title: Temporal regulation of mRNAs for select bone morphogenetic proteins (BMP), BMP receptors and their associated SMAD proteins during bovine early embryonic development: effects of exogenous BMP2 on embryo developmental progression.
abstract: BACKGROUND
  We previously demonstrated embryotrophic actions of maternal (oocyte-derived) follistatin during bovine early embryogenesis. Classical actions of follistatin are attributed to inhibition of activity of growth factors including activins and bone morphogenetic proteins (BMP). However, temporal changes in BMP mRNA in early bovine embryos and the effects of exogenous BMP on embryo developmental progression are not understood. The objectives of present studies were to characterize mRNA abundance for select BMP, BMP receptors and BMP receptor associated SMADs during bovine oocyte maturation and early embryogenesis and determine effects of addition of exogenous BMP protein on early development.
  
  
  METHODS
  Relative abundance of mRNA for BMP2, BMP3, BMP7, BMP10, SMAD1, SMAD5, ALK3, ALK6, ALK2, BMPR2, ACVR2A and ACVR2B was determined by RT-qPCR analysis of germinal vesicle (GV) and in vitro matured metaphase II (MII) oocytes and in vitro produced embryos collected at pronuclear, 2-cell (C), 4C, 8C, 16C, morula and blastocyst stages. Effects of addition of recombinant human BMP2 (0, 1, 10 and 100 ng/ml) during initial 72 h of embryo culture on early cleavage (within 30 h post insemination), total cleavage, development to 8C-16C and blastocyst stages and blastocyst mRNA abundance for markers of inner cell mass (NANOG) and trophectoderm (CDX2) were also determined.
  
  
  RESULTS
  Abundance of mRNA for BMP2, BMP10, SMAD1, SMAD5, ALK3, ALK2, BMPR2 and ACVR2B was elevated in MII oocytes and/or pronuclear stage embryos (relative to GV) and remained elevated through the 8C -16C stages, whereas BMP3, BMP7 and ALK2 mRNAs were transiently elevated. Culture of embryos to the 8C stage in the presence of α-amanitin resulted in increased abundance for all of above transcripts examined relative to untreated 8C embryos. Effects of addition of exogenous BMP2 on early cleavage rates and rates of development to 8C-16C and blastocyst stages were not observed, but BMP2 treatment increased blastocyst mRNA for CDX2 and NANOG.
  
  
  CONCLUSIONS
  Abundance of maternally derived mRNAs for above BMP system components are dynamically regulated during oocyte maturation and early embryogenesis. Exogenous BMP2 treatment does not influence progression to various developmental endpoints, but impacts characteristics of resulting blastocysts. Results support a potential role for BMPs in bovine early embryogenesis.
authors.forename: Kyung-Bon
authors.initials: KB
authors.lastname: Lee
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Folger
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Rajput
authors.affiliation: Department of Laboratory of Mammalian Reproductive Biology and Genomics, Michigan State University, East Lansing, MI 48824, USA. smithge7@msu.edu.
authors.forename: George W
authors.initials: GW
authors.lastname: Smith
mesh_terms: D053959:Alpha-Amanitin / Q000494:pharmacology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001755:Blastocyst / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D052004:Bone Morphogenetic Protein Receptors / Q000235:genetics / Q000378:metabolism*; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004477:Ectogenesis / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D053959:Alpha-Amanitin; C525718:BMP2 protein, human; D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018398:Homeodomain Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D051785:Smad Proteins; D052004:Bone Morphogenetic Protein Receptors; D012319:RNA Polymerase II