Project description:We develop a high-throughput nucleoside analog incorporation sequencing assay and identify thousands of early replication initiation zones (ERIZs) in both mouse and human cells. The identified ERIZs fall in open chromatin compartments while are mutually exclusive with transcription elongation and occupy mainly non-transcribed regions adjacent to transcribed regions. Furthermore, we reveal that RNA polymerase II actively redistributes the chromatin-encircled mini-chromosome maintenance (MCM) complex but not the origin-recognition complex (ORC) to actively restrict early DNA replication initiation outside of transcribed regions. The coupling of RNA polymerase II and MCM is further validated by detected MCM accumulation and DNA replication initiation after RNA polymerase II stalling via anchoring nuclease-dead Cas9 at the transcribed genes. Importantly, we also find that the orchestration of DNA replication initiation by transcription can efficiently prevent gross DNA damage.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.
Project description:Replication stress is a main driver of functional decline of hematopoietic stem cells (HSCs), which carry the highest burden of maintaining genomic integrity and functionality within the hematopoietic system. Here, we identify a novel signaling axis in which β-catenin and Hoxa9 function in a compensatory manner to preserve HSC functionality by protecting DNA replication dynamics and genomic integrity, in part via regulation of Prmt1 activity. Co-inactivation of β-catenin and Hoxa9 induces severe hematopoietic defects accompanied by accumulating replication stress and DNA damage resulting in functional HSC decline. Furthermore, we illustrate how β-catenin and Hoxa9 pathways converge on the pivotal downstream target, Prmt1, which functions to maintain an adequate supply of DNA replication and repair factors. Prmt1 aids in alleviating replication stress and DNA damage accumulation thereby preserving HSC integrity and functionality.
Project description:Replication stress is a main driver of functional decline of hematopoietic stem cells (HSCs), which carry the highest burden of maintaining genomic integrity and functionality within the hematopoietic system. Here, we identify a novel signaling axis in which β-catenin and Hoxa9 function in a compensatory manner to preserve HSC functionality by protecting DNA replication dynamics and genomic integrity, in part via regulation of Prmt1 activity. Co-inactivation of β-catenin and Hoxa9 induces severe hematopoietic defects accompanied by accumulating replication stress and DNA damage resulting in functional HSC decline. Furthermore, we illustrate how β-catenin and Hoxa9 pathways converge on the pivotal downstream target, Prmt1, which functions to maintain an adequate supply of DNA replication and repair factors. Prmt1 aids in alleviating replication stress and DNA damage accumulation thereby preserving HSC integrity and functionality.
Project description:Cohesin participates in loop formation by extruding DNA fibers from its ring-shaped structure. Cohesin dysfunction eliminates chromatin loops but only causes modest transcription perturbation, which cannot fully explain the frequently observed mutations of cohesin in various cancers. Here, we found that DNA replication initiates at more than one thousand extra dormant origins after acute depletion of RAD21, a core subunit of cohesin, resulting in earlier replicating timing at approximately 30% of the human genomic regions. In contrast, CTCF is dispensable for suppressing the early firing of dormant origins that are distributed away from the loop boundaries. Furthermore, greatly elevated levels of gross DNA breaks and genome-wide chromosomal translocations arise in RAD21-depleted cells, accompanied by dysregulated replication timing at dozens of hotspot genes. Thus, we conclude that cohesin coordinates DNA replication initiation to ensure proper replication timing and safeguards genome integrity.