Saito Shiori, Ando Yukio, Nakamura Masaaki, Ueda Mitsuharu, Kim Jaemi, Ishima Yu, Akaike Takaaki, Otagiri Masaki
Department of Biopharmaceutics, Graduate School of Pharmaceutical Science, Kumamoto University, Kumamoto, Japan.
Biochemistry. 2005 Aug 23;44(33):11122-9. doi: 10.1021/bi050327i.
Although oxidative stress is said to play an important role in the amyloid formation mechanism in several types of amyloidosis, few details about this role have been described. Amyloid is commonly deposited around the vessels that are the primary site of action of nitric oxide generated from endothelial cells and smooth muscle cells, so nitric oxide may be also implicated in amyloid formation. For this study, we examined the in vitro effect of S-nitrosylation on amyloid formation induced by wild-type transthyretin, a precursor protein of senile systemic amyloidosis, and amyloidogenic transthyretin V30M, a precursor protein of amyloid deposition in familial amyloidotic polyneuropathy. S-Nitrosylation of amyloidogenic transthyretin V30M via the cysteine at position 10 was 2 times more extensive than that of wild-type transthyretin in a nitric oxide-generating solution. Both wild-type transthyretin and amyloidogenic transthyretin V30M formed amyloid fibrils under acidic conditions, and S-nitrosylated transthyretins exhibited higher amyloidogenicity than did unmodified transthyretins. Moreover, S-nitrosylated amyloidogenic transthyretin V30M formed more fibrils than did S-nitrosylated wild-type transthyretin. Structural studies revealed that S-nitrosylation of amyloidogenic transthyretin V30M induced a change in its conformation, as well as instability of the tetramer conformation. These results suggest that the nitric oxide-mediated modification of transthyretin, especially variant transthyretin, may play an important role in amyloid formation in senile systemic amyloidosis and familial amyloidotic polyneuropathy.
尽管氧化应激据说在几种类型的淀粉样变性的淀粉样蛋白形成机制中起重要作用，但关于这一作用的细节描述甚少。淀粉样蛋白通常沉积在内皮细胞和平滑肌细胞产生的一氧化氮的主要作用部位——血管周围，因此一氧化氮可能也与淀粉样蛋白形成有关。在本研究中，我们检测了S-亚硝基化对野生型转甲状腺素蛋白（老年系统性淀粉样变性的前体蛋白）和淀粉样变性转甲状腺素蛋白V30M（家族性淀粉样多神经病中淀粉样蛋白沉积的前体蛋白）诱导的淀粉样蛋白形成的体外影响。在一氧化氮生成溶液中，淀粉样变性转甲状腺素蛋白V30M第10位的半胱氨酸的S-亚硝基化程度比野生型转甲状腺素蛋白高2倍。野生型转甲状腺素蛋白和淀粉样变性转甲状腺素蛋白V30M在酸性条件下均形成淀粉样纤维，且S-亚硝基化的转甲状腺素蛋白比未修饰的转甲状腺素蛋白表现出更高的淀粉样变性。此外，S-亚硝基化的淀粉样变性转甲状腺素蛋白V30M比S-亚硝基化的野生型转甲状腺素蛋白形成更多的纤维。结构研究表明，淀粉样变性转甲状腺素蛋白V30M的S-亚硝基化诱导了其构象变化以及四聚体构象的不稳定性。这些结果表明，一氧化氮介导的转甲状腺素蛋白修饰，尤其是变异型转甲状腺素蛋白的修饰，可能在老年系统性淀粉样变性和家族性淀粉样多神经病的淀粉样蛋白形成中起重要作用。
