PDF(Pubmed)
Abstract：
Selenophosphate synthetase (SEPHS) plays an essential role in selenium metabolism. Two mammalian SEPHS paralogues, SEPHS1 and SEPHS2, share high sequence identity and structural homology with SEPHS. Here, we report nine individuals from eight families with developmental delay, growth and feeding problems, hypotonia, and dysmorphic features, all with heterozygous missense variants in SEPHS1. Eight of these individuals had a recurrent variant at amino acid position 371 of SEPHS1 (p.Arg371Trp, p.Arg371Gln, and p.Arg371Gly); seven of these variants were known to be de novo. Structural modeling and biochemical assays were used to understand the effect of these variants on SEPHS1 function. We found that a variant at residue Trp352 results in local structural changes of the C-terminal region of SEPHS1 that decrease the overall thermal stability of the enzyme. In contrast, variants of a solvent-exposed residue Arg371 do not impact enzyme stability and folding but could modulate direct protein-protein interactions of SEPSH1 with cellular factors in promoting cell proliferation and development. In neuronal SH-SY5Y cells, we assessed the impact of SEPHS1 variants on cell proliferation and ROS production and investigated the mRNA expression levels of genes encoding stress-related selenoproteins. Our findings provided evidence that the identified SEPHS1 variants enhance cell proliferation by modulating ROS homeostasis. Our study supports the hypothesis that SEPHS1 plays a critical role during human development and provides a basis for further investigation into the molecular mechanisms employed by SEPHS1. Furthermore, our data suggest that variants in SEPHS1 are associated with a neurodevelopmental disorder.
摘要：
硒磷酸合成酶（SEPHS）在硒代谢中起着至关重要的作用。两个哺乳动物SEPHS旁系同源物，SEPHS1和SEPHS2与SEPHS具有高度的序列同一性和结构同源性。这里,我们报告了来自八个家庭的九个人发育迟缓，生长和喂养问题，低张力,和畸形特征，所有在SEPHS1中具有杂合错义变体。这些个体中有8个在SEPHS1的371位氨基酸处具有复发性变体（p。Arg371Trp,p.Arg371Gln,和p.Arg371Gly）；已知这些变体中的七个是从头的。使用结构建模和生化测定来理解这些变体对SEPHS1功能的影响。我们发现残基Trp352的变体导致SEPHS1的C末端区域的局部结构变化，从而降低了酶的整体热稳定性。相比之下,暴露于溶剂的Arg371残基的变体不影响酶的稳定性和折叠,但可以调节SEPSH1与细胞因子的直接蛋白质-蛋白质相互作用,促进细胞增殖和发育.在神经元SH-SY5Y细胞中，我们评估了SEPHS1变异体对细胞增殖和ROS产生的影响,并研究了编码应激相关硒蛋白的基因的mRNA表达水平.我们的发现提供了证据，表明鉴定的SEPHS1变体通过调节ROS稳态来增强细胞增殖。我们的研究支持SEPHS1在人类发育中起关键作用的假设，并为进一步研究SEPHS1采用的分子机制提供了基础。此外，我们的数据提示,SEPHS1变异与神经发育障碍相关.
