Mammalian Selenocysteine Lyase Is Involved in Selenoprotein Biosynthesis
Mammalian Selenocysteine Lyase Is Involved in Selenoprotein Biosynthesis
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DOI：
10.3177/jnsv.57.298
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发表时间：
2011-08-01
影响因子：
1.6
通讯作者：
Esaki, Nobuyoshi
中科院分区：
文献类型：
--
作者：
Kurokawa, Suguru;Takehashi, Masanori;Esaki, Nobuyoshi
硒半胱氨酸裂解酶通过专属作用于L-硒半胱氨酸，催化L-硒半胱氨酸分解生成L-丙氨酸和硒。大鼠SCL的X射线结构分析表明，SCL是如何从分子水平上区分L-硒半胱氨酸和L-半胱氨酸的。SCL被认为在从含硒半胱氨酸残基的降解硒蛋白中回收微量营养素硒的过程中发挥作用。但SCL在体内硒代谢中的作用尚不清楚。在此，我们证明了在HeLa细胞中，用(75)Se标记的硒蛋白P(Sepp1)作为硒来源的硒蛋白的(75)Se标记效率比转染对照siRNA的细胞降低。免疫细胞化学分析显示，SCL在肾和肝细胞中高表达，其中硒半胱氨酸是从硒蛋白中回收的。小鼠成熟的睾丸在活跃地产生硒蛋白的精子细胞中表现出一种特殊的SCL染色模式。然而，SCL在Sertoli细胞中弱表达，Sertoli细胞接受Sepp1并向生殖细胞供应硒。这些结果表明，SCL发生在需要硒蛋白的细胞中，可能是为了回收来自硒蛋白(如Sepp1)的硒。
Selenocysteine lyase (SCL) catalyzes the decomposition of L-selenocysteine to yield L-alanine and selenium by acting exclusively on L-selenocysteine. The X-ray structural analysis of rat SCL has demonstrated how SCL discriminates L-selenocysteine from L-cysteine on the molecular basis. SCL has been proposed to function in the recycling of the micronutrient selenium from degraded selenoproteins containing selenocysteine residues. but the role of SCL in selenium metabolism in vivo remains unclear. We here demonstrate that the (75)Se-labeling efficiency of selenoproteins with (75)Se-labeled selenoprotein P (Sepp1) as a selenium source was decreased in HeLa cells transfected with SCL siRNA as compared to the cells transfected with control siRNA. Immunocytochemical analyses showed high SCL expression in kidney and liver cells, where selenocysteine is recovered from selenoproteins. Mature testes of mice exhibited a specific staining pattern of SCL in spermatids that actively produce selenoproteins. However, SCL was weakly expressed in Sertoli cells, which receive Sepp1 and supply selenium to germ cells. These demonstrate that SCL occurs in the cells requiring selenoproteins, probably to recycle selenium derived from selenoproteins such as Sepp1.