title: In vitro follicular growth affects oocyte imprinting establishment in mice.
abstract: In vitro folliculogenesis of cryopreserved ovarian tissue could be an effective method for insuring fertility for patients who receive gonadotoxic treatment. Although several culture systems have been described for growing female gametes in vitro, the production of competent oocytes for further development remains a considerable challenge. The purpose of our study was to determine whether maternal primary imprinting progresses normally during mouse oocyte growth in vitro. We analysed the DNA methylation status of differentially methylated regions of the imprinted genes H19, Mest/Peg1 and Igf2R using fully grown germinal vesicle-stage oocytes (fg oocytes) produced by in vitro folliculogenesis from early preantral follicles. When compared to fg oocytes removal from control females, we observed after in vitro development, a loss of methylation at the Igf2R locus in six out of seven independent experiments and Mest/Peg1 locus (one out of seven), and a gain of methylation at the H19 locus (one out of seven). These results provide insight into the dysregulation of the process of primary imprinting during oocyte growth in vitro and highlight the need for effective new biomarkers to identify complete nuclear reprogramming competence after in vitro folliculogenesis.
authors.affiliation: GDPM, Institut Cochin, INSERM, CNRS-Université Paris V and CHU Cochin, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France. kerjean@cochin.inserm.fr
authors.forename: Antoine
authors.initials: A
authors.lastname: Kerjean
authors.forename: Philippe
authors.initials: P
authors.lastname: Couvert
authors.forename: Thomas
authors.initials: T
authors.lastname: Heams
authors.forename: Céline
authors.initials: C
authors.lastname: Chalas
authors.forename: Karine
authors.initials: K
authors.lastname: Poirier
authors.forename: Jamel
authors.initials: J
authors.lastname: Chelly
authors.forename: Pierre
authors.initials: P
authors.lastname: Jouannet
authors.forename: Andras
authors.initials: A
authors.lastname: Paldi
authors.forename: Catherine
authors.initials: C
authors.lastname: Poirot
mesh_terms: D000818:Animals; D019175:DNA Methylation; D005260:Female; D018392:Genomic Imprinting / Q000502:physiology*; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D006080:Ovarian Follicle / Q000254:growth & development*; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated
chemical_list: C094335:H19 long non-coding RNA; D011506:Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C103637:mesoderm specific transcript protein