Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA.
Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
Life Sci Alliance. 2022 Feb 24;5(5). doi: 10.26508/lsa.202101291. Print 2022 May.
The dietary requirement for selenium is based on its incorporation into selenoproteins, which contain the amino acid selenocysteine (Sec). The Sec insertion sequence (SECIS) is an RNA structure found in the 3' UTR of all selenoprotein mRNAs, and it is required to convert in-frame UGA codons from termination to Sec-incorporating codons. SECIS-binding protein 2 (Sbp2) is required for Sec incorporation, but its paralogue, SECIS-binding protein 2-like (Secisbp2l), while conserved, has no known function. Here we determined the relative roles of Sbp2 and Secisbp2l by introducing CRISPR mutations in both genes in zebrafish. By monitoring selenoprotein synthesis with Se labeling during embryogenesis, we found that embryos still make a select subset of selenoproteins but embryos retain the full complement. Abrogation of both genes completely prevents selenoprotein synthesis and juveniles die at 14 days post fertilization. Embryos lacking Sbp2 are sensitive to oxidative stress and express the stress marker Vtg1. We propose a model where Secisbp2l is required to promote essential selenoprotein synthesis when Sbp2 activity is compromised.
硒的膳食需求是基于其掺入到包含氨基酸硒代半胱氨酸（Sec）的硒蛋白中。Sec 插入序列（SECIS）是一种在所有硒蛋白 mRNA 的 3'UTR 中发现的 RNA 结构，它需要将框内 UGA 密码子从终止密码子转换为掺入 Sec 的密码子。SECIS 结合蛋白 2（Sbp2）是 Sec 掺入所必需的，但它的同源物 SECIS 结合蛋白 2 样（Secisbp2l）虽然保守，但没有已知的功能。在这里，我们通过在斑马鱼中引入这两个基因的 CRISPR 突变来确定 Sbp2 和 Secisbp2l 的相对作用。通过在胚胎发生过程中用 Se 标记监测硒蛋白的合成，我们发现 胚胎仍然合成一组选定的硒蛋白，但 胚胎保留了完整的硒蛋白。两个基因的缺失完全阻止了硒蛋白的合成，幼鱼在受精后 14 天死亡。缺乏 Sbp2 的胚胎对氧化应激敏感，并表达应激标记物 Vtg1。我们提出了一个模型，当 Sbp2 活性受损时，Secisbp2l 被需要来促进必需的硒蛋白合成。
