Probing the signaling requirements for naive human pluripotency by high-throughput chemical screening

H1FOO-DD promotes efficiency and uniformity in reprogramming to naive pluripotency

Heterogeneity among both primed and naive pluripotent stem cell lines remains a major unresolved problem. Here we show that expressing the maternal-specific linker histone H1FOO fused to a destabilizing domain (H1FOO-DD), together with OCT4, SOX2, KLF4, and LMYC, in human somatic cells improves the quality of reprogramming to both primed and naive pluripotency. H1FOO-DD expression was associated with altered chromatin accessibility around pluripotency genes and with suppression of the innate immune response. Notably, H1FOO-DD generates naive induced pluripotent stem cells with lower variation in transcriptome and methylome among clones and a more uniform and superior differentiation potency. Furthermore, we elucidated that upregulation of FKBP1A, driven by these five factors, plays a key role in H1FOO-DD-mediated reprogramming.

Resistance to Naïve and Formative Pluripotency Conversion in RSeT Human Embryonic Stem Cells

One of the most important properties of human embryonic stem cells (hESCs) is related to their primed and naïve pluripotent states. Our previous meta-analysis indicates the existence of heterogeneous pluripotent states derived from diverse naïve protocols. In this study, we have characterized a commercial medium (RSeT)-based pluripotent state under various growth conditions. Notably, RSeT hESCs can circumvent hypoxic growth conditions as required by naïve hESCs, in which some RSeT cells (e.g., H1 cells) exhibit much lower single cell plating efficiency, having altered or much retarded cell growth under both normoxia and hypoxia. Evidently, hPSCs lack many transcriptomic hallmarks of naïve and formative pluripotency (a phase between naive and primed states). Integrative transcriptome analysis suggests our primed and RSeT hESCs are close to the early stage of post-implantation embryos, similar to the previously reported primary hESCs and early hESC cultures. Moreover, RSeT hESCs did not express naïve surface markers such as CD75, SUSD2, and CD130 at a significant level. Biochemically, RSeT hESCs exhibit a differential dependency of FGF2 and co-independency of both Janus kinase (JAK) and TGFβ signaling in a cell-line-specific manner. Thus, RSeT hESCs represent a previously unrecognized pluripotent state downstream of formative pluripotency. Our data suggest that human naïve pluripotent potentials may be restricted in RSeT medium. Hence, this study provides new insights into pluripotent state transitions in vitro.

An optimized culture system for efficient derivation of porcine expanded potential stem cells from preimplantation embryos and by reprogramming somatic cells

Pigs share anatomical and physiological traits with humans and can serve as a large-animal model for translational medicine. Bona fide porcine pluripotent stem cells (PSCs) could facilitate testing cell and drug therapies. Agriculture and biotechnology may benefit from the ability to produce immune cells for studying animal infectious diseases and to readily edit the porcine genome in stem cells. Isolating porcine PSCs from preimplantation embryos has been intensively attempted over the past decades. We previously reported the derivation of expanded potential stem cells (EPSCs) from preimplantation embryos and by reprogramming somatic cells of multiple mammalian species, including pigs. Porcine EPSCs (pEPSCs) self-renew indefinitely, differentiate into embryonic and extra-embryonic lineages, and permit precision genome editing. Here we present a highly reproducible experimental procedure and data of an optimized and robust porcine EPSC culture system and its use in deriving new pEPSC lines from preimplantation embryos and reprogrammed somatic cells. No particular expertise is required for the protocols, which take ~4-6 weeks to complete. Importantly, we successfully established pEPSC lines from both in vitro fertilized and somatic cell nuclear transfer-derived embryos. These new pEPSC lines proliferated robustly over long-term passaging and were amenable to both simple indels and precision genome editing, with up to 100% targeting efficiency. The pEPSCs differentiated into embryonic cell lineages in vitro and teratomas in vivo, and into porcine trophoblast stem cells in human trophoblast stem cell medium. We show here that pEPSCs have unique epigenetic features, particularly H3K27me3 levels substantially lower than fibroblasts.

Hallmarks of totipotent and pluripotent stem cell states

Though totipotency and pluripotency are transient during early embryogenesis, they establish the foundation for the development of all mammals. Studying these in vivo has been challenging due to limited access and ethical constraints, particularly in humans. Recent progress has led to diverse culture adaptations of epiblast cells in vitro in the form of totipotent and pluripotent stem cells, which not only deepen our understanding of embryonic development but also serve as invaluable resources for animal reproduction and regenerative medicine. This review delves into the hallmarks of totipotent and pluripotent stem cells, shedding light on their key molecular and functional features.

IndiSPENsable for X Chromosome Inactivation and Gene Silencing

For about 30 years, SPEN has been the subject of research in many different fields due to its variety of functions and its conservation throughout a wide spectrum of species, like worms, arthropods, and vertebrates. To date, 216 orthologues have been documented. SPEN had been studied for its role in gene regulation in the context of cell signaling, including the NOTCH or nuclear hormone receptor signaling pathways. More recently, SPEN has been identified as a major regulator of initiation of chromosome-wide gene silencing during X chromosome inactivation (XCI) in mammals, where its function remains to be fully understood. Dependent on the biological context, SPEN functions via mechanisms which include different domains. While some domains of SPEN are highly conserved in sequence and secondary structure, species-to-species differences exist that might lead to mechanistic differences. Initiation of XCI appears to be different between humans and mice, which raises additional questions about the extent of generalization of SPEN's function in XCI. In this review, we dissect the mechanism of SPEN in XCI. We discuss its subregions and domains, focusing on its role as a major regulator. We further highlight species-related research, specifically of mouse and human SPEN, with the aim to reveal and clarify potential species-to-species differences in SPEN's function.

Short C-terminal Musashi-1 proteins regulate pluripotency states in embryonic stem cells

The RNA-binding protein Musashi-1 (MSI1) regulates the proliferation and differentiation of adult stem cells. However, its role in embryonic stem cells (ESCs) and early embryonic development remains poorly understood. Here, we report the presence of short C-terminal MSI1 (MSI1-C) proteins in early mouse embryos and mouse ESCs, but not in human ESCs, under conventional culture conditions. In mouse embryos and mESCs, deletion of MSI1-C together with full-length MSI1 causes early embryonic developmental arrest and pluripotency dissolution. MSI1-C is induced upon naive induction and facilitates hESC naive pluripotency acquisition, elevating the pluripotency of primed hESCs toward a formative-like state. MSI1-C proteins are nuclear localized and bind to RNAs involved in DNA-damage repair (including MLH1, BRCA1, and MSH2), conferring on hESCs better survival in human-mouse interspecies cell competition and prolonged ability to form blastoids. This study identifies MSI1-C as an essential regulator in ESC pluripotency states and early embryonic development.

A comprehensive review of human trophoblast fusion models: recent developments and challenges

As an essential component of the maternal-fetal interface, the placental syncytiotrophoblast layer contributes to a successful pregnancy by secreting hormones necessary for pregnancy, transporting nutrients, mediating gas exchange, balancing immune tolerance, and resisting pathogen infection. Notably, the deficiency in mononuclear trophoblast cells fusing into multinucleated syncytiotrophoblast has been linked to adverse pregnancy outcomes, such as preeclampsia, fetal growth restriction, preterm birth, and stillbirth. Despite the availability of many models for the study of trophoblast fusion, there exists a notable disparity from the ideal model, limiting the deeper exploration into the placental development. Here, we reviewed the existing models employed for the investigation of human trophoblast fusion from several aspects, including the development history, latest progress, advantages, disadvantages, scope of application, and challenges. The literature searched covers the monolayer cell lines, primary human trophoblast, placental explants, human trophoblast stem cells, human pluripotent stem cells, three-dimensional cell spheres, organoids, and placenta-on-a-chip from 1938 to 2023. These diverse models have significantly enhanced our comprehension of placental development regulation and the underlying mechanisms of placental-related disorders. Through this review, our objective is to provide readers with a thorough understanding of the existing trophoblast fusion models, making it easier to select most suitable models to address specific experimental requirements or scientific inquiries. Establishment and application of the existing human placental trophoblast fusion models.

Modeling X-chromosome inactivation and reactivation during human development

Stem-cell-based embryo models generate much excitement as they offer a window into an early phase of human development that has remained largely inaccessible to scientific investigation. An important epigenetic phenomenon during early embryogenesis is the epigenetic silencing of one of the two X chromosomes in female embryos, which ensures an equal output of X-linked gene expression between the sexes. X-chromosome inactivation (XCI) is thought to be established within the first three weeks of human development, although the inactive X-chromosome is reactivated in primordial germ cells (PGCs) that migrate to the embryonic gonads. Here, we summarize our current understanding of X-chromosome dynamics during human development and comment on the potential of recently established stem-cell-based models to reveal the underlying mechanisms.

Shifting early embryology paradigms: Applications of stem cell-based embryo models in bioengineering

Technologies to reproduce specific aspects of early mammalian embryogenesis in vitro using stem cells have skyrocketed over the last several years. With these advances, we have gained new perspectives on how embryonic and extraembryonic cells self-organize to form the embryo. These reductionist approaches hold promise for the future implementation of precise environmental and genetic controls to understand variables affecting embryo development. Our review discusses recent progress in cellular models of early mammalian embryo development and bioengineering advancements that can be leveraged to study the embryo-maternal interface. We summarize current gaps in the field, emphasizing the importance of understanding how intercellular interactions at this interface contribute to reproductive and developmental health.

A single cell transcriptomic fingerprint of stressed premature, imbalanced differentiation of embryonic stem cells

Cultured naïve pluripotent ESC differentiate into first lineage, XEN or second lineage, formative pluripotency. Hyperosmotic stress (sorbitol), like retinoic acid, decreases naive pluripotency and increases XEN in two ESC lines, as reported by bulk and scRNAseq, analyzed by UMAP. Sorbitol overrides pluripotency in two ESC lines as reported by bulk and scRNAseq, analyzed by UMAP. UMAP analyzed the effects of 5 stimuli - three stressed (200-300mM sorbitol with leukemia inhibitory factor +LIF) and two unstressed (+LIF, normal stemness-NS and -LIF, normal differentiation-ND). Sorbitol and RA decrease naive pluripotency and increase subpopulations of 2-cell embryo-like and XEN sub-lineages; primitive, parietal, and visceral endoderm (VE). Between the naïve pluripotency and primitive endoderm clusters is a stress-induced cluster with transient intermediate cells with higher LIF receptor signaling, with increased Stat3, Klf4, and Tbx3 expression. Sorbitol, like RA, also suppresses formative pluripotency, increasing lineage imbalance. Although bulk RNAseq and gene ontology group analyses suggest that stress induces head organizer and placental markers, scRNAseq reveals few cells. But VE and placental markers/cells were in adjacent clusters, like recent reports. UMAPs show that dose-dependent stress overrides stemness to force premature lineage imbalance. Hyperosmotic stress induces lineage imbalance, and other toxicological stresses, like drugs with RA, may cause lineage imbalance, resulting in miscarriages or birth defects.

Molecular Mechanisms Underlying Pluripotency and Self-Renewal of Embryonic Stem Cells

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. ESCs have two distinctive properties: ability to proliferate indefinitely, a feature referred as "self-renewal", and to differentiate into different cell types, a peculiar characteristic known as "pluripotency". Self-renewal and pluripotency of ESCs are finely orchestrated by precise external and internal networks including epigenetic modifications, transcription factors, signaling pathways, and histone modifications. In this systematic review, we examine the main molecular mechanisms that sustain self-renewal and pluripotency in both murine and human ESCs. Moreover, we discuss the latest literature on human naïve pluripotency.

Induction and application of human naive pluripotency

Over the past few decades, many attempts have been made to capture different states of pluripotency in vitro. Naive and primed pluripotent stem cells, corresponding to the pluripotency states of pre- and post-implantation epiblasts, respectively, have been well characterized in mice and can be interconverted in vitro. Here, we summarize the recently reported strategies to generate human naive pluripotent stem cells in vitro. We discuss their applications in studies of regulatory mechanisms involved in early developmental processes, including identification of molecular features, X chromosome inactivation modeling, transposable elements regulation, metabolic characteristics, and cell fate regulation, as well as potential for extraembryonic differentiation and blastoid construction for embryogenesis modeling. We further discuss the naive pluripotency-related research, including 8C-like cell establishment and disease modeling. We also highlight limitations of current naive pluripotency studies, such as imperfect culture conditions and inadequate responsiveness to differentiation signals.

Chemical conversion of human conventional PSCs to TSCs following transient naive gene activation

In human embryos, naive pluripotent cells of the inner cell mass (ICM) generate epiblast, primitive endoderm and trophectoderm (TE) lineages, whence trophoblast cells derive. In vitro, naive pluripotent stem cells (PSCs) retain this potential and efficiently generate trophoblast stem cells (TSCs), while conventional PSCs form TSCs at low efficiency. Transient histone deacetylase and MEK inhibition combined with LIF stimulation is used to chemically reset conventional to naive PSCs. Here, we report that chemical resetting induces the expression of both naive and TSC markers and of placental imprinted genes. A modified chemical resetting protocol allows for the fast and efficient conversion of conventional PSCs into TSCs, entailing shutdown of pluripotency genes and full activation of the trophoblast master regulators, without induction of amnion markers. Chemical resetting generates a plastic intermediate state, characterised by co-expression of naive and TSC markers, after which cells steer towards one of the two fates in response to the signalling environment. The efficiency and rapidity of our system will be useful to study cell fate transitions and to generate models of placental disorders.

Generating human blastoids modeling blastocyst-stage embryos and implantation

Human early development sets the stage for embryonic and adult life but remains difficult to investigate. A solution came from the ability of stem cells to organize into structures resembling preimplantation embryos-blastocysts-that we termed blastoids. This embryo model is available in unlimited numbers and could thus support scientific and medical advances. However, its predictive power depends on how faithfully it recapitulates the blastocyst. Here, we describe how we formed human blastoids that (1) efficiently achieve the morphology of the blastocyst and (2) form lineages according to the pace and sequence of blastocyst development, (3) ultimately forming cells that transcriptionally reflect the blastocyst (preimplantation stage). We employ three different commercially available 96- and 24-well microwell plates with results similar to our custom-made ones, and show that blastoids form in clinical in vitro fertilization medium and can be cryopreserved for shipping. Finally, we explain how blastoids replicate the directional process of implantation into endometrial organoids, specifically when these are hormonally stimulated. It takes 4 d for human blastoids to form and 10 d to prepare the endometrial implantation assay, and we have cultured blastoids up to 6 d (time-equivalent of day 13). On the basis of our experience, we anticipate that a person with ~1 year of human pluripotent stem cell culture experience and of organoid culture should be able to perform the protocol. Altogether, blastoids offer an opportunity to establish scientific and biomedical discovery programs for early pregnancy, and an ethical alternative to the use of embryos.

Human iPS Cells for Clinical Applications and Cellular Products

Human induced pluripotent stem cells (iPSCs), since their discovery in 2007, have rapidly become a starting cell type of choice for the differentiation of many mature cell types. Their flexibility, amenability to gene editing and functional equivalence to embryonic stem cells ensured their subsequent adoption by many manufacturing processes for cellular products. In this chapter, we will discuss the process whereby iPSCs are generated, key quality control steps which should be considered during manufacturing, the application of good manufacturing practice to production processes and iPSC-derived cellular products which are already undergoing clinical trials. iPSCs provide a new avenue for the next generation of cellular therapeutics and by combining new differentiation protocols, quality control and reproducible manufacturing, iPSC-derived cellular products could provide treatments for many currently untreatable diseases, allowing the large-scale manufacture of high-quality cell therapies.

Using high throughput screens to predict miscarriages with placental stem cells and long-term stress effects with embryonic stem cells

A problem in developmental toxicology is the massive loss of life from fertilization through gastrulation, and the surprising lack of knowledge of causes of miscarriage. Half to two-thirds of embryos are lost, and environmental and genetic causes are nearly equal. Simply put, it can be inferred that this is a difficult period for normal embryos, but that environmental stresses may cause homeostatic responses that move from adaptive to maladaptive with increasing exposures. At the lower 50% estimate, miscarriage causes greater loss-of-life than all cancers combined or of all cardio- and cerebral-vascular accidents combined. Surprisingly, we do not know if miscarriage rates are increasing or decreasing. Overshadowed by the magnitude of miscarriages, are insufficient data on teratogenic or epigenetic imbalances in surviving embryos and their stem cells. Superimposed on the difficult normal trajectory for peri-gastrulation embryos are added malnutrition, hormonal, and environmental stresses. An overarching hypothesis is that high throughput screens (HTS) using cultured viable reporter embryonic and placental stem cells (e.g., embryonic stem cells [ESC] and trophoblast stem cells [TSC] that report status using fluorescent reporters in living cells) from the pre-gastrulation embryo will most rapidly test a range of hormonal, environmental, nutritional, drug, and diet supplement stresses that decrease stem cell proliferation and imbalance stemness/differentiation. A second hypothesis is that TSC respond with greater sensitivity in magnitude to stress that would cause miscarriage, but ESC are stress-resistant to irreversible stemness loss and are best used to predict long-term health defects. DevTox testing needs more ESC and TSC HTS to model environmental stresses leading to miscarriage or teratogenesis and more research on epidemiology of stress and miscarriage. This endeavor also requires a shift in emphasis on pre- and early gastrulation events during the difficult period of maximum loss by miscarriage.

Dichotomous role of Shp2 for naïve and primed pluripotency maintenance in embryonic stem cells

Background

The requirement of the Mek1 inhibitor (iMek1) during naïve pluripotency maintenance results from the activation of the Mek1-Erk1/2 (Mek/Erk) signaling pathway upon leukemia inhibitory factor (LIF) stimulation.

Methods

Through a meta-analysis of previous genome-wide screening for negative regulators of naïve pluripotency, Ptpn11 (encoding the Shp2 protein, which serves both as a tyrosine phosphatase and putative adapter), was predicted as one of the key factors for the negative modulation of naïve pluripotency through LIF-dependent Jak/Stat3 signaling. Using an isogenic pair of naïve and primed mouse embryonic stem cells (mESCs), we demonstrated the differential role of Shp2 in naïve and primed pluripotency.

Results

Loss of Shp2 increased naïve pluripotency by promoting Jak/Stat3 signaling and disturbed in vivo differentiation potential. In sharp contrast, Shp2 depletion significantly impeded the self-renewal of ESCs under primed culture conditions, which was concurrent with a reduction in Mek/Erk signaling. Similarly, upon treatment with an allosteric Shp2 inhibitor (iShp2), the cells sustained Stat3 phosphorylation and decoupled Mek/Erk signaling, thus iShp2 can replace the use of iMek1 for maintenance of naïve ESCs.

Conclusions

Taken together, our findings highlight the differential roles of Shp2 in naïve and primed pluripotency and propose the usage of iShp2 instead of iMek1 for the efficient maintenance and establishment of naïve pluripotency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02976-z.

Succinate as a New Actor in Pluripotency and Early Development?

Pluripotent cells have been stabilized from pre- and post-implantation blastocysts, representing respectively naïve and primed stages of embryonic stem cells (ESCs) with distinct epigenetic, metabolic and transcriptomic features. Beside these two well characterized pluripotent stages, several intermediate states have been reported, as well as a small subpopulation of cells that have reacquired features of the 2C-embryo (2C-like cells) in naïve mouse ESC culture. Altogether, these represent a continuum of distinct pluripotency stages, characterized by metabolic transitions, for which we propose a new role for a long-known metabolite: succinate. Mostly seen as the metabolite of the TCA, succinate is also at the crossroad of several mitochondrial biochemical pathways. Its role also extends far beyond the mitochondrion, as it can be secreted, modify proteins by lysine succinylation and inhibit the activity of alpha-ketoglutarate-dependent dioxygenases, such as prolyl hydroxylase (PHDs) or histone and DNA demethylases. When released in the extracellular compartment, succinate can trigger several key transduction pathways after binding to SUCNR1, a G-Protein Coupled Receptor. In this review, we highlight the different intra- and extracellular roles that succinate might play in the fields of early pluripotency and embryo development.

Dynamic reprogramming of H3K9me3 at hominoid-specific retrotransposons during human preimplantation development

Reprogramming of H3K9me3-dependent heterochromatin is required for early development. How H3K9me3 is involved in early human development remains, however, largely unclear. Here, we resolve the temporal landscape of H3K9me3 during human preimplantation development and its regulation for diverse hominoid-specific retrotransposons. At the 8-cell stage, H3K9me3 reprogramming at hominoid-specific retrotransposons termed SINE-VNTR-Alu (SVA) facilitates interaction between certain promoters and SVA-derived enhancers, promoting the zygotic genome activation. In trophectoderm, de novo H3K9me3 domains prevent pluripotent transcription factors from binding to hominoid-specific retrotransposons-derived regulatory elements for inner cell mass (ICM)-specific genes. H3K9me3 re-establishment at SVA elements in the ICM is associated with higher transcription of DNA repair genes, when compared with naive human pluripotent stem cells. Our data demonstrate that species-specific reorganization of H3K9me3-dependent heterochromatin at hominoid-specific retrotransposons plays important roles during early human development, shedding light on how the epigenetic regulation for early development has evolved in mammals.

Recapitulating early human development with 8C-like cells

In human embryos, major zygotic genome activation (ZGA) initiates at the eight-cell (8C) stage. Abnormal ZGA leads to developmental defects and even contributes to the failure of human blastocyst formation or implantation. An in vitro cell model mimicking human 8C blastomeres would be invaluable to understanding the mechanisms regulating key biological events during early human development. Using the non-canonical promoter of LEUTX that putatively regulates human ZGA, we developed an 8C::mCherry reporter, which specifically marks the 8C state, to isolate rare 8C-like cells (8CLCs) from human preimplantation epiblast-like stem cells. The 8CLCs express a panel of human ZGA genes and have a unique transcriptome resembling that of the human 8C embryo. Using the 8C::mCherry reporter, we further optimize the chemical-based culture condition to increase and maintain the 8CLC population. Functionally, 8CLCs can self-organize to form blastocyst-like structures. The discovery and maintenance of 8CLCs provide an opportunity to recapitulate early human development.

Stem-cell-derived trophoblast organoids model human placental development and susceptibility to emerging pathogens

Trophoblast organoids derived from placental villi provide a 3D model system of human placental development, but access to first-trimester tissues is limited. Here, we report that trophoblast stem cells isolated from naive human pluripotent stem cells (hPSCs) can efficiently self-organize into 3D stem-cell-derived trophoblast organoids (SC-TOs) with a villous architecture similar to primary trophoblast organoids. Single-cell transcriptome analysis reveals the presence of distinct cytotrophoblast and syncytiotrophoblast clusters and a small cluster of extravillous trophoblasts, which closely correspond to trophoblast identities in the post-implantation embryo. These organoid cultures display clonal X chromosome inactivation patterns previously described in the human placenta. We further demonstrate that SC-TOs exhibit selective vulnerability to emerging pathogens (SARS-CoV-2 and Zika virus), which correlates with expression levels of their respective entry factors. The generation of trophoblast organoids from naive hPSCs provides an accessible 3D model system of the developing placenta and its susceptibility to emerging pathogens.

From Mice to Men: Generation of Human Blastocyst-Like Structures In Vitro

Advances in the field of stem cell-based models have in recent years lead to the development of blastocyst-like structures termed blastoids. Blastoids can be used to study key events in mammalian pre-implantation development, as they mimic the blastocyst morphologically and transcriptionally, can progress to the post-implantation stage and can be generated in large numbers. Blastoids were originally developed using mouse pluripotent stem cells, and since several groups have successfully generated blastocyst models of the human system. Here we provide a comparison of the mouse and human protocols with the aim of deriving the core requirements for blastoid formation, discuss the models’ current ability to mimic blastocysts and give an outlook on potential future applications.

Genome-scale screening in a rat haploid system identifies Thop1 as a modulator of pluripotency exit

OBJECTIVES

The rats are crucial animal models for the basic medical researches. Rat embryonic stem cells (ESCs), which are widely studied, can self-renew and exhibit pluripotency in long-term culture, but the mechanism underlying how they exit pluripotency remains obscure. To investigate the key modulators on pluripotency exiting in rat ESCs, we perform genome-wide screening using a unique rat haploid system.

MATERIALS AND METHODS

Rat haploid ESCs (haESCs) enable advances in the discovery of unknown functional genes owing to their homozygous and pluripotent characteristics. REX1 is a sensitive marker for the naïve pluripotency that is often utilized to monitor pluripotency exit, thus rat haESCs carrying a Rex1-GFP reporter are used for genetic screening. Genome-wide mutations are introduced into the genomes of rat Rex1-GFP haESCs via piggyBac transposon, and differentiation-retarded mutants are obtained after random differentiation selection. The exact mutations are elucidated by high-throughput sequencing and bioinformatic analysis. The role of candidate mutation is validated in rat ESCs by knockout and overexpression experiments, and the phosphorylation of ERK1/2 (p-ERK1/2) is determined by western blotting.

RESULTS

High-throughput sequencing analysis reveals numerous insertions related to various pathways affecting random differentiation. Thereafter, deletion of Thop1 (one candidate gene in the screened list) arrests the differentiation of rat ESCs by inhibiting the p-ERK1/2, whereas overexpression of Thop1 promotes rat ESCs to exit from pluripotency.

CONCLUSIONS

Our findings provide an ideal tool to study functional genomics in rats: a homozygous haploid system carrying a pluripotency reporter that facilitates robust discovery of the mechanisms involved in the self-renewal or pluripotency of rat ESCs.

Fostering Research Synergies between Chemists in Swiss Academia and at Novartis

We present a short overview of the way Novartis chemists interact and collaborate with the academic chemistry community in Switzerland. This article exemplifies a number of collaborations, and illustrates opportunities to foster research synergies between academic and industrial researchers. It also describes established programs available to academic groups, providing them access to Novartis resources and expertise.