Piwi-like 2 mediates fibroblast growth factor signaling during gastrulation of zebrafish embryo.
Piwi-like 2 mediates fibroblast growth factor signaling during gastrulation of zebrafish embryo.
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DOI：
10.1620/tjem.222.63
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发表时间：
2010-09
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通讯作者：
Jun Zhao;Huaqin Sun;Wenqian Deng;Dan Li;Yanyan Liu;Yi-lu Lu;Yunqiang Liu;D. Tao;Si-zhong Zhang;Yongxin Ma
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文献类型：
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作者：
Jun Zhao;Huaqin Sun;Wenqian Deng;Dan Li;Yanyan Liu;Yi-lu Lu;Yunqiang Liu;D. Tao;Si-zhong Zhang;Yongxin Ma
Piwi（P-element-induced wimpy testis）蛋白在生殖系干细胞的维持、生殖细胞的增殖和分化以及Piwi相互作用RNA（PiRNA）的调控中发挥重要作用。PiRNA包括广泛的一类小的非编码RNA，其作为针对转座因子的内源防御系统发挥作用。成纤维细胞生长因子（Fgf）信号部分由无尾基因（ntl）介导，负责图案化胚胎和中胚层的形成。为了了解Piwi蛋白的功能，我们使用斑马鱼作为模型系统。在斑马鱼中，piwi-like 2基因（piwil 2）也是生殖细胞分化和减数分裂所必需的。在这里，我们报告piwil 2敲低能够抑制成纤维细胞生长因子8a（fgf 8a）的表达。相反，注射piwil 2 mRNA增强fgf 8a表达。piwil 2的敲除降低了fgf 8a对背侧化表型的诱导作用，背侧化表型中胚胎在外包阶段结束时延伸到椭圆形。与fgf 8a mRNA和piwil 2-cMO共注射相比，fgf 8a mRNA和piwil 2-cMO共注射导致更严重的背侧化表型。此外，piwil 2的敲低抑制了fgf 8a对ntl的诱导作用，而piwil 2的过表达增强了fgf 8a对ntl的诱导作用。我们还证明piwil 2在芽期正调控ntl表达，而piwil 2在受精后24小时负调控ntl表达。因此，在斑马鱼胚胎的早期发育过程中，piwil 2表达的功能后果是不同的。综上所述，我们认为斑马鱼piwil 2是原肠胚期FGF信号的介导者。
Piwi (P-element-induced wimpy testis) proteins have been shown to play important roles in maintenance of germ line stem cells, germ cell proliferation and differentiation, and control of Piwi-interacting RNAs (PiRNAs). PiRNAs comprise a broad class of small noncoding RNAs that function as an endogenous defense system against transposable elements. Fibroblast growth factor (Fgf) signals, mediated partly by no tail gene (ntl), are responsible for patterning embryo and mesoderm formation. To understand the function of Piwi proteins, we used zebrafish as a model system. In zebrafish, piwi-like 2 gene (piwil2) is also required for germ cell differentiation and meiosis. Here we report that piwil2 knockdown is able to inhibit the expression of fibroblast growth factor 8a (fgf8a). In contrast, injection with piwil2 mRNA enhances fgf8a expression. Knockdown of piwil2 reduces the inductive effect of fgf8a on dorsalized phenotype, in which embryos extend to an oval shape at the end of epiboly stage. Coinjection with fgf8a and piwil2 mRNAs led to more seriously dorsalized phenotype than coinjection with fgf8a mRNA and piwil2-cMO. In addition, knockdown of piwil2 inhibits the inductive effect of fgf8a on ntl, whereas overexpression of piwil2 enhances the inductive effect of fgf8a on ntl. We also demonstrate that piwil2 positively regulates ntl expression at bud stage, while piwil2 negatively regulates ntl expression at 24 hours post-fertilization. Thus, the functional consequences of piwil2 expression vary during early development of zebrafish embryo. Taken together, we suggest that zebrafish piwil2 is a mediator of Fgf signals in gastrula period.