Project description:Reconstructing lineage relationships in complex tissues can reveal mechanisms underlying development and disease. Recent methods combine single-cell transcriptomics with mitochondrial DNA variant detection to establish lineage relationships in primary human cells, but are not scalable to interrogate complex tissues. To overcome this limitation, here we develop a technology for high-confidence detection of mitochondrial mutations from high-throughput single-cell RNA-sequencing. We use the new method to identify skewed immune cell expansions in primary human clonal hematopoiesis.
Project description:Mitochondrial heteroplasmy, the presence of more than one mtDNA variant in a cell or individual is not as uncommon as previously thought. It is mostly due to the high mutation rate of the mtDNA and limited repair mechanisms present in the mitochondrion. The phenomenon has been studied mostly in human samples and in medical contexts. Heteroplasmy has also been researched in other species in fields such as forensics or genetic foot printing, but these studies usually focused on contained families within closely related species. Here we describe a large cross-species evaluation of heteroplasmy in mammals. We employed a novel approach to detect mitochondrial heteroplasmy in both novel and previously reported ChIP-sequencing datasets, which include concomitant mitochondrial DNA sequenced in the experiment. Here, we report novel ChIP-seq experiments for H3K4me1 and CEBPA across mammals, as well as some H3K4me3, H3K27ac and total histone H3 experiments. Most of the reported CEBPA experiments are good quality pull-downs, however the quality of many of the other experiments reported here has not been interrogated in detail. Whereas this does not affect the investigation of mitochondrial DNA pollution for the purposes of this study, both H3K4me1 and total histone H3 ChIP-seq datasets were often sequenced to relatively low depth and showed low ChIP enrichment compared to the other antibodies.
Project description:Mitochondrial DNA (mtDNA) 3243A>G tRNALeu(UUR) heteroplasmic mutation (m.3243A>G) exhibits clinically heterogeneous phenotypes. While the high mtDNA heteroplasmy exceeding a critical threshold causes mitochondrial encephalomyopathy, lactic acidosis with stroke-like episodes (MELAS) syndrome, the low mtDNA heteroplasmy causes maternally inherited diabetes with or without deafness (MIDD) syndrome. How quantitative differences in mtDNA heteroplasmy produces distinct pathological states has remained elusive. Here we show that despite striking similarities in the energy metabolic gene expression signature, the mitochondrial bioenergetics, biogenesis and fuel catabolic functions are distinct in cells harboring low or high levels of the m.3243A>G mutation compared to wild type cells. We further demonstrate that the low heteroplasmic mutant cells exhibit a coordinate induction of transcriptional regulators of the mitochondrial biogenesis, glucose and fatty acid metabolism pathways that lack in near homoplasmic mutant cells compared to wild type cells. Altogether, these results shed new biological insights on the potential mechanisms by which low mtDNA heteroplasmy may progressively cause diabetes mellitus.
Project description:We report our newly developed method for high-throughput sequencing of 2'-O methylation sites using positive signal and site specific approach. The pilot experiment using MiSeq generated ~2.5 million reads per sample. The 2'-O methylation site identification produced a promising distribution pattern matching known sites. For accurate and sensitive base call, >10 million reads are required per sample as evidenced in the NextSeq experiment.
Project description:Abstract Mutations in the gene encoding nucleophosmin (NPM1) carry prognostic value for patients with acute myeloid leukemia (AML). Various techniques are currently being used to detect these mutations in routine molecular diagnostics. Incorporation of accurate NPM1 mutation detection on a gene expression platform would enable simultaneous detection with various other expression biomarkers. Here we present an array based mutation detection using custom probes for NPM1 WT mRNA and NPM1 type A, B, and D mutant mRNA. This method was 100% accurate on a training cohort of 505 newly diagnosed unselected AML cases. Validation on an independent cohort of 143 normal karyotype AML cases revealed no false negative results, and one false positive (sensitivity 100.0%, and specificity 98.7%). Based on this, we conclude that this method provides a reliable method for NPM1 mutation detection. The method can be applied to other genes/mutations as long as the mutant alleles are sufficiently high expressed. Validation cohort of 143 AML cases analyzed using the AMLprofiler
Project description:Abstract Mutations in the gene encoding nucleophosmin (NPM1) carry prognostic value for patients with acute myeloid leukemia (AML). Various techniques are currently being used to detect these mutations in routine molecular diagnostics. Incorporation of accurate NPM1 mutation detection on a gene expression platform would enable simultaneous detection with various other expression biomarkers. Here we present an array based mutation detection using custom probes for NPM1 WT mRNA and NPM1 type A, B, and D mutant mRNA. This method was 100% accurate on a training cohort of 505 newly diagnosed unselected AML cases. Validation on an independent cohort of 143 normal karyotype AML cases revealed no false negative results, and one false positive (sensitivity 100.0%, and specificity 98.7%). Based on this, we conclude that this method provides a reliable method for NPM1 mutation detection. The method can be applied to other genes/mutations as long as the mutant alleles are sufficiently high expressed. Training cohort of 505 AML cases analyzed using the AMLprofiler
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.