ABSTRACT: CGH of stage 13 amplifying follicle cells to measure changes in replication fork progression in DNA damage checkpoint and double-strand break repair mutants
Project description:CGH of stage 13 amplifying follicle cells to measure changes in replication fork progression in double-strand break repair mutants Comparative genomic hybridization was performed to compare amplification gradients of stage 13 follicle cells from several double-strand break repair mutants to wild type (OrR) gradients. Two-three replicates were done for each genotype.
Project description:Comparative genomic hybridization was performed to compare amplification gradients of stage 13 follicle cells from several DNA damage checkpoint and double-strand break repair mutants to wild-type (OrR) gradients. Two-three replicates were done for each genotype.
Project description:Transcription hinders replication fork progression and stability, and the Mec1/ATR checkpoint protects fork integrity. Examining checkpoint-dependent mechanisms controlling fork stability, we find that fork reversal or dormant origin firing owing to checkpoint defects are rescued in checkpoint mutants lacking THO, TREX-2 or inner basket nucleoporins. Gene gating tethers transcribed genes to the nuclear periphery and is counteracted by checkpoint kinases through phosphorylation of nucleoporins such as Mlp1. Checkpoint mutants fail to detach transcribed genes from nuclear pores, thus generating topological impediments for incoming forks. Releasing this topological complexity by introducing a double-strand break between a fork and a transcribed unit prevents fork collapse. Mlp1 mutants mimicking constitutive checkpoint-dependent phosphorylation also alleviate checkpoint defects. We propose that the checkpoint assists fork progression and stability at transcribed genes by phosphorylating key nucleoporins and counteracting gene gating, thus neutralizing the topological tension generated at nuclear pore gated genes.
Project description:Transient obstruction of DNA polymerase progression activates the ATR checkpoint kinase, which suppresses fork breakage, strand resection, and RPA accumulation. Herein, we use a developed DNA break-detection assay, BrITL, to identify replication-problematic loci (RPLs) that become processed into persistent double-strand breaks across the mammalian genome from ATR inhibition.
Project description:Transient obstruction of DNA polymerase progression activates the ATR checkpoint kinase, which suppresses fork breakage, strand resection, and RPA accumulation. Herein, we use a developed DNA break-detection assay, BrITL, to identify replication-problematic loci that become processed into persistent double-strand breaks across the human genome from ATR inhibition.
Project description:<p>Outlier analyses represent a versatile method to identify predictive biomarkers of response to both targeted agents and chemotherapy. We performed whole genome sequencing (WGS) of tumor and germline blood from a patient with metastatic small cell carcinoma of the ureter who experienced a durable complete response to a combination of irinotecan plus AZD7762, a checkpoint kinase inhibitor. The patient initially had resection of the ureter followed by metastatic recurrence within the kidney and lymph nodes and underwent nephrectomy with lymph node dissection. Through WGS of tissue from the second surgery, we detected a hypomorphic L1237F mutation within RAD50, a component of the Mre11 double strand break repair complex, which resulted in heightened sensitivity to the combination of checkpoint inhibition and clastogenic chemotherapy. We validated the WGS findings using a combination of an exon capture assay and validation in model systems. The tumor samples sequenced by exon capture were derived from tissue taken from both the initial and second surgeries.</p>
