NCBI Summary:
Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. This structure consists of approximately 146 bp of DNA wrapped around a nucleosome, an octamer composed of pairs of each of the four core histones (H2A, H2B, H3, and H4). The chromatin fiber is further compacted through the interaction of a linker histone, H1, with the DNA between the nucleosomes to form higher order chromatin structures. This gene is intronless and encodes a member of the histone H3 family. Transcripts from this gene lack polyA tails; instead, they contain a palindromic termination element. This gene is found in the large histone gene cluster on chromosome 6p22-p21.3.
Differences in H3K4 trimethylation in in vivo and in vitro fertilization mouse preimplantation embryos. Wu FR et al. Trimethylation of lysine 4 at histone 3 (H3K4me3) is considered a marker of active transcription; it plays an important role in transcription reprogramming efficiency. We compared the levels of H3K4me3 in mouse preimplantation embryos from MII stage oocytes produced by in vivo and in vitro fertilization (IVF) using immunofluorescence histochemistry. IVF embryos were further treated with trichostatin A (a histione deacetylase inhibitor) to investigate the effect of histone acetylation on H3K4me3. We found higher levels of H3K4me3 in MII stage oocytes in metaphase chromosomes. The pattern of H3K4 trimethylation of in vivo embryos from zygote to blastocyst stages was similar to that of IVF embryos; however, the concentration of H3K4me3 was significantly higher in the in vivo fertilization embryos. The levels of H3K4me3 in the trichostatin A-treated groups were also significantly increased. We conclude that culture condition and environmental changes can cause histone modification and that the effect of these environmental conditions on epigenetic changes should be taken into consideration.
Dynamic replacement of histone h3 variants reprograms epigenetic marks in early mouse embryos. Akiyama T et al. Upon fertilization, reprogramming of gene expression is required for embryo development. This step is marked by DNA demethylation and changes in histone variant composition. However, little is known about the molecular mechanisms causing these changes and their impact on histone modifications. We examined the global deposition of the DNA replication-dependent histone H3.1 and H3.2 variants and the DNA replication-independent H3.3 variant after fertilization in mice. We showed that H3.3, a euchromatic marker of gene activity, transiently disappears from the maternal genome, suggesting erasure of the oocyte-specific modifications carried by H3.3. After fertilization, H3.2 is incorporated into the transcriptionally silent heterochromatin, whereas H3.1 and H3.3 occupy unusual heterochromatic and euchromatin locations, respectively. After the two-cell stage, H3.1 and H3.3 variants resume their usual respective locations on heterochromatin and euchromatin. Preventing the incorporation of H3.1 and H3.2 by knockdown of the histone chaperone CAF-1 induces a reciprocal increase in H3.3 deposition and impairs heterochromatin formation. We propose that the deposition of different H3 variants influences the functional organization of chromatin. Taken together, these findings suggest that dynamic changes in the deposition of H3 variants are critical for chromatin reorganization during epigenetic reprogramming.
Expression regulated by
FSH, Steroids
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Ovarian localization
Oocyte, Granulosa
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Estrogen mediates phosphorylation of histone H3 in ovarian follicle and mammary epithelial tumor cells via the mitotic kinase, Aurora B Ruiz-Cortes ZT, et al .
Cells of the ovarian follicle undergo extensive proliferation and differentiation from the time that the follicle escapes from the primordial state to its acquisition of ovulatory capacity. We examined the dynamic modification of the phosphorylation state of the histone H3 N-terminal tail in granulosa cells during follicular development. In rodent follicles, the granulosa cell H3 phosphorylation on Ser10 peaks during proestrus. This epigenetic mark is induced by both FSH and 17beta-estradiol (E2), acting independently. E2-induced H3 phosphorylation fails to occur in mice with inactivated alpha-isoform of the nuclear estrogen receptor. E2 induction of histone phosphorylation is attenuated by cell cycle inhibition. Further, E2 induces the activity of the mitotic kinase, Aurora B, in a mammary tumor cell model where mitosis is estrogen receptor-alpha dependent. These results provide evidence for mitotic regulation in follicle development by estrogen and demonstrate a previously undiscovered mechanism for induction of cell proliferation in ovarian and mammary gland cells.