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The abilities of opioids to activate downstream signaling pathways normally depend on the binding between opioids and their receptors. However, opioids may also function in a receptor-independent manner, especially in neural stem cells (NSCs) in which the expression of opioid receptors and endogenous opioid agonists is low. When two opioids, morphine and naloxone, were used during the early stage of NSC differentiation, increased neurogenesis was observed. However, naloxone methiodide, a membrane impenetrable analog of naloxone, did not affect the NSC differentiation. The abilities of morphine and naloxone to facilitate neurogenesis were also observed in opioid receptor-knockout NSCs. Therefore, morphine and naloxone promote neurogenesis in a receptor-independent manner at least during the early stage. In addition, the receptor-independent functions of opioids were not observed in methylcytosine dioxygenase ten-eleven translocation 1 (Tet1) knockout NSCs. When the expression of opioid receptors increased and the expression of Tet1 decreased during the late stage of NSC differentiation, morphine, but not naloxone, inhibited neurogenesis via traditional receptor-dependent and miR181a-Prox1-Notch-related pathway. In summary, the current results demonstrated the time-dependent effects of opioids during the differentiation of NSCs and provided additional insight on the complex functions of opioids.

Neurogenesis, a highly orchestrated process, entails the transition from a pluripotent to neural state and involves neural progenitor cells (NPCs) and neuronal/glial subtypes. However, the precise epigenetic mechanisms underlying fate decision remain poorly understood. Here, we delete KDM6s (JMJD3 and/or UTX), the H3K27me3 demethylases, in human embryonic stem cells (hESCs) and show that their deletion does not impede NPC generation from hESCs. However, KDM6-deficient NPCs exhibit poor proliferation and a failure to differentiate into neurons and glia. Mechanistically, both JMJD3 and UTX are found to be enriched in gene loci essential for neural development in hNPCs, and KDM6 impairment leads to H3K27me3 accumulation and blockade of DNA accessibility at these genes. Interestingly, forced expression of neuron-specific chromatin remodelling BAF (nBAF) rescues the neuron/glia defect in KDM6-deficient NPCs despite H3K27me3 accumulation. Our findings uncover the differential requirement of KDM6s in specifying NPCs and neurons/glia and highlight the contribution of individual epigenetic regulators in fate decisions in a human development model., Neurogenesis is an ordered transition from pluriptotent cells to neural precursor cells (NPCs) to neurons. Here the authors show that loss of the lysine demethylases JMJD3 and UTX leads reduced DNA accessibility at neurogenesis loci in human NPCs, and that the chromatin remodeller BAF can rescue differentiation defects.

Transposable elements (TEs) are the major sources of lineage-specific genomic innovation and comprise nearly half of the human genome, but most of their functions remain unclear. Here, we identify that a series of endogenous retroviruses (ERVs), a TE subclass, regulate the transcriptome at the definitive endoderm stage with in vitro differentiation model from human embryonic stem cell. Notably, these ERVs perform as enhancers containing binding sites for critical transcription factors for endoderm lineage specification. Genome-wide methylation analysis shows most of these ERVs are derepressed by TET1-mediated DNA demethylation. LTR6B, a representative definitive endoderm activating ERV, contains binding sites for FOXA2 and GATA4 and governs the primate-specific expression of its neighboring developmental genes such as ERBB4 in definitive endoderm. Together, our study proposes evidence that recently evolved ERVs represent potent de novo developmental regulatory elements, which, in turn, fine-tune species-specific transcriptomes during endoderm and embryonic development.

Description, MSC-exo eye drops alleviate GVHD-associated dry eye disease by shifting M1 macrophages to M2 via miR-204., Graft-versus-host disease (GVHD)–associated dry eye disease is characterized by extensive inflammatory destruction in the ocular surface and causes unbearable pain and visual impairment. Current treatments provide limited benefits. Here, we report that exosomes from mesenchymal stromal cells (MSC-exo) administered as eye drops notably alleviate GVHD-associated dry eye disease by suppressing inflammation and improving epithelial recovery in mice and humans. In a prospective clinical trial, 28 eyes with refractory GVHD–dry eye disease exhibited substantial relief after MSC-exo treatment, showing reduced fluorescein scores, longer tear-film breakup time, increased tear secretion, and lower OSDI scores. Mechanistically, MSC-exo reprogramed proinflammatory M1 macrophages toward the immunosuppressive M2 via miR-204–mediated targeting of the IL-6/IL-6R/Stat3 pathway. Blockade of miR-204 abolished the effects of MSC-exo, while overloading L929-exo with miR-204 markedly attenuated dry eye. Thus, this study suggests that MSC-exo are efficacious in treating GVHD-associated dry eye disease and highlights miR-204 as a potential therapeutic agent.

The human RecQ DNA helicase, RECQL4, plays a pivotal role in maintaining genomic stability by regulating the DNA double-strand breaks (DSBs) repair pathway, and is, thus, involved in the regulation of aging and cancer onset. However, the regulatory mechanisms of RECQL4, especially its post-translational modifications, have not been fully illustrated. Here, we report that the E2/E3 hybrid ubiquitin-conjugating enzyme, UBE2O, physically interacts with RECQL4, and mediates the multi-monoubiquitinylation of RECQL4, subsequently leading to its proteasomal degradation. Functionally, we showed that UBE2O inhibits homologous recombination (HR)-mediated DSBs repair, and this inhibition depends on its E2 catalytic activity and RECQL4 expression. Mechanistically, we showed that UBE2O attenuates the interaction of RECQL4 and DNA damage repair proteins, the MRE11-RAD50-NBS1 complex and CtIP. Furthermore, we show that deubiquitinylase USP7 interacts with both UBE2O and RECQL4, and in that it antagonizes UBE2O-mediated regulation of RECQL4 stability and function. Collectively, we found a novel regulatory mechanism of ubiquitin-mediated regulation of RECQL4 in HR-mediated DSBs repair process.

The test for the cancer stem cell (CSC) hypothesis is to find a target expressed on all, and only CSCs in a patient tumor, then eliminate all cells with that target that eliminates the cancer. That test has not yet been achieved, but CSC diagnostics and targets found on CSCs and some other cells have resulted in a few clinically relevant therapies. However, it has become apparent that eliminating the subset of tumor cells characterized by self-renewal properties is essential for long-term tumor control. CSCs are able to regenerate and initiate tumor growth, recapitulating the heterogeneity present in the tumor before treatment. As great progress has been made in identifying and elucidating the biology of CSCs as well as their interactions with the tumor microenvironment, the time seems ripe for novel therapeutic strategies that target CSCs to find clinical applicability. On May 19-21, 2021, researchers in cancer stem cells met virtually for the Keystone eSymposium "Cancer Stem Cells: Advances in Biology and Clinical Translation" to discuss recent advances in the understanding of CSCs as well as clinical efforts to target these populations.

Somatic cell reprogramming is an ideal model for studying epigenetic regulation as it undergoes dramatic chromatin remodeling. However, a role for phosphorylation signaling in chromatin protein modifications for reprogramming remains unclear. Here, we identified mitogen-activated protein kinase kinase 6 (Mkk6) as a chromatin relaxer and found that it could significantly enhance reprogramming. The function of Mkk6 in heterochromatin loosening and reprogramming requires its kinase activity but does not depend on its best-known target, P38. We identified Gatad2b as a novel target of Mkk6 phosphorylation that acts downstream to elevate histone acetylation levels and loosen heterochromatin. As a result, Mkk6 over-expression facilitates binding of Sox2 and Klf4 to their targets and promotes pluripotency gene expression during reprogramming. Our studies not only reveal an Mkk phosphorylation mediated modulation of chromatin status in reprogramming, but also provide new rationales to further investigate and improve the cell fate determination processes.

How master regulators such as Oct4 can shape 3D genome architecture during cell reprogramming remains poorly understood. In this issue of Cell Stem Cell, Wang et al. (2021) demonstrate that Oct4 undergoes phase separation to reconfigure TAD architecture for cell fate control.

The spatiotemporal relationships in high-resolution during odontogenesis remain poorly understood. We report a cell lineage and atlas of developing mouse teeth. We performed a large-scale (92,688 cells) single cell RNA sequencing, tracing the cell trajectories during odontogenesis from embryonic days 10.5 to 16.5. Combined with an assay for transposase-accessible chromatin with high-throughput sequencing, our results suggest that mesenchymal cells show the specific transcriptome profiles to distinguish the tooth types. Subsequently, we identified key gene regulatory networks in teeth and bone formation and uncovered spatiotemporal patterns of odontogenic mesenchymal cells. CD24

Cell-surface ancillary glycoproteins basigin or embigin form heterodimeric complexes with proton-coupled monocarboxylate transporters (MCTs), facilitating the membrane trafficking of MCTs and regulating their transport activities. Here, we determine the cryoelectron microscopy (cryo-EM) structure of the human MCT1-embigin complex and observe that embigin forms extensive interactions with MCT1 to facilitate its localization to the plasma membrane. In addition, the formation of the heterodimer effectively blocks MCT1 from forming a homodimer through a steric hindrance effect, releasing the coupling between two signature motifs and driving a significant conformation change in transmembrane helix 5 (TM5) of MCTs. Consequently, the substrate-binding pocket alternates between states of homodimeric coupling and heterodimeric decoupling states and exhibits differences in substrate-binding affinity, supporting the hypothesis that the substrate-induced motion originating in one subunit of the MCT dimer could be transmitted to the adjacent subunit to alter its substrate-binding affinity.

BackgroundThere is a huge controversy about whether xenograft or allograft in the “immune-privileged” brain needs immunosuppression. In animal studies, the prevailing sophisticated use of immunosuppression or immunodeficient animal is detrimental for the recipients, which results in a short lifespan of animals, confounds functional behavioral readout of the graft benefits, and discourages long-term follow-up.MethodsNeuron-restricted neural progenitor cells (NPCs) were derived from human embryonic stem cells (ESCs, including H1, its gene-modified cell lines for better visualization, and HN4), propagated for different passages, and then transplanted into the brain of immunocompetent rats without immunosuppressants. The graft survivals, their cell fates, and HLA expression levels were examined over time (up to 4 months after transplantation). We compared the survival capability of NPCs from different passages and in different transplantation sites (intra-parenchyma vs. para- and intra-cerebroventricle). The host responses to the grafts were also investigated.ResultsOur results show that human ESC-derived neuron-restricted NPCs survive extendedly in adult rat brain parenchyma with no need of immunosuppression whereas a late-onset graft rejection seems inevitable. Both donor HLA antigens and host MHC-II expression level remain relatively low with little change over time and cannot predict the late-onset rejection. The intra-/para-cerebroventricular human grafts are more vulnerable to the immune attack than the intrastriatal counterparts. Prevention of graft hyperplasia by using hypoproliferative late passaged human NPCs further significantly extends the graft survival time. Our new data also shows that a subpopulation of host microglia upregulate MHC-II expression in response to the human graft, but fail to present the human antigen to the host immune system, suggestive of the immune-isolation role of the blood–brain barrier (BBB).ConclusionsThe present study confirms the “immune privilege” of the brain parenchyma and, more importantly, unveils that choosing hypoproliferative NPCs for transplantation can benefit graft outcome in terms of both lower tumor-genic risk and the prolonged survival time without immunosuppression.

Forkhead box (Fox) transcription factors play important roles in mammalian development and disease. However, their function in mouse somatic cell reprogramming remains unclear. Here, we report that FoxD subfamily and FoxG1 accelerate induced pluripotent stem cells (iPSCs) generation from mouse fibroblasts as early as day4 while FoxA and FoxO subfamily impede this process obviously. More importantly, FoxD3, FoxD4 and FoxG1 can replace Oct4 respectively and generate iPSCs with germline transmission together with Sox2 and Klf4. On the contrary, FoxO6 almost totally blocks reprogramming through inhibiting cell proliferation, suppressing the expression of pluripotent genes and hindering the process of mesenchymal to epithelial transition (MET). Thus, our study uncovers unexpected roles of Fox transcription factors in reprogramming and offers new insights into cell fate transition. Supplementary Information The online version contains supplementary material available at 10.1186/s13619-021-00078-4.

The transition from pluripotent to somatic states marks a critical event in mammalian development, but remains largely unresolved. Here we report the identification of SS18 as a regulator for pluripotent to somatic transition or PST by CRISPR-based whole genome screens. Mechanistically, SS18 forms microscopic condensates in nuclei through a C-terminal intrinsically disordered region (IDR) rich in tyrosine, which, once mutated, no longer form condensates nor rescue SS18−/− defect in PST. Yet, the IDR alone is not sufficient to rescue the defect even though it can form condensates indistinguishable from the wild type protein. We further show that its N-terminal 70aa is required for PST by interacting with the Brg/Brahma-associated factor (BAF) complex, and remains functional even swapped onto unrelated IDRs or even an artificial 24 tyrosine polypeptide. Finally, we show that SS18 mediates BAF assembly through phase separation to regulate PST. These studies suggest that SS18 plays a role in the pluripotent to somatic interface and undergoes liquid-liquid phase separation through a unique tyrosine-based mechanism., Emerging evidence suggests that exit from pluripotency is a regulated, rather than passive process. Here the authors identify a requirement for SS18-mediated Brg/Brahma-associated factors (BAF) chromatin remodeling complex assembly during exit from pluripotency, and that SS18 promotes BAF assembly through liquidliquid phase separation.

Purpose: Pancreatic cancer remains one of the most lethal cancers, and late detection renders most tumors refractory to conventional therapies. Development of cancer prophylaxis may be the most realistic option for improving mortality associated with this disease. Here, we develop a novel individualized prophylactic and therapeutic vaccination regimen using induced pluripotent stem cells (iPSC), gene editing, and tumor-targeted replicating oncolytic viruses. Experimental Design: We created a Virus-Infected, Reprogrammed Somatic cell-derived Tumor cell (VIReST) regime. iPSCs from healthy cells were induced to pancreatic tumor cells using in situ gene editing via stable provision of KRasG12D and p53R172H tumor driver mutations. These cells were preinfected with oncolytic Adenovirus (AdV) as prime or Vaccinia virus (VV) as boost, to improve vaccine immunogenicity, prior to delivery of vaccines in a sequential regime to young KPC transgenic mice, genetically programmed to develop pancreatic cancer, to prevent and delay disease development. Results: Tumor cells preinfected with oncolytic AdV as prime or VV as boost were the best regime to induce tumor-specific immunity. iPSC-derived tumor cells were highly related in antigen repertoire to pancreatic cancer cells of KPC transgenic mice, suggesting that an individual9s stem cells can provide an antigenically matched whole tumor cell vaccine. The VIReST vaccination primed tumor-specific T-cell responses, resulting in delayed disease emergence and progression and significantly prolonged survival of KPC transgenic mice. Importantly, this regime was well-tolerated and nontoxic. Conclusions: These results provide both proof of concept and a robust technology platform for the development of personalized prophylactic cancer vaccines to prevent pancreatic malignancies in at-risk individuals.

Hematopoietic stem cells (HSCs)/progenitor cells (HPCs) are generated from hemogenic endothelial cells (HECs) during the endothelial-to-hematopoietic transition (EHT); however, the underlying mechanism remains poorly understood. Here, using an array of approaches, including CRSPR/Cas9 gene knockouts, RNA-Seq, ChIP-Seq, ATAC-Seq etc., we report that vitamin C (Vc) is essential in HPC generation during human pluripotent stem cell (hPSC) differentiation in defined culture conditions. Mechanistically, we found that the endothelial cells generated in the absence of Vc fail to undergo the EHT because of an apparent failure in opening up genomic loci essential for hematopoiesis. Under Vc deficiency, these loci exhibited abnormal accumulation of histone H3 trimethylation at Lys-27 (H3K27me3), a repressive histone modification that arose because of lower activities of demethylases that target H3K27me3. Consistently, deletion of the two H3K27me3 demethylases, Jumonji domain-containing 3 (JMJD3 or KDM6B) and histone demethylase UTX (UTX or KDM6A), impaired HPC generation even in the presence of Vc. Furthermore, we noted that Vc and jmjd3 are also important for HSC generation during zebrafish development. Together, our findings reveal an essential role for Vc in the EHT for hematopoiesis, and identify KDM6-mediated chromatin demethylation as an important regulatory mechanism in hematopoietic cell differentiation.

During organogenesis, epithelial cells can give rise to mesenchymal cells through epithelial-mesenchymal transition. The reverse process, mesenchymal-epithelial transition (MET), can similarly generate epithelial cells. Transitions between epithelial and mesenchymal states are also critical for the induction of pluripotent stem cells from somatic cells. This Review discusses the relatively less characterized process of MET, focusing on the genesis of apicobasal cell polarity and exploring the roles of MET in development and reprogramming.

Human pluripotent stem cells (hPSCs) exhibit very limited contribution to interspecies chimeras. One explanation is that the conventional hPSCs are in a primed state and so unable to form chimeras in pre-implantation embryos. Here, we show that the conventional hPSCs undergo rapid apoptosis when injected into mouse pre-implantation embryos. While, forced-expression of BMI1, a polycomb factor in hPSCs overcomes the apoptosis and enables hPSCs to integrate into mouse pre-implantation embryos and subsequently contribute to chimeras with both embryonic and extra-embryonic tissues. In addition, BMI1 also enables hPSCs to integrate into pre-implantation embryos of other species, such as rabbit and pig. Notably, BMI1 high expression and anti-apoptosis are also indicators for naïve hPSCs to form chimera in mouse embryos. Together, our findings reveal that the apoptosis is an initial barrier in interspecies chimerism using hPSCs and provide a rational to improve it., Conventional human pluripotent stem cells (hPSCs) fail to contribute to interspecies chimaeras when injected into mouse blastocysts. Here the authors show that forced expression of BMI1 overcomes apoptosis of hPSCs in blastocysts of mouse, rabbit and pig allowing them to contribute to chimaeras.

Background Epigenetic modifications, namely non-coding RNAs, DNA methylation, and histone modifications such as methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation play a significant role in brain development. DNA methyltransferases, methyl-CpG binding proteins, and ten-eleven translocation proteins facilitate the maintenance, interpretation, and removal of DNA methylation, respectively. Different forms of methylation, including 5-methylcytosine, 5-hydroxymethylcytosine, and other oxidized forms, have been detected by recently developed sequencing technologies. Emerging evidence suggests that the diversity of DNA methylation patterns in the brain plays a key role in fine-tuning and coordinating gene expression in the development, plasticity, and disorders of the mammalian central nervous system. Neural stem cells (NSCs), originating from the neuroepithelium, generate neurons and glial cells in the central nervous system and contribute to brain plasticity in the adult mammalian brain. Main body Here, we summarized recent research in proteins responsible for the establishment, maintenance, interpretation, and removal of DNA methylation and those involved in the regulation of the proliferation and differentiation of NSCs. In addition, we discussed the interactions of chemicals with epigenetic pathways to regulate NSCs as well as the connections between proteins involved in DNA methylation and human diseases. Conclusion Understanding the interplay between DNA methylation and NSCs in a broad biological context can facilitate the related studies and reduce potential misunderstanding.

Single cell analysis provides clarity unattainable with bulk approaches. Here we apply single cell RNA-seq to a newly established BMP4 induced mouse primed to naive transition (Bi-PNT) system and show that the reset is not a direct reversal of cell fate but through developmental intermediates. We first show that mEpiSCs bifurcate into c-Kit+ naïve and c-Kit- placenta-like cells, among which, the naive branch undergoes further transition through a primordial germ cell-like cells (PGCLCs) intermediate capable of spermatogenesis in vivo. Indeed, deficiency of Prdm1/Blimp1, the key regulator for PGC specification, blocks the induction of PGCLCs and naïve cells. Instead, Gata2 knockout arrests placenta-like fate, but facilitates the generation of PGCLCs. Our results not only reveal a newly cell fate dynamics between primed and naive states at single-cell resolution, but also provide a model system to explore mechanisms involved in regaining germline competence from primed pluripotency.

Mesenchymal stromal cells (MSCs), also known as mesenchymal stem cells, have been intensely investigated for clinical applications within the last decades. However, the majority of registered clinical trials applying MSC therapy for diverse human diseases have fallen short of expectations, despite the encouraging pre-clinical outcomes in varied animal disease models. This can be attributable to inconsistent criteria for MSCs identity across studies and their inherited heterogeneity. Nowadays, with the emergence of advanced biological techniques and substantial improvements in bio-engineered materials, strategies have been developed to overcome clinical challenges in MSC application. Here in this review, we will discuss the major challenges of MSC therapies in clinical application, the factors impacting the diversity of MSCs, the potential approaches that modify MSC products with the highest therapeutic potential, and finally the usage of MSCs for COVID-19 pandemic disease.

Definitive hematopoiesis generates hematopoietic stem/progenitor cells (HSPCs) that give rise to all mature blood and immune cells, but remains poorly defined in human. Here, we resolve human hematopoietic populations at the earliest hematopoiesis stage by single-cell RNA-seq. We characterize the distinct molecular profiling between early primitive and definitive hematopoiesis in both human embryonic stem cell (hESC) differentiation and early embryonic development. We identify CD44 to specifically discriminate definitive hematopoiesis and generate definitive HSPCs from hESCs. The multipotency of hESCs-derived HSPCs for various blood and immune cells is validated by single-cell clonal assay. Strikingly, these hESCs-derived HSPCs give rise to blood and lymphoid lineages in vivo. Lastly, we characterize gene-expression dynamics in definitive and primitive hematopoiesis and reveal an unreported role of ROCK-inhibition in enhancing human definitive hematopoiesis. Our study provides a prospect for understanding human early hematopoiesis and a firm basis for generating blood and immune cells for clinical purposes.

Background: There is a huge controversy about whether xenograft or allograft in the “immune-privileged” brain needs immunosuppression. In animal studies, prevailing sophiscated immunosuppression or immunodeficiency is detrimental for the recipients, which results in short lifespan of animals, and confounds functional behavioral readout of the graft benefit, discouraging long-term follow-up. Methods: Neuron-restricted human neural progenitor cells (NPCs) were derived from human embryonic stem cells (ESCs, including H1, its gene-modified cell lines for better visualization, and HN4), propagated for different passages and then transplanted into the brain of immunocompetent rats without use of immunosuppressant. The graft survivals, their cell fates and HLA expression levels were examined over time (up to months after transplantation). We compared the survival capability of NPCs from different passages, and in different transplantation sites (brain parenchyma vs. para-and intra-ventricular sites). The host responses to the grafts were also investigated.Results: Our results show that human ESC-derived neuron-restricted NPCs survive extendedly in adult rat cerebro-parenchyma with no need of immunosuppression whereas a late-onset graft rejection seems inevitable. Both donor HLA expression level and host MHC-II expression level remain relatively low and little change over the long-term survival, and therefore can’t predict the late-onset rejection. Human grafts in or close to cerebroventricle are more vulnerable to the immune attack than the intra-striatum grafts. Prevention of graft hyperplasia by using hypoproliferative late-passaged human NPCs further significantly extends the graft survival time. Our new data also shows that a subpopulation of host microglia upregulate MHC-II expression in response to the human graft, but fail to present the human antigen to the host immune system, suggestive of the immune-isolation role of the blood–brain barrier (BBB). Conclusions: The present study confirms the “immune privilege” of the brain parenchyma, and more importantly, unveils that choosing hypoproliferative NPCs for transplantation can benefit graft outcome in terms of both lower tumor-genic risk and the prolonged survival time without immunosuppression.

Human induced pluripotent stem cells (iPSCs) technology has been widely applied to cell regeneration and disease modeling. However, most mechanism of somatic reprogramming is studied on mouse system, which is not always generic in human. Consequently, the generation of human iPSCs remains inefficient. Here, we map the chromatin accessibility dynamics during the induction of human iPSCs from urine cells. Comparing to the mouse system, we found that the closing of somatic loci is much slower in human. Moreover, a conserved AP-1 motif is highly enriched among the closed loci. The introduction of AP-1 repressor, JDP2, enhances human reprogramming and facilitates the reactivation of pluripotent genes. However, ESRRB, KDM2B and SALL4, several known pluripotent factors promoting mouse somatic reprogramming fail to enhance human iPSC generation. Mechanistically, we reveal that JDP2 promotes the closing of somatic loci enriching AP-1 motifs to enhance human reprogramming. Furthermore, JDP2 can rescue reprogramming deficiency without MYC or KLF4. These results indicate AP-1 activity is a major barrier to prevent chromatin remodeling during somatic cell reprogramming.

The research can be used to generate animal models of severe disease based on the hACE2 mice for development of treatment against severe COVID-19 and also quickly establish specific mouse models in response to other emergency situations in the future.

Myeloid-derived suppressor cells (MDSCs) suppress antitumor immune activities and facilitate cancer progression. Although the concept of immunosuppressive MDSCs is well established, the mechanism that MDSCs regulate non-small cell lung cancer (NSCLC) progression through the paracrine signals is still lacking. Here, we reported that the infiltration of MDSCs within NSCLC tissues was associated with the progression of cancer status, and was positively correlated with the Patient-derived xenograft model establishment, and poor patient prognosis. Intratumoral MDSCs directly promoted NSCLC metastasis and highly expressed chemokines that promote NSCLC cells invasion, including CCL11. CCL11 was capable of activating the AKT and ERK signaling pathways to promote NSCLC metastasis through the epithelial-mesenchymal transition (EMT) process. Moreover, high expression of CCL11 was associated with a poor prognosis in lung cancer as well as other types of cancer. Our findings underscore that MDSCs produce CCL11 to promote NSCLC metastasis via activation of ERK and AKT signaling and induction of EMT, suggesting that the MDSCs-CCL11-ERK/AKT-EMT axis contains potential targets for NSCLC metastasis treatment.

Genome architecture and chromatin dynamics govern the fate and identify of a cell. Recent advances in mapping chromatin landscapes offer valuable tools for the acquisition of accurate information regarding chromatin dynamics. Here we discuss recent findings linking chromatin dynamics to cell fate control. Specifically, chromatin undergoes a binary off/on switch during iPSC reprogramming, closing and opening loci occupied by somatic and pluripotency transcription factors, respectively. This logic of a binary off/on switch may also be operational in cell fate control during normal development and implies that further approaches could potentially be developed to direct cell fate changes both in vitro and in vivo., This review discusses how chromatin binary on/off switches are linked to cell identity in iPSC reprogramming, with closing and opening loci occupied by somatic and pluripotent transcription factors, respectively.

Lung cancer is one of the most commonly diagnosed cancer and despite therapeutic advances, mortality remains high. The long period of clinical latency associated with lung cancer provides an ideal window of opportunity to administer vaccines to at-risk individuals that can prevent tumor progression and initiate long-term anti-tumor immune surveillance. Here we describe a personalized vaccination regime that could be applied for both therapeutic and prophylactic prevention of lung cancer, based on the derivation of lung cancer cells from induced pluripotent stem cells. Stem cells from healthy mice were modified to express Cre-dependent KRASG12D and Trp53R172H prior to differentiation to lung progenitor cells. Subsequent viral delivery of Cre caused activation of exogenous driver mutations, resulting in transformation and development of lung cancer cells. iPSC-derived lung cancer cells were highly antigenically related to lung cancer cells induced in LSL-KRASG12D/+; Trp53R172H/+ transgenic mice and were antigenically unrelated to original pluripotent stem cells or pancreatic cancer cells derived using the same technological platform. For vaccination, induced lung cancer cells were infected with oncolytic Adenovirus or Vaccinia virus, to act as vaccine adjuvants, prior to delivery of vaccines sequentially to a murine inducible transgenic model of lung cancer. Application of this Virus-Infected, Reprogrammed Somatic cell-derived Tumor cell (VIReST) regime primed tumor-specific T cell responses that significantly prolonged survival in both subcutaneous post-vaccine challenge models and induced transgenic models of lung cancer, demonstrating that stem cell-derived prophylactic vaccines may be a feasible intervention for treatment or prevention of lung cancer development in at-risk individuals.

BackgroundEffective therapies are urgently needed for the SARS-CoV-2 pandemic. Chloroquine has been proved to have antiviral effect against coronavirus in vitro. In this study, we aimed to assess the efficacy and safety of chloroquine with different doses in COVID-19.MethodIn this multicenter prospective observational study, we enrolled patients older than 18 years old with confirmed SARS-CoV-2 infection excluding critical cases from 12 hospitals in Guangdong and Hubei Provinces. Eligible patients received chloroquine phosphate 500mg, orally, once (half dose) or twice (full dose) daily. Patients treated with non-chloroquine therapy were included as historical controls. The primary endpoint is the time to undetectable viral RNA. Secondary outcomes include the proportion of patients with undetectable viral RNA by day 10 and 14, hospitalization time, duration of fever, and adverse events.ResultsA total of 197 patients completed chloroquine treatment, and 176 patients were included as historical controls. The median time to achieve an undetectable viral RNA was shorter in chloroquine than in non-chloroquine (absolute difference in medians −6.0 days; 95% CI −6.0 to −4.0). The duration of fever is shorter in chloroquine (geometric mean ratio 0.6; 95% CI 0.5 to 0.8). No serious adverse events were observed in the chloroquine group. Patients treated with half dose experienced lower rate of adverse events than with full dose.ConclusionsAlthough randomised trials are needed for further evaluation, this study provides evidence for safety and efficacy of chloroquine in COVID-19 and suggests that chloroquine can be a cost-effective therapy for combating 102 the COVID-19 pandemic.

Animal models used to evaluate efficacies of immune checkpoint inhibitors are insufficient or inaccurate. We thus examined two xenograft models used for this purpose, with the aim of optimizing them. One method involves the use of peripheral blood mononuclear cells and cell line-derived xenografts (PBMCs-CDX model). For this model, we implanted human lung cancer cells into NOD-scid-IL2Rg−/− (NSI) mice, followed by injection of human PBMCs. The second method involves the use of hematopoietic stem and progenitor cells and CDX (HSPCs-CDX model). For this model, we first reconstituted the human immune system by transferring human CD34+ hematopoietic stem and progenitor cells (HSPCs-derived humanized model) and then transplanted human lung cancer cells. We found that the PBMCs-CDX model was more accurate in evaluating PD-L1/PD-1 targeted immunotherapies. In addition, it took only four weeks with the PBMCs-CDX model for efficacy evaluation, compared to 10–14 weeks with the HSPCs-CDX model. We then further established PBMCs-derived patient-derived xenografts (PDX) models, including an auto-PBMCs-PDX model using cancer and T cells from the same tumor, and applied them to assess the antitumor efficacies of anti-PD-L1 antibodies. We demonstrated that this PBMCs-derived PDX model was an invaluable tool to study the efficacies of PD-L1/PD-1 targeted cancer immunotherapies. Overall, we found our PBMCs-derived models to be excellent preclinical models for studying immune checkpoint inhibitors.

The oncogene c-Jun plays a key role in development and cancer. Yet, its role in cell fate decision remains poorly understood at the molecular level. Here we report that c-Jun confers different fate decisions upon mouse embryonic stem cells (mESCs) in adhesion vs suspension culture. We developed a Tet-on system for temporal induction of c-Jun expression by Doxycycline treatment in mESCs. We show that mESCs carrying the inducible c-Jun TetOn remain pluripotent and grow slowly in suspension when c-Jun expression is induced, whilst when the cells adhere they undergo differentiation and show normal proliferative potential upon c-Jun induction. Our data indicates that c-Jun pushes mESCs in suspension into cell cycle arrest at G1/S, by activating the cell cycle inhibitors Cdkn1a/b and Cdkn2/a/b/c. Despite this cell cycle arrest, they can still re-enter the cell cycle upon transfer to an adhesive surface, and grow into typical mESC colonies, albeit at a lower efficiency. These results demonstrate that mESCs respond to induced c-Jun overexpression differently in suspension or adherent cultures. Our results suggest that cells in suspension may be more resistant to differentiation than when they adhere. Keywords: c-Jun, mESCs, Differentiation, Suspension

Background Induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) share many common features, including similar morphology, gene expression and in vitro differentiation profiles. However, genomic stability is much lower in iPSCs than in ESCs. In the current study, we examined whether changes in DNA damage repair in iPSCs are responsible for their greater tendency towards mutagenesis. Methods Mouse iPSCs, ESCs and embryonic fibroblasts were exposed to ionizing radiation (4 Gy) to introduce double-strand DNA breaks. At 4 h later, fidelity of DNA damage repair was assessed using whole-genome re-sequencing. We also analyzed genomic stability in mice derived from iPSCs versus ESCs. Results In comparison to ESCs and embryonic fibroblasts, iPSCs had lower DNA damage repair capacity, more somatic mutations and short indels after irradiation. iPSCs showed greater non-homologous end joining DNA repair and less homologous recombination DNA repair. Mice derived from iPSCs had lower DNA damage repair capacity than ESC-derived mice as well as C57 control mice. Conclusions The relatively low genomic stability of iPSCs and their high rate of tumorigenesis in vivo appear to be due, at least in part, to low fidelity of DNA damage repair.

Summary Polycomb repressive complex 1 (PRC1) plays essential roles in cell-fate determination. Recent studies have found that the composition of mammalian PRC1 is particularly varied and complex; however, little is known about the functional consequences of these variant PRC1 complexes on cell-fate determination. Here, we show that Kdm2b promotes Oct4-induced somatic reprogramming through recruitment of a variant PRC1 complex (PRC1.1) to CpG islands (CGIs). Furthermore, we find that bone morphogenetic protein (BMP) represses Oct4/Kdm2b-induced somatic reprogramming selectively. Mechanistically, BMP-SMAD pathway attenuates PRC1.1 occupation and H2AK119 ubiquitination at genes linked to development, resulting in the expression of mesendodermal factors such as Sox17 and a consequent suppression of somatic reprogramming. These observations reveal that PRC1.1 participates in the establishment of pluripotency and identify BMP4 signaling as a modulator of PRC1.1 function.

// Zhiwu Jiang 1, 2, 3 , Di Wu 1, 2 , Wei Ye 1, 2 , Jianyu Weng 4 , Peilong Lai 4 , Pengcheng Shi 5 , Xutao Guo 5 , Guohua Huang 6 , Qiuhua Deng 6 , Yanlai Tang 7 , Hongyu Zhao 8 , Shuzhong Cui 9 , Simiao Lin 1, 2 , Suna Wang 1, 2 , Baiheng Li 1, 2 , Qiting Wu 1, 2 , Yangqiu Li 10 , Pentao Liu 11 , Duanqing Pei 1, 2 , Xin Du 4 , Yao Yao 1, 2, 3 and Peng Li 1, 2, 3 1 Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China 2 Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China 3 Department of Abdominal Surgery, Affiliated Cancer Hospital and Institute of Guangzhou Medical University of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong 510095, China 4 Department of Hematology, Guangdong Provincial People’s Hospital, Guangzhou 510500, China 5 Department of Hematology, Nanfang Hospital, Guangzhou 510500, China 6 Department of Respiratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China 7 Department of Hematology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510500, China 8 The First Affiliated Hospital, University of Zhengzhou, Zhengzhou 450000, China 9 Affiliated Caner Hospital and Institute of Guangzhou Medical University, Guangzhou 510095, China 10 Department of Hematology, Medical College, Jinan University, Guangzhou 510632, China 11 Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1HH, England, UK Correspondence to: Peng Li, email: li_peng@gibh.ac.cn Yao Yao, email: yao_yao@gibh.ac.cn Keywords: B-ALL; microenvironment; growth factors; drug screening; kinase inhibitors Abbreviations: B-ALL: B Acute lymphoblastic leukemia; OP9TA: OP9-derived adipocytes; CDK: cyclin-dependent kinase; FBS: fetal bovine serum; NSI: NOD/SCID/IL2Rg −/− mice Received: June 21, 2017 Accepted: October 28, 2017 Published: November 15, 2017 ABSTRACT Functional screening for compounds represents a major hurdle in the development of rational therapeutics for B-acute lymphoblastic leukemia (B-ALL). In addition, using cell lines as valid models for evaluating responses to novel drug therapies raises serious concerns, as cell lines are prone to genotypic/phenotypic drift and loss of heterogeneity in vitro . Here, we reported that OP9 cells, not OP9-derived adipocytes (OP9TA), support the growth of primary B-ALL cells in vitro . To identify the factors from OP9 cells that support the growth of primary B-ALL cells, we performed RNA-Seq to analyze the gene expression profiles of OP9 and OP9TA cells. We thus developed a defined, serum/feeder-free condition (FI76V) that can support the expansion of a range of clinically distinct primary B-ALL cells that still maintain their leukemia-initiating ability. We demonstrated the suitability of high-throughput drug screening based on our B-ALL cultured conditions. Upon screening 378 kinase inhibitors, we identified a cluster of 17 kinase inhibitors that can efficiently kill B-ALL cells in vitro . Importantly, we demonstrated the synergistic cytotoxicity of dinaciclib/BTG226 to B-ALL cells. Taken together, we developed a defined condition for the ex vivo expansion of primary B-ALL cells that is suitable for high-throughput screening of novel compounds.

How can a skin cell become a nerve cell? This is one of the 125 big questions raised in Science magazine for its 125th anniversary. Here we summarize what we know on this subject. In particular, we discuss recent success in converting fibroblasts, one of the common cells found in skin, into nerve cells including neuron. Despite these successes in making nerve cells of skin cells in laboratory, it is quite challenging in translating these breakthroughs into success in clinic. The nervous system includes the central nervous system, the peripheral nervous system and the autonomic nervous system. Many insults, including infection, poisoning, immune damage, nutritional disorders, endocrine disorders and genetic factors, may damage the nervous system such that nerve cells undergo degeneration, apoptosis, or necrosis, leading to neurological impairments. The impairments in peripheral nerve system may be repaired without much defects with skilled microsurgical techniques. However, options are quite limited in repair lesions in the central nerve system as it was known that neurons in the central nervous system (CNS) could not regenerate after damage and would only be replaced by glial cells. Neuronal stem cells hold great promise in repairing lesions in the nerve systems. While embryonic stem cells may be complicated with ethical issues, adult stem cells such as neuronal stem cells are difficult to isolate and purify, with limited differentiation capacity. One solution is the induction of neuronal cells from skin fibroblast directly. Indeed, in 2010, Vierbuchen et la use three transcription factors, Ascl1 , Brn2/4 and Myt1L (ABM), to directly convert fibroblasts into induced neurons (iNs). Because fibroblasts are easy to obtain, they have become the first choice of the initial cells to induce nerve cells. This technology has become an active area of research in recent years. Going forward, it is possible to apply many similar strategies including transcription factors, small molecules, microRNAs to the induction of neuron, glial cell, astrocyte oligodendrocyte and Schwann cells from fibroblast. The cells generated from these strategies can be used to treat Parkinson′s disease and Amyotrophic lateral sclerosis. There is a bright future for the generation of nerve cells from skin cells. In deed, similar approaches have been attempted in animal models. For human therapy, we must perform more safety tests, improve efficiency and enhance survival rate. Therefore, we need a lot of work done in clinical practice. Most importantly, the investigation of nerve cell generation from skin fibroblast may help us to understand the basic rules and laws of cell fate determination and the mechanism for human developments. Current work is laying a solid foundation for the development of therapies.

Polycomb repressive complex 2 and the epigenetic mark that it deposits, H3K27me3, are evolutionarily conserved and play critical roles in development and cancer. However, their roles in cell fate decisions in early embryonic development remain poorly understood. Here we report that knockout of polycomb repressive complex 2 genes in human embryonic stem cells causes pluripotency loss and spontaneous differentiation toward a meso-endoderm fate, owing to de-repression of BMP signalling. Moreover, human embryonic stem cells with deletion of EZH1 or EZH2 fail to differentiate into ectoderm lineages. We further show that polycomb repressive complex 2-deficient mouse embryonic stem cells also release Bmp4 but retain their pluripotency. However, when converted into a primed state, they undergo spontaneous differentiation similar to that of hESCs. In contrast, polycomb repressive complex 2 is dispensable for pluripotency when human embryonic stem cells are converted into the naive state. Our studies reveal both lineage- and pluripotent state-specific roles of polycomb repressive complex 2 in cell fate decisions., Polycomb repressive complex 2 (PRC2) plays an essential role in development by modifying chromatin but what this means at a cellular level is unclear. Here, the authors show that ablation of PRC2 genes in human embryonic stem cells and in mice results in changes in pluripotency and the primed state of cells.

Chimeric antigen receptor (CAR) T-cell immunotherapies have shown unprecedented success in treating leukemia but limited clinical efficacy in solid tumors. Here, we generated 1928zT2 and m28zT2, targeting CD19 and mesothelin, respectively, by introducing the Toll/interleukin-1 receptor domain of Toll-like receptor 2 (TLR2) to 1928z and m28z. T cells expressing 1928zT2 or m28zT2 showed improved expansion, persistency and effector function against CD19+ leukemia or mesothelin+ solid tumors respectively in vitro and in vivo. In a patient with relapsed B-cell acute lymphoblastic leukemia, a single dose of 5 × 104/kg 1928zT2 T cells resulted in robust expansion and leukemia eradication and led to complete remission. Hence, our results demonstrate that TLR2 signaling can contribute to the efficacy of CAR T cells. Further clinical trials are warranted to establish the safety and efficacy of this approach.

What controls organ regeneration? This is one of the 125 big questions of Science 125th anniversary. And it is one of the most important 25 questions. Many organisms have remarkable regeneration ability, such as earthworm, turbellarian, Gekko japonicas and newt. Unfortunately, all of them are in the bottom of phylogenetic tree, the more higher the loss of this kind of magic. What controls this program? The research of this problem not only could tell us where are we from? Why we are? The most important is the answer would decide our future: it is the dream of developmental biologist and medicine research, all of us. Regeneration means the self-repair and replacement of the organism after the partial structure has been lost. Or recover the shape, structure and function of the original organs after the injury. Some lowly creatures can regenerate damaged organs completely. For example, planarian, cut it from the center, it would become two individuals. In fact even cut it into 279 pieces, it would become 279 individuals. This magic comes from a special kind of cell: neoblasts. These kind of adult stem cells diffuse distribution in the whole body of planarians. As long as the existence of such a cell, they can regenerate a whole planarian. Newt is the master of regeneration in vertebrates. Its limbs, tail, heart, jaw, brain, and retina and lens can be completely regenerated. There is not a fraction of difference of morphology and function of tissue and organ between the original and the regeneration. There are different regeneration mechanisms. The young Japanese salamander often uses stem / progenitor cells in its tissues to regenerate limbs, After adult they use their skeletal muscles to differentiate or transdifferentiate. Despite young or old, all of Salamanders have the common powerful ability of regeneration. By contrast, the regenerative capacity of Xenopus gradually loses as it grows. Early tadpole can regenerate their limb, the late tadpoles and adult Xenopus that after metamorphosis cannot regenerate absolutely. With the evolution, the ability of regeneration is lost step by step. Just like the process of development of embryo, as differentiation becomes more complex, more and more functional, the more loose of pluripotent. Humans, as mammals, retain only a small capacity of regeneration. Replacing damaged, diseased and senescent parts of the human body is always one of humanity’s dreams. The discovery of induced pluripotent stem cells has enabled us to move cells back to their infancy, provide us a useful tool and material to investigate the organ regeneration. But what we know about the mechanism of human regeneration is still very limited. It can be said that 11 years have passed, we have learned a lot, but it is far from enough to reach the goal.

Reprogramming has been shown to involve EMT–MET; however, its role in cell differentiation is unclear. We report here that in vitro differentiation of hESCs to hepatic lineage undergoes a sequential EMT–MET with an obligatory intermediate mesenchymal phase. Gene expression analysis reveals that Activin A-induced formation of definitive endoderm (DE) accompanies a synchronous EMT mediated by autocrine TGFβ signalling followed by a MET process. Pharmacological inhibition of TGFβ signalling blocks the EMT as well as DE formation. We then identify SNAI1 as the key EMT transcriptional factor required for the specification of DE. Genetic ablation of SNAI1 in hESCs does not affect the maintenance of pluripotency or neural differentiation, but completely disrupts the formation of DE. These results reveal a critical mesenchymal phase during the acquisition of DE, highlighting a role for sequential EMT–METs in both differentiation and reprogramming., Reprogramming has been shown to involve EMT-MET; however, its role in cell differentiation is unclear. Here the authors show that during in vitro differentiation of hepatocytes, Activin A-induced formation of definitive endoderm requires EMT mediated by TGFβ signalling, followed by a MET process.

Centriolar satellites are non-membrane cytoplasmic granules that deliver proteins to centrosome during centrosome biogenesis and ciliogenesis. Centriolar satellites are highly dynamic during cell cycle or ciliogenesis and how they are regulated remains largely unknown. We report here that sorting nexin 17 (SNX17) regulates the homeostasis of a subset of centriolar satellite proteins including PCM1, CEP131, and OFD1 during serum-starvation-induced ciliogenesis. Mechanistically, SNX17 recruits the deubiquitinating enzyme USP9X to antagonize the mindbomb 1 (MIB1)-induced ubiquitination and degradation of PCM1. SNX17 deficiency leads to enhanced degradation of USP9X as well as PCM1 and disrupts ciliogenesis upon serum starvation. On the other hand, SNX17 is dispensable for the homeostasis of PCM1 and USP9X in serum-containing media. These findings reveal a SNX17/USP9X mediated pathway essential for the homeostasis of centriolar satellites under serum starvation, and provide insight into the mechanism of USP9X in ciliogenesis, which may lead to a better understating of USP9X-deficiency-related human diseases such as X-linked mental retardation and neurodegenerative diseases.

The success of Yamanaka factor reprogramming of somatic cells into induced pluripotent stem cells suggests that some factor(s) must remodel the nuclei from a condensed state to a relaxed state. How factor‐dependent chromatin opening occurs remains unclear. Using FRAP and ATAC‐seq, we found that Oct4 acts as a pioneer factor that loosens heterochromatin and facilitates the binding of Klf4 and the expression of epithelial genes in early reprogramming, leading to enhanced mesenchymal‐to‐epithelial transition. A mutation in the Oct4 linker, L80A, which shows impaired interaction with the BAF complex component Brg1, is inactive in heterochromatin loosening. Oct4‐L80A also blocks the binding of Klf4 and retards MET. Finally, vitamin C or Gadd45a could rescue the reprogramming deficiency of Oct4‐L80A by enhancing chromatin opening and Klf4 binding. These studies reveal a cooperation between Oct4 and Klf4 at the chromatin level that facilitates MET at the cellular level and shed light into the research of multiple factors in cell fate determination.

Somatic cell reprogramming provides insight into basic principles of cell fate determination, which remain poorly understood. Here we show that the transcription factor Glis1 induces multi-level epigenetic and metabolic remodelling in stem cells that facilitates the induction of pluripotency. We find that Glis1 enables reprogramming of senescent cells into pluripotent cells and improves genome stability. During early phases of reprogramming, Glis1 directly binds to and opens chromatin at glycolytic genes, whereas it closes chromatin at somatic genes to upregulate glycolysis. Subsequently, higher glycolytic flux enhances cellular acetyl-CoA and lactate levels, thereby enhancing acetylation (H3K27Ac) and lactylation (H3K18la) at so-called 'second-wave' and pluripotency gene loci, opening them up to facilitate cellular reprogramming. Our work highlights Glis1 as a powerful reprogramming factor, and reveals an epigenome-metabolome-epigenome signalling cascade that involves the glycolysis-driven coordination of histone acetylation and lactylation in the context of cell fate determination.

The interplay between the Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC) and transcriptional/epigenetic co-regulators in somatic cell reprogramming is incompletely understood. Here, we demonstrate that the histone H3 lysine 27 trimethylation (H3K27me3) demethylase JMJD3 plays conflicting roles in mouse reprogramming. On one side, JMJD3 induces the pro-senescence factor Ink4a and degrades the pluripotency regulator PHF20 in a reprogramming factor-independent manner. On the other side, JMJD3 is specifically recruited by KLF4 to reduce H3K27me3 at both enhancers and promoters of epithelial and pluripotency genes. JMJD3 also promotes enhancer-promoter looping through the cohesin loading factor NIPBL and ultimately transcriptional elongation. This competition of forces can be shifted towards improved reprogramming by using early passage fibroblasts or boosting JMJD3’s catalytic activity with vitamin C. Our work, thus, establishes a multifaceted role for JMJD3, placing it as a key partner of KLF4 and a scaffold that assists chromatin interactions and activates gene transcription., Previous work suggested that histone demethylase JMJD3 is detrimental to somatic cell reprogramming. Here, the authors show that while JMJD3 has a context-independent detrimental effect on early stages of reprogramming, during late stages it activates epithelial and pluripotency genes together with Klf4.

Both metabolic switch from oxidative phosphorylation to glycolysis (OGS) and epithelial–mesenchymal transition (EMT) promote cellular reprogramming at early stages. However, their connections have not been elucidated. Here, when a chemically defined medium was used to induce early EMT during mouse reprogramming, a facilitated OGS was also observed at the same time. Additional investigations suggested that the two events formed a positive feedback loop via transcriptional activation, cooperated to upregulate epigenetic factors such as Bmi1, Ctcf, Ezh2, Kdm2b, and Wdr5, and accelerated pluripotency induction at the early stage. However, at late stages, by over‐inducing glycolysis and preventing the necessary mesenchymal–epithelial transition, the two events trapped the cells at a new pluripotency state between naïve and primed states and inhibited further reprogramming toward the naïve state. In addition, the pluripotent stem cells at the new state have high similarity to epiblasts from E4.5 and E5.5 embryos, and have distinct characteristics from the previously reported epiblast‐like or formative states. Therefore, the time‐dependent cooperation between OGS and EMT in regulating pluripotency should extend our understanding of related fields., Stage‐specific synergy between EMT and energy metabolism defines a new intermediate state in reprogramming.

Although theSleeping Beauty(SB) transposon is the most validated DNA transposon used as a gene delivery vehicle in vertebrates, many details of the excision and integration steps in the transposition process are unclear. We have probed in detail the products of the excision step and apparent selective integration of a subset of those products during transposition. The standard model of SB transposase-mediated transposition includes symmetrical cleavages at both ends of the transposon for excision and re-integration in another DNA sequence. In our analysis of excised transposon fragments (ETFs), we found evidence for the requirement of certain flanking sequences for efficient cleavage and a significant rate of asymmetrical cleavage during the excision process that generates multiple ETFs. Our results suggest that the cleavage step by SB transposase is not as precise as indicated in most models. Repair of the donor ends can produce eight footprint sequences (TACTGTA, TACAGTA, TACATA, TACGTA, TATGTA, TACTA, TAGTA and TATA). Our data also suggest that mismatch repair (MMR) is not an essential requirement for footprint formation. Among the twenty liberated ETFs, only eight appear to effectively re-integrate into TA sites distributed across the genome, supporting earlier findings of unequal rates of excision and reintegration during SB transposition. These findings may be important in considerations of efficiency of SB transposon remobilization, selection of TA integration sites and detection of SB excision and integration loci, all of which may be important in human gene therapy.

We recently derived mouse expanded potential stem cells (EPSCs) from individual blastomeres by inhibiting the critical molecular pathways that predispose their differentiation. EPSCs had enriched molecular signatures of blastomeres and possessed developmental potency for all embryonic and extra-embryonic cell lineages. Here, we report the derivation of porcine EPSCs, which express key pluripotency genes, are genetically stable, permit genome editing, differentiate to derivatives of the three germ layers in chimeras and produce primordial germ cell-like cells in vitro. Under similar conditions, human embryonic stem cells and induced pluripotent stem cells can be converted, or somatic cells directly reprogrammed, to EPSCs that display the molecular and functional attributes reminiscent of porcine EPSCs. Importantly, trophoblast stem-cell-like cells can be generated from both human and porcine EPSCs. Our pathway-inhibition paradigm thus opens an avenue for generating mammalian pluripotent stem cells, and EPSCs present a unique cellular platform for translational research in biotechnology and regenerative medicine.

Summary: Known as a histone H3K9 methyltransferase, SETDB1 is essential for embryonic development and pluripotent inner cell mass (ICM) establishment. However, its function in pluripotency regulation remains elusive. In this study, we find that under the “ground state” of pluripotency with two inhibitors (2i) of the MEK and GSK3 pathways, Setdb1-knockout fails to induce trophectoderm (TE) differentiation as in serum/LIF (SL), indicating that TE fate restriction is not the direct target of SETDB1. In both conditions, Setdb1-knockout activates a group of genes targeted by SETDB1-mediated H3K9 methylation, including Dux. Notably, Dux is indispensable for the reactivation of 2C-like state genes upon Setdb1 deficiency, delineating the mechanistic role of SETDB1 in totipotency restriction. Furthermore, Setdb1-null ESCs maintain pluripotent marker (e.g., Nanog) expression in the 2i condition. This “ground state” Setdb1-null population undergoes rapid cell death by activating Ripk3 and, subsequently, RIPK1/RIPK3-dependent necroptosis. These results reveal the essential role of Setdb1 between totipotency and pluripotency transition. : Wu et al. report the essential role of Setdb1 in the cell fate transition between totipotency and pluripotency. Setdb1-KO ESCs activate a group of genes targeted by SETDB1-mediated H3K9 methylation, including Dux, then initiate 2C-like totipotency transition. Moreover, Setdb1-KO triggers ESC necroptosis in the “ground state” by activating Ripk3. Keywords: Setdb1, H3K9 methylation, 2C-like totipotency, necroptosis