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This Article Full Text Full Text (PDF) [Supplemental Data] All Versions of this Article: 75/4/531    most recent biolreprod.106.051722v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lucifero, D. Articles by Trasler, J. M. Search for Related Content PubMed PubMed Citation Articles by Lucifero, D. Articles by Trasler, J. M. Agricola Articles by Lucifero, D. Articles by Trasler, J. M.

Bovine SNRPN Methylation Imprint in Oocytes and Day 17 In Vitro-Produced and Somatic Cell Nuclear Transfer Embryos¹

McGill University and Montreal Children's Hospital Research Institute⁵ Departments of Pediatrics,⁶ Human Genetics,⁷ and Pharmacology & Therapeutics,⁸McGill University, Montreal, Quebec, Canada H3H 1A1 Centre de Recherche en Reproduction Animale,⁹ Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Quebec, Canada J2S 7C6

ABSTRACT

Findings from recent studies have suggested that the low survival rate of animals derived via somatic cell nuclear transfer (SCNT) may be in part due to epigenetic abnormalities brought about by this procedure. DNA methylation is an epigenetic modification of DNA that is implicated in the regulation of imprinted genes. Genes subject to genomic imprinting are expressed monoallelically in a parent of origin-dependent manner and are important for embryo growth, placental function, and neurobehavioral processes. The vast majority of imprinted genes have been studied in mice and humans. Herein, our objectives were to characterize the bovine SNRPN gene in gametes and to compare its methylation profile in in vivo-produced, in vitro-produced, and SCNT-derived Day 17 elongating embryos. A CpG island within the 5' region of SNRPN was identified and examined using bisulfite sequencing. SNRPN alleles were unmethylated in sperm, methylated in oocytes, and approximately 50% methylated in somatic samples. The examined SNRPN region appeared for the most part to be normally methylated in three in vivo-produced Day 17 embryos and in eight in vitro-produced Day 17 embryos examined, while alleles from Day 17 SCNT embryos were severely hypomethylated in seven of eight embryos. In this study, we showed that the SNRPN methylation profiles previously observed in mouse and human studies are also conserved in cattle. Moreover, SCNT-derived Day 17 elongating embryos were abnormally hypomethylated compared with in vivo-produced and in vitro-produced embryos, which in turn suggests that SCNT may lead to faulty reprogramming or maintenance of methylation imprints at this locus.

assisted reproductive technology, bovine, DNA methylation, early development, embryo, epigenetic, gamete biology, genomic imprinting, in vitro culture, in vitro fertilization, SCNT, somatic cell nuclear transfer, SNRPN

¹ Supported by the Fonds de la Recherche en Santé du Québec (FRSQ) and by the Natural Sciences and Engineering Research Council of Canada. This work was part of the Program on Oocyte Health (http://www.ohri.ca/oocyte) funded by grant HGG62293 under the Healthy Gametes and Great Embryos Strategic Initiative of the Canadian Institutes of Health Research (CIHR) Institute of Human Development, Child and Youth Health. D.L. is the recipient of FRSQ and CIHR studentships and a European Molecular Biology Organization long-term fellowship. J.M.T. is a William Dawson Scholar of McGill University and a Scholar of the FRSQ.

² Correspondence: Jacquetta M. Trasler, McGill University and Montreal Children's Hospital Research Institute, 2300 Tupper Street, Montreal, Quebec, Canada H3H 1P3. FAX: 514 412 4331; jacquetta.trasler{at}mcgill.ca

³ Current address: Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge CB2 4AT, United Kingdom.

⁴ Current address: Department of Animal Science, McGill University, Macdonald Campus, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9.