Int. J. Dev. Biol. 53: 541 - 548 (2009)

https://doi.org/10.1387/ijdb.082619ea

Vol 53, Issue 4

Unaltered imprinting establishment of key imprinted genes in mouse oocytes after in vitro follicle culture under variable follicle-stimulating hormone exposure

Original Article | Published: 1 May 2009

Ellen Anckaert*^,1, Tom Adriaenssens¹, Sergio Romero¹, Sarah Dremier² and Johan Smitz¹

¹Follicle Biology Laboratory, Universitair Ziekenhuis Brussel, Brussels and ²Cloning department, BioVallée, Gosselies, Belgium

Abstract

Imprinted genes are differentially methylated during gametogenesis to allow parental-specific monoallelic expression of genes. During mouse oogenesis, DNA methylation at imprinted genes is established during the transition from primordial to antral follicle stages. Studies in human and mouse suggest aberrant imprinting in oocytes following in vitro maturation and after superovulation with high doses of gonadotrophines. The exact mechanisms leading to aberrant imprinting are unknown. We examined the methylation status of differentially methylated regions of key imprinted genes (by bisulphite sequencing) in mouse metaphase II oocytes, grown in a long-term pre-antral follicle culture system and matured in vitro, in the presence of a physiological (10 IU/L) and a high (100 IU/L) recombinant FSH dose. Our results showed a normal DNA methylation at the studied regulatory sequences of Snrpn, Igf2r and H19, demonstrating that 1) prolonged culture and in vitro maturation do not per se modify the establishment of imprinting in oocytes and 2) supraphysiological FSH doses do not induce aberrant DNA methylation at the studied regulatory sequences in this system.

Keywords

DNA methylation, follicle culture, genome imprinting, in vitro maturation, FSH, mouse oocyte