title: Evidence supporting a functional requirement of SMAD4 for bovine preimplantation embryonic development: a potential link to embryotrophic actions of follistatin.
abstract: Transforming growth factor beta (TGFbeta) superfamily signaling controls various aspects of female fertility. However, the functional roles of the TGFbeta-superfamily cognate signal transduction pathway components (e.g., SMAD2/3, SMAD4, SMAD1/5/8) in early embryonic development are not completely understood. We have previously demonstrated pronounced embryotrophic actions of the TGFbeta superfamily member-binding protein, follistatin, on oocyte competence in cattle. Given that SMAD4 is a common SMAD required for both SMAD2/3- and SMAD1/5/8-signaling pathways, the objectives of the present studies were to determine the temporal expression and functional role of SMAD4 in bovine early embryogenesis and whether embryotrophic actions of follistatin are SMAD4 dependent. SMAD4 mRNA is increased in bovine oocytes during meiotic maturation, is maximal in 2-cell stage embryos, remains elevated through the 8-cell stage, and is decreased and remains low through the blastocyst stage. Ablation of SMAD4 via small interfering RNA microinjection of zygotes reduced proportions of embryos cleaving early and development to the 8- to 16-cell and blastocyst stages. Stimulatory effects of follistatin on early cleavage, but not on development to 8- to 16-cell and blastocyst stages, were observed in SMAD4-depleted embryos. Therefore, results suggest SMAD4 is obligatory for early embryonic development in cattle, and embryotrophic actions of follistatin on development to 8- to 16-cell and blastocyst stages are SMAD4 dependent.
authors.affiliation: Laboratory of Mammalian Reproductive Biology and Genomics, Michigan State University, East Lansing, Michigan Department of Biology Education, College of Education, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Kyung-Bon
authors.initials: KB
authors.lastname: Lee
authors.affiliation: Laboratory of Mammalian Reproductive Biology and Genomics, Michigan State University, East Lansing, Michigan Department of Animal Science, Michigan State University, East Lansing, Michigan.
authors.forename: Kun
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Laboratory of Mammalian Reproductive Biology and Genomics, Michigan State University, East Lansing, Michigan Department of Animal Science, Michigan State University, East Lansing, Michigan.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Folger
authors.affiliation: Developmental Epigenetics Laboratory, Michigan State University, East Lansing, Michigan Department of Animal Science, Michigan State University, East Lansing, Michigan.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Knott
authors.affiliation: Laboratory of Mammalian Reproductive Biology and Genomics, Michigan State University, East Lansing, Michigan Department of Animal Science, Michigan State University, East Lansing, Michigan Department of Physiology, Michigan State University, East Lansing, Michigan smithge7@msu.edu.
authors.forename: George W
authors.initials: GW
authors.lastname: Smith
mesh_terms: D000003:Abattoirs; D053959:Alpha-Amanitin / Q000494:pharmacology; D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D001757:Blastomeres / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002417:Cattle; D004477:Ectogenesis / Q000187:drug effects; D046149:Embryo Culture Techniques; D005260:Female; D005307:Fertilization in Vitro; D019084:Fluorescent Antibody Technique, Indirect; D038681:Follistatin / Q000378:metabolism*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D020868:Gene Silencing; D059471:In Vitro Oocyte Maturation Techniques; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D051901:Smad4 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D053959:Alpha-Amanitin; D038681:Follistatin; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051901:Smad4 Protein
keywords: SMAD4; TGFβ signaling; cattle; embryo; follistatin; oocyte