Project description:Genome wide comparison of gene expression between EpiSC lines derived from fertilized (FT) embryos and somatic cell nuclear transfer (NT) embryos. EpiSC lines were derived from fertilized and somatic cell nuclear transfer embryos and cultured until 15 to 20 passages. RNA was then extracted in order to compare transcriptomic profiles.
Project description:Somatic cell nuclear transfer and transcription factor overexpression can induce reprogramming of somatic cells, whereby one cell fate is changed into another cell fate of choice. Yet the efficiency of this process for generating functional cells is low, limiting their therapeutic applications. The persistence of transcriptional memory from the cell's prior identity is thought to be a major hindrance to effective reprogramming and differentiation to functional cell types. To explore the effects of transcriptional memory on cell fate specification of reprogrammed cells, we analyzed epidermal tissue development in nuclear transfer embryos derived from endoderm nuclei. Our findings reveal variations in the success rate of differentiation to functional cells across cell types in cloned embryos. While some cell types, such as goblet cells, differentiated normally, a specific subset of cells resisted cell fate reprogramming, adopting a new endoderm-like state and disrupting normal body patterning. Furthermore, inefficient transcriptional reprogramming correlated with reduced basal stem cell populations, faulty differentiation of basal stem cell-derived fates, and increased cell death in the epidermis of cloned embryos. Crucially, we identified that the memory of active transcriptional states linked to key endoderm transcription factors plays a significant role in these issues. Mimicking active state transcriptional memory of these genes through the forced expression of Sox17b and Foxa4 in the epidermis of fertilized embryos produced the same defects. On the contrary, reducing transcriptional memory by interfering with the expression of Sox17b led to the rescue of observed epidermal defects. In summary, our study suggests that transcriptional memory tends to persist predominantly in specific reprogrammed cell types, hindering their differentiation into functional cells and embryonic structures. This underscores the critical need to assess and reduce transcriptional memory from the previous somatic identity during reprogramming, to efficiently generate functional cell types for therapeutic applications.
Project description:Although somatic cell nuclear transfer (SCNT) cloning is more efficient in bovine than in all other species tested so far, there is a high rate of pregnancy failure that has been linked to structural and functional abnormalities of the placenta. We tested the hypothesis that these changes may originate from disturbed embryo-maternal interactions in the pre-implantation period. Therefore, we evaluated the transcriptome response of the endometrium to SCNT embryos (produced from five different donor cell cultures) as compared to embryos derived from in vitro fertilization (IVF). SCNT embryos and IVF embryos were cultured under identical conditions to the blastocyst stage (Day 8) and transferred to recipients. The recipients were slaughtered at day 18 of pregnancy and the uterus was recovered. Pregnancy was verified by the presence of at least one normally developed embryo. Transcriptome profiling of endometrium samples using a custom cDNA microarray covering transcripts expressed in the endometrium and/or oviduct epithelium revealed 58 transcripts that were differently abundant between endometrium samples from SCNT vs. IVF pregnancies. Prominent examples are NR2F2 (encoding the orphan nuclear receptor COUP-TFII) and GJA1 (encoding connexin 43). Both transcripts are known to play important roles in placentation and were significantly less abundant in endometrium from SCNT vs. IVF pregnancies. These findings suggest that placental failure in bovine clone pregnancies may originate from abnormal embryo-maternal communication already in the pre- or peri-implantation period. Endometrium transcriptome profiles may serve as a novel readout to evaluate SCNT embryos for their ability to induce pregnancy with a functional placenta. Keywords: response to different embryos Nineteen German Fleckvieh (Simmental) heifers were slaughtered at day 18 of pregnancy. Cycle-synchronized recipient heifers received either IVP or SCNT embryos at day 7 of the estrous cycle. Animals were slaughtered at day 18. Endometrial (intercaruncular) tissue samples were obtained from 10 pregnant animals after transfer of IVP embryos and from 9 pregnant animals after transfer of SCNT embryos.
Project description:Affymetrix Human GeneChips are used to profile gene expression of bovine tissues and embryos to identify uniquely expressed genes in bovine in-vitro fertilized embryos by comparing with seven bovine adult tissues through gene clustering Keywords: other
Project description:We aimed to identify a reprogramming factor in mammalian oocytes. DJ-1 is one candidate gene of the factor. Inhibition of DJ-1 function in nuclear transfer embryos affected developmental abilities. The downstream effect of this DJ-1 inhibition was examined using microarrays. Nuclear transfer (NT) embryos (23-26 embryos per each sample) were collected at 28 h after nuclear transfer when many of the embryos had just reached the 2-cell stage. Total RNA was extracted and hybridized on the Affymetrix GeneChip Porcine Genome Array. Global transcripts were compared among NT embryos injected with anti-DJ1 antibody (αDJ1-NT_1), NT embryos injected with IgG (IgG-NT_1), non-injected NT embryos (NT_1) and donor cells (DonorCell_1). Biologically different samples of αDJ1-NT (αDJ1-NT_2) and IgG-NT (IgG-NT_2) were prepared and the microarray analysis was repeated. In both trials, NT embryos injected with IgG (IgG-NT_1 or IgG-NT_2) were used as controls.
Project description:The extremely low efficiency of human embryonic stem cell (hESC) derivation using somatic cell nuclear transfer (SCNT) limits potential application. Blastocyst formation from human SCNT embryos occurs at a low rate and with only some oocyte donors. We previously showed in mice that reduction of histone H3 lysine 9 trimethylation (H3K9me3) through ectopic expression of the H3K9me3 demethylase Kdm4d greatly improves SCNT embryo development. Here we show that overexpression of a related H3K9me3 demethylase KDM4A improves human SCNT, and that, as in mice, H3K9me3 in the human somatic cell genome is an SCNT reprogramming barrier. Overexpression of KDM4A significantly improves the blastocyst formation rate in human SCNT embryos by facilitating transcriptional reprogramming, allowing derivation of NTESCs from all oocyte donors tested using adult AMD patient somatic nuclei donors. This conserved mechanistic insight has potential applications for improving SCNT in a variety of contexts, including regenerative medicine. Here we perform RNA-seq based transcriptome profiling in human Donor (fibroblast cells), in vitro fertilized embryos at 8-cell stages (IVF_8Cell), somatic cell nuclear transfer embryos at 8-cell stages (SCNT_8Cell), SCNT assisted by KDM4A 8-cell embryos (SCNT_KDM4A_8Cell). Besides, we also perform RNA-seq in Control human ES cells (CTR_hES) and SCNT assisted by KDM4A derived human ES cells (NTK) with duplicates.Â
Project description:Although somatic cell nuclear transfer (SCNT) cloning is more efficient in bovine than in all other species tested so far, there is a high rate of pregnancy failure that has been linked to structural and functional abnormalities of the placenta. We tested the hypothesis that these changes may originate from disturbed embryo-maternal interactions in the pre-implantation period. Therefore, we evaluated the transcriptome response of the endometrium to SCNT embryos (produced from five different donor cell cultures) as compared to embryos derived from in vitro fertilization (IVF). SCNT embryos and IVF embryos were cultured under identical conditions to the blastocyst stage (Day 8) and transferred to recipients. The recipients were slaughtered at day 18 of pregnancy and the uterus was recovered. Pregnancy was verified by the presence of at least one normally developed embryo. Transcriptome profiling of endometrium samples using a custom cDNA microarray covering transcripts expressed in the endometrium and/or oviduct epithelium revealed 58 transcripts that were differently abundant between endometrium samples from SCNT vs. IVF pregnancies. Prominent examples are NR2F2 (encoding the orphan nuclear receptor COUP-TFII) and GJA1 (encoding connexin 43). Both transcripts are known to play important roles in placentation and were significantly less abundant in endometrium from SCNT vs. IVF pregnancies. These findings suggest that placental failure in bovine clone pregnancies may originate from abnormal embryo-maternal communication already in the pre- or peri-implantation period. Endometrium transcriptome profiles may serve as a novel readout to evaluate SCNT embryos for their ability to induce pregnancy with a functional placenta. Keywords: response to different embryos
Project description:Endogenous retroviruses (ERVs) in the mammalian genome play diverse roles in embryonic development. These development-related ERVs are generally repressed in somatic cells and are therefore likely repressed in embryos derived from somatic cell nuclear transfer (SCNT). In this study, we sought to identify ERVs that are repressed in SCNT-derived morula embryos, which may consequently cause previously unexplained embryonic deaths shortly after implantation. Our transcriptome analysis revealed that, amongst ERV families, ERVK was specifically and strongly downregulated in SCNT embryos while other transposable elements including LINE and ERVL were unchanged. Among subfamilies of ERVK, RLTR45-int was most repressed in SCNT embryos despite its highest expression in control fertilized embryos. Interestingly, the nearby genes (within 5–50 kb, n = 19) of the repressed RLTR45-int loci were also repressed in SCNT embryos with a significant correlation between them. Furthermore, lysine H3K27 acetylation was enriched around the RLTR45-int loci. These findings indicate that RLTR45-int elements function as enhancers of nearby genes. Indeed, deletion of two sequential RLTR45-int loci on chromosome 4 or 18 resulted in downregulations of nearby genes at the morula stage. We also found that RLTR45-int loci, especially SCNT-low, enhancer-like loci, were strongly enriched with H3K9me3, a repressive histone mark. Importantly, these H3K9me3-enriched regions were resistant to histone demethylase Kdm4d in SCNT embryos. Thus, we identified ERVK subfamily RLTR45-int, putative enhancer elements, as a strong reprogramming barrier for SCNT. A large-scale downregulations of their regulating genes in SCNT morulae might cumulatively affect postimplantation development of SCNT embryos.