参考文献

During viral infections viruses express molecules that interfere with the host-cell death machinery and thus inhibit cell death responses. For example the viral FLIP (vFLIP) encoded by Kaposi's sarcoma-associated herpesvirus interacts and inhibits the central cell death effector,Caspase-8. In order to analyze the impact of anti-apoptotic viral proteins,like vFlip,on liver physiology in vivo,mice expressing vFlip constitutively in hepatocytes (vFlipAlbCre+) were generated. Transgenic expression of vFlip caused severe liver tissue injury accompanied by massive hepatocellular necrosis and inflammation that finally culminated in early postnatal death of mice. On a molecular level,hepatocellular death was mediated by RIPK1-MLKL necroptosis driven by an autocrine TNF production. The loss of hepatocytes was accompanied by impaired bile acid production and disruption of the bile duct structure with impact on the liver-gut axis. Notably,embryonic development and tissue homeostasis were unaffected by vFlip expression. In summary our data uncovered that transgenic expression of vFlip can cause severe liver injury in mice,culminating in multiple organ insufficiency and death. These results demonstrate that viral cell death regulatory molecules exhibit different facets of activities beyond the inhibition of cell death that may merit more sophisticated in vitro and in vivo analysis. View Publication

We identified individuals with variations in ACTL6B,a component of the chromatin remodeling machinery including the BAF complex. Ten individuals harbored bi-allelic mutations and presented with global developmental delay,epileptic encephalopathy,and spasticity,and ten individuals with de novo heterozygous mutations displayed intellectual disability,ambulation deficits,severe language impairment,hypotonia,Rett-like stereotypies,and minor facial dysmorphisms (wide mouth,diastema,bulbous nose). Nine of these ten unrelated individuals had the identical de novo c.1027G{\textgreater}A (p.Gly343Arg) mutation. Human-derived neurons were generated that recaptured ACTL6B expression patterns in development from progenitor cell to post-mitotic neuron,validating the use of this model. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development,a result recapitulated in two individuals with different bi-allelic mutations,and reversed on clonal genetic repair or exogenous expression of ACTL6B. Whole-transcriptome analyses and whole-genomic profiling of the BAF complex in wild-type and bi-allelic mutant ACTL6B neural progenitor cells and neurons revealed increased genomic binding of the BAF complex in ACTL6B mutants,with corresponding transcriptional changes in several genes including TPPP and FSCN1,suggesting that altered regulation of some cytoskeletal genes contribute to altered dendrite development. Assessment of bi-alleic and heterozygous ACTL6B mutations on an ACTL6B knock-out human background demonstrated that bi-allelic mutations mimic engineered deletion deficits while heterozygous mutations do not,suggesting that the former are loss of function and the latter are gain of function. These results reveal a role for ACTL6B in neurodevelopment and implicate another component of chromatin remodeling machinery in brain disease. View Publication

Drug-induced gastrointestinal toxicity (GIT) is a common treatment-emergent adverse event that can negatively impact dosing,thereby limiting efficacy and treatment options for patients. An in vitro assay of GIT is needed to address patient variability,mimic the microphysiology of the gut,and accurately predict drug-induced GIT. Primary human ileal organoids (termed 'enteroids') have proven useful for stimulating intestinal stem cell proliferation and differentiation to multiple cell types present in the gut epithelium. Enteroids have enabled characterization of gut biology and the signaling involved in the pathogenesis of disease. Here,enteroids were differentiated from four healthy human donors and assessed for culture duration-dependent differentiation status by immunostaining for gut epithelial markers lysozyme,chromogranin A,mucin,and sucrase isomaltase. Differentiated enteroids were evaluated with a reference set of 31 drugs exhibiting varying degrees of clinical incidence of diarrhea,a common manifestation of GIT that can be caused by drug-induced thinning of the gut epithelium. An assay examining enteroid viability in response to drug treatment demonstrated 90{\%} accuracy for recapitulating the incidence of drug-induced diarrhea. The human enteroid viability assay developed here presents a promising in vitro model for evaluating drug-induced diarrhea. View Publication

Exposure to thalidomide during a critical window of development results in limb defects in humans and non-human primates while mice and rats are refractory to these effects. Thalidomide-induced teratogenicity is dependent on its binding to cereblon (CRBN),the substrate receptor of the Cul4A-DDB1-CRBN-RBX1 E3 ubiquitin ligase complex. Thalidomide binding to CRBN elicits subsequent ubiquitination and proteasomal degradation of CRBN neosubstrates including SALL4,a transcription factor of which polymorphisms phenocopy thalidomide-induced limb defects in humans. Herein,thalidomide-induced degradation of SALL4 was examined in human induced pluripotent stem cells (hiPSCs) that were differentiated either to lateral plate mesoderm (LPM)-like cells,the developmental ontology of the limb bud,or definitive endoderm. Thalidomide and its immunomodulatory drug (IMiD) analogs,lenalidomide,and pomalidomide,dose-dependently inhibited hiPSC mesendoderm differentiation. Thalidomide- and IMiD-induced SALL4 degradation can be abrogated by CRBN V388I mutation or SALL4 G416A mutation in hiPSCs. Genetically modified hiPSCs expressing CRBN E377V/V388I mutant or SALL4 G416A mutant were insensitive to the inhibitory effects of thalidomide,lenalidomide,and pomalidomide on LPM differentiation while retaining sensitivity to another known limb teratogen,all-trans retinoic acid (atRA). Finally,disruption of LPM differentiation by atRA or thalidomide perturbed subsequent chondrogenic differentiation in vitro. The data here show that thalidomide,lenalidomide,and pomalidomide affect stem cell mesendoderm differentiation through CRBN-mediated degradation of SALL4 and highlight the utility of the LPM differentiation model for studying the teratogenicity of new CRBN modulating agents. View Publication

The origin and function of blood IgM+IgD+CD27+ B cells is controversial,and they are considered a heterogeneous population. Previous staining of circulating B cells of healthy donors with rotavirus fluorescent virus-like particles allowed us to differentiate two subsets of IgM+IgD+CD27+: IgMhi and IgMlo B cells. Here,we confirmed this finding and compared the phenotype,transcriptome,in vitro function,and Ig gene repertoire of these two subsets. Eleven markers phenotypically discriminated both subsets (CD1c,CD69,IL21R,CD27,MTG,CD45RB,CD5,CD184,CD23,BAFFR,and CD38) with the IgMhi phenotypically resembling previously reported marginal zone B cells and the IgMlo resembling both na{\{i}}ve and memory B cells. Transcriptomic analysis showed that both subpopulations clustered close to germinal center-experienced IgM only B cells with a Principal Component Analysis but differed in expression of 78 genes. Moreover IgMhi B cells expressed genes characteristic of previously reported marginal zone B cells. After stimulation with CpG and cytokines significantly (p {\textless} 0.05) higher frequencies (62.5{\%}) of IgMhi B cells proliferated compared with IgMlo B cells (35.37{\%}) and differentiated to antibody secreting cells (14.22{\%} for IgMhi and 7.19{\%} for IgMlo). IgMhi B cells had significantly (p {\textless} 0.0007) higher frequencies of mutations in IGHV and IGKV regions IgMlo B cells had higher usage of IGHJ6 genes (p {\textless} 0.0001) and both subsets differed in their HCDR3 properties. IgMhi B cells shared most of their shared IGH clonotypes with IgM only memory B cells and IgMlo B cells with IgMhi B cells. These results support the notion that differential expression of IgM and IgD discriminates two subpopulations of human circulating IgM+IgD+CD27+ B cells with the IgMhi B cells having similarities with previously described marginal zone B cells that passed through germinal centers and the IgMlo B cells being the least differentiated amongst the IgM+CD27+ subsets." View Publication

BACKGROUND Lymphotoxin $\beta$ receptor (LT$\beta$R) plays important roles in the development of the immune system and immune response. At the cellular level,ligand-bound LT$\beta$R activates the pro-inflammatory NF-$\kappa$B pathway but the detailed mechanisms regulating its signaling remain unknown. Understanding them is of high importance since LT$\beta$R and its ligands are promising therapeutic targets. Here,we studied the consequences of perturbed cellular cholesterol content on LT$\beta$R-induced NF-$\kappa$B signaling. METHODS To modulate cholesterol availability and/or level in lung carcinoma A549 and H2228,and endothelial HUVEC cells different treatment regimens with filipin,methyl-$\beta$-cyclodextrin and simvastatin were applied. LT$\beta$R localization was studied by confocal microscopy. The activity of LT$\beta$R-induced NF-$\kappa$B pathway was assessed by measuring the levels of NF-$\kappa$B pathway inhibitor I$\kappa$B$\alpha$ and phosphorylation of RelA transcription factor by Western blotting. The NF-$\kappa$B transcriptional response,production of chemokines and adhesion molecules were examined by qRT-PCR,ELISA,and Western blotting,respectively. Adherence of different types of primary immune cells to epithelial A549 cells and endothelial HUVECs was measured fluorometrically. Interactions of LT$\beta$R with its protein partners were investigated by immunoprecipitation. RESULTS We showed that filipin-mediated sequestration of cholesterol or its depletion from the plasma membrane with methyl-$\beta$-cyclodextrin impaired LT$\beta$R internalization and potentiated LT$\beta$R-dependent activation of the canonical branch of the NF-$\kappa$B pathway. The latter was manifested by enhanced degradation of I$\kappa$B$\alpha$ inhibitor,elevated RelA phosphorylation,substantial increase in the expression of NF-$\kappa$B target genes encoding,among others,cytokines and adhesion molecules known to play important roles in immune response. It was followed by robust secretion of CXCL8 and upregulation of ICAM1,that favored the adhesion of immune cells (NK and T cells,neutrophils) to A549 cells and HUVECs. Mechanistically,we showed that cholesterol depletion stabilized interactions of ligand-stimulated LT$\beta$R with modified forms of TRAF2 and NEMO proteins. CONCLUSIONS Our results showed that the reduction of the plasma membrane content of cholesterol or its sequestration strongly potentiated signaling outcome initiated by LT$\beta$R. Thus,drugs modulating cholesterol levels could potentially improve efficacy of LT$\beta$R-based therapies. Video abstract. View Publication

PURPOSE The outgrowth of antigen-negative variants is a significant challenge for adoptive therapy with T cells that target a single specificity. Chimeric antigen receptors (CAR) are typically designed with one or two scFvs that impart antigen specificity fused to activation and costimulation domains of T-cell signaling molecules. We designed and evaluated the function of CARs with up to three specificities for overcoming tumor escape using Designed Ankyrin Repeat Proteins (DARPins) rather than scFvs for tumor recognition. EXPERIMENTAL DESIGN A monospecific CAR was designed with a DARPin binder (E01) specific for EGFR and compared with a CAR designed using an anti-EGFR scFv. CAR constructs in which DARPins specific for EGFR,EpCAM,and HER2 were linked together in a single CAR were then designed and optimized to achieve multispecific tumor recognition. The efficacy of CAR-T cells bearing a multispecific DARPin CAR for treating tumors with heterogeneous antigen expression was evaluated in vivo. RESULTS The monospecific anti-EGFR E01 DARPin conferred potent tumor regression against EGFR+ targets that was comparable with an anti-EGFR scFv CAR. Linking three separate DARPins in tandem was feasible and in an optimized format generated a single tumor recognition domain that targeted a mixture of heterogeneous tumor cells,each expressing a single antigen,and displayed synergistic activity when tumor cells expressed more than one target antigen. CONCLUSIONS DARPins can serve as high-affinity recognition motifs for CAR design,and their robust architecture enables linking of multiple binders against different antigens to achieve functional synergy and reduce antigen escape. View Publication

Medulloblastoma (MB) is the most frequent malignant pediatric brain tumor,representing 20{\%} of newly diagnosed childhood central nervous system malignancies. Although advances in multimodal therapy yielded a 5-year survivorship of 80{\%},MB still accounts for the leading cause of childhood cancer mortality. In this work,we describe the epigenetic regulator BMI1 as a novel therapeutic target for the treatment of recurrent human Group 3 MB,a childhood brain tumor for which there is virtually no treatment option beyond palliation. Current clinical trials for recurrent MB patients based on genomic profiles of primary,treatment-naive tumors will provide limited clinical benefit since recurrent metastatic MBs are highly genetically divergent from their primary tumor. Using a small molecule inhibitor against BMI1,PTC-028,we were able to demonstrate complete ablation of self-renewal of MB stem cells in vitro. When administered to mice xenografted with patient tumors,we observed significant reduction in tumor burden in both local and metastatic compartments and subsequent increased survival,without neurotoxicity. Strikingly,serial in vivo re-transplantation assays demonstrated a marked reduction in tumor initiation ability of recurrent MB cells upon re-transplantation of PTC-028-treated cells into secondary recipient mouse brains. As Group 3 MB is often metastatic and uniformly fatal at recurrence,with no current or planned trials of targeted therapy,an efficacious targeted agent would be rapidly transitioned to clinical trials. View Publication

The recent advances,offered by cell therapy in the regenerative medicine field,offer a revolutionary potential for the development of innovative cures to restore compromised physiological functions or organs. Adult myogenic precursors,such as myoblasts or satellite cells,possess a marked regenerative capacity,but the exploitation of this potential still encounters significant challenges in clinical application,due to low rate of proliferation in vitro,as well as a reduced self-renewal capacity. In this scenario,induced pluripotent stem cells (iPSCs) can offer not only an inexhaustible source of cells for regenerative therapeutic approaches,but also a valuable alternative for in vitro modeling of patient-specific diseases. In this study we established a reliable protocol to induce the myogenic differentiation of iPSCs,generated from pericytes and fibroblasts,exploiting skeletal muscle-derived extracellular vesicles (EVs),in combination with chemically defined factors. This genetic integration-free approach generates functional skeletal myotubes maintaining the engraftment ability in vivo. Our results demonstrate evidence that EVs can act as biological shuttles" to deliver specific bioactive molecules for a successful transgene-free differentiation offering new opportunities for disease modeling and regenerative approaches." View Publication

Prenatal cannabis exposure (PCE) influences human brain development,but it is challenging to model PCE using animals and current cell culture techniques. Here,we developed a one-stop microfluidic platform to assemble and culture human cerebral organoids from human embryonic stem cells (hESC) to investigate the effect of PCE on early human brain development. By incorporating perfusable culture chambers,air-liquid interface,and one-stop protocol,this microfluidic platform can simplify the fabrication procedure and produce a large number of organoids (169 organoids per 3.5 cm × 3.5 cm device area) without fusion,as compared with conventional fabrication methods. These one-stop microfluidic assembled cerebral organoids not only recapitulate early human brain structure,biology,and electrophysiology but also have minimal size variation and hypoxia. Under on-chip exposure to the psychoactive cannabinoid,$\Delta$-9-tetrahydrocannabinol (THC),cerebral organoids exhibited reduced neuronal maturation,downregulation of cannabinoid receptor type 1 (CB1) receptors,and impaired neurite outgrowth. Moreover,transient on-chip THC treatment also decreased spontaneous firing in these organoids. This one-stop microfluidic technique enables a simple,scalable,and repeatable organoid culture method that can be used not only for human brain organoids but also for many other human organoids including liver,kidney,retina,and tumor organoids. This technology could be widely used in modeling brain and other organ development,developmental disorders,developmental pharmacology and toxicology,and drug screening. View Publication