Mi S, Lee X, Li X, Veldman G M, Finnerty H, Racie L, LaVallie E, Tang X Y, Edouard P, Howes S, Keith J C, McCoy J M
Genetics Institute, Inc., Cambridge, Massachusetts 02140, USA.
Nature. 2000 Feb 17;403(6771):785-9. doi: 10.1038/35001608.
Many mammalian viruses have acquired genes from their hosts during their evolution. The rationale for these acquisitions is usually quite clear: the captured genes are subverted to provide a selective advantage to the virus. Here we describe the opposite situation, where a viral gene has been sequestered to serve an important function in the physiology of a mammalian host. This gene, encoding a protein that we have called syncytin, is the envelope gene of a recently identified human endogenous defective retrovirus, HERV-W. We find that the major sites of syncytin expression are placental syncytiotrophoblasts, multinucleated cells that originate from fetal trophoblasts. We show that expression of recombinant syncytin in a wide variety of cell types induces the formation of giant syncytia, and that fusion of a human trophoblastic cell line expressing endogenous syncytin can be inhibited by an anti-syncytin antiserum. Our data indicate that syncytin may mediate placental cytotrophoblast fusion in vivo, and thus may be important in human placental morphogenesis.
许多哺乳动物病毒在进化过程中从宿主那里获得了基因。这些基因获取的基本原理通常相当明确：被捕获的基因被病毒利用以提供选择优势。在此我们描述一种相反的情况，即一个病毒基因被宿主隔离，在哺乳动物宿主的生理过程中发挥重要作用。这个基因编码一种我们称为合胞素的蛋白质，它是最近鉴定出的人类内源性缺陷逆转录病毒HERV-W的包膜基因。我们发现合胞素表达的主要部位是胎盘合体滋养层细胞，这是一种源自胎儿滋养层细胞的多核细胞。我们表明，在多种细胞类型中重组合胞素的表达会诱导巨大合胞体的形成，并且表达内源性合胞素的人滋养层细胞系的融合可被抗合胞素抗血清抑制。我们的数据表明，合胞素可能在体内介导胎盘细胞滋养层融合，因此可能在人类胎盘形态发生中起重要作用。
