Generation of a Panel of Induced Pluripotent Stem Cells From Chimpanzees: a Resource for Comparative Functional Genomics [ChIP-Seq]
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ABSTRACT: Comparative genomics studies in primates are extremely restricted due to our limited access to samples from non-human apes. In order to gain better insight into the genetic processes that underlie variation in complex phenotypes in primates, we must have access to faithful model systems for a wide range of cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee induced pluripotent stem cell (iPSC) lines derived from healthy donors. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-sequencing and DNA methylation data from the chimpanzee iPSCs and the corresponding fibroblast lines, as well as from 7 human iPSCs and their source lines, which encompass multiple populations and cell types. We observe much less within-species variation in iPSCs than in somatic cells, indicating that the reprogramming process erases many inter-individual differences. The low within-species regulatory variation in iPSCs allowed us to identify many novel inter-species regulatory differences of small magnitude.
Project description:Comparative genomics studies in primates are extremely restricted due to our limited access to samples from non-human apes. In order to gain better insight into the genetic processes that underlie variation in complex phenotypes in primates, we must have access to faithful model systems for a wide range of cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee induced pluripotent stem cell (iPSC) lines derived from healthy donors. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-sequencing and DNA methylation data from the chimpanzee iPSCs and the corresponding fibroblast lines, as well as from 7 human iPSCs and their source lines, which encompass multiple populations and cell types. We observe much less within-species variation in iPSCs than in somatic cells, indicating that the reprogramming process erases many inter-individual differences. The low within-species regulatory variation in iPSCs allowed us to identify many novel inter-species regulatory differences of small magnitude. We used ChIP-seq to characterize the genome-wide distribution of two types of histone modifications (H3K27me3 and H3K27ac) in three of our chimpanzee iPSCs and compared them to histone modification data from three human iPSC lines from the Roadmap Epigenomics project:
Project description:Comparative studies in primates are extremely restricted because we only have access to a few types of cell lines from non-human apes and to a limited collection of frozen tissues. In order to gain better insight into regulatory processes that underlie variation in complex phenotypes, we must have access to faithful model systems for a wide range of tissues and cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee (Pan troglodytes) induced pluripotent stem cell (iPSC) lines derived from fibroblasts of healthy donors. All lines are free of integration from exogenous reprogramming vectors, can be maintained using standard iPSC culture techniques, and have proliferative and differentiation potential similar to human and mouse lines. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-seq data and methylation profiles from the chimpanzee iPSCs and their corresponding fibroblast precursors, as well as from 7 human iPSCs and their precursors, which were of multiple cell type and population origins. Overall, we observed much less regulatory variation within species in the iPSCs than in the somatic precursors, indicating that the reprogramming process has erased many of the differences observed between somatic cells of different origins. We identified 4,918 differentially expressed genes and 1,986 differentially methylated regions between iPSCs of the two species, many of which are novel inter-species differences and not observed between the somatic cells of the two species. Our panel will help realize the potential of iPSCs, and in combination with genomic technologies, transform studies of comparative evolution in primates. We obtained RNA sequencing and methylation profiles from 7 chimpanzee iPSCs and the fibroblasts used to generate them, as well as 7 human iPSCs and the LCLs and fibroblasts used to generate them.
Project description:Comparative studies in primates are extremely restricted because we only have access to a few types of cell lines from non-human apes and to a limited collection of frozen tissues. In order to gain better insight into regulatory processes that underlie variation in complex phenotypes, we must have access to faithful model systems for a wide range of tissues and cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee (Pan troglodytes) induced pluripotent stem cell (iPSC) lines derived from fibroblasts of healthy donors. All lines are free of integration from exogenous reprogramming vectors, can be maintained using standard iPSC culture techniques, and have proliferative and differentiation potential similar to human and mouse lines. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-seq data and methylation profiles from the chimpanzee iPSCs and their corresponding fibroblast precursors, as well as from 7 human iPSCs and their precursors, which were of multiple cell type and population origins. Overall, we observed much less regulatory variation within species in the iPSCs than in the somatic precursors, indicating that the reprogramming process has erased many of the differences observed between somatic cells of different origins. We identified 4,918 differentially expressed genes and 1,986 differentially methylated regions between iPSCs of the two species, many of which are novel inter-species differences and not observed between the somatic cells of the two species. Our panel will help realise the potential of iPSCs, and in combination with genomic technologies, transform studies of comparative evolution in primates. We obtained RNA sequencing and methylation profiles from 7 chimpanzee iPSCs and the fibroblasts used to generate them, as well as 7 human iPSCs and the LCLs and fibroblasts used to generate them.
Project description:Comparative studies in primates are extremely restricted because we only have access to a few types of cell lines from non-human apes and to a limited collection of frozen tissues. In order to gain better insight into regulatory processes that underlie variation in complex phenotypes, we must have access to faithful model systems for a wide range of tissues and cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee (Pan troglodytes) induced pluripotent stem cell (iPSC) lines derived from fibroblasts of healthy donors. All lines are free of integration from exogenous reprogramming vectors, can be maintained using standard iPSC culture techniques, and have proliferative and differentiation potential similar to human and mouse lines. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-seq data and methylation profiles from the chimpanzee iPSCs and their corresponding fibroblast precursors, as well as from 7 human iPSCs and their precursors, which were of multiple cell type and population origins. Overall, we observed much less regulatory variation within species in the iPSCs than in the somatic precursors, indicating that the reprogramming process has erased many of the differences observed between somatic cells of different origins. We identified 4,918 differentially expressed genes and 1,986 differentially methylated regions between iPSCs of the two species, many of which are novel inter-species differences and not observed between the somatic cells of the two species. Our panel will help realize the potential of iPSCs, and in combination with genomic technologies, transform studies of comparative evolution in primates.
Project description:Comparative studies in primates are extremely restricted because we only have access to a few types of cell lines from non-human apes and to a limited collection of frozen tissues. In order to gain better insight into regulatory processes that underlie variation in complex phenotypes, we must have access to faithful model systems for a wide range of tissues and cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee (Pan troglodytes) induced pluripotent stem cell (iPSC) lines derived from fibroblasts of healthy donors. All lines are free of integration from exogenous reprogramming vectors, can be maintained using standard iPSC culture techniques, and have proliferative and differentiation potential similar to human and mouse lines. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-seq data and methylation profiles from the chimpanzee iPSCs and their corresponding fibroblast precursors, as well as from 7 human iPSCs and their precursors, which were of multiple cell type and population origins. Overall, we observed much less regulatory variation within species in the iPSCs than in the somatic precursors, indicating that the reprogramming process has erased many of the differences observed between somatic cells of different origins. We identified 4,918 differentially expressed genes and 1,986 differentially methylated regions between iPSCs of the two species, many of which are novel inter-species differences and not observed between the somatic cells of the two species. Our panel will help realise the potential of iPSCs, and in combination with genomic technologies, transform studies of comparative evolution in primates.
Project description:To study regulatory differences between species, the field of comparative primate genomics has used several approaches, including the use of post mortem frozen tissues, cell lines, and model organisms. However, there are limited quality cell lines from primates and post-mortem tissues cannot be staged, are not amenable to experimental perturbations and are often subject to high environmental variances. Inducible pluripotent stem cells (iPSCs) are an attractive system to study primate biology in a comparative context. However, the fidelity of iPSC derived cell types to primary tissues needs to be assayed in a comparative primate context before the utility of iPSCs can be fully realized for comparative genomics. In order to comprehensively benchmark the performance of iPSC model systems in a comparative framework, we collected RNA-sequencing from primary adult heart tissue and iPSC derived cardiomyocytes from multiple human and chimpanzee individuals. We identified the optimal parameters of iPSC differentiation into cardiomyocytes that minimized differences between each species and their respective adult tissue counterparts in a balanced manner across species. We found that iPSC derived cardiomyocytes are able to recapitulate 50% of the interspecies gene expression differences identified between human and chimpanzee in primary post mortem heart tissues. Furthermore, we determined that cultured cardiomyocytes appear more similar to adult hearts than any other single tissue in their ability to recapitulate differences in gene regulation between human and chimpanzee.
Project description:There is substantial interest in the genetic regulatory framework that is established in early human development, and in the evolutionary forces that shaped early developmental processes in humans. Progress in these areas has been slow because it is difficult to obtain relevant biological samples. Recent technological developments in the generation and differentiation of inducible pluripotent stem cells (iPSCs) provide the ability to develop in vitro models of early human and non-human primates developmental stages. We have previously established matched iPSC panels from humans and chimpanzees. Using these panels, we comparatively characterized gene regulatory changes through a four-day timecourse differentiation of iPSCs (day 1) into primary streak (day 2), endoderm progenitors (day 3), and definitive endoderm (day 4). As might be expected, we found that differentiation stage (in effect, cell type) is the major driver of variation in gene expression levels in our study, followed by species. We then identified thousands of differentially expressed genes between humans and chimpanzees in each differentiation stage. Yet, when we considered gene-specific dynamic regulatory trajectories throughout the timecourse, we found that 75% of genes, including nearly all known endoderm developmental markers, have conserved trajectories in the two species. Interestingly, we observed a marked reduction of both intra- and inter-species variation in gene expression levels in primitive streak samples compared to the iPSCs, with a recovery of variation in endoderm progenitors. The reduction in variation in gene expression levels at a specific developmental stage, paired with the high degree of conservation of temporal expression across species, is consistent with the dynamics of developmental canalization. Overall, we conclude that endoderm development in iPSC-based models are highly conserved and canalized between humans and our closest evolutionary relative.
Project description:Understanding evolutionary mechanisms underlying expansion and reorganization of the human brain represents an important aspect in analyzing the emergence of cognitive abilities typical of our species. Comparative analyses of neuronal phenotypes in closest living relatives (Pan troglodytes; the common chimpanzee) can shed the light into changes in neuronal morphology compared to the last common ancestor (LCA), opening possibilities for analyses of the timing of their appearance, and the role of evolutionary mechanisms favoring a particular type of information processing in humans. Here, we use induced pluripotent stem cell (iPSC) technology to model neural progenitor cell migration and early development of cortical pyramidal neurons in humans and chimpanzees. In addition, we provide morphological characterization of the early stages of neuronal development in human and chimpanzee transplanted cells, and examine the role of developmental mechanisms previously proposed for the evolutionary expansions of the human brain on the early development of pyramidal neurons in the two species. The strategy proposed here lay down the basis for further comparative analysis between human and non-human primates and opens new avenues for understanding cognitive capability and neurological disease susceptibility differences between species. PolyA RNA-Seq profiling of neural progenitor cells (NPCs) and neurons differentiated from human and chimpanzee iPSCs.
Project description:Conventional embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) derived from primates resemble mouse epiblast stem cells, raising an intriguing question regarding whether the naïve pluripotent state resembling mouse embryonic stem cells (mESCs) exists in primates and how to capture it in vitro. Here we identified several specific signaling modulators that are sufficient to generate rhesus monkey fibroblast-derived iPSCs with the features of naïve pluripotency in terms of growth properties, gene expression profiles, self-renewal signaling, X-reactivation and the potential to generate cross-species chimeric embryos. Interestingly, together with recent reports of naïve human pluripotent stem cells, our findings suggest several conserved signaling pathways shared with rodents and specific to primates, providing significant insights for acquiring naïve pluripotency from other mammal species. In addition, the derivation of rhesus monkey naïve iPSCs also provides a valuable cell source for use in preclinical research and disease modeling. mRNA expression analysis of 4 rhesus monkey naive iPSC lines and 2 primed iPSC lines were examed.
Project description:Despite anatomical similarities, there are differences in susceptibility to cardiovascular disease (CVD) between primates; humans are prone to myocardial ischemia, while chimpanzees are prone to myocardial fibrosis. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) allow for direct inter-species comparisons of the gene regulatory response to CVD-relevant perturbations such as oxygen deprivation, a consequence of ischemia. To gain insight into the evolution of disease susceptibility, we characterized gene expression levels in iPSC-CMs in humans and chimpanzees, before and after hypoxia and re-oxygenation. The transcriptional response to hypoxia is generally conserved across species, yet we were able to identify hundreds of species-specific regulatory responses including in genes previously associated with CVD. The 1,920 genes that respond to hypoxia in both species are enriched for loss-of-function intolerant genes; but are depleted for expression quantitative trait loci and cardiovascular-related genes. Our results indicate that response to hypoxic stress is highly conserved in humans and chimpanzees.