Single-cell RNA-sequencing of in vitro fertilized and nuclear transfer embryos
Ontology highlight
ABSTRACT: Somatic cell nuclear transfer and transcription factor overexpression can induce reprogramming of somatic cells, whereby one cell fate is changed into another cell fate of choice. Yet the efficiency of this process for generating functional cells is low, limiting their therapeutic applications. The persistence of transcriptional memory from the cell's prior identity is thought to be a major hindrance to effective reprogramming and differentiation to functional cell types. To explore the effects of transcriptional memory on cell fate specification of reprogrammed cells, we analyzed epidermal tissue development in nuclear transfer embryos derived from endoderm nuclei. Our findings reveal variations in the success rate of differentiation to functional cells across cell types in cloned embryos. While some cell types, such as goblet cells, differentiated normally, a specific subset of cells resisted cell fate reprogramming, adopting a new endoderm-like state and disrupting normal body patterning. Furthermore, inefficient transcriptional reprogramming correlated with reduced basal stem cell populations, faulty differentiation of basal stem cell-derived fates, and increased cell death in the epidermis of cloned embryos. Crucially, we identified that the memory of active transcriptional states linked to key endoderm transcription factors plays a significant role in these issues. Mimicking active state transcriptional memory of these genes through the forced expression of Sox17b and Foxa4 in the epidermis of fertilized embryos produced the same defects. On the contrary, reducing transcriptional memory by interfering with the expression of Sox17b led to the rescue of observed epidermal defects. In summary, our study suggests that transcriptional memory tends to persist predominantly in specific reprogrammed cell types, hindering their differentiation into functional cells and embryonic structures. This underscores the critical need to assess and reduce transcriptional memory from the previous somatic identity during reprogramming, to efficiently generate functional cell types for therapeutic applications.
Project description:Xenopus eggs can induce the reversal of differentiation processes of somatic cells. Yet, the egg is not fully efficient in reprogramming a differentiated nucleus, as certain genes retain a memory of gene expression of their somatic cell of origin. This is thought to be a reason for the low success rate of current cloning and reprogramming strategies. While previous studies addressed extensively the mechanisms that maintain an inactive state of genes (OFF-memory), we investigated the importance of memory of an active transcriptional state (ON-memory) in maintaining cell fate identity and on resistance to reprogramming. We find that donor cell-type specific ON-memory gene-expression in the wrong cell-type of nuclear transfer (NT)-embryos is as common as OFF-memory gene-expression. When compared to properly reprogrammed genes, we find that ON-memory genes show an elevated level of the active histone mark H3K4me3 in endoderm donor cells. Importantly, we show that a reduction of H3K4 methylation level in donor cells decreases the extent of ON-memory gene expression, globally improves transcriptional reprogramming, and enhances the development of NT-embryos. Therefore, our study reveals that H3K4 methylation safeguards endoderm cell identity and acts as a major barrier for efficient reprogramming in NT-embryos. Furthermore, our results suggest that efficient cell fate reprogramming not only relies on the erasure of epigenetic modifications conferring OFF-memory but also crucially depends on the removal of H3 lysine 4 methylation-mediated memory of an active state of gene expression.
Project description:Transcription factor-mediated reprogramming is a powerful method to study cell fate changes. In this work, we demonstrate that the transcription factor Gata6 can initiate reprograming of multiple cell types to induced extraembryonic endoderm (iXEN) cells. Intriguingly, Gata6 is sufficient to drive iXEN cells from mouse pluripotent cells and differentiated neural cells. Furthermore, GATA6 induction in human ES (hES) cells also downregulates pluripotency gene expression and upregulates extraembryonic endoderm genes, revealing a conserved function in mediating this cell fate switch. Profiling transcriptional changes following Gata6 induction in mES cells reveals step-wise pluripotency factor disengagement, with initial repression of Nanog and Esrrb, then Sox2 and finally Oct4, alongside step-wise activation of extraembryonic endoderm genes. Chromatin immunoprecipitation and subsequent high-throughput sequencing analysis shows Gata6 enrichment near both pluripotency and endoderm genes, suggesting that Gata6 functions as both a direct repressor and activator. Together this demonstrates that Gata6 is a versatile and potent reprogramming factor that can act alone to drive a cell fate switch from diverse cell types. Time-course microarray analysis of Gata6-mediated reprogramming from 12 to 144 hours of doxycycline treatment in mouse embryonic stem (mES) cells compared to uninduced mES cells, embryo-derived extraembryonic endoderm (XEN) cells and Sox7 overexpressing mES cells after 144 hours of doxycycline treatment.
Project description:One critical task in pluripotent reprogramming is to erase the somatic transcriptional program of starting cells. No strategy or theory exists for achieving erasure of somatic gene expression memory. Here, we present a proof-of-principle strategy in which reprogramming to pluripotency is facilitated by small molecules that erase somatic cell transcription memory. We show that mild chemical targeting of the acetyllysine-binding pockets of the BET bromodomains, the transcriptional bookmarking domains, robustly enhances reprogramming. Furthermore, we show that chemical targeting of the transcriptional bookmarking BET bromodomains dramatically downregulates specific somatic gene expression programs in both naïve and reprogramming fibroblasts. Chemical blocking of the BET bromodomains also resulted in loss of fibroblast morphology early in reprograming. In this study, we experimentally demonstrate a concept for cell fate conversion: facilitating the conversion by chemically targeting the transcriptional bookmarking BET bromodomains responsible for transcriptional memory. human BJ cells were treated with JQ1 at 50 nM for 48 hours. Differential expression was compared with DMSO treatment. The same treatments and comparsion were conducted for reprogramming BJ cells, which were transduced with OCT4, SOX2, and KLF4. JQ1iPSC5 is a iPSC (induced pluripotent stem cell) line generated in this study using small molecules JQ1.
Project description:One critical task in pluripotent reprogramming is to erase the somatic transcriptional program of starting cells. No strategy or theory exists for achieving erasure of somatic gene expression memory. Here, we present a proof-of-principle strategy in which reprogramming to pluripotency is facilitated by small molecules that erase somatic cell transcription memory. We show that mild chemical targeting of the acetyllysine-binding pockets of the BET bromodomains, the transcriptional bookmarking domains, robustly enhances reprogramming. Furthermore, we show that chemical targeting of the transcriptional bookmarking BET bromodomains dramatically downregulates specific somatic gene expression programs in both naïve and reprogramming fibroblasts. Chemical blocking of the BET bromodomains also resulted in loss of fibroblast morphology early in reprograming. In this study, we experimentally demonstrate a concept for cell fate conversion: facilitating the conversion by chemically targeting the transcriptional bookmarking BET bromodomains responsible for transcriptional memory.
Project description:Transcription factor-mediated reprogramming is a powerful method to study cell fate changes. In this work, we demonstrate that the transcription factor Gata6 can initiate reprograming of multiple cell types to induced extraembryonic endoderm (iXEN) cells. Intriguingly, Gata6 is sufficient to drive iXEN cells from mouse pluripotent cells and differentiated neural cells. Furthermore, GATA6 induction in human ES (hES) cells also downregulates pluripotency gene expression and upregulates extraembryonic endoderm genes, revealing a conserved function in mediating this cell fate switch. Profiling transcriptional changes following Gata6 induction in mES cells reveals step-wise pluripotency factor disengagement, with initial repression of Nanog and Esrrb, then Sox2 and finally Oct4, alongside step-wise activation of extraembryonic endoderm genes. Chromatin immunoprecipitation and subsequent high-throughput sequencing analysis shows Gata6 enrichment near both pluripotency and endoderm genes, suggesting that Gata6 functions as both a direct repressor and activator. Together this demonstrates that Gata6 is a versatile and potent reprogramming factor that can act alone to drive a cell fate switch from diverse cell types. (1) Microarray analysis of Gata6 overexpressing cells from 12 to 144 hours of doxycycline treatment in mouse embryonic stem (mES) cells compared to uninduced mES cells, embryo-derived XEN cells and Sox7 overexpressing mES cells after 144 hours of doxycycline treatment. (2) ChIP-seq analysis of Gata6 binding 36 hours following doxycycline treatment. (3) ChIP-seq analysis of Gata6 binding in embryo-derived XEN cells. (4) RNA-seq analysis of GATA6 overexpressing cells following 144 hours of induction in hES cells.
Project description:Transcription factor-mediated reprogramming is a powerful method to study cell fate changes. In this work, we demonstrate that the transcription factor Gata6 can initiate reprograming of multiple cell types to induced extraembryonic endoderm (iXEN) cells. Intriguingly, Gata6 is sufficient to drive iXEN cells from mouse pluripotent cells and differentiated neural cells. Furthermore, GATA6 induction in human ES (hES) cells also downregulates pluripotency gene expression and upregulates extraembryonic endoderm genes, revealing a conserved function in mediating this cell fate switch. Profiling transcriptional changes following Gata6 induction in mES cells reveals step-wise pluripotency factor disengagement, with initial repression of Nanog and Esrrb, then Sox2 and finally Oct4, alongside step-wise activation of extraembryonic endoderm genes. Chromatin immunoprecipitation and subsequent high-throughput sequencing analysis shows Gata6 enrichment near both pluripotency and endoderm genes, suggesting that Gata6 functions as both a direct repressor and activator. Together this demonstrates that Gata6 is a versatile and potent reprogramming factor that can act alone to drive a cell fate switch from diverse cell types.
Project description:Transcription factor-mediated reprogramming is a powerful method to study cell fate changes. In this work, we demonstrate that the transcription factor Gata6 can initiate reprograming of multiple cell types to induced extraembryonic endoderm (iXEN) cells. Intriguingly, Gata6 is sufficient to drive iXEN cells from mouse pluripotent cells and differentiated neural cells. Furthermore, GATA6 induction in human ES (hES) cells also downregulates pluripotency gene expression and upregulates extraembryonic endoderm genes, revealing a conserved function in mediating this cell fate switch. Profiling transcriptional changes following Gata6 induction in mES cells reveals step-wise pluripotency factor disengagement, with initial repression of Nanog and Esrrb, then Sox2 and finally Oct4, alongside step-wise activation of extraembryonic endoderm genes. Chromatin immunoprecipitation and subsequent high-throughput sequencing analysis shows Gata6 enrichment near both pluripotency and endoderm genes, suggesting that Gata6 functions as both a direct repressor and activator. Together this demonstrates that Gata6 is a versatile and potent reprogramming factor that can act alone to drive a cell fate switch from diverse cell types.
Project description:Understanding how distinct cell types arise from common multipotent progenitor cells is a major quest in stem cell biology. This knowledge will aid in the targeted differentiation and growth of stem cells, but also in the discovery of the basis of cellular plasticity and of how tissue programming can be controlled. The liver and pancreas share many aspects of their early development, being both specified in the same region of the endoderm, and, possibly, originating from a common progenitor. However, how pancreas versus liver cell fate decision occurs during embryogenesis and the molecular basis of this cellular plasticity are poorly understood. Here, we use RNA-Seq to define the molecular identity of liver and pancreas progenitors directly in mouse embryos and to investigate the mechanisms regulating the emergence of liver or pancreas as alternative fates from the endoderm. Progenitor cell-specific RNA was obtained from mouse Prox1-EGFP-labeled embryonic cells isolated by FACS at distinct developmental stages, before and after the onset of organogenesis. By integrating the temporal and spatial gene expression profiles, we found mutually exclusive signaling signatures in hepatic and pancreatic progenitors. Importantly, we identified the non-canonical Wnt pathway as a potential developmental regulator of the pancreas versus liver fate decision, being expressed in the foregut endoderm, before the cell fate choice is made, and then maintained in pancreas progenitors but absent in hepatic progenitors. Moreover, when assayed in Xenopus embryos, the non-canonical Wnt pathway is able to promote pancreatic fate and repress hepatic fate in the endoderm, suggesting an ancient mechanism for controlling pancreas versus liver fate choice. We expect that this knowledge will be key to formulate reprogramming strategies to convert adult hepatic cells into pancreatic cells as a cell-based therapeutic approach for diabetes. We performed sequencing-based expression profiling (RNA-Seq) of hepatic and pancreatic progenitors in the mouse at two distinct developmental stages.
Project description:Many studies have already shown the reprogramming of somatic cells into other cell types such as neural stem cells, blood progenitor cells, and hepatocytes by inducing combinations of transcription factors. One of the recent development in cellular reprogramming is the direct reprogramming, that can change cell fate towards different lineages. This strategy provides an alternative to the use of pluripotent stem cells ruling out the concerns of tumorigenicity caused by undifferentiated cell populations. Here, we generated induced oligodendrocyte progenitor cells (iOPCs) from mouse fibroblasts by direct reprogramming. The generated iOPCs are homogenous, self-renewing, and multipotent. Once differentiated, the somatic stem cells exhibit morphological and molecular characteristics of oligodendrocyte progenitor cells (OPCs). Thus, we demonstrated that terminally differentiated somatic cells can be converted into functional iOPCs by induction of transcription factors offering a new strategies to cure myelin disorders. To identify the global gene expression profiles of iOPCs, we analyzed total 6 samples.