An endogenous retroviral envelope syncytin and its cognate receptor identified in the viviparous placental Mabuya lizard
An endogenous retroviral envelope syncytin and its cognate receptor identified in the viviparous placental Mabuya lizard
复制标题
DOI：
10.1073/pnas.1714590114
复制
发表时间：
2017-12-19
影响因子：
11.1
通讯作者：
Heidmann, Thierry
中科院分区：
文献类型：
--
作者：
Cornelis, Guillaume;Funk, Mathis;Heidmann, Thierry
合胞素是内源性逆转录病毒的包膜基因，在进化过程中被捕获，在胎盘形成中发挥作用。它们在所有被搜索过的胎盘哺乳动物中都被发现，包括有袋动物。胎盘结构不仅限于哺乳动物，也出现在一些其他脊椎动物中，最常见于蜥蜴，如胎生的Mabuya Scincidae。在这里，我们进行了高通量RNA测序的Mabuya胎盘转录组和筛选的逆转录病毒env基因与全长ORF的存在。我们发现了一个这样的基因，我们将其命名为“合胞素-Mab 1”，它具有合胞素基因的所有预期特征。它编码一种膜结合的包膜蛋白与融合活性离体，在胎盘水平上表达的原位杂交和免疫组化显示，并在所有的马布亚物种测试，跨越25我的进化是保守的。通过使用GeneBridge 4人/中国仓鼠辐射杂交板的筛选试验搜索其融合活性所需的同源受体，发现其为MPZL 1基因，该基因先前在哺乳动物中被鉴定为参与细胞迁移的信号转导跨膜蛋白。总之，这些结果表明，合胞素捕获并不局限于胎盘哺乳动物，但也可以发生在罕见的非哺乳类脊椎动物，其中出现了胎生胎盘营养模式的繁殖。这表明类似的分子工具已被用于独立进化和高度遥远的脊椎动物胎盘的趋同进化。
Syncytins are envelope genes from endogenous retroviruses that have been captured during evolution for a function in placentation. They have been found in all placental mammals in which they have been searched, including marsupials. Placental structures are not restricted to mammals but also emerged in some other vertebrates, most frequently in lizards, such as the viviparous Mabuya Scincidae. Here, we performed high-throughput RNA sequencing of a Mabuya placenta transcriptome and screened for the presence of retroviral env genes with a full-length ORF. We identified one such gene, which we named "syncytin-Mab1," that has all the characteristics expected for a syncytin gene. It encodes a membrane-bound envelope protein with fusogenic activity ex vivo, is expressed at the placental level as revealed by in situ hybridization and immunohistochemistry, and is conserved in all Mabuya species tested, spanning over 25 My of evolution. Its cognate receptor, required for its fusogenic activity, was searched for by a screening assay using the GeneBridge4 human/Chinese hamster radiation hybrid panel and found to be the MPZL1 gene, previously identified in mammals as a signal-transducing transmembrane protein involved in cell migration. Together, these results show that syncytin capture is not restricted to placental mammals, but can also take place in the rare nonmammalian vertebrates in which a viviparous placentotrophic mode of reproduction emerged. It suggests that similar molecular tools have been used for the convergent evolution of placentation in independently evolved and highly distant vertebrates.