Chromatin configuration and transcriptional control in human and mouse oocytes.
In vitro maturation of human oocytes at the germinal vesicle (GV) stage could offer an alternative in several cases of female infertility. It however rests on a better knowledge of the quality of human oocyte. Using fluorescence imaging of DNA and of the transcription sites, combined with electron microscopy, we show that human oocytes follow size-dependent changes in chromatin configuration, transcription sites distribution and nuclear ultrastructure that follow those observed in mouse GV oocytes. We thus analyzed in mouse GV oocytes the phosphorylation dependence of the transcriptional activity. We show by Western blot that, while active GV oocytes have approximately the same proportion of hypo- and hyperphosphorylated forms of the RNA polymerase II (RNAP II), the hyperphosphorylated form is almost absent from inactive oocytes. We also show that (1) RNAP II-dependent transcription is much less sensitive to various kinase inhibitors in mouse oocytes than in somatic cells or mouse one-cell embryos, although the phosphorylation equilibrium of RNAP II was largely shifted towards the hypo-phosphorylated form upon treatment with these inhibitors (2) RNAP I is completely insensitive to kinase inhibitors in GV oocytes.
Miyara
Faïçal
F
INRA 806/EA 2703, IFR 63, Muséum National d'histoire Naturelle, Institut de Biologie Physico-Chimique, 13 rue P. et M. Curie, F75005 Paris, France.
Migne
Carole
C
Dumont-Hassan
Martine
M
Le Meur
Alain
A
Cohen-Bacrie
Paul
P
Aubriot
François-Xavier
FX
Glissant
Amélie
A
Nathan
Catherine
C
Douard
Stéphane
S
Stanovici
Alexandre
A
Debey
Pascale
P
D000818:Animals; D015153:Blotting, Western; D002843:Chromatin / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000037:antagonists & inhibitors; D012319:RNA Polymerase II / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*; D015053:Zygote / Q000378:metabolism
D002843:Chromatin; D010770:Phosphotransferases; D012319:RNA Polymerase II