Identification and characterization of a fibroblast growth factor gene in the planarian Dugesia japonica
Identification and characterization of a fibroblast growth factor gene in the planarian Dugesia japonica
复制标题
DOI：
10.1111/dgd.12696
复制
发表时间：
2020-12-02
影响因子：
2.5
通讯作者：
Umesono, Yoshihiko
中科院分区：
文献类型：
--
作者：
Auwal, Mohammad Abdul;Kashima, Makoto;Umesono, Yoshihiko
扁形动物属于扁形蠕虫门，在受伤后可以通过激活被称为新生母细胞的体细胞多能干细胞来再生它们缺失的身体部分。以往的研究表明，成纤维细胞生长因子信号在浮游生物再生过程中对头部组织分化的调控起着至关重要的作用。然而，到目前为止，还没有关于扁形蠕虫中的成纤维细胞生长因子同源物的报道。在这里，我们使用了一个涡虫模型，并鉴定了一个名为Djfgf的成纤维细胞生长因子基因，它编码了一个具有FGF8/17/18亚家族特征的核心成纤维细胞生长因子结构域的分泌性蛋白。利用非洲爪哇胚胎进行Xbra诱导实验，发现DjFGF具有成纤维细胞生长因子的活性。接下来，我们研究了Djfgf在不再生的完整和再生的行星动物中的表达。在完整的浮游生物中，Djfgf在头部和咽部的耳廓中表达。在再生的早期过程中，Djfgf在伤口周围的分化细胞亚群中瞬时表达。值得注意的是，与尾部再生相比，Djfgf在头部再生过程中的表达被高度诱导。此外，从尾部碎片再生头部的分析表明，前部细胞外信号调节激酶(ERK)和后部Wnt/ss-catenin信号的联合作用限制了Djfgf在身体前部的表达。在这一区域，新生母细胞经历活跃的增殖，以产生其分化的后代，以响应创伤。这些数据表明，DjFGF可能作为Wnt分子的前部对应物，触发与脊椎动物头部再生有关的新胚细胞反应。
Planarians belong to the phylum Platyhelminthes and can regenerate their missing body parts after injury via activation of somatic pluripotent stem cells called neoblasts. Previous studies suggested that fibroblast growth factor (FGF) signaling plays a crucial role in the regulation of head tissue differentiation during planarian regeneration. To date, however, no FGF homologues in the Platyhelminthes have been reported. Here, we used a planarian Dugesia japonica model and identified an fgf gene termed Djfgf, which encodes a putative secreted protein with a core FGF domain characteristic of the FGF8/17/18 subfamily in bilaterians. Using Xenopus embryos, we found that DjFGF has FGF activity as assayed by Xbra induction. We next examined Djfgf expression in non-regenerating intact and regenerating planarians. In intact planarians, Djfgf was expressed in the auricles in the head and the pharynx. In the early process of regeneration, Djfgf was transiently expressed in a subset of differentiated cells around wounds. Notably, Djfgf expression was highly induced in the process of head regeneration when compared to that in the tail regeneration. Furthermore, assays of head regeneration from tail fragments revealed that combinatorial actions of the anterior extracellular signal-regulated kinase (ERK) and posterior Wnt/ss-catenin signaling restricted Djfgf expression to a certain anterior body part. This is the region where neoblasts undergo active proliferation to give rise to their differentiating progeny in response to wounding. The data suggest the possibility that DjFGF may act as an anterior counterpart of posteriorly localized Wnt molecules and trigger neoblast responses involved in planarian head regeneration.