Fully grown mouse oocyte contains transcription inhibiting activity which acts through histone deacetylation.
Mouse ovarian oocytes remain transcriptionally active during the entire period of oocyte growth. In the fully grown antral oocytes, RNA synthesis is terminated before initiation of maturation. The mechanism involved in this process remains unknown. It was proposed that some signals provided by companion granulosa cells, and accumulating in the cytoplasm of the oocyte, play a role in the termination of RNA synthesis. It seems possible that under influence of these signals, the oocyte cytoplasm becomes transcriptionally nonpermissive. In the present study, transcriptionally active, single blastomeres of the 8-cell mouse embryo were fused with nontranscribing fully grown oocytes, and RNA synthesis was analyzed in the resulting hybrids. We show that after 27 hr of culture of hybrid cells, transcription in the blastomere nuclei was finally silenced. This process occurs without nuclear envelope breakdown and is accompanied by progressive condensation of the chromatin in the blastomere nuclei. We show also the involvement of core histone deacetylation in the modification of chromatin configuration and termination of RNA synthesis in the blastomere nuclei.
Borsuk
Ewa
E
Department of Embryology, Institute of Zoology, Warsaw University, Warsaw, Poland. borsuk@biol.uw.edu.pl
Milik
Elwira
E
D000818:Animals; D001562:Benzimidazoles; D001757:Blastomeres / Q000502:physiology; D002459:Cell Fusion; D002467:Cell Nucleus / Q000502:physiology; D002843:Chromatin / Q000502:physiology; D005260:Female; D006655:Histone Deacetylases / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D009865:Oocytes / Q000201:enzymology*; D014158:Transcription, Genetic / Q000502:physiology*
D001562:Benzimidazoles; D002843:Chromatin; D006657:Histones; D006655:Histone Deacetylases; C017807:bisbenzimide ethoxide trihydrochloride