Characterization of the finch embryo supports evolutionary conservation of the naive stage of development in amniotes.
Characterization of the finch embryo supports evolutionary conservation of the naive stage of development in amniotes.
复制标题
DOI：
10.7554/elife.07178
复制
发表时间：
2015-09-11
期刊：
影响因子：
7.7
通讯作者：
Ladher RK
中科院分区：
文献类型：
--
作者：
Mak SS;Alev C;Nagai H;Wrabel A;Matsuoka Y;Honda A;Sheng G;Ladher RK
当内细胞团分化为外胚层时，小鼠胚胎的先天多能性从幼稚状态过渡到致敏状态。在体外，它们的对应物分别是胚胎干细胞（ESC）和外胚层干细胞（EpiSC）。FGF信号级联的激活导致小鼠ESC分化成mEpiSC，表明其需要在这些状态之间转换。然而，只有小鼠胚胎干细胞对应于幼稚状态;其他哺乳动物和鸡的胚胎干细胞显示启动状态特征。因此，幼稚状态的意义是不清楚的。在这项研究中，我们使用斑胸草雀作为比较ESC研究的模型。雀类胚盘具有mESC样特性，而鸡胚盘具有EpiSC特征。在没有FGF信号的情况下，雀细胞保留了多能标记物的表达，这些标记物在来自小鸡或老年雀外胚层的细胞中丢失。我们的数据表明，幼稚状态的多能性是进化保守的之间的多能性。http://dx.doi.org/10.7554/eLife.07178.001在动物中，干细胞分裂产生在体内具有特殊作用的其他细胞。“多能”干细胞能够产生任何类型的细胞，可以从年轻的小鼠胚胎中获得。一旦在实验室中生长，这些细胞被称为幼稚胚胎干细胞（ESC），它们的发现对于理解哺乳动物如何发育至关重要。胚胎干细胞还具有相当大的医学潜力，因为它们可以用于修复或替代因损伤或疾病而失去的组织。一种称为成纤维细胞生长因子（FGF）的蛋白质家族触发幼稚ESCs成熟为另一类干细胞，这些干细胞被“启动”以仅产生特定类型的细胞。奇怪的是，从其他哺乳动物胚胎中收集的干细胞已经处于这种启动状态。因此，生物学家想知道这种幼稚状态是否只存在于小鼠胚胎中，或者它是否存在于其他动物中，但迄今为止尚未被发现。鸡和其他鸟类胚胎的发育与哺乳动物有许多相似之处。然而，鸡蛋中的胚胎不含幼稚ESCs。这可能是由于鸡蛋是在胚胎发育到后期阶段时产下的，其中幼稚干细胞已经成熟为引发细胞。在这里，Mak等人比较了鸡胚胎中的干细胞和另一种叫做斑胸草雀的鸟的干细胞。实验表明，雀胚胎含有与小鼠ESCs共有的干细胞。特别是，这些雀细胞继续表达基因所需的幼稚状态，以保持在FGF的情况下。另一方面，这些基因在鸡胚细胞和老年斑胸草雀干细胞中被关闭。Mak等人的研究结果表明，雀蛋在胚胎发育的早期阶段就比鸡蛋产下了。实验还表明，鸟类和哺乳动物在胚胎发育的早期阶段都有幼稚多能干细胞。将来，斑胸草雀可以作为研究干细胞和动物发育其他方面的模型。DOI：http://dx.doi.org/10.7554/eLife.07178.002网站
Innate pluripotency of mouse embryos transits from naive to primed state as the inner cell mass differentiates into epiblast. In vitro, their counterparts are embryonic (ESCs) and epiblast stem cells (EpiSCs), respectively. Activation of the FGF signaling cascade results in mouse ESCs differentiating into mEpiSCs, indicative of its requirement in the shift between these states. However, only mouse ESCs correspond to the naive state; ESCs from other mammals and from chick show primed state characteristics. Thus, the significance of the naive state is unclear. In this study, we use zebra finch as a model for comparative ESC studies. The finch blastoderm has mESC-like properties, while chick blastoderm exhibits EpiSC features. In the absence of FGF signaling, finch cells retained expression of pluripotent markers, which were lost in cells from chick or aged finch epiblasts. Our data suggest that the naive state of pluripotency is evolutionarily conserved among amniotes. DOI: http://dx.doi.org/10.7554/eLife.07178.001 In animals, stem cells divide to give rise to other cells that have specialized roles in the body. ‘Pluripotent’ stem cells—which are able to produce cells of any type—can be obtained from young mouse embryos. Once grown in the laboratory, these cells are called naive embryonic stem cells (ESCs) and their discovery has been vitally important for understanding how mammals develop. ESCs also have considerable medical potential because they could be used to repair or replace tissues that have been lost to injury or disease. A family of proteins called fibroblast growth factors (FGFs) triggers naive ESCs to mature into another class of stem cell that are ‘primed’ to only produce particular types of cells. Curiously, the stem cells that have been collected from other mammal embryos are already in this primed state. Therefore, biologists wonder whether the naive state is exclusive to mice embryos, or whether it is present in other animals but has so far remained undetected. The development of chick and other bird embryos shares many parallels with that of mammals. However, embryos in chicken eggs do not contain naive ESCs. It is possible that this is due to chicken eggs being laid when the embryos have reached a later stage in development where the naive stem cells have already matured into the primed cells. Here, Mak et al. compared the stem cells in chick embryos to those from another bird called the zebra finch. The experiments show that the finch embryos contain stem cells that share several features with mouse ESCs. In particular, these finch cells continue to express genes that are required for the naive state to be maintained in the absence of FGF. On the other hand, these genes are switched off in cells from chick embryos and in older zebra finch stem cells. Mak et al.'s findings show that finch eggs are laid at an earlier stage of embryo development than chicken eggs. The experiments also suggest that both birds and mammals have naive pluripotent stem cells during the early stages of embryo development. In future, the zebra finch could be used as a model to study stem cells and other aspects of animal development. DOI: http://dx.doi.org/10.7554/eLife.07178.002