Division of Nephrology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
FASEB J. 2019 Mar;33(3):3718-3730. doi: 10.1096/fj.201800885RR. Epub 2018 Dec 6.
Protein tyrosine (Tyr) nitration, the covalent addition of a nitro group (NO) to Tyr residues, is emerging as a candidate mechanism of endothelial dysfunction. Previous studies have shown that Tyr nitration is primarily induced by nitrosative stress, a process characterized by the production of reactive nitrogen species, especially peroxynitrite anion (ONOO), which is considered a secondary product of NO in the presence of superoxide radicals (O). However, the impact of nitrosative stress-induced Tyr nitration on endothelial dysfunction has not been thoroughly elucidated to date. We developed an endothelial dysfunction model, a process called "endothelial-to-mesenchymal transition (EndMT)," and evaluated the production of NO, O, and protein nitration during EndMT. The results showed that TGF-β1 stimulation induced EndMT and elevated endothelial NO and O production as well as nitration of the catalytic subunit of protein phosphatase (PP)2A. Mass spectrometry analysis showed that Tyr265 was the nitration site in the catalytic subunit of protein phosphatase (PP)2A, and this Tyr nitration increased PP2A activity and disrupted endothelial integrity. To devise an endothelial-targeted anti-PP2Ac nitration strategy, a mimic peptide, tyrosine 265 wild type (Y265WT), conjugated with the cell-penetrating peptide HIV-1 TAT protein (TAT) was synthesized. PP2Ac nitration and PP2A activity were significantly inhibited by pretreatment with TAT-265WT, and the integrity of endothelial cells was maintained. Furthermore, injection of TAT-265WT attenuated renal nitration formation and caused anticapillary rarefaction in a unilateral urethral obstructive nephropathy model. Taken together, these results offer preclinical proof of concept for TAT-265WT as a tractable agent to protect against nitrosative stress-induced endothelial dysfunction in renal microvessels.-Deng,Y., Cai, Y., Liu, L., Lin, X., Lu, P., Guo, Y., Han, M., Xu, G. Blocking Tyr265 nitration of protein phosphatase 2A attenuates nitrosative stress-induced endothelial dysfunction in renal microvessels.
蛋白质酪氨酸（Tyr）硝化是指硝基（NO）共价添加到 Tyr 残基上，这是内皮功能障碍的候选机制之一。先前的研究表明，Tyr 硝化主要由硝化应激诱导，该过程的特征是活性氮物种的产生，特别是过氧亚硝酸盐阴离子（ONOO-），其被认为是超氧化物自由基（O）存在下的 NO 的次级产物。然而，迄今为止，硝化应激诱导的 Tyr 硝化对内皮功能障碍的影响尚未得到充分阐明。我们开发了一种内皮功能障碍模型，称为“内皮向间充质转化（EndMT）”，并评估了 EndMT 过程中 NO、O 和蛋白质硝化的产生。结果表明，TGF-β1 刺激诱导 EndMT，并升高内皮 NO 和 O 的产生以及蛋白磷酸酶（PP）2A 催化亚基的硝化。质谱分析表明，蛋白磷酸酶（PP）2A 催化亚基的 Tyr265 是硝化位点，这种 Tyr 硝化增加了 PP2A 的活性并破坏了内皮完整性。为了设计一种针对内皮的抗 PP2Ac 硝化策略，合成了一种模拟肽，酪氨酸 265 野生型（Y265WT），与细胞穿透肽 HIV-1 TAT 蛋白（TAT）缀合。TAT-265WT 的预处理可显著抑制 PP2Ac 硝化和 PP2A 活性，并维持内皮细胞的完整性。此外，TAT-265WT 的注射可减轻单侧输尿管梗阻肾病模型中的肾脏硝化形成并导致毛细血管稀疏。总之，这些结果为 TAT-265WT 作为一种可行的药物提供了临床前概念验证，可用于保护肾脏微血管免受硝化应激诱导的内皮功能障碍。-邓，Y.，蔡，Y.，刘，L.，林，X.，陆，P.，郭，Y.，韩，M.，徐，G. 阻断 Tyr265 硝化的蛋白磷酸酶 2A 可减轻肾脏微血管硝化应激诱导的内皮功能障碍。
