title: Piwi-like 2 mediates fibroblast growth factor signaling during gastrulation of zebrafish embryo.
abstract: 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.
authors.affiliation: Department of Medical Genetics & Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Huaqin
authors.initials: H
authors.lastname: Sun
authors.forename: Wenqian
authors.initials: W
authors.lastname: Deng
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Liu
authors.forename: Yilu
authors.initials: Y
authors.lastname: Lu
authors.forename: Yunqiang
authors.initials: Y
authors.lastname: Liu
authors.forename: Dachang
authors.initials: D
authors.lastname: Tao
authors.forename: Sizhong
authors.initials: S
authors.lastname: Zhang
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000818:Animals; D060565:Argonaute Proteins; D015415:Biomarkers / Q000378:metabolism; D019521:Body Patterning / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D005306:Fertilization; D005326:Fetal Proteins; D051524:Fibroblast Growth Factor 8 / Q000235:genetics / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism*; D054262:Gastrulation / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D008648:Mesoderm / Q000378:metabolism; D016601:RNA-Binding Proteins; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000098908:Brachyury Protein
chemical_list: D060565:Argonaute Proteins; D015415:Biomarkers; D005326:Fetal Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors; D016601:RNA-Binding Proteins; D020825:T-Box Domain Proteins; D029961:Zebrafish Proteins; D000098908:Brachyury Protein; C532956:Piwil2 protein, zebrafish; C517774:fgf8a protein, zebrafish