Project description:Tumors with the same driver mutations can display a striking variation in their progression and treatment response, but the origins of this variation are still unclear. In this study, we use state-fate analysis to unveil that heritable stem cell states can influence how individual cells respond to the acquisition of the same cancer mutation. We develop a new methodological pipeline, single-cell Tracking of Recombinase Activation And Clonal Kinetics, and apply it to hematopoietic stem cells carrying Cre/Flp-conditional leukemia alleles. Tracking the gene expression changes and expansion kinetics of a common set of stem cell clones, with and without the same myeloid leukemia mutations, we unveil a striking heterogeneity in the malignant fates of diverse stem cells. First, we define that heritable clonal states persist in expansion cultures and cause the selection of a small group of clones with a specific fitness signature. Then, using mouse models of the most frequent initiating mutations, we define that these pre-existent stem cell states influence the mutation-induced changes in expansion, fate, and malignant gene expression programs. Initiating driver mutations increase the survival probability of clones with low fitness through enhancing their stemness programs. Surprisingly, the fate of high-fitness stem-cell clones is sometimes reversed, producing more mature leukemias, yet still carrying markers of their cell of origin. We further validate these HSC-of-origin signatures in bulk and single-cell RNAseq datasets from cancer patients. Our findings suggest that aggressive premalignant clonal expansions arise from low-fitness stem cells more frequently than previously expected.
Project description:Understanding clonal evolution and cancer development requires experimental approaches for characterizing the consequences of somatic mutations on gene regulation. However, no methods currently exist that efficiently link chromatin accessibility with genotype in single cells. To address this, we developed Genotyping with the Assay for Transposase-Accessible Chromatin (GTAC), enabling accurate mutation detection at multiple amplified loci, coupled with robust chromatin accessibility readout. We applied GTAC to primary acute myeloid leukemia, obtaining high-quality chromatin accessibility profiles and clonal identities for multiple mutations in 88% of cells. We traced chromatin variation throughout clonal evolution, showing the restriction of different clones to distinct differentiation stages. Furthermore, we identified switches in transcription factors motif accessibility associated with a specific combination of driver mutations, which biased transformed progenitors towards a leukemia stem cell-like chromatin state. GTAC is a powerful tool to study clonal heterogeneity across a wide spectrum of pre-malignant and neoplastic conditions.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.
Project description:Natural mitochondrial DNA (mtDNA) sequence variation plays a fundamental role in human disease and enables the clonal tracing of native human cells. While various genotyping approaches revealed mutational heterogeneity in human tissues and single cells, current methodologies are limited by scale. Here, we introduce a high-throughput, droplet-based mitochondrial single-cell Assay for Transposase Accessible Chromatin with sequencing (mtscATAC-seq) protocol and computational framework that facilitate high-confidence mtDNA mutation calling in thousands of single cells. Further, the concomitant high-quality accessible chromatin readout enables the paired inference of individual cell mtDNA heteroplasmy, clonal lineage, cell state, and accessible chromatin regulatory features. Our multi-omic analyses reveals single-cell variation in heteroplasmy of a pathologic mtDNA variant (m.8344A>G), which we tie to intra-individual chromatin variability and clonal evolution. Further, using somatic mtDNA mutations, we clonally trace thousands of hematopoietic cells in vitro and in patients with chronic lymphocytic leukemia, linking epigenomic variability to subclonal evolution in vivo.