（PP1-α）、Ppp3ca（PP2-B或钙调神经磷酸酶）、Ppp2ca（PP2A-α）、Ppp1cc（PP1-γ）、Ppp2cb（PP2A-β）、Ppp6c（PP6C）和Ppp5c（PP5）。这种排名与先前对肾集合管细胞中离子和水通道的简化研究结果高度相关。
