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
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.
Project description:The Purpose of this series of experiments is to identify copy number variations, duplications, and deletions in human induced pluripotent stem (hiPSC) cell lines. Genomic DNA of different human induced pluripotent stem cell lines are extracted and hybridized to NimbleGen CGH microarray, using genomic DNA of hESC H1 or H9 as common reference. Difference between different stem cell lines will be revealed.
Project description:The purpose of this series of experiments is to identify copy number variations, duplications, deletions and regions of homozygosity in human induced pluripotent stem (hiPSC) cell lines. Genomic DNA of human induced pluripotent stem cell lines are extracted and hybridized to Agilent aCGH+SNP microarray, using genotyped Agilent Reference DNA as common reference. Differences and similarities between fibroblast and stem cell lines will be revealed.
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. Prior to this CNV study, the human iPSC lines and one hES (H1) were characterized by a set of quality control criteria, including gene expression analyses by microarray. This analysis demonstrated uniform up-regulation of hESC-specific genes in all our hiPSC lines, while fibroblast specific genes were downregulated
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. Prior to this CNV study, the human iPSC lines and one hES (H1) were characterized by a set of quality control criteria, including gene expression analyses by microarray. This analysis demonstrated uniform up-regulation of hESC-specific genes in all our hiPSC lines, while fibroblast specific genes were downregulated Total RNA obtained from iPSC lines and H1 line was submitted for microarray analysis using HumanHT-12 v4 BEADCHIP (Illumina).
Project description:Human development relies on the correct replication, maintenance and segregation of our genetic blueprints. How these processes are monitored across embryonic lineages, and why genomic mosaicism varies during development remain unknown. Using pluripotent stem cells, we identify that several patterning signals –including WNT, BMP and FGF– converge into the modulation of DNA replication stress and damage during S-phase, which in turn controls chromosome segregation fidelity in mitosis. We show that the WNT and BMP signals protect from excessive origin firing, DNA damage and chromosome missegregation derived from stalled forks in pluripotency. Cell signalling control of chromosome segregation declines during lineage specification into the three germ layers, but re-emerges in neural progenitors. In particular, we find that the neurogenic factor FGF2 induces DNA replication stress-mediated chromosome missegregation during the onset of neurogenesis, which could provide a rationale for the elevated chromosomal mosaicism of the developing brain. Our results highlight roles for morphogens and cellular identity in genome maintenance that contribute to somatic mosaicism during mammalian development.