Romanelli-Cedrez Laura, Carrera Inés, Otero Lucía, Miranda-Vizuete Antonio, Mariotti Marco, Alkema Mark J, Salinas Gustavo
Worm Biology Laboratory, Institut Pasteur de Montevideo, Uruguay; Cátedra de Inmunología, Departamento de Biociencias, Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Worm Biology Laboratory, Institut Pasteur de Montevideo, Uruguay.
Free Radic Biol Med. 2017 Jul;108:174-182. doi: 10.1016/j.freeradbiomed.2017.03.021. Epub 2017 Mar 24.
Selenoprotein T (SELENOT) is an endoplasmatic reticulum (ER)-associated redoxin that contains the amino acid selenocysteine (Sec, U) within a CXXU motif within a thioredoxin-like fold. Its precise function in multicellular organisms is not completely understood although it has been shown in mammals to be involved in Ca homeostasis, antioxidant and neuroendocrine functions. Here, we use the model organism C. elegans to address SELENOT function in a whole organism throughout its life cycle. C. elegans possess two genes encoding SELENOT protein orthologues (SELT-1.1 and SELT-1.2), which lack Sec and contain the CXXC redox motif instead. Our results show that a Sec→Cys replacement and a gene duplication were two major evolutionary events that occurred in the nematode lineage. We find that worm SELT-1.1 localizes to the ER and is expressed in different cell types, including the nervous system. In contrast, SELT-1.2 exclusively localizes in the cytoplasm of the AWB neurons. We find that selt-1.1 and selt-1.2 single mutants as well as the double mutant are viable, but the selt-1.1 mutant is compromised under rotenone-induced oxidative stress. We demonstrate that selt-1.1, but not selt-1.2, is required for avoidance to the bacterial pathogens Serratia marcescens and Pseudomonas aeruginosa. Aversion to the noxious signal 2-nonanone is also significantly impaired in selt-1.1, but not in selt-1.2 mutant animals. Our results suggest that selt-1.1 would be a redox transducer required for nociception and optimal organismal fitness. The results highlight C. elegans as a valuable model organism to study SELENOT-dependent processes.
硒蛋白T（SELENOT）是一种与内质网（ER）相关的氧化还原蛋白，在硫氧还蛋白样折叠结构的CXXU基序中含有氨基酸硒代半胱氨酸（Sec，U）。尽管在哺乳动物中已表明它参与钙稳态、抗氧化和神经内分泌功能，但其在多细胞生物中的精确功能尚未完全了解。在这里，我们使用模式生物秀丽隐杆线虫来研究SELENOT在整个生命周期中的全生物体功能。秀丽隐杆线虫拥有两个编码SELENOT蛋白直系同源物的基因（SELT-1.1和SELT-1.2），它们缺乏Sec，而是含有CXXC氧化还原基序。我们的结果表明，Sec→Cys替换和基因复制是线虫谱系中发生的两个主要进化事件。我们发现线虫SEL-1.1定位于内质网，并在包括神经系统在内的不同细胞类型中表达。相比之下，SEL-1.2仅定位于AWB神经元的细胞质中。我们发现selt-1.1和selt-1.2单突变体以及双突变体都是可行的，但selt-1.1突变体在鱼藤酮诱导的氧化应激下受损。我们证明，逃避细菌病原体粘质沙雷氏菌和铜绿假单胞菌需要selt-1.1，而不是selt-1.2。对有害信号2-壬酮的厌恶在selt-1.突变体动物中也显著受损，但在selt-1.2突变体动物中没有。我们的结果表明，selt-1.1可能是伤害感受和最佳机体适应性所需的氧化还原传感器。这些结果突出了秀丽隐杆线虫作为研究SELENOT依赖性过程的有价值的模式生物。
