Project description:Embryonic genome activation (EGA) marks the onset of embryonic program and enables the transition toward the first lineage specification. However, the molecular features of EGA and the transcription factors (TFs) orchestrating this process remain unclear. Here, by performing single-cell RNA-seq on bovine embryos, we reveal that major EGA is asynchronously initiated among blastomeres at the 8-cell stage. Integrative analyses reveal distinctive protein accumulation compared to transcription and translation activation during bovine EGA. Furthermore, we investigate the role of SP1, a TF activated at the minor EGA stage, with motifs enriched in accessible chromatin during major EGA stage in bovine and human embryos. SP1 deficiency leads to morula arrest in bovine and impairs EGA in human embryos. Multi-omics analysis demonstrates that SP1 promotes early lineage gene expression by modulating nearby chromatin states in bovine and directly targets key EGA genes in human embryos. Together, our study delineates the dynamics of bovine EGA and uncovers the conserved and species-specific roles of SP1 in regulating EGA and early development in mammals.
Project description:The identification of gene mutation and structural genomic aberrations that are critically involved in CLL pathogenesis is still evolving. One may postulate that genomic driver lesions with effects on CLL proliferation, apoptosis thresholds, or chemotherapy resistance should increase in frequency over time when measured sequentially in a large CLL cohort. We sequentially sampled a large, well-characterized CLL cohort at a mean of 4 years between samplings. The paired analysis included 156 patients, of whom 114 remained untreated and 42 received intercurrent therapies. Results: we identify a strong effect of intercurrent therapies on the frequency of acquisition of aCNAs in CLL. Importantly, the spectrum of acquired genomic changes was largely similar in patients that did or did not receive intercurrent therapies; therefore, various genomic changes that become part of the dominant clones are often already present in CLL cell populations prior to therapy. Further, we provide evidence that therapy of CLL with preexisting TP53 mutations results in the outgrowth of genomically very complex clones which dominate at relapse. Using complementary technologies directed at the detection of genomic events that are present in substantial proportions of of the clinically relevant CLL disease bulk, we capture aspects of genomic evolution in CLL over time, including increases in the frequency of genomic complexity, specific recurrent aCNAs, and TP53 mutations.
Project description:The identification of gene mutation and structural genomic aberrations that are critically involved in CLL pathogenesis is still evolving. One may postulate that genomic driver lesions with effects on CLL proliferation, apoptosis thresholds, or chemotherapy resistance should increase in frequency over time when measured sequentially in a large CLL cohort. We sequentially sampled a large, well-characterized CLL cohort at a mean of 4 years between samplings. The paired analysis included 156 patients, of whom 114 remained untreated and 42 received intercurrent therapies. Results: we identify a strong effect of intercurrent therapies on the frequency of acquisition of aCNAs in CLL. Importantly, the spectrum of acquired genomic changes was largely similar in patients that did or did not receive intercurrent therapies; therefore, various genomic changes that become part of the dominant clones are often already present in CLL cell populations prior to therapy. Further, we provide evidence that therapy of CLL with preexisting TP53 mutations results in the outgrowth of genomically very complex clones which dominate at relapse. Using complementary technologies directed at the detection of genomic events that are present in substantial proportions of of the clinically relevant CLL disease bulk, we capture aspects of genomic evolution in CLL over time, including increases in the frequency of genomic complexity, specific recurrent aCNAs, and TP53 mutations. Data from 156 paired samples (enrollment and one longitudinal sample) are included in this data set. Of these, 27 patients were assayed at two (or, rarely, more than two) time points. Please note: normal DNA and enrollment date tumor DNA CEL files and SNP call files will be found in a separate GEO data submission: GSE30777
Project description:Reprogramming of the gamete into a developmentally competent embryo identity is a fundamental aspect of preimplantation development. One of the most important processes of this reprogramming is the transcriptional awakening during embryonic genome activation (EGA), which robustly occurs in fertilized embryos but is defective in most somatic cell nuclear transfer (SCNT) embryos. However, little is known about the genome-wide underlying chromatin landscape during EGA in SCNT embryos and how it differs from a fertilized embryo. By profiling open chromatin genome-wide in both types of bovine embryos, we find that SCNT embryos fail to reprogram a subset of the EGA gene targets that are normally activated in fertilized embryos. Importantly, a small number of transcription factor (TF) motifs explain most chromatin regions that fail to open in SCNT embryos suggesting that over-expression of a limited number of TFs may provide more robust reprogramming. One such TF, the zygotically-expressed bovine gene DUXC which is a homologue of EGA factors DUX/DUX4 in mouse/human, is alone capable of activating ~84% of all EGA transcripts that fail to activate normally in SCNT embryos. Additionally, single-cell chromatin profiling revealed low intra-embryo heterogeneity but high inter-embryo heterogeneity in SCNT embryos and an uncoupling of cell division and open chromatin reprogramming during EGA. Surprisingly, our data also indicate that transcriptional defects may arise downstream of promoter chromatin opening in SCNT embryos, suggesting additional mechanistic insights into how and why transcription at EGA is dysregulated. We anticipate that our work will lead to altered SCNT protocols to increase the developmental competency of bovine SCNT embryos.
Project description:Reprogramming of the gamete into a developmentally competent embryo identity is a fundamental aspect of preimplantation development. One of the most important processes of this reprogramming is the transcriptional awakening during embryonic genome activation (EGA), which robustly occurs in fertilized embryos but is defective in most somatic cell nuclear transfer (SCNT) embryos. However, little is known about the genome-wide underlying chromatin landscape during EGA in SCNT embryos and how it differs from a fertilized embryo. By profiling open chromatin genome-wide in both types of bovine embryos, we find that SCNT embryos fail to reprogram a subset of the EGA gene targets that are normally activated in fertilized embryos. Importantly, a small number of transcription factor (TF) motifs explain most chromatin regions that fail to open in SCNT embryos suggesting that over-expression of a limited number of TFs may provide more robust reprogramming. One such TF, the zygotically-expressed bovine gene DUXC which is a homologue of EGA factors DUX/DUX4 in mouse/human, is alone capable of activating ~84% of all EGA transcripts that fail to activate normally in SCNT embryos. Additionally, single-cell chromatin profiling revealed low intra-embryo heterogeneity but high inter-embryo heterogeneity in SCNT embryos and an uncoupling of cell division and open chromatin reprogramming during EGA. Surprisingly, our data also indicate that transcriptional defects may arise downstream of promoter chromatin opening in SCNT embryos, suggesting additional mechanistic insights into how and why transcription at EGA is dysregulated. We anticipate that our work will lead to altered SCNT protocols to increase the developmental competency of bovine SCNT embryos.