Project description:Phenotypic variability among different knockout clones of the same gene is a common problem confounding the establishment of robust genotype-phenotype correlations. Optimized genome editing protocols to enhance reproducibility include measures to reduce off-target effects. However, even if current state-of-the-art protocols are applied phenotypic variability is frequently observed. Here we identify heterogeneity of wild-type cells as an important and often neglected confounding factor in genome-editing experiments. We demonstrate that isolation of individual wild-type clones from an apparently homogenous stable cell line uncovers significant phenotypic differences between clones. Strikingly, we observe hundreds of differentially regulated transcripts when comparing two populations of wild-type cells. Heterogeneity of wild-type cells thus contributes to variability in genome-edited cells when these are generated through isolation of clones. We show that the generation of monoclonal isogenic wild-type cells prior to genomic manipulation reduces phenotypic variability.
Project description:Genetic heterogeneity is an important feature of solid tumors, however it is often assumed that most cancer cell lines are genetically homogeneous. A disparity in genetic complexity between cell lines and the disease they model could result in problems such as in vitro preclinical experiments overstating the effectiveness of putative therapeutics. We therefore derived clonal sublines by single cell cloning of in house derived early passage melanoma cell lines (LM-MEL-series), and compared their genomes to each other and the parental cell line using Illumina 610-Quad SNP arrays.
Project description:The existence of clonal heterogeneity of mantle cell lymphoma based on genomic aberration evaluated by log2 ratio(clinical samples)
Project description:Gene editing using engineered nucleases frequently produces unintended genetic lesions in hematopoietic stem cells (HSCs). Gene-edited HSC cultures thus contain heterogenous populations, the majority of which either do not carry the desired edit or harbor unwanted mutations. In consequence, transplanting edited HSCs carries the risks of suboptimal efficiency and of unwanted mutations in the graft. Here, we present an approach for expanding gene-edited HSCs at clonal density, allowing for genetic profiling of individual clones before transplantation. We achieved this by developing a defined, polymer-based expansion system and identifying long-term expanding clones within the CD201+CD150+CD48-c-Kit+Sca-1+Lin-(KSL) population of pre-cultured HSCs. This dataset compares the gene expression in three different populations: (1) CD201+CD150+CD48-KSL (2) CD201+CD150+CD48+KSL and (3) CD201-KSL cells.
Project description:Tumor heterogeneity results from clonal diversity and evolutionary selection, and is a major cause of therapeutic resistance. Immunotherapy may exploit alternative vulnerabilities of drug resistant cells, and tumor-specific HLA peptide ligands on the cell surface are promising leads to invoke such targeted anti-tumor responses. In this work, we investigate the variability in HLA class I peptide presentation between tumor cells of the same patient, as differential ligand presentation could impact the efficacy of immunological interventions. By organoid amplification, we modeled single-cell level heterogeneity in a MSI- colorectal cancer patient, and directly correlated clonal tumor proteomes with the respective ligandomes. With deep comparative proteome profiling and sensitive detection of >7000 peptide ligands from each tumor organoid line, we found tumor-surface peptide presentation to be largely uncoupled from the steady-state protein abundance. Within the small minority of tumor-specific ligands (~3%), source proteins needed for DNA damage sensing and repair, and tumor suppression were prominently featured, leading us to speculate that such peptides may be consistently presented, as degradative byproducts of intended silencing. While clone-specific differences in peptide presentation were observed, inter-clone variability was also highly prevalent (15-25%). Collectively, these illustrate the heterogeneous peptide presentation landscape even within one individual, and hint that a multi-peptide vaccination approach against highly conserved tumor suppressors may be a viable option in patients with low tumor-mutational burden.
Project description:Composed of negative feedback loops, circadian oscillations are thought to be noise-resistant. Yet, individual cells in culture are remarkably heterogenous, oscillating independently and with different period lengths. To assess whether differential methylation contributes to heritable heterogeneity of circadian periods, we used reduced representation bisulfite sequencing (RRBS) to explore DNA methylation profiles and their correlation with the transcriptome in the 10 clonal cell lines. To investigate the mechanisms underlying this heterogeneity, we generated and characterized hundreds of clonal cell lines from the same parent culture. By comparing clonal lines with different circadian periods, we identified a group of differentially methylated regions (DMRs).
Project description:Background: Cell-to-cell heterogeneity is a major driver of cancer evolution, progression, and emergence of drug resistance. Epigenomic variation at the single-cell level can rapidly create cancer heterogeneity, but is difficult to detect and assess functionally. Results: We develop a strategy to bridge the gap between measurement and function in single-cell epigenomics. Using single-cell chromatin accessibility and RNA-seq data in K562 leukemic cells, we identify the cell surface marker CD24 as co-varying with chromatin accessibility changes linked to GATA transcription factors in single cells. Fluorescence-activated cell sorting of CD24 high vs. low cells prospectively isolated GATA1 and GATA2 high vs. low cells. GATA high vs. low cells express differential gene regulatory networks, differential sensitivity to the drug imatinib mesylate, and differential self-renewal capacity. Lineage tracing experiments show that GATA/CD24hi cells have the capability to rapidly reconstitute the heterogeneity within the entire starting population, suggesting that GATA expression levels drive a phenotypically relevant source of epigenomic plasticity. Conclusion: Single-cell chromatin accessibility can guide prospective characterization of cancer heterogeneity. Epigenomic subpopulations in cancer impact drug sensitivity and the clonal dynamics of cancer evolution.
Project description:Intratumour heterogeneity provides a fuel for cancer evolution enabling tumour cell populations to adapt to selective pressures imposed by the tumour microenvironment or therapeutic interventions. To uncover functionally heterogeneous subpopulations of tumour cells with different treatment sensitivity and to understand how clonal lineage-dependent transcriptomic diveristy contributes, we developed WILDseq, a hihg-complexity expressed barcode library for simultanous mapping of each cells' clonal identity and transcriptional states.
Project description:Phenotypic cell-to-cell variability is central for microbial populations and contributes to cell function, stress adaptation and drug resistance. Gene-expression heterogeneity underpins this variability, but has been challenging to study genome-wide. Here, we report a novel approach which combines imaging of individual fission yeast cells with single-cell RNA sequencing (scRNA-seq) and Bayesian normalisation. We analyse >2000 single cells and >700 matching RNA controls in various environmental conditions that include reposnse to various stresses as well as growth and entry into stationary phase.
Project description:Th2 cells provide effector functions in type 2 immune responses to helminths and allergens. Despite substantial knowledge about molecular mechanisms of Th2 cell differentiation, there is little information on Th2 cell heterogeneity and clonal distribution between organs mainly due to technical limitations. To address this issue, we performed combined single-cell transcriptome and TCR clonotype analysis on murine Th2 cells in mesenteric lymph nodes (MLN) and lung after infection with Nippostrongylus brasiliensis (Nb) as a model of human hookworm infection. We identified strong organ-specific expression profiles, but also found populations with conserved effector or migration signatures. A substantial MLN subpopulation with an interferon response signature suggests a role for interferon-signaling in Th2 cell differentiation or diversification. RNA-inferred developmental directions further implied proliferation as a hub for differentiation decisions. Although the TCR repertoire appeared to be highly heterogeneous, we identified expanded Th2 clones and CDR3 motifs. Clonal relatedness between distant organs confirmed the effective exchange of Th2 effector cells. However, locally expanded clones dominated the response, as the most expanded clones in MLN and lung did not overlap. This new insight in Th2 cell subsets and clonal relatedness in distant organs demonstrates their heterogeneity and suggests that they serve distinct effector functions.