Project description:Genomic DNA from 191 asy1/+ Col x Ler F2 individuals was extracted using CTAB and used to generate sequencing libraries as described (Lawrence et al, 2019 Current Biology). Sequencing data was analysed to identify crossovers using the TIGER pipeline as previously described (Rowan et al, 2015 G3 (Bethesda); Yelina et al, 2015 Genes & Dev; Lawrence et al, 2019 Current Biology).
Project description:Genomic DNA from 187 wild type and 169 asy1 Col-0 x Ws-4 F2 individuals was extracted using CTAB and used to generate sequencing libraries as described (Lawrence et al, 2019 Current Biology). Sequencing data was analysed to identify crossovers using the TIGER pipeline as previously described (Rowan et al, 2015 G3 (Bethesda); Yelina et al, 2015 Genes & Dev; Lawrence et al, 2019 Current Biology).
Project description:In recent years, several small molecule cytotoxic drugs have been identified as potential inhibitors of ribosome biogenesis (Drygin et al., 2011; Peltonen et al., 2014a; Peltonen et al., 2014b). CX-5461 is one such drug that has also demonstrated anticancer potential for a wide range of malignancies (Bywater et al., 2012; Cornelison et al., 2017; Devlin et al., 2015; Drygin et al., 2011; Hald et al., 2019; Hein et al., 2017; Ismael et al., 2019; Lawrence et al., 2018; Lee et al., 2017; Negi and Brown, 2015; Taylor et al., 2019; Xu et al., 2017; Yan et al., 2017) (Haddach et al., 2012), and is presently under phase I trials for the treatment of both hematological cancers and solid tumours (Group, 2016; Khot et al., 2019). CX-5461 was initially characterized as an inhibitor of RNA Polymerase I (RPI/PolR1/PolI) that is responsible for the synthesis of the major ribosomal RNAs and the initial step in ribosome biogenesis (Drygin et al., 2011). Since RPI and its corresponding core transcription factors are dedicated to this task alone, they present ideal molecular targets by which to modulate ribosome biogenesis. However, the specificity of CX-5461 has been questioned and it has been suggested that this drug may also act by stabilizing DNA G-quadruplexes or by “poisoning” topoisomerase II (Topo II). Thus, the primary target of this drug and its mode of action are still in doubt. Here we used Deconvolution-ChIP-Seq in NIH3T3 and HEK293T cells treated for different times with CX-5461. The data show that the primary target of CX5461 is the initiation of ribosomal RNA gene (rDNA) transcription. CX-5461 blocks transcription initiation in vitro and in vivo by arresting RNA polymerase I (RPI/Pol1) within the preinitiation complex. In contrast to previous suggestions, CX-5461 does not effect recruitment of the TBP-TAF complex SL1 to the rDNA promoter, the recruitment of the initiation competent RPI-Rrn3 complex or ongoing transcription elongation, arguing against a role for G-quadruplex stabilization or topoisomerase II poisoning. Inhibition of transcription by CX-5461 is not reversible, the RPI-Rrn3 complex remains arrested in the preinitiation complex even after drug removal. This leads to nucleolar stress, extensive DNA damage and cell senescence. Our data show that the cytotoxicity of CX-5461 is the downstream result of the highly specific inhibition of rDNA transcription. The observation that this inhibition is irreversible will be important for the future design of chemotherapeutic strategies and the avoidance of drug resistance.
Project description:Single cells from human colorectal cancer and normal adjacent colon of 16 patients were used for single-cell RNA-seq, TCR-seq, CITE-seq and Cell hashing. In brief, single cells were incubated for 3h with or without PMA/Ionomycin, and were treated with Cell hashing and CITE-seq antibodies to distinguish samples, stimulation/non-stimulation, and cell surface proteins. Sorted viable CD3+TCRαβ+ single cells were loaded into 10x genomics ChromiumTM controller to make nanoliter-scale droplets with uniquely barcoded 5’ gel beads called GEMs. After GEM-RT and the following some cDNA amplification steps, cDNAs derived from cellular mRNA were pooled for downstream processing and library preparation according to the manufacturer’s instructions. The 5’ transcript library was sequenced with Illumina Novaseq. The single cell TCR enriched library was sequenced with Illumina Miseq using 150 paired-end reads. HTO/ADTs from Cell hashing or CITE-seq were amplified using specific primers that append P5 and P7 sequences for illumina sequencing (Miseq or Nextseq). All fastq files were demultiplexed. Cell hashing and CITE-seq barcodes are available in attached text files. Fastq files from RNA-seq and TCR-seq can be processed through cellranger and vdjranger by 10xgenomics. The datasets include the data of independent experiments at May 29, June 16, June 23, and Aug 13, 2019. Details are available in Masuda et al., bioRxiv, 2020, The functional and phenotypic diversity of single T-cell infiltrates in human colorectal cancer as correlated with clinical outcome.