Initiation of a chromatin-based transcriptionally repressive state in the preimplantation mouse embryo: Lack of a primary role for expression of somatic histone H1
✍ Scribed by Paula Stein; Richard M. Schultz
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 180 KB
- Volume
- 55
- Category
- Article
- ISSN
- 1040-452X
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✦ Synopsis
A chromatin-based transcriptionally repressive state develops during the two-cell stage in preimplantation mouse embryos. Correlated with the initial formation of this state is the expression of somatic histone H1, which could confer repression by promoting the formation of a transcriptionally repressive chromatin structure. To ascertain if the expression of histone H1 could play such a primary role in initiating the formation of this transcriptionally repressive state, the endogenous pool of somatic histone H1 in the two-cell embryo was greatly expanded by injection of 25 or 100 pg of histone H1 at the one-cell stage. The expression of the transcription-requiring complex, which is an accepted marker for genome activation, was then assessed during the two-cell stage. No significant inhibition was noted following the injection of 25 pg of histone H1. A transient inhibition was observed following injection of 100 pg, but this was likely due to a delay in cleavage to the two-cell stage. We conclude that it is unlikely that the expression of somatic histone H1 is a major factor in the initial establishment of the chromatinbased transcriptionally repressive state that accompanies genome activation.