State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
Cell Death Dis. 2018 Jan 22;9(2):67. doi: 10.1038/s41419-017-0106-4.
Amyotrophic lateral sclerosis (ALS) involves the abnormal posttranslational modifications and fibrillization of copper, zinc superoxide dismutase (SOD1) and TDP-43. However, how SOD1-catalyzed reaction product hydrogen peroxide affects amyloid formation of SOD1 and TDP-43 remains elusory. 90% of ALS cases are sporadic and the remaining cases are familial ALS. In this paper, we demonstrate that HO at pathological concentrations triggers the fibrillization of wild-type SOD1 both in vitro and in SH-SY5Y cells. Using an anti-dimedone antibody that detects sulfenic acid modification of proteins, we found that Cys-111 in wild-type SOD1 is oxidized to C-SOH by pathological concentration of HO, followed by the formation of sulfenic acid modified SOD1 oligomers. Furthermore, we show that such SOD1 oligomers propagate in a prion-like manner, and not only drive wild-type SOD1 to form fibrils in the cytoplasm but also induce cytoplasm mislocalization and the subsequent fibrillization of wild-type TDP-43, thereby inducing apoptosis of living cells. Thus, we propose that HO at pathological concentrations triggers the fibrillization of wild-type SOD1 and subsequently induces SOD1 toxicity and TDP-43 toxicity in neuronal cells via sulfenic acid modification of Cys-111 in SOD1. Our Western blot and ELISA data demonstrate that sulfenic acid modified wild-type SOD1 level in cerebrospinal fluid of 15 sporadic ALS patients is significantly increased compared with 6 age-matched control patients. These findings can explain how HO at pathologic concentrations regulates the misfolding and toxicity of SOD1 and TDP-43 associated with ALS, and suggest that sulfenic acid modification of wild-type SOD1 should play pivotal roles in the pathogenesis of sporadic ALS.
肌萎缩侧索硬化症（ALS）涉及铜、锌超氧化物歧化酶（SOD1）和 TDP-43 的异常翻译后修饰和纤维化。然而，SOD1 催化反应产物过氧化氢如何影响 SOD1 和 TDP-43 的淀粉样形成仍然难以捉摸。90%的 ALS 病例为散发性，其余病例为家族性 ALS。在本文中，我们证明了病理浓度的 HO 在体外和 SH-SY5Y 细胞中触发野生型 SOD1 的纤维化。使用一种检测蛋白质亚磺酸修饰的抗二甲基酮抗体，我们发现野生型 SOD1 中的 Cys-111 被病理浓度的 HO 氧化为 C-SOH，随后形成亚磺酸修饰的 SOD1 寡聚物。此外，我们表明，这种 SOD1 寡聚物以类朊病毒的方式传播，不仅驱动野生型 SOD1 在细胞质中形成纤维，而且还诱导细胞质定位错误和随后野生型 TDP-43 的纤维化，从而诱导活细胞凋亡。因此，我们提出病理浓度的 HO 通过 SOD1 中 Cys-111 的亚磺酸修饰触发野生型 SOD1 的纤维化，随后诱导神经元细胞中 SOD1 毒性和 TDP-43 毒性。我们的 Western blot 和 ELISA 数据表明，与 6 名年龄匹配的对照患者相比，15 名散发性 ALS 患者脑脊液中亚磺酸修饰的野生型 SOD1 水平显著增加。这些发现可以解释病理浓度的 HO 如何调节与 ALS 相关的 SOD1 和 TDP-43 的错误折叠和毒性，并表明野生型 SOD1 的亚磺酸修饰应该在散发性 ALS 的发病机制中发挥关键作用。
