Jumonji domain-containing protein 3 regulates histone 3 lysine 27 methylation during bovine preimplantation development. Canovas S et al. Understanding the mechanisms of epigenetic remodeling that follow fertilization is a fundamental step toward understanding the bases of early embryonic development and pluripotency. Extensive and dynamic chromatin remodeling is observed after fertilization, including DNA methylation and histone modifications. These changes underlie the transition from gametic to embryonic chromatin and are thought to facilitate embryonic genome activation. In particular, trimethylation of histone 3 lysine 27 (H3K27me3) is associated with gene-specific transcription repression. Global levels of this epigenetic mark are high in oocyte chromatin and decrease to minimal levels at the time of embryonic genome activation. We provide evidence that the decrease in H3K27me3 observed during early development is cell-cycle independent, suggesting an active mechanism for removal of this epigenetic mark. Among H3K27me3-specific demethylases, Jumonji domain-containing protein 3 (JMJD3), but not ubiquitously transcribed tetratricopeptide repeat X (UTX), present high transcript levels in oocytes. Soon after fertilization JMJD3 protein levels increase, concurrent with a decrease in mRNA levels. This pattern of expression suggests maternal inheritance of JMJD3. Knockdown of JMJD3 by siRNA injection in parthenogenetically activated metaphase II oocytes resulted in inhibition of the H3K27me3 decrease normally observed in preimplantation embryos. Moreover, knockdown of JMJD3 in oocytes reduced the rate of blastocyst development. Overall, these results indicate that JMJD3 is involved in active demethylation of H3K27me3 during early embryo development and that this mark plays an important role during the progression of embryos to blastocysts.
General function
, Epigenetic modifications
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Cellular localization
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Ovarian function
Early embryo development
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The Maternal Effect Genes UTX and JMJD3 Play Contrasting Roles in Mus musculus Preimplantation Embryo Development. Yang L et al. (2016) During the process of embryonic development in mammals, epigenetic modifications must be erased and reconstructed. In particular, the trimethylation of histone 3 lysine 27 (H3K27me3) is associated with gene-specific transcriptional repression and contributes to the maintenance of the pluripotent embryos. In this study, we determined that the global levels of the H3K27me3 marker were elevated in MII oocyte chromatin and decrease to minimal levels at the 8-cell and morula stages. When the blastocyst hatched, H3K27me3 was re-established in the inner cell mass. We also determined that H3K27me3-specific demethylases, UTX and JMJD3, were observed at high transcript and protein levels in mouse preimplantation embryos. In the activated oocytes, when the H3K27me3 disappeared at the 8-cell stage, the UTX (but not JMJD3) protein levels were undetectable. Using RNA interference, we suppressed UTX and JMJD3 gene expression in the embryos and determined that the functions of UTX and JMJD3 were complementary. When JMJD3 levels were decreased by RNA interference, the embryo development rate and quality were improved, but the knockdown of UTX produced the opposite results. Understanding the epigenetic mechanisms controlling preimplantation development is critical to comprehending the basis of embryonic development and to devise methods and approaches to treat infertility.//////////////////
Proteome of mouse oocytes at different developmental stages. Wang S et al. The mammalian oocyte possesses powerful reprogramming factors, which can reprogram terminally differentiated germ cells (sperm) or somatic cells within a few cell cycles. Although it has been suggested that use of oocyte-derived transcripts may enhance the generation of induced pluripotent stem cells, the reprogramming factors in oocytes are undetermined, and even the identified proteins composition of oocytes is very limited. In the present study, 7,000 mouse oocytes at different developmental stages, including the germinal vesicle stage, the metaphase II (MII) stage, and the fertilized oocytes (zygotes), were collected. We successfully identified 2,781 proteins present in germinal vesicle oocytes, 2,973 proteins in MII oocytes, and 2,082 proteins in zygotes through semiquantitative MS analysis. Furthermore, the results of the bioinformatics analysis indicated that different protein compositions are correlated with oocyte characteristics at different developmental stages. For example, specific transcription factors and chromatin remodeling factors are more abundant in MII oocytes, which may be crucial for the epigenetic reprogramming of sperm or somatic nuclei. These results provided important knowledge to better understand the molecular mechanisms in early development and may improve the generation of induced pluripotent stem cells.
Epigenetic modification-related proteins are expressed more abundantly in
MII oocytes. The MII oocytes express four histone demethylases, including Padi6, Jmjd3, Fbxl10, and Aof2, five histone acetyltransferases, including Nat11, Hat1,
Taf15, Btaf1, and Taf7, six histone deacetylases, including Hdac2, Hdac6, Sirt2, Sirt5, Sap30, and Satb1, and eight histone methyltranferases, including Men1, Mll3,
Mllt10, Mllt4, Nsd1, Prmt1, Dpy30, and Carm1.
Expression regulated by
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Ovarian localization
Oocyte
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SSR 2010 abstract 238. Role of a Histone H3K27-Specific Demethylase (JMJD3) During
Bovine Preimplantation Development. Sebastian Canovas, Jose Cibelli, and Pablo
J. Ross. Andalucian Initiative for Advanced Therapies, Fundacion Progreso y Salud,
Andalucia, Spain; Michigan State University, East Lansing, MI, USA; University of
California, Davis, CA, USA
Histone lysine methylation is an epigenetic mark involved in gene transcriptional
repression or activation depending on the specific lysine residue and methylation
level. JMJD3 is a histone H3 lysine 27 (H3K27)-specific demethylase with activity at
di- and tri-methylated residues, both epigenetic marks associated with gene
repression. JMJD3 has been involved in the temporal expression of different genes
during posterior embryo development, neural commitment, inflammatory process and
mammalian epidermal differentiation. Since we have shown that H3K27 trimethylation
levels decrease during preimplantation development, it is possible that JMJD3
is active during early bovine development. We hypothesize that JMJD3 plays an
important role in gene expression regulation during early embryo development. The
aim of this study was to identify the expression pattern of JMJD3 in bovine oocytes
and preimplantation embryos and to determine if depletion of JMJD3 by siRNA
injection into oocytes or zygotes has any effect on preimplantation embryonic
development. Embryos were produced by parthenogenetic activation or in vitro
fertilization (IVF) and total RNA was collected at GV, MII, PN, 2-, 4-, 8-, 16-cell,
morula, and blastocyst stages. Total and polyadenylated JMJD3 mRNA levels were
determined by quantitative real-time PCR (qRT-PCR). The presence of JMJD3
protein was analyzed using western blot (WB) in 2- and 8- to 16-cell stage embryos.
Two different siRNA species were designed and produced using the Silencer siRNA
construction kit (Ambion). MII oocytes were injected with ~6pl of 25-lM JMJD3-1,
JMJD3-2, or control (non-specific) siRNA, followed by parthenogenetic activation.
Embryos were in vitro-cultured for 7 days. Four-cell and blastocyst stage embryos
were collected to determine the levels of JMJD3, GADPH, B-Actin, 18s rRNA and
RPL15 mRNA by qRT-PCR. Fertilized embryos were injected 17 hour postfertilization
as described for MII oocytes and cultured for 7 days. Cleavage rate,
blastocysts rate and blastocyst cell number were analyzed in all groups. Relative
JMJD3 mRNA levels were highest at the GV stage, decreasing from MII to morula
stage and increasing again at the blastocyst stage. No differences were observed
between total and poly-A mRNA levels. WB analysis of embryos showed a ~190kDa
specific band, which disappeared when the antibody was pre-incubated with JMJD3
peptide. MII injected oocytes with both JMJD3 siRNA species showed a significant
reduction in JMJD3 mRNA levels at 4-cell (~90% decrease) and blastocyst stages
(~50% decrease), compared to siRNA control injected embryos. Meanwhile, other
genes tested were not affected. Also, blastocyst rate was significantly reduced in the
JMJD3 siRNA treated groups (~50% reduction, P , 0.05). Furthermore, the cell
number in parthenogenetic blastocysts tended to be lower in JMJD3 siRNA injected
groups than in control groups (~20% reduction). Fertilized embryos, injected with
JMJD3 siRNA, developed to blastocyst stage at similar rates than control groups,
although the cell number in treated embryos was significantly reduced (~30%
reduction, P , 0.05). The differential effects observed in the parthenogenetic and IVF
studies could result from the different nature of the embryos used or the timing of
siRNA injection. Nevertheless, these studies provide the first experimental evidence
demostrating that JMJD3 plays an important role in preimplantation embryonic
development.