Scientific Resources

Mitochondria are critical to neurogenesis,but the mechanisms of mitochondria in neurogenesis have not been well explored. We fully characterized mitochondrial alterations and function in relation to the development of human induced pluripotent stem cell (hiPSC)-derived dopaminergic (DA) neurons. Following directed differentiation of hiPSCs to DA neurons,mitochondria in these neurons exhibit pronounced changes during differentiation,including mature neurophysiology characterization and functional synaptic network formation. Inhibition of mitochondrial respiratory chains via application of complex IV inhibitor KCN (potassium cyanide) or complex I inhibitor rotenone restricted neurogenesis of DA neurons. These results demonstrated the direct importance of mitochondrial development and bioenergetics in DA neuronal differentiation. Our study also provides a neurophysiologic model of mitochondrial involvement in neurogenesis,which will enhance our understanding of the role of mitochondrial dysfunctions in neurodegenerative diseases. View Publication

T cell activation in response to Ag is largely regulated by protein posttranslational modifications. Although phosphorylation has been extensively characterized in T cells,much less is known about the glycosylation of serine/threonine residues by O-linked N-acetylglucosamine (O-GlcNAc). Given that O-GlcNAc appears to regulate cell signaling pathways and protein activity similarly to phosphorylation,we performed a comprehensive analysis of O-GlcNAc during T cell activation to address the functional importance of this modification and to identify the modified proteins. Activation of T cells through the TCR resulted in a global elevation of O-GlcNAc levels and in the absence of O-GlcNAc,IL-2 production and proliferation were compromised. T cell activation also led to changes in the relative expression of O-GlcNAc transferase (OGT) isoforms and accumulation of OGT at the immunological synapse of murine T cells. Using a glycoproteomics approach,we identified textgreater200 O-GlcNAc proteins in human T cells. Many of the identified proteins had a functional relationship to RNA metabolism,and consistent with a connection between O-GlcNAc and RNA,inhibition of OGT impaired nascent RNA synthesis upon T cell activation. Overall,our studies provide a global analysis of O-GlcNAc dynamics during T cell activation and the first characterization,to our knowledge,of the O-GlcNAc glycoproteome in human T cells. View Publication

Autosomal dominant vitreoretinochoroidopathy (ADVIRC) is a rare,early-onset retinal dystrophy characterised by distinct bands of circumferential pigmentary degeneration in the peripheral retina and developmental eye defects. ADVIRC is caused by mutations in the Bestrophin1 (BEST1) gene,which encodes a transmembrane protein thought to function as an ion channel in the basolateral membrane of retinal pigment epithelial (RPE) cells. Previous studies suggest that the distinct ADVIRC phenotype results from alternative splicing of BEST1 pre-mRNA. Here,we have used induced pluripotent stem cell (iPSC) technology to investigate the effects of an ADVIRC associated BEST1 mutation (c.704T textgreater C,p.V235A) in patient-derived iPSC-RPE. We found no evidence of alternate splicing of the BEST1 transcript in ADVIRC iPSC-RPE,however in patient-derived iPSC-RPE,BEST1 was expressed at the basolateral membrane and the apical membrane. During human eye development we show that BEST1 is expressed more abundantly in peripheral RPE compared to central RPE and is also expressed in cells of the developing retina. These results suggest that higher levels of mislocalised BEST1 expression in the periphery,from an early developmental stage,could provide a mechanism that leads to the distinct clinical phenotype observed in ADVIRC patients. View Publication

Regulation of gene expression in immune cells is known to be under genetic control,and likely contributes to susceptibility to autoimmune diseases such as multiple sclerosis (MS). How this occurs in concert across multiple immune cell types is poorly understood. Using a mouse model that harnesses the genetic diversity of wild-derived mice,more accurately reflecting genetically diverse human populations,we provide an extensive characterization of the genetic regulation of gene expression in five different naive immune cell types relevant to MS. The immune cell transcriptome is shown to be under profound genetic control,exhibiting diverse patterns: global,cell-specific and sex-specific. Bioinformatic analysis of the genetically controlled transcript networks reveals reduced cell type specificity and inflammatory activity in wild-derived PWD/PhJ mice,compared with the conventional laboratory strain C57BL/6J. Additionally,candidate MS-GWAS (genome-wide association study candidate genes for MS susceptibility) genes were significantly enriched among transcripts overrepresented in C57BL/6J cells compared with PWD. These expression level differences correlate with robust differences in susceptibility to experimental autoimmune encephalomyelitis,the principal model of MS,and skewing of the encephalitogenic T-cell responses. Taken together,our results provide functional insights into the genetic regulation of the immune transcriptome,and shed light on how this in turn contributes to susceptibility to autoimmune disease.Genes and Immunity advance online publication,22 September 2016; doi:10.1038/gene.2016.37. View Publication

BACKGROUND Recently,accumulating evidence has shown that exosomes,the naturally secreted nanocarriers of cells,can exert therapeutic effects in various disease models in the absence of parent cells. However,application of exosomes in bone defect repair and regeneration has been rarely reported,and little is known regarding their underlying mechanisms. METHODS Exosomes derived from human-induced pluripotent stem cell-derived mesenchymal stem cells (hiPS-MSC-Exos) were combined with tricalcium phosphate (β-TCP) to repair critical-sized calvarial bone defects,and the efficacy was assessed by histological examination. We evaluated the in vitro effects of hiPSC-MSC-Exos on the proliferation,migration,and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) by cell-counting,scratch assays,and qRT-PCR,respectively. Gene expression profiling and bioinformatics analyses were also used to identify the underlying mechanisms in the repair. RESULTS We found that the exosome/β-TCP combination scaffolds could enhance osteogenesis as compared to pure β-TCP scaffolds. In vitro assays showed that the exosomes could release from β-TCP and could be internalized by hBMSCs. In addition,the internalization of exosomes into hBMSCs could profoundly enhance the proliferation,migration,and osteogenic differentiation of hBMSCs. Furthermore,gene expression profiling and bioinformatics analyses demonstrated that exosome/β-TCP combination scaffolds significantly altered the expression of a network of genes involved in the PI3K/Akt signaling pathway. Functional studies further confirmed that the PI3K/Akt signaling pathway was the critical mediator during the exosome-induced osteogenic responses of hBMSCs. CONCLUSIONS We propose that the exosomes can enhance the osteoinductivity of β-TCP through activating the PI3K/Akt signaling pathway of hBMSCs,which means that the exosome/β-TCP combination scaffolds possess better osteogenesis activity than pure β-TCP scaffolds. These results indicate that naturally secreted nanocarriers-exosomes can be used as a bioactive material to improve the bioactivity of the biomaterials,and that hiPS-MSC-Exos combined with β-TCP scaffolds can be potentially used for repairing bone defects. View Publication

Leukocyte microvilli are flexible projections enriched with adhesion molecules. The role of these cellular projections in the ability of T cells to probe antigen-presenting cells has been elusive. In this study,we probe the spatial relation of microvilli and T-cell receptors (TCRs),the major molecules responsible for antigen recognition on the T-cell membrane. To this end,an effective and robust methodology for mapping membrane protein distribution in relation to the 3D surface structure of cells is introduced,based on two complementary superresolution microscopies. Strikingly,TCRs are found to be highly localized on microvilli,in both peripheral blood human T cells and differentiated effector T cells,and are barely found on the cell body. This is a decisive demonstration that different types of T cells universally localize their TCRs to microvilli,immediately pointing to these surface projections as effective sensors for antigenic moieties. This finding also suggests how previously reported membrane clusters might form,with microvilli serving as anchors for specific T-cell surface molecules. View Publication

Wnt signaling is a key regulator of vertebrate heart development; however,specific roles for human cardiomyocyte development remain uncertain. Here we use human embryonic stem cells (hESCs) to analyze systematically in human cardiomyocyte development the expression of endogenous Wnt signaling components,monitor pathway activity,and dissect stage-specific requirements for canonical and noncanonical Wnt signaling mechanisms using small-molecule inhibitors. Our analysis suggests that WNT3 and WNT8A,via FZD7 and canonical signaling,regulate BRACHYURY expression and mesoderm induction; that WNT5A/5B,via ROR2 and noncanonical signaling,regulate MESP1 expression and cardiovascular development; and that later in development WNT2,WNT5A/5B,and WNT11,via FZD4 and FZD6,regulate functional cardiomyocyte differentiation via noncanonical Wnt signaling. Our findings confirm in human development previously proposed roles for canonical Wnt signaling in sequential stages of vertebrate cardiomyogenesis,and identify more precise roles for noncanonical signaling and for individual Wnt signal and Wnt receptor genes in human cardiomyocyte development. View Publication

Human induced pluripotent stem cells (hiPSCs) secrete essential autocrine factors that are removed along with toxic metabolites when the growth medium is exchanged daily. In this study,after determining the minimum inhibitory level of lactic acid for hiPSCs,a medium refining system was constructed by which toxic metabolites were removed from used culture medium and autocrine factors as well as other growth factors were recycled. Specifically,about 87 % of the basic fibroblast growth factor and 80 % of transforming growth factor beta 1 were retained in the refined medium after dialysis. The refined medium efficiently potentiated the proliferation of hiPS cells in adherent culture. When the refining system was used to refresh medium in suspension culture,a final cell density of (1.1 ± 0.1) × 10(6) cells mL(-1) was obtained,with 99.5 ± 0.2 % OCT 3/4 and 78.3 ± 1.1 % TRA-1-60 expression,on day 4 of culture. These levels of expression were similar to those observed in the conventional suspension culture. With this method,culture medium refinement by dialysis was established to remove toxic metabolites,recycle autocrine factors as well as other growth factors,and reduce the use of macromolecules for the expansion of hiPSCs in suspension culture. View Publication

The mechanisms of how signaling pathways are coordinated and integrated for the maintenance of the self-renewal of human embryonic stem cells (hESCs) and the acquisition of pluripotency in reprogramming are still only partly understood. CDK1 is a key regulator of mitosis. Recently,CDK1 has been shown to be involved in regulating self-renewal of stem cells,even though the mechanistic role of how CDK1 regulates pluripotency is unknown. In this report,we aim to understand how CDK1 can control pluripotency by reducing CDK1 activity to a level that has no effect on cell cycle progression. We demonstrated that high levels of CDK1 is associated with the pluripotency stage of hESCs; and decreased CDK1 activity to a level without perturbing the cell cycle is sufficient to induce differentiation. CDK1 specifically targets the phosphorylation of PDK1 and consequently the activity of PI3K/Akt and its effectors ERK and GSK3β. Evidence of the reversion of inactive CDK1-mediated differentiation by the inhibition of Akt signaling effectors suggests that the CDK1-PDK1-PI3K/Akt kinase cascade is a functional signaling pathway for the pluripotency of hESCs. Moreover,cyclin B1-CDK1 complexes promote somatic reprogramming efficiency,probably by regulating the maturation of induced pluripotent stem cells (iPSCs),as cyclin B1 stimulates a higher cellular level of LIN28A,suggesting that monitoring iPSC factors could be a new path for the enhancement of reprogramming efficiency. Together,we demonstrate an essential role for the CDK1-PDK1-PI3K/Akt kinase signaling pathway in the regulation of self-renewal,differentiation,and somatic reprogramming,which provides a novel kinase cascade mechanism for pluripotency control and acquisition.Cell Death and Differentiation advance online publication,16 September 2016; doi:10.1038/cdd.2016.84. View Publication

A comprehensive genetics-based precision medicine strategy to selectively and permanently inactivate only mutant,not normal allele,could benefit many dominantly inherited disorders. Here,we demonstrate the power of our novel strategy of inactivating the mutant allele using haplotype-specific CRISPR/Cas9 target sites in Huntington's disease (HD),a late-onset neurodegenerative disorder due to a toxic dominant gain-of-function CAG expansion mutation. Focusing on improving allele specificity,we combined extensive knowledge of huntingtin (HTT) gene haplotype structure with a novel personalized allele-selective CRISPR/Cas9 strategy based on Protospacer Adjacent Motif (PAM)-altering SNPs to target patient-specific CRISPR/Cas9 sites,aiming at the mutant HTT allele-specific inactivation for a given diplotype. As proof-of-principle,simultaneously using two CRISPR/Cas9 guide RNAs (gRNAs) that depend on PAM sites generated by SNP alleles on the mutant chromosome,we selectively excised ∼44 kb DNA spanning promoter region,transcription start site,and the CAG expansion mutation of the mutant HTT gene,resulting in complete inactivation of the mutant allele without impacting the normal allele. This excision on the disease chromosome completely prevented the generation of mutant HTT mRNA and protein,unequivocally indicating permanent mutant allele-specific inactivation of the HD mutant allele. The perfect allele selectivity with broad applicability of our strategy in disorders with diverse disease haplotypes should also support precision medicine through inactivation of many other gain-of-function mutations. View Publication

AIMS The aim of this study was to improve a method that induce cartilage differentiation of human embryoid stem cells (hESCs) in vitro,and test the effect of in vivo environments on the further maturation of hESCs derived cells. MAIN METHODS Embryoid bodies (EBs) formed from hESCs,with serum-free KSR-based medium and mesodermal specification related factors,CHIR,and Noggin for first 8days. Then cells were digested and cultured as micropellets in serum-free KSR-based chondrogenic medium that was supplemented with PDGF-BB,TGF β3,BMP4 in sequence for 24days. The morphology,FACS,histological staining as well as the expression of chondrogenic specific genes were detected in each stage,and further in vivo experiments,cell injections and tissue transplantations,further verified the formation of chondrocytes. KEY FINDINGS We were able to obtain chondrocyte/cartilage from hESCs using serum-free KSR-based conditioned medium. qPCR analysis showed that expression of the chondroprogenitor genes and the chondrocyte/cartilage matrix genes. Morphology analysis demonstrated we got PG+COL2+COL1-particles. It indicated we obtained hyaline cartilage-like particles. 32-Day differential cells were injected subcutaneous. Staining results showed grafts developed further mature in vivo. But when transplanted in subrenal capsule,their effect was not good as in subcutaneous. Microenvironment might affect the cartilage formation. SIGNIFICANCE The results of this study provide an absolute serum-free and efficient approach for generation of hESC-derived chondrocytes,and cells will become further maturation in vivo. It provides evidence and technology for the hypothesis that hESCs may be a promising therapy for the treatment of cartilage disease. View Publication

OBJECTIVE The aim of this study was to evaluate the distribution,concentration and toxicity of cinnamaldehyde in electronic cigarette (e-cigarette) refill fluids and aerosols. METHODS The distribution and concentration of cinnamaldehyde were determined in 39 e-cigarette refill fluids plus 6 duplicates using gas chromatography and mass spectrometry (GC/MS). A cinnamaldehyde toxicity profile was established for embryonic and adult cells using a live cell imaging assay,immunocytochemistry,the comet assay and a recovery assay. RESULTS Twenty of the 39 refill fluids contained cinnamaldehyde at concentrations that are cytotoxic to human embryonic and lung cells in the MTT assay. Cinnamon Ceylon aerosol produced in a cartomizer-style e-cigarette was cytotoxic. Cinnamon Ceylon aerosols and refill fluid aerosols (80% propylene glycol or cinnamaldehyde/propylene glycol) made using a tank/boxmod e-cigarette were more cytotoxic at 5 V than 3 V. Using GC/MS,aerosols produced at 5 V contained 10 additional peaks not present in aerosol generated at 3 V. One of these,2,3-butandione (diacetyl),was confirmed with an authentic standard. Cinnamaldehyde depolymerised microtubules in human pulmonary fibroblasts. At concentrations that produced no effect in the MTT assay,cinnamaldehyde decreased growth,attachment and spreading; altered cell morphology and motility; increased DNA strand breaks; and increased cell death. At the MTT IC50 concentration,lung cells were unable to recover from cinnamaldehyde after 2 hours of treatment,whereas embryonic cells recovered after 8 hours. CONCLUSIONS Cinnamaldehyde-containing refill fluids and aerosols are cytotoxic,genotoxic and low concentrations adversely affect cell processes and survival. These data indicate that cinnamaldehyde in e-cigarette refill fluids/aerosols may impair homeostasis in the respiratory system. View Publication