Clonal copy-number mosaicism in T-lymphocytes in NOD mice
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PROVIDER: PRJNA472316 | ENA |
REPOSITORIES: ENA
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Project description:In Type 1 Diabetes (T1D), imperfect concordance in monozygotic twins and in males of the inbred NOD mouse model, despite genetic identity and shared environment during the years of peak incidence, points to stochastic determinants. One plausible such stochastic event, never explored, is post-zygotic genetic changes in the expanding antigen-specific autoreactive T-cell lineages. The contribution of such mutations in tumorigenesis is well established but little is known about potential role in autoimmunity. Here, with high-resolution comparative genomic hybridization (CGH) of DNA from memory CD4 T-cells from pancreatic lymph nodes of NOD mice, we found mosaic somatic copy-number aberrations (CNAs) with highly non-random independent involvement of the same gene(s) across different mice. A few CNAs were also found in lymphocytes expanded during normal host defense but were significantly smaller. Our data strongly support a causal role for post-zygotic mutations in autoreactive T-cells in T1D. They challenge the classical notions of autoimmune disease and open conceptual avenues towards individualized prevention and therapeutics.
2019-09-13 | GSE114660 | GEO
Project description:Concordance for type 1 diabetes (T1D) is far from 100% in monozygotic twins and in inbred nonobese diabetic (NOD) mice, despite genetic identity and shared environment during incidence peak years. This points to stochastic determinants, such as postzygotic mutations (PZMs) in the expanding antigen-specific autoreactive T cell lineages, by analogy to their role in the expanding tumor lineage in cancer. Using comparative genomic hybridization of DNA from pancreatic lymph-node memory CD4+ T cells of 25 diabetic NOD mice, we found lymphocyte-exclusive mosaic somatic copy-number aberrations (CNAs) with highly nonrandom independent involvement of the same gene(s) across different mice, some with an autoimmunity association (e.g., Ilf3 and Dgka). We confirmed genes of interest using the gold standard approach for CNA quantification, multiplex ligation-dependent probe amplification (MLPA), as an independent method. As controls, we examined lymphocytes expanded during normal host defense (17 NOD and BALB/c mice infected with Leishmania major parasite). Here, CNAs found were fewer and significantly smaller compared to those in autoreactive cells (P = 0.0019). We determined a low T cell clonality for our samples suggesting a prethymic formation of these CNAs. In this study, we describe a novel, unexplored phenomenon of a potential causal contribution of PZMs in autoreactive T cells in T1D pathogenesis. We expect that exploration of point mutations and studies in human T cells will enable the further delineation of driver genes to target for functional studies. Our findings challenge the classical notions of autoimmunity and open conceptual avenues toward individualized prevention and therapeutics.
| S-EPMC6886509 | biostudies-literature
Project description:Reprogramming human somatic cells into induced pluripotent stem cells (iPSC) has been suspected of causing de novo copy number variations (CNVs). To explore this issue, we performed a whole-genome and transcriptome analysis of 20 human iPSC lines derived from primary skin fibroblasts of 7 individuals using next-generation sequencing. We find that, on average, an iPSC line manifests two CNVs not apparent in the fibroblasts from which the iPSC was derived. Using qPCR, PCR, and digital droplet PCR (ddPCR) to amplify across the CNVs' breakpoints, we show that at least 50% of those CNVs are present as low frequency somatic genomic variants in parental fibroblasts and are manifested in iPSC colonies due to their clonal origin. Hence, reprogramming does not necessarily lead to de novo CNVs in iPSC, since most of line-manifested CNVs reflect somatic mosaicism in the human skin. Moreover, our findings demonstrate that clonal expansion, and iPSC lines in particular, can be used as a discovery tool to reliably detect low frequency CNVs in the tissue of origin. Overall, we estimate that approximately 30% of the fibroblast cells have somatic CNVs, suggesting widespread somatic mosaicism in the human body. Our study paves the way to understanding the fundamental question of the extent to which cells of the human body normally acquire structural alterations in their DNA post-zygotically.
2012-10-31 | GSE41716 | GEO
Project description:Reprogramming human somatic cells into induced pluripotent stem cells (iPSC) has been suspected of causing de novo copy number variations (CNVs). To explore this issue, we performed a whole-genome and transcriptome analysis of 20 human iPSC lines derived from primary skin fibroblasts of 7 individuals using next-generation sequencing. We find that, on average, an iPSC line manifests two CNVs not apparent in the fibroblasts from which the iPSC was derived. Using qPCR, PCR, and digital droplet PCR (ddPCR) to amplify across the CNVs' breakpoints, we show that at least 50% of those CNVs are present as low frequency somatic genomic variants in parental fibroblasts and are manifested in iPSC colonies due to their clonal origin. Hence, reprogramming does not necessarily lead to de novo CNVs in iPSC, since most of line-manifested CNVs reflect somatic mosaicism in the human skin. Moreover, our findings demonstrate that clonal expansion, and iPSC lines in particular, can be used as a discovery tool to reliably detect low frequency CNVs in the tissue of origin. Overall, we estimate that approximately 30% of the fibroblast cells have somatic CNVs, suggesting widespread somatic mosaicism in the human body. Our study paves the way to understanding the fundamental question of the extent to which cells of the human body normally acquire structural alterations in their DNA post-zygotically. We have generated and characterized hiPSC lines derived from skin fibroblasts collected from seven members of two families, which were competent to be differentiated into neuronal progenitors and neurons
2012-10-31 | E-GEOD-41716 | biostudies-arrayexpress
Project description:Genetic variation is responsible for the generation of phenotypic diversity, including susceptibility to disease. Two major types of variation are known: single nucleotide polymorphisms (SNPs) and a more recently discovered structural variation, involving changes in copy number (CNVs) of kilobase- to megabase-sized chromosomal segments. Variation caused by CNVs has exceeded the amount of SNP-based differences expected to exist between two unrelated humans. Furthermore, many CNVs have been associated with disease predisposition. It is unknown whether CNVs arise in somatic cells, but it is, however, generally assumed that normal cells are genetically identical. Here we show that CNVs are frequent in healthy somatic cells of adult humans. We tested 34 tissue samples from three subjects and, having analyzed for each tissue <10-6 of all cells expected in an adult human, we observed at least six CNVs, affecting a single organ or one or more tissues of the same subject. The CNVs ranged from 82-176 kb, often encompassing known genes, potentially affecting gene function. Our results point to a paradigm shift in the genetics of somatic cells and indicate that humans are commonly affected by somatic mosaicism for stochastic CNVs, which occur in a substantial fraction of cells. A considerable number of phenotypes and diseases affecting humans are a consequence of a somatic process. Thus, our conclusions will be important for the delineation of genetic factors behind these phenotypes. Consequently, biobanks should consider sampling multiple tissues in order to better address mosaicism in the studies of somatic disorders. Furthermore, forensic medicine laboratories should be sensitized to the issue of underestimated frequency of somatic CNV mosaicism. Keywords: copy number variation (CNV), phenotype diversity, somatic cells
2008-09-16 | GSE9598 | GEO
Project description:Genetic variation is responsible for the generation of phenotypic diversity, including susceptibility to disease. Two major types of variation are known: single nucleotide polymorphisms (SNPs) and a more recently discovered structural variation, involving changes in copy number (CNVs) of kilobase- to megabase-sized chromosomal segments. Variation caused by CNVs has exceeded the amount of SNP-based differences expected to exist between two unrelated humans. Furthermore, many CNVs have been associated with disease predisposition. It is unknown whether CNVs arise in somatic cells, but it is, however, generally assumed that normal cells are genetically identical. Here we show that CNVs are frequent in healthy somatic cells of adult humans. We tested 34 tissue samples from three subjects and, having analyzed for each tissue <10-6 of all cells expected in an adult human, we observed at least six CNVs, affecting a single organ or one or more tissues of the same subject. The CNVs ranged from 82-176 kb, often encompassing known genes, potentially affecting gene function. Our results point to a paradigm shift in the genetics of somatic cells and indicate that humans are commonly affected by somatic mosaicism for stochastic CNVs, which occur in a substantial fraction of cells. A considerable number of phenotypes and diseases affecting humans are a consequence of a somatic process. Thus, our conclusions will be important for the delineation of genetic factors behind these phenotypes. Consequently, biobanks should consider sampling multiple tissues in order to better address mosaicism in the studies of somatic disorders. Furthermore, forensic medicine laboratories should be sensitized to the issue of underestimated frequency of somatic CNV mosaicism. Keywords: copy number variation (CNV), phenotype diversity, somatic cells 31 experiments; each experiment consists of two hybridizations, i.e. regular and dye-swap (62 hybridizations in total); cerebellum from corresponding subject was used as a reference; additionally 12 control self-self hybridizations are included (cerrebellum vs self)
2008-09-16 | E-GEOD-9598 | biostudies-arrayexpress
Project description:Copy number mosaicism in the human brain has been reported recently by several authors. This experiment was performed to further investigate our preliminary data of apparent widespread deletions in brain DNA, detected in a custom Agilent aCGH designed for Parkinson's disease (PD) genes in both patients and controls, and supported by droplet digital PCR. To avoid any effect of diseased tissue, we used only controls here. All DNA was freshly extracted. A validated SNP array was chosen to ensure that our results were not due to artefacts specific to the aCGH design used, with SNP array giving the additional advantage of B allele frequency estimation.
2016-02-01 | GSE71429 | GEO
Project description:Whole mouse genome microarrays from Agilent were used to determine expression profile of pancreas-infiltrating T CD3+ and total T lymphocytes of NOD mice.
2015-05-29 | E-MTAB-3555 | biostudies-arrayexpress
Project description:The microRNA oligo microarrays from Agilent were used to determine miRNA expression profile of pancreas-infiltrating T CD3+ and total T lymphocytes of NOD mice.
2015-05-29 | E-MTAB-3556 | biostudies-arrayexpress