title: Zili inhibits transforming growth factor-beta signaling by interacting with Smad4.
abstract: Piwi proteins are required for germ cell proliferation, differentiation, and germ line stem cell maintenance. In normal tissues, human and mouse Piwil2 are primarily expressed in testis but widely expressed in tumors. However, the underlying mechanism remains largely unknown. In vertebrates, transforming growth factor (TGF)-beta signaling plays an important role in patterning embryo and control of cell growth and differentiation. A previous study has shown a role for Zili, a Piwil2 gene in zebrafish, in germ cells in zebrafish. Here we report that zili functions in patterning the early embryo and inhibits TGF-beta signaling. Whole mount expression analysis shows that zili expresses not only in PGCs but also in axis. Ectopic expression of zili causes fusion of the eyes and reduction of mesodermal marker genes expression, suggesting that zili functions to inhibit Nodal signaling and mesoderm formation. Genetic interaction shows that zili inhibits Nodal and bone morphogenetic protein signaling. The results of protein interaction assays identify that Zili binds to Smad4 via its N-terminal domain and prevents the formation of Smad2/3/4 and Smad1/5/9/4 complexes to antagonize TGF-beta signaling. This work shows that zili plays a role in early embryogenesis beyond germ line as a novel negative regulator of TGF-beta signaling, extending the function of Piwi proteins in vertebrates.
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Huaqin
authors.initials: H
authors.lastname: Sun
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Liao
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Wenqian
authors.initials: W
authors.lastname: Deng
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zeng
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Dachang
authors.initials: D
authors.lastname: Tao
authors.affiliation: From the Department of Medical Genetics and Division of Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China. Electronic address: mayongxin@gmail.com.
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019521:Body Patterning / Q000235:genetics; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D004843:Epistasis, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D008297:Male; D055457:Nodal Protein / Q000235:genetics; D016376:Oligonucleotides, Antisense / Q000235:genetics; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051896:Smad Proteins, Receptor-Regulated / Q000235:genetics / Q000378:metabolism; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D055457:Nodal Protein; D016376:Oligonucleotides, Antisense; C532956:Piwil2 protein, zebrafish; D016601:RNA-Binding Proteins; D018125:Receptors, Transforming Growth Factor beta; D051896:Smad Proteins, Receptor-Regulated; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta; D029961:Zebrafish Proteins