T95 Nucleophosmin Phosphorylation as a Novel Mediator and Marker of Regulated Cell Death in Acute Kidney Injury.
T95 Nucleophosmin Phosphorylation as a Novel Mediator and Marker of Regulated Cell Death in Acute Kidney Injury.
复制标题
DOI：
10.1152/ajprenal.00230.2020
复制
发表时间：
2020-07
期刊：
影响因子：
--
通讯作者：
Zhiyong Wang;Mostafa E. Belghasem;E. Salih;J. Henderson;C. Igwebuike;A. Havasi;S. Borkan
中科院分区：
文献类型：
--
作者：
Zhiyong Wang;Mostafa E. Belghasem;E. Salih;J. Henderson;C. Igwebuike;A. Havasi;S. Borkan
核磷蛋白（NPM）是一种重要的Bax伴侣蛋白，其位点特异性磷酸化在应激诱导的细胞死亡中的作用尚不清楚。我们假设NPM苏氨酸95 （T95）磷酸化既发出信号又促进细胞死亡。在静止细胞中，NPM只存在于细胞核中，苏氨酸95不被磷酸化。相比之下，磷酸化的T95 NPM （pNPM T95）在代谢应激后的细胞质中、在伽马辐射后的多种人类癌细胞系中以及在缺血后的人类肾组织中积累。基于T95磷酸化共识序列，我们假设糖原合成酶激酶3 β (GSK-3b)通过磷酸化T95 NPM调控胞内NPM易位。在无细胞系统中，GSK-3β磷酸化了含有T95的合成NPM肽。在体外，GSK-3b活性的双向操作实质上改变了T95磷酸化，胞质NPM易位和应激下的细胞存活，机制地将这些致死事件联系起来。此外，体内GSK-3β抑制可减少实验性缺血后肾组织中pNPM T95的胞浆积累。在急性肾损伤患者中，在冷冻肾活检组织中检测到近端小管细胞内的胞浆性NPM积累和小管内富含NPM的铸型。这些观察结果首次表明GSK-3β部分通过磷酸化T95磷酸化和胞质NPM积累来促进细胞死亡。T95 NPM也是改善缺血性肾细胞损伤的合理治疗靶点，可能是哺乳动物细胞中普遍存在的损伤标志物。
The function of site-specific phosphorylation of nucleophosmin (NPM), an essential Bax chaperone, in stress-induced cell death is unknown. We hypothesized that NPM threonine 95 (T95) phosphorylation both signals and promotes cell death. In resting cells, NPM exclusively resides in the nucleus and threonine 95 is non-phosphorylated. In contrast, phosphorylated T95 NPM (pNPM T95) accumulates in the cytosol after metabolic stress, in multiple human cancer cell lines following gamma radiation, and in post-ischemic human kidney tissue. Based on the T95 phosphorylation consensus sequence, we hypothesized that glycogen synthase kinase 3 beta (GSK-3b) regulates cytosolic NPM translocation by phosphorylating T95 NPM. In a cell-free system, GSK-3β phosphorylated a synthetic NPM peptide containing T95. In vitro, bi-directional manipulation of GSK-3b activity substantially altered T95 phosphorylation, cytosolic NPM translocation, and cell survival during stress, mechanistically linking these lethal events. Furthermore, GSK-3β inhibition in vivo decreased cytosolic pNPM T95 accumulation in kidney tissue after experimental ischemia. In patients with acute kidney injury, both cytosolic NPM accumulation in proximal tubule cells and NPM-rich intratubular casts were detected in frozen renal biopsy tissue. These observations show for the first time that GSK-3β promotes cell death partly by phosphorylating T95 phosphorylation and cytosolic NPM accumulation. T95 NPM is also a rational therapeutic target to ameliorate ischemic renal cell injury and may be a universal injury marker in mammalian cells.