Project description:H3.3-mediated paternal chromatin remodeling is essential for the development of preimplantation embryos and the activation of the paternal genome during embryogenesis.
Project description:Derepression of chromatin-mediated transcriptional repression of paternal and maternal genomes is considered the first major step that initiates zygotic gene expression after fertilization. The histone variant H3.3 is present in both male and female gametes and is thought to be important for remodeling the paternal and maternal genomes for activation during both fertilization and embryogenesis. However, the underlying mechanisms remain poorly understood. Using our H3.3B-HA-tagged mouse model, engineered to report H3.3 expression in live animals and to distinguish different sources of H3.3 protein in embryos, we show here that sperm-derived H3.3 (sH3.3) protein is removed from the sperm genome shortly after fertilization and extruded from the zygotes via the second polar bodies (PBII) during embryogenesis. We also found that the maternal H3.3 (mH3.3) protein is incorporated into the paternal genome as early as 2 h postfertilization and is detectable in the paternal genome until the morula stage. Knockdown of maternal H3.3 resulted in compromised embryonic development both of fertilized embryos and of androgenetic haploid embryos. Furthermore, we report that mH3.3 depletion in oocytes impairs both activation of the Oct4 pluripotency marker gene and global de novo transcription from the paternal genome important for early embryonic development. Our results suggest that H3.3-mediated paternal chromatin remodeling is essential for the development of preimplantation embryos and the activation of the paternal genome during embryogenesis.
Project description:Mature oocyte cytoplasm can reprogram somatic cell nuclei to the pluripotent state through a series of sequential events including protein exchange between the donor nucleus and ooplasm, chromatin remodeling, and pluripotency gene reactivation. Maternal factors that are responsible for this reprogramming process remain largely unidentified. Here, we demonstrate that knockdown of histone variant H3.3 in mouse oocytes results in compromised reprogramming and down-regulation of key pluripotency genes; and this compromised reprogramming both for developmental potentials and transcription of pluripotency genes can be rescued by injecting exogenous H3.3 mRNA, but not H3.2 mRNA into oocytes in somatic cell nuclear transfer (SCNT) embryos. We show that maternal H3.3, and not H3.3 in the donor nucleus, is essential for successful reprogramming of somatic cell nucleus into the pluripotent state. Furthermore, H3.3 is involved in this reprogramming process by remodeling the donor nuclear chromatin through replacement of donor nucleus-derived H3 with de novo synthesized maternal H3.3 protein. Our study shows that H3.3 is a crucial maternal factor for oocyte reprogramming and provides a practical model to directly dissect the oocyte for its reprogramming capacity. Transcriptome sequencing of 4-cell NT embryos, Luciferase 4-cell SCNT embryos, 4-cell NT embryos_H3.3KD, 4-cell NT embryos_H3.3KD+H3.3mRNA, H3.3 KD + H3.2 mRNA SCNT embryos
Project description:Poor parental health can influence the development and eventual health outcomes of their offspring. Many studies have detailed the maternal role yet a father’s health requires further examination as his poor nutritional status has also been shown to have negative consequences on fetal development and impact the long-term health of his offspring. The present study examined how preimplantation embryo development was altered by sub-optimal paternal diet, with specific focus on sperm- and seminal plasma-mediated mechanisms. To address this, male mice were fed a diet to model either under (low protein diet (LPD)) or over (high fat/sugar ‘Western’ diet (WD)) nutrition, LPD or WD supplemented with methyl-donors or a control diet (CD) before mating. Embryo development was assessed using in vitro time-lapse imaging of preimplantation embryos which revealed a significant increase in embryo development rates in all experimental groups when compared to CD embryos. Further analysis of the semen revealed a significant number of differentially expressed seminal plasma proteins in all groups (LPD: 13, MD-LPD: 27, WD: 24, MD-WD: 19) when compared to control. This study highlights a role for paternal nutritional status influencing embryonic development and the maternal reproductive tract via changes to his metabolic and reproductive health. These findings demonstrate potential direct (sperm-mediated) and indirect (seminal plasma-mediated) pathways in which a father's poor diet could shape the long-term health of his offspring
Project description:In animals, replication coupled histone H3.1 can be distinguished from replication independent histone H3.3. H3.3 variants are enriched at active genes and their promoters. Furthermore, H3.3 is specifically incorporated upon gene activation. Histone H3 variants evolved independently in plants and animals and it is unclear whether different replication independent H3.3 variants developed similar properties in both phyla. We studied Arabidopsis H3 variants in order to find core properties of this class of histones. Here we present genome-wide maps of H3.3 and H3.1 enrichment and the dynamic changes of their profiles upon cell division arrest. We find H3.3 enrichment to positively correlate with gene expression and to be biased towards the transcription termination site. While heterochromatic regions are mostly depleted of H3.3, H3.1 shows a more even distribution along the genome. We report that in planta, dynamic changes in H3.3 profiles are associated with the extensive remodeling of the transcriptome that occurs during cell differentiation. We propose that H3.3 dynamics are linked to transcription and are involved in resetting covalent histone marks at a genomic scale during plant development. Similarities between plant and animal H3.3 deposition profiles indicate that H3 variants likely result from functionally convergent evolution. Analysis of 2 different histone H3 variants and transcriptome in 2 conditions.
Project description:In animals, replication coupled histone H3.1 can be distinguished from replication independent histone H3.3. H3.3 variants are enriched at active genes and their promoters. Furthermore, H3.3 is specifically incorporated upon gene activation. Histone H3 variants evolved independently in plants and animals and it is unclear whether different replication independent H3.3 variants developed similar properties in both phyla. We studied Arabidopsis H3 variants in order to find core properties of this class of histones. Here we present genome-wide maps of H3.3 and H3.1 enrichment and the dynamic changes of their profiles upon cell division arrest. We find H3.3 enrichment to positively correlate with gene expression and to be biased towards the transcription termination site. While heterochromatic regions are mostly depleted of H3.3, H3.1 shows a more even distribution along the genome. We report that in planta, dynamic changes in H3.3 profiles are associated with the extensive remodeling of the transcriptome that occurs during cell differentiation. We propose that H3.3 dynamics are linked to transcription and are involved in resetting covalent histone marks at a genomic scale during plant development. Similarities between plant and animal H3.3 deposition profiles indicate that H3 variants likely result from functionally convergent evolution. Analysis of 2 different histone H3 variants and transcriptome in 2 conditions.
Project description:This SuperSeries is composed of the following subset Series: GSE36626: Dynamic Deposition of the Histone H3.3 Variant Accompanies Developmental Remodeling of Arabidopsis Transcriptome (mRNA-Seq) GSE36629: Dynamic Deposition of the Histone H3.3 Variant Accompanies Developmental Remodeling of Arabidopsis Transcriptome (ChIP-Seq) Refer to individual Series
Project description:Histone variants can replace canonical histones in the nucleosome and modify chromatin structure and gene expression. The histone variant H3.3 preferentially associates with active chromatin and has been implicated in the regulation of a diverse range of developmental processes. However, the mechanisms by which H3.3 may regulate gene activity are unclear and gene duplication has hampered an analysis of H3.3 function in mouse. Here, we report that the specific knockdown of H3.3 in fertilized mouse zygotes leads to developmental arrest at the morula stage. This phenotype can be rescued by exogenous H3.3 but not by canonical H3.1 mRNA. Loss of H3.3 leads to over-condensation and mis-segregation of chromosomes as early as the two-cell stage, with corresponding high levels of aneuploidy, but does not appear to affect zygotic gene activation at the two-cell stage or lineage gene transcription at the morula stage. H3.3-deficient embryos have significantly reduced levels of markers of open chromatin, such as H3K36me2 and H4K16Ac. Importantly, a mutation in H3.3K36 that disrupts H3K36 methylation (H3.3K36R) does not rescue the H3.3 knockdown (KD) phenotype. In addition, H3.3 KD embryos have increased incorporation of linker H1. Knockdown of Mof (Kat8), an acetyltransferase specific for H4K16, similarly leads to excessive H1 incorporation. Remarkably, pan-H1 RNA interference (RNAi) partially rescues the chromosome condensation of H3.3 KD embryos and allows development to the blastocyst stage. These results reveal that H3.3 mediates a balance between open and condensed chromatin that is crucial for the fidelity of chromosome segregation during early mouse development.
Project description:Mature oocyte cytoplasm can reprogram somatic cell nuclei to the pluripotent state through a series of sequential events including protein exchange between the donor nucleus and ooplasm, chromatin remodeling, and pluripotency gene reactivation. Maternal factors that are responsible for this reprogramming process remain largely unidentified. Here, we demonstrate that knockdown of histone variant H3.3 in mouse oocytes results in compromised reprogramming and down-regulation of key pluripotency genes; and this compromised reprogramming both for developmental potentials and transcription of pluripotency genes can be rescued by injecting exogenous H3.3 mRNA, but not H3.2 mRNA into oocytes in somatic cell nuclear transfer (SCNT) embryos. We show that maternal H3.3, and not H3.3 in the donor nucleus, is essential for successful reprogramming of somatic cell nucleus into the pluripotent state. Furthermore, H3.3 is involved in this reprogramming process by remodeling the donor nuclear chromatin through replacement of donor nucleus-derived H3 with de novo synthesized maternal H3.3 protein. Our study shows that H3.3 is a crucial maternal factor for oocyte reprogramming and provides a practical model to directly dissect the oocyte for its reprogramming capacity.
Project description:Profiles of H3K4me3, H3K27ac, H3K27me3 and H3K9me3 in bovine GV oocytes and preimplantation embryos, and the characterization of chromatin accessibility in bovine blastocyst, inner cell mass and trophectoderm.