title: Identification of PIWIL1 Isoforms and Their Expression in Bovine Testes, Oocytes, and Early Embryos.
abstract: PIWI proteins are members of the larger Argonaute family and bind to specific 24-32 nucleotide RNAs called PIWI-interacting RNAs (piRNAs). PIWI-interacting RNAs direct PIWI-mediated suppression of retrotransposon expression in the male germline in humans and mice, but their roles in bovine reproduction and embryogenesis are unknown. Although the majority of research in mammals has focused on the functions of PIWI proteins during spermatogenesis, this family of proteins and their associated piRNAs have recently been identified in early embryos. The goals of this study were to characterize the expression of PIWIL1 in bovine testis, oocytes, and early embryos. A full-lengthPIWIL1transcript and protein was found in the testis, specifically in the germs cells of mature seminiferous tubules. RNA-immunoprecipitation demonstrated the presence of putative piRNAs with a mean length of 30 nucleotides bound to PIWIL1 in testes. 3'-Rapid amplification of cDNA ends analysis ofPIWIL1transcripts in testes and oocytes revealed two shorter isoforms in addition to the full-length transcript that was only present in testes. TruncatedPIWIL1isoforms in oocytes and testes were confirmed through amplification of their unique intronic fragments. Expression profiling ofPIWIL1through early embryogenesis demonstrated peak mRNA expression at the 2-cell stage with decreasing levels through to the blastocyst. PIWIL1-YFP fusion plasmids were produced for each isoform and expressed in HEK 293 cells, demonstrating nuclear exclusion and size-specific banding of the different isoforms. These data represent the first comprehensive characterization of PIWIL1 in bovine, revealing functional similarities with PIWIL1 in other species and suggest tissue-specific expression of several isoforms.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Stewart J
authors.initials: SJ
authors.lastname: Russell
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Leanne
authors.initials: L
authors.lastname: Stalker
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Graham
authors.initials: G
authors.lastname: Gilchrist
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Alanna
authors.initials: A
authors.lastname: Backx
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Molledo
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Foster
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada jlamarre@uoguelph.ca.
authors.forename: Jonathan
authors.initials: J
authors.lastname: LaMarre
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D003001:Cloning, Molecular; D004622:Embryo, Mammalian / Q000378:metabolism*; D047108:Embryonic Development; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D010053:Ovary / Q000378:metabolism*; D011247:Pregnancy; D020033:Protein Isoforms / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013737:Testis / Q000378:metabolism*
chemical_list: D060565:Argonaute Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering
keywords: gamete biology; piRNA; preimplantation embryo; spermatogenesis; testis