Project description:We found that PRMT5 deletion or inhibition impairs homologous recombination (HR) DNA repair, leading to DNA damage accumulation, p53 activation, cell cycle arrest and cell death through missplicing of KAT5. We show that PRMT5 inhibitors and PARP inhibitors have synergistic effects on human acute leukemia cell lines, demonstrating the advantages of combining targeted epigenetic and non-epigenetic inhibitors.
Project description:The de novo DNA methyltransferase 3A (DNMT3A) plays a pivotal role in hematopoietic differentiation. In this study, we followed the hypothesis that alternative splicing of DNMT3A has characteristic epigenetic and functional sequels. Various transcripts of DNMT3A were either knocked down or overexpressed in human hematopoietic stem and progenitor cells resulting in complementary and transcript-specific DNA methylation (DNAm) and gene expression changes. Our results demonstrate that different splice variants of DNMT3A have distinct epigenetic and functional sequels.
Project description:The de novo DNA methyltransferase 3A (DNMT3A) plays a pivotal role in hematopoietic differentiation. In this study, we followed the hypothesis that alternative splicing of DNMT3A has characteristic epigenetic and functional sequels. Various transcripts of DNMT3A were either knocked down or overexpressed in human hematopoietic stem and progenitor cells resulting in complementary and transcript-specific DNA methylation (DNAm) and gene expression changes. Our results demonstrate that different splice variants of DNMT3A have distinct epigenetic and functional sequels.
Project description:DNA-protein crosslinks (DPCs) are abundant DNA lesions, which constantly challenge genome stability by interfering with DNA replication. SPARTAN (SPRTN) protease plays a central role in DPCs repair in proliferative vertebrate cells. SPRTN is a constitutive part of the DNA replication machinery and its protease activity is essential for DNA replication fork progression. How this essential protease is activated and regulated during DNA replication is not known. By using biochemical, cell biological and genetic approaches in human cell lines and Zebrafish model system, we identified that SPRTN cleaves covalently crosslinked Checkpoint kinase 1 (CHK1) from chromatin and releases CHK1 during physiological DNA replication. Proteolysed CHK1 is activated and in turn phosphorylates SPRTN. Phosphorylated SPRTN is further recruited to chromatin to proteolyse DPCs that ensures unperturbed DNA replication. Our data suggest SPRTN-CHK1 cross-activation loop is essential for genome stability.
Project description:The generation of distinct messenger RNA isoforms through alternative RNA processing influences the expression and function of genes, often in a cell-type specific manner. Here, we assess the regulatory relationships between transcription initiation, alternative splicing, and 3ʹ end site selection. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest transcripts from end to end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3ʹ end site choice is globally influenced by the site of transcription initiation. “Dominant promoters”, characterized by specific epigenetic signatures including p300/CBP binding, impose a transcriptional constraint to define splice and polyadenylation variants. In vivo deletion or overexpression of dominant promoters as well as CBP/p300 loss disrupted the 3ʹ end expression landscape. Our study demonstrates the crucial impact of TSS choice on the regulation of transcript diversity and tissue identity.ct messenger RNA isoforms through alternative splicing and alternative 3' end formation influences the expression and function of genes, often in a cell-type specific manner. Here, we quantitatively assess the regulatory relationships between transcription initiation and co-transcriptional processing steps, particularly 3' end formation. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest mRNA isoforms from end-to-end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3' end site choice is globally influenced by the site of transcription start. We define a subset of TSSs, “dominant promoters” that impose a transcriptional constraint to predetermine splice and polyadenylation variants, which are characterized by specific epigenetic signatures. In vivo deletion or overexpression of dominant promoters disrupted the 3' end expression landscape. Our study demonstrates the crucial impact of transcription initiation site choice on the regulation of transcript diversity and tissue identity.