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Heterozygous loss-of-function mutations in GRIN2B,a subunit of the NMDA receptor,cause intellectual disability and language impairment. We developed clonal models of GRIN2B deletion and loss-of-function mutations in a region coding for the glutamate binding domain in human cells and generated neurons from a patient harboring a missense mutation in the same domain. Transcriptome analysis revealed extensive increases in genes associated with cell proliferation and decreases in genes associated with neuron differentiation,a result supported by extensive protein analyses. Using electrophysiology and calcium imaging,we demonstrate that NMDA receptors are present on neural progenitor cells and that human mutations in GRIN2B can impair calcium influx and membrane depolarization even in a presumed undifferentiated cell state,highlighting an important role for non-synaptic NMDA receptors. It may be this function,in part,which underlies the neurological disease observed in patients with GRIN2B mutations. View Publication

In this study,we sought to establish a novel method to prospectively and dynamically identify live human oligodendrocyte precursor cells (OPCs) and oligodendrocyte lineage cells from brain dissociates and pluripotent stem cell culture. We selected a highly conserved enhancer element of the Sox10 gene,known as MCS5,which directs reporter expression to oligodendrocyte lineage cells in mouse and zebrafish. We demonstrate that lentiviral Sox10-MCS5 induced expression of GFP at high levels in a subpopulation of human CD140a/PDGF??R-sorted OPCs as well as their immature oligodendrocyte progeny. Furthermore,we show that almost all Sox10-MCS5:GFPhigh cells expressed OPC antigen CD140a and human OPCs expressing SOX10,OLIG2,and PDGFRA mRNAs could be prospectively identified using GFP based fluorescence activated cells sorting alone. Additionally,we established a human induced pluripotent cell (iPSC) line transduced with the Sox10-MCS5:GFP reporter using a Rex-Neo cassette. Similar to human primary cells,GFP expression was restricted to embryoid bodies containing both oligodendrocyte progenitor and oligodendrocyte cells and co-localized with NG2 and O4-positive cells respectively. As such,we have developed a novel reporter system that can track oligodendrocyte commitment in human cells,establishing a valuable tool to improve our understanding and efficiency of human oligodendrocyte derivation. ?? 2013 Elsevier Inc. View Publication

The developmental pathway for human megakaryocytes remains unclear and the definition of pure unipotent megakaryocyte progenitor is still controversial. Using single-cell transcriptome analysis,we have identified a cluster of cells within immature hematopoietic stem and progenitor cell populations that specifically express genes related to the megakaryocyte lineage. We used CD41 as a positive marker to identify these cells within the CD34(+)CD38(+)IL-3Rα(dim)CD45RA(-) common myeloid progenitor (CMP) population. These cells lacked erythroid and granulocyte/macrophage potential,but exhibited robust differentiation into the megakaryocyte lineage at a high frequency,both in vivo and in vitro The efficiency and expansion potential of these cells exceeded those of conventional bipotent megakaryocyte/erythrocyte progenitors. Accordingly,the CD41(+) CMP was defined as a unipotent megakaryocyte progenitor (MegP) that is likely to represent the major pathway for human megakaryopoiesis,independent of canonical megakaryocyte-erythroid lineage bifurcation. In the bone marrow of patients with essential thrombocythemia,the MegP population was significantly expanded in the context of a high burden of Janus kinase 2 mutations. Thus,the prospectively isolatable and functionally homogeneous human MegP will be useful for the elucidation of the mechanisms underlying normal and malignant human hematopoiesis. View Publication

In mammals,early embryonic gastrulation process is high energy demanding. Previous studies showed that,unlike endoderm and mesoderm cells,neuroectoderm differentiated from human embryonic stem cells relied on aerobic glycolysis as the major energy metabolic process,which generates lactate as the final product. Here we explored the function of intracellular lactate during neuroectoderm differentiation. Our results revealed that the intracellular lactate level was elevated in neuroectoderm and exogenous lactate could further promote hESCs differentiation towards neuroectoderm. Changing intracellular lactate levels by sodium lactate or LDHA inhibitors had no obvious effect on BMP or WNT/?-catenin signaling during neuroectoderm differentiation. Notably,histone lactylation,especially H3K18 lactylation was significant upregulated during this process. We further performed CUT&Tag experiments and the results showed that H3K18la is highly enriched at gene promoter regions. By analyzing data from CUT&Tag and RNA-seq experiments,we further identified that four genes,including PAX6,were transcriptionally upregulated by lactate during neuroectoderm differentiation. A H3K18la modification site at PAX6 promoter was verified and exogenous lactate could also rescue the level of PAX6 after shPAX6 inhibition.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00018-024-05510-x. View Publication

We recently reported the development of three monoclonal antibodies (MoAbs) to biologically active human erythropoietin (Ep). In the present study,we investigated the epitope specificity of these three antibodies,as well as their reactivity with Eps derived from species other than man. All three antibodies reacted with the Ep polypeptide itself,rather than with its carbohydrate moieties. Moreover,all three antibodies recognized separate nonoverlapping epitopes. Further studies with reduced/alkylated Ep and with sodium dodecyl sulfate-denatured Ep suggested that two of the MoAbs,anti-Ep-2 and anti-Ep-16,were specific for conformational,nonlinear determinants on the Ep molecule,whereas the third MoAb,anti-Ep-26,appeared to recognize a linear epitope. However,anti-Ep-26 did not react with synthetic peptides representing the 26 amino-,the 99-129 mid-region,or the 10 carboxy-terminal residues of Ep,nor with trypsin-,chymotrypsin-,or V8 protease-digested fragments of Ep. When tested with Ep from different species,the neutralizing capabilities of the three MoAbs were clearly different. Comparing their effectiveness against baboon,ovine and murine Ep,antibody 2 was most effective at neutralizing baboon Ep,antibody 16 was most effective against murine Ep,and antibody 26 showed little reactivity with any of these nonhuman Eps. Because these various Eps readily stimulate across species barriers,it is likely that the receptor binding domain on Ep has remained relatively conserved during evolution. Our results therefore suggest that the neutralizing capacity of our three anti-Ep MoAbs is caused not by binding directly to the Ep receptor binding domain on Ep,but by binding to distant regions,causing conformational changes in Ep,or by binding to regions close to the binding site,steric hindrance. View Publication

Efficient strategies for precise genome editing in human-induced pluripotent cells (hiPSCs) will enable sophisticated genome engineering for research and clinical purposes. The development of programmable sequence-specific nucleases such as Transcription Activator-Like Effectors Nucleases (TALENs) and Cas9-gRNA allows genetic modifications to be made more efficiently at targeted sites of interest. However,many opportunities remain to optimize these tools and to enlarge their spheres of application. We present several improvements: First,we developed functional re-coded TALEs (reTALEs),which not only enable simple one-pot TALE synthesis but also allow TALE-based applications to be performed using lentiviral vectors. We then compared genome-editing efficiencies in hiPSCs mediated by 15 pairs of reTALENs and Cas9-gRNA targeting CCR5 and optimized ssODN design in conjunction with both methods for introducing specific mutations. We found Cas9-gRNA achieved 7-8× higher non-homologous end joining efficiencies (3%) than reTALENs (0.4%) and moderately superior homology-directed repair efficiencies (1.0 versus 0.6%) when combined with ssODN donors in hiPSCs. Using the optimal design,we demonstrated a streamlined process to generated seamlessly genome corrected hiPSCs within 3 weeks. View Publication

Standardization of mesenchymal stromal cells (MSCs) remains a major obstacle in regenerative medicine. Starting material and culture expansion affect cell preparations and render comparison between studies difficult. In contrast,induced pluripotent stem cells (iPSCs) assimilate toward a ground state and may therefore give rise to more standardized cell preparations. We reprogrammed MSCs into iPSCs,which were subsequently redifferentiated toward MSCs. These iPS-MSCs revealed similar morphology,immunophenotype,in vitro differentiation potential,and gene expression profiles as primary MSCs. However,iPS-MSCs were impaired in suppressing T cell proliferation. DNA methylation (DNAm) profiles of iPSCs maintained donor-specific characteristics,whereas tissue-specific,senescence-associated,and age-related DNAm patterns were erased during reprogramming. iPS-MSCs reacquired senescence-associated DNAm during culture expansion,but they remained rejuvenated with regard to age-related DNAm. Overall,iPS-MSCs are similar to MSCs,but they reveal incomplete reacquisition of immunomodulatory function and MSC-specific DNAm patterns - particularly of DNAm patterns associated with tissue type and aging. View Publication

Normal prion protein (PrP(c)),an essential substrate for development of prion disease,is widely distributed in hematopoietic cells. Recent evidence that variant Creutzfeldt-Jakob disease can be transmitted by transfusion of red cell preparations has highlighted the need for a greater understanding of the biology of PrP(c) in blood and blood-forming tissues. Here,we show that in contrast to another glycosylphosphoinositol-anchored protein CD59,PrP(c) at the cell surface of cultured human erythroblasts is rapidly internalized through the endosomal pathway,where it colocalizes with the tetraspanin CD63. In the plasma membrane,PrP(c) colocalizes with the tetraspanin CD81. Cross-linking with anti-PrP(c) or anti-CD81 causes clustering of PrP(c) and CD81,suggesting they can share the same microdomain. These data are consistent with a role for tetraspanin-enriched microdomains in trafficking of PrP(c). These results,when taken together with recent evidence that exosomes released from cells as a result of endosomal-mediated recycling to the plasma membrane contain prion infectivity,provide a pathway for the propagation of prion diseases. View Publication

Induced pluripotent stem (iPS) cells hold the potential to revolutionize regenerative medicine through their capacity to generate cells of diverse lineages for future patient-specific cell-based therapies. To facilitate the transition of iPS cells to clinical practice,a variety of technologies have been developed for transgene-free pluripotency reprogramming. We recently reported efficient iPS cell generation from human fibroblasts using synthetic modified mRNAs. Here we describe a stepwise protocol for the generation of modified mRNA-derived iPS cells from primary human fibroblasts,focusing on the critical parameters including medium choice,quality control,and optimization steps needed for synthesizing modified mRNAs encoding reprogramming factors and introducing these into cells over the course of 2-3 weeks to ensure successful reprogramming. The protocol described herein is for reprogramming of human fibroblasts to pluripotency; however,the properties of modified mRNA make it a powerful platform for protein expression,which has broad applicability in directed differentiation,cell fate specification and therapeutic applications. View Publication

The principal organization of mammalian neuromuscular junctions (NMJs) shares essential features across species. However,human NMJs (hNMJs) exhibit distinct structural and physiological properties. While recent advances in stem-cell-based systems have significantly improved in vitro modeling of hNMJs,the extent to which these models recapitulate in vivo development remains unclear. Here,we performed temporal transcriptomic analysis of human three-dimensional (3D) neuromuscular co-cultures,composed of iPSC-derived motoneurons and skeletal muscle engineered from primary myoblasts. We found that the expression pattern follows a temporally coordinated gene expression program underlying NMJ maturation. The model recapitulates transcriptional features of NMJ development,including early myoblast fusion and presynaptic development,followed by a late-stage upregulation of postsynaptic markers and embryonic AChR subunits. Importantly,comparable transcriptional dynamics across two independent hiPSC lines confirm the reproducibility and robustness of this system. This study confirms on a transcriptional level that human 3D neuromuscular co-cultures are a robust and physiologically relevant model for investigating hNMJ development and function. View Publication

We have studied the mechanism of A-769662,a new activator of AMP-activated protein kinase (AMPK). Unlike other pharmacological activators,it directly activates native rat AMPK by mimicking both effects of AMP,i.e. allosteric activation and inhibition of dephosphorylation. We found that it has no effect on the isolated alpha subunit kinase domain,with or without the associated autoinhibitory domain,or on interaction of glycogen with the beta subunit glycogen-binding domain. Although it mimics actions of AMP,it has no effect on binding of AMP to the isolated Bateman domains of the gamma subunit. The addition of A-769662 to mouse embryonic fibroblasts or primary mouse hepatocytes stimulates phosphorylation of acetyl-CoA carboxylase (ACC),effects that are completely abolished in AMPK-alpha1(-/-)alpha2(-/-) cells but not in TAK1(-/-) mouse embryonic fibroblasts. Phosphorylation of AMPK and ACC in response to A-769662 is also abolished in isolated mouse skeletal muscle lacking LKB1,a major upstream kinase for AMPK in this tissue. However,in HeLa cells,which lack LKB1 but express the alternate upstream kinase calmodulin-dependent protein kinase kinase-beta,phosphorylation of AMPK and ACC in response to A-769662 still occurs. These results show that in intact cells,the effects of A-769662 are independent of the upstream kinase utilized. We propose that this direct and specific AMPK activator will be a valuable experimental tool to understand the physiological roles of AMPK. View Publication

Protein kinase Ciota (PKCiota) is an oncogene required for maintenance of the transformed phenotype of non-small cell lung cancer cells. However,the role of PKCiota in lung tumor development has not been investigated. To address this question,we established a mouse model in which oncogenic Kras(G12D) is activated by Cre-mediated recombination in the lung with or without simultaneous genetic loss of the mouse PKCiota gene,Prkci. Genetic loss of Prkci dramatically inhibits Kras-initiated hyperplasia and subsequent lung tumor formation in vivo. This effect correlates with a defect in the ability of Prkci-deficient bronchioalveolar stem cells to undergo Kras-mediated expansion and morphologic transformation in vitro and in vivo. Furthermore,the small molecule PKCiota inhibitor aurothiomalate inhibits Kras-mediated bronchioalveolar stem cell expansion and lung tumor growth in vivo. Thus,Prkci is required for oncogene-induced expansion and transformation of tumor-initiating lung stem cells. Furthermore,aurothiomalate is an effective antitumor agent that targets the tumor-initiating stem cell niche in vivo. These data have important implications for PKCiota as a therapeutic target and for the clinical use of aurothiomalate for lung cancer treatment. View Publication