Novel endogenous retrovirus-derived transcript expressed in the bovine placenta is regulated by WNT signaling.
Novel endogenous retrovirus-derived transcript expressed in the bovine placenta is regulated by WNT signaling.
复制标题
DOI：
10.1042/bcj20170531
复制
发表时间：
2017-10-10
期刊：
影响因子：
--
通讯作者：
Imakawa K
中科院分区：
文献类型：
--
作者：
Sakurai T;Nakagawa S;Bai H;Bai R;Kusama K;Ideta A;Aoyagi Y;Kaneko K;Iga K;Yasuda J;Miyazawa T;Imakawa K
内源性逆转录病毒（ERVs）参与胎盘；也许，最著名的erv是合胞素，积极转录的环境基因参与细胞-细胞融合和可能的形态变化。然而，除合胞素外，在胎盘发育中起重要作用的erv尚未得到很好的表征。为了鉴定在牛胎盘发生期间表达的ERV基因，我们利用RNA-seq分析表征了附着期牛妊娠转录本的表达谱，并通过实时PCR确认了一些候选基因。通过计算机和PCR分析，我们鉴定出了一个新的ERV前病毒序列，该序列来源于一个gag区，被命名为牛内源性逆转录病毒(BERV)-K3，含有锌指结构域的Gag_p10和Gag_p24。该ERV在牛胎体中首次表达是在第20天（发情第0天），在胎体附着于子宫内膜上皮后不久，其在胎盘中的高表达一直保持到妊娠中期。在子宫腔上皮、腺上皮、肝、肾、肠和皮肤中也发现了BERV-K3转录本。BERV-K3位于第7号染色体上，整合于LOC100848658内，可从中转录非编码RNA。此外，内源性BERV-K3在牛滋养细胞系中的表达被WNT激动剂诱导，WNT激动剂是胎盘中表达的基因共同的信号系统。这些数据支持了在进化过程中，哺乳动物不仅具有相似的ERV序列，而且具有个体物种特有的ERV序列的观点。在后一种情况下，BERV-K3可能提供反刍动物妊娠特有的功能。
Endogenous retroviruses (ERVs) are involved in placentation; perhaps, the most well-known ERVs are the syncytins, actively transcribed env genes involved in cell–cell fusion and possible morphological variations. However, ERVs other than syncytins that play an important role in placental development have not been well characterized. To identify ERV genes expressed during the onset of placentation in the bovine species, we characterized the expression profiles of bovine conceptus transcripts during the peri-attachment period using RNA-seq analysis, and confirming some candidates through real-time PCR. Using in silico and PCR analyses, we identified a novel ERV proviral sequence derived from a gag region, designated bovine endogenous retroviruses (BERV)-K3, containing Gag_p10 and Gag_p24, zinc finger domain. Initial expression of this ERV in bovine conceptuses was on day 20 (day 0 = day of estrus), soon after conceptus attachment to the endometrial epithelium, and its high placental expression was maintained up to the middle of pregnancy. The BERV-K3 transcript was also found in the uterine luminal and glandular epithelia, liver, kidney, intestine, and skin. BERV-K3 is located on chromosome 7 and integrated within LOC100848658, from which noncoding RNA could be transcribed. Furthermore, the expression of endogenous BERV-K3 in bovine trophoblast cell lines was induced by a WNT agonist, a signaling system common to genes expressed in placentas. These data support the argument that during the evolutionary process, mammals incorporated not only similar ERV sequences, but also ERVs unique to individual species. BERV-K3 is in the latter case, likely providing functions unique to ruminant gestation.