State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, 215123, Suzhou, China.
Department of Oncology, Wuxi No.2 People's Hospital, Jiangnan University Medical Center, 214002, Wuxi, China.
Exp Mol Med. 2024 May;56(5):1107-1122. doi: 10.1038/s12276-024-01208-z. Epub 2024 May 1.
Genotoxic therapy triggers reactive oxygen species (ROS) production and oxidative tissue injury. S-nitrosylation is a selective and reversible posttranslational modification of protein thiols by nitric oxide (NO), and 5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for NO synthesis. However, the mechanism by which BH4 affects protein S-nitrosylation and ROS generation has not been determined. Here, we showed that ionizing radiation disrupted the structural integrity of BH4 and downregulated GTP cyclohydrolase I (GCH1), which is the rate-limiting enzyme in BH4 biosynthesis, resulting in deficiency in overall protein S-nitrosylation. GCH1-mediated BH4 synthesis significantly reduced radiation-induced ROS production and fueled the global protein S-nitrosylation that was disrupted by radiation. Likewise, GCH1 overexpression or the administration of exogenous BH4 protected against radiation-induced oxidative injury in vitro and in vivo. Conditional pulmonary Gch1 knockout in mice (Gch1; Sftpa1-Cre mice) aggravated lung injury following irradiation, whereas Gch1 knock-in mice (Gch1; Sftpa1-Cre mice) exhibited attenuated radiation-induced pulmonary toxicity. Mechanistically, lactate dehydrogenase (LDHA) mediated ROS generation downstream of the BH4/NO axis, as determined by iodoacetyl tandem mass tag (iodoTMT)-based protein quantification. Notably, S-nitrosylation of LDHA at Cys163 and Cys293 was regulated by BH4 availability and could restrict ROS generation. The loss of S-nitrosylation in LDHA after irradiation increased radiosensitivity. Overall, the results of the present study showed that GCH1-mediated BH4 biosynthesis played a key role in the ROS cascade and radiosensitivity through LDHA S-nitrosylation, identifying novel therapeutic strategies for the treatment of radiation-induced lung injury.
致瘤治疗会引发活性氧（ROS）的产生和氧化组织损伤。S-亚硝基化是一氧化氮（NO）对蛋白质巯基的一种选择性和可逆的翻译后修饰，而 5,6,7,8-四氢生物蝶呤（BH4）是 NO 合成的必需辅助因子。然而，BH4 影响蛋白质 S-亚硝基化和 ROS 生成的机制尚未确定。在这里，我们表明，电离辐射破坏了 BH4 的结构完整性，并下调了 GTP 环化水解酶 I（GCH1），后者是 BH4 生物合成的限速酶，导致整体蛋白质 S-亚硝基化不足。GCH1 介导的 BH4 合成显著减少了辐射诱导的 ROS 生成，并为辐射破坏的全局蛋白质 S-亚硝基化提供了燃料。同样，GCH1 过表达或外源性 BH4 的给予可在体外和体内预防辐射诱导的氧化损伤。在小鼠中条件性肺 Gch1 敲除（Gch1; Sftpa1-Cre 小鼠）加剧了照射后的肺损伤，而 Gch1 敲入小鼠（Gch1; Sftpa1-Cre 小鼠）则表现出减轻的辐射诱导的肺毒性。在机制上，LDHA 通过 BH4/NO 轴下游的乳酸脱氢酶（LDHA）介导 ROS 的生成，这是通过碘乙酰基串联质量标签（iodoTMT）-基于蛋白质定量来确定的。值得注意的是，LDHA 的 Cys163 和 Cys293 上的 S-亚硝基化受 BH4 可用性的调节，并可限制 ROS 的生成。照射后 LDHA 中的 S-亚硝基化丢失增加了放射敏感性。总的来说，本研究的结果表明，GCH1 介导的 BH4 生物合成通过 LDHA S-亚硝基化在 ROS 级联和放射敏感性中发挥关键作用，为治疗辐射诱导的肺损伤提供了新的治疗策略。
Zotero 插件
