Project description:Fused in sarcoma (FUS) encodes a low complexity RNA-binding protein with diverse roles in transcriptional activation and RNA processing. While oncogenic fusions of FUS and transcription factor DNA-binding domains are associated with soft tissue sarcomas, dominant mutations in FUS cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). FUS has also been implicated in DNA double-strand break repair (DSBR) and genome maintenance. However, the underlying mechanisms are unknown. Here we employed quantitative proteomics, transcriptomics, and DNA copy number analysis (Sort-Seq), in conjunction with FUS-/- cells to ascertain roles of FUS in genome protection. FUS-/- cells exhibited alterations in the recruitment and retention of DSBR factors BRCA1 and 53BP1 but were not overtly sensitive to genotoxins. By contrast, FUS-deficient cells had reduced proliferative potential that correlated with reduced replication fork speed, diminished loading of pre-replication complexes, and attenuated expression of S-phase associated genes. FUS interacted with lagging strand DNA synthesis factors and other replisome components, but did not translocate with active replication forks. Using a Sort-Seq workflow, we show that FUS contributes to genome-wide control of DNA replication timing and is essential for the early replication of transcriptionally active DNA. These findings illuminate new roles for FUS in DNA replication initiation and timing that may contribute to genome instability and functional defects in cells harboring disease-associated FUS fusions.
Project description:Fused-in-sarcoma (FUS) encodes an RNA-binding protein with diverse roles in transcriptional activation and RNA splicing. While oncogenic fusions of FUS and transcription factor DNA-binding domains are associated with soft tissue sarcomas, dominant mutations in FUS cause amyotrophic lateral sclerosis (ALS). FUS has also been implicated in genome maintenance. However, the underlying mechanisms are unknown.
Here, we applied gene editing, functional reconstitution and integrated proteomic and transcriptomics to illuminate roles for FUS in DNA replication and repair. Consistent with a supportive role in DNA double-strand break (DSB) repair FUS deficient cells exhibited subtle alterations in the recruitment and retention of DSB-associated factors, including 53BP1 and BRCA1. FUS-/- cells also exhibited reduced proliferative potential that correlated with reduced replication fork speed, diminished loading of pre-replication complexes, enhanced micronucleus formation, and attenuated expression and splicing of S-phase associated genes. Finally, FUS-deficient cells exhibited genome-wide alterations in DNA replication timing that were reversed upon reeexpression of FUS cDNA. FUS-dependent replication domains were enriched in transcriptionally active chromatin and FUS was required for the timely replication of transcriptionally active DNA. These findings suggest that alterations DNA replication kinetics and programming contribute to genome instability and functional defects in FUS deficient cells.
2021-06-24 | MSV000087698 | MassIVE
Project description:Fused in sarcoma regulates DNA replication timing and progression
Project description:Fused in sarcoma (FUS) encodes an RNA-binding protein with diverse roles in transcriptional activation and RNA splicing. While oncogenic fusions of FUS and transcription factor DNA-binding domains are associated with soft tissue sarcomas, dominant mutations in FUS can cause amyotrophic lateral sclerosis. FUS has also been implicated in genome maintenance. However, the underlying mechanisms of its actions in genome stability are unknown. Here, we applied gene editing, functional reconstitution, and integrated proteomics and transcriptomics to illuminate roles for FUS in DNA replication and repair. Consistent with a supportive role in DNA double-strand break repair, FUS-deficient cells exhibited subtle alterations in the recruitment and retention of double-strand break-associated factors, including 53BP1 and BRCA1. FUS-/- cells also exhibited reduced proliferative potential that correlated with reduced speed of replication fork progression, diminished loading of prereplication complexes, enhanced micronucleus formation, and attenuated expression and splicing of S-phase-associated genes. Finally, FUS-deficient cells exhibited genome-wide alterations in DNA replication timing that were reversed upon re-expression of FUS complementary DNA. We also showed that FUS-dependent replication domains were enriched in transcriptionally active chromatin and that FUS was required for the timely replication of transcriptionally active DNA. These findings suggest that alterations in DNA replication kinetics and programming contribute to genome instability and functional defects in FUS-deficient cells.
Project description:DNA replication is spatially and temporally regulated during S-phase. DNA replication timing is established in early G1-phase at a point referred to as TDP (timing decision point). We show that Rif1 (Rap1-interacting-factor1), originally identified as a telomere binding factor in yeast, is a critical determinant of the replication timing program in human cells. Depletion of Rif1 results in specific loss of mid-S replication foci profiles, stimulation of initiation events in early S-phase and changes in long-range replication timing domain structures. Overall replication timing is shifted toward mid-S in both directions, suggesting that replication timing regulation is abrogated in the absence of Rif1. Rif1 tightly binds to nuclear insoluble structures at late-M to early-G1 and regulates the chromatin-loop sizes. Furthermore, Rif1 colocalizes specifically with the mid-S replication foci. Thus, Rif1 establishes the mid-S replication domains that are restrained from being activated at early S-phase. Our results indicate that Rif1 plays crucial roles in determining the replication timing domain structures through regulating higher-order chromatin architecture. HeLa cells (ATCC), with a total of 4 individual replicates
Project description:We have characterized allele-specific regulation of replication in human cultured primary basophilic erythroblasts using TimEX-seq. We show that in most of the genome the timing of replication of the two chromosome homologs is robustly and tightly regulated since the two alleles replicate almost at the same time. We also show that small genetic differences such as SNPs and indels do not affect replication timing. We identify two major causes of replication asynchrony: the presence of large structural variants and parental imprinting. Both are associated with the formation of asynchronously replicated domains that can reach several megabases in size. We also report that replication timing domains have a previously undetected fine structure. Compare DNA content in cells in S and G1 phase of cell cycle using TimEX-seq The goal of these experiments was to measure the timing of replication in human basophilic erythroblasts in an allele-specific manner by comparing DNA content in cells in S and G1 phase of cell cycle using TimEX-seq. Cells in S phase were obtained by sorting propidium iodide stained exponentially growing basophilic erythroblasts produce after 14 days of culture of circulating peripheral blood stem and progenitor cells. The cells in G1, which are used to normalize the results from the cells in S phase for mapability, were circulating mononuclear cells (WBCs) which are in the G1 cell for the cell cycle at 99.5%. The processed files represent S/G1 ratio values which are surrogate values for the timing of replication. Allele-specific TimEX-seq profiles and hi-resolution non-allele specific profiles are provided at different smoothing levels. The following processed files are derived from the multiple files as indicated below; >FNY01_3_2_Ery_MAT_S.bed is generated from FNY01_3_2_Ery_round *_S_Phase.bed >FNY01_3_2_Ery_PAT_S.bed is generated from FNY01_3_2_Ery_round *_S_Phase.bed >FNY01_3_2_Ery_MAT_G1.bed is generated from FNY01_3_2_WBC_round *_G1_600.bed FNY01_3_2_WBC_round *_G1_300.bed >FNY01_3_2_WBC_PAT_G1.bed is generated from FNY01_3_2_WBC_round *_G1_600.bed FNY01_3_2_WBC_round *_G1_300.bed >FNY01_3_2_Ery_S_G1 ratio_MAT_100kb_smooth.bedGraph is from FNY01_3_2_Ery_MAT_S.bed FNY01_3_2_Ery_MAT_G1.bed >FNY01_3_2_Ery_S_G1 ratio_PAT_100kb_smooth.bedGraph is from FNY01_3_2_Ery_PAT_S.bed FNY01_3_2_Ery_PAT_G1.bed >FNY01_3_2_Ery_S_G1 ratio_unsmooth.bedGraph, FNY01_3_2_Ery_S_G1 ratio_20Kb_smooth.bedGraph, and FNY01_3_2_Ery_S_G1 ratio_100Kb_smooth.bedGraph are from FNY01_3_2_Ery_round *_S_Phase.bed FNY01_3_2_WBC_round *_G1_600.bed FNY01_3_2_WBC_round *_G1_300.bed >FNY01_3_2&3_3_Ery* files are generated from 14 .bed files linked to the corresponding sample records. Please note that *3_3* files follow the same pattern as *3_2*
Project description:We have characterized allele-specific regulation of replication in human cultured primary basophilic erythroblasts using TimEX-seq. We show that in most of the genome the timing of replication of the two chromosome homologs is robustly and tightly regulated since the two alleles replicate almost at the same time. We also show that small genetic differences such as SNPs and indels do not affect replication timing. We identify two major causes of replication asynchrony: the presence of large structural variants and parental imprinting. Both are associated with the formation of asynchronously replicated domains that can reach several megabases in size. We also report that replication timing domains have a previously undetected fine structure.