参考文献

The effector potential of NK cells is counterbalanced by their sensitivity to inhibition by self" MHC class I molecules in a process called "education." In humans� View Publication

Human embryonic stem cells (hESCs) can differentiate into all somatic lineages including stratified squamous epithelia. Thus,efficient methods are required to direct hESC differentiation to obtain a pure subpopulation for tissue engineering. The study aimed to assess the effects of retinoic acid (RA),bone morphogenetic protein-4 (BMP4),and ascorbic acid (AA) on the differentiation of hESCs into keratinocyte progenitors in vitro. The first media contained AA and BMP4; the second contained RA,AA,and BMP4; the third was commercial-defined keratinocyte serum-free medium,which was used to differentiate H9 hESCs (direct approach) or embryoid bodies (EBs) (indirect approach) into keratinocyte progenitors. Real-time RT-PCR,immunofluorescence,and flow-cytometry were used to characterize the differentiated cells. Cells induced by AA + BMP4 + RA showed the typical epithelial morphology,while cells induced by AA + BMP4 showed multiple appearances. CK14 and p63 messenger RNA (mRNA) expressions in the AA + BMP4 + RA-treated cells were higher than those of the AA + BMP4-treated cells (CK14: 22.4-fold; p63: 84.7-fold). Epithelial marker CK18 mRNA expressions at 14 d of differentiation and keratinocyte marker CK14 and transcription factor p63 mRNA expressions at 35 d of differentiation were higher in cells differentiated from hESCs compared with those differentiated from EBs (CK18 10.51 ± 3.26 vs. 6.67 ± 1.28; CK14 9.27 ± 3.61 vs. 5.32 ± 1.86; p63 0.73 ± 0.06 vs. 0.44 ± 0.12,all P textless 0.05) After hESC induction by AA+BMP4+RA,CK14 mRNA expression was upregulated after day 21,peaking by 35 d of differentiation. Combined RA,BMP4,and AA could effectively induce differentiation of hESCs into keratinocyte progenitors in vitro. These keratinocytes could be used for oral mucosa and skin tissue engineering. View Publication

PURPOSE Proliferative vitreoretinopathy (PVR) is a blinding disorder that develops after a retinal tear or detachment. Activation of the retinal pigmented epithelium (RPE) is implicated in PVR; however,the mechanisms leading to enhanced RPE proliferation,migration,and contraction remain largely unknown. This study utilized an in vitro model of PVR to investigate the role of acetylation in RPE activation and its contribution to the progression of this disease. METHODS ARPE-19 cells,primary cultures of porcine RPE,and induced pluripotent stem cell-derived RPE (iPS-RPE) were utilized for cellular and molecular analyses. Cells treated with transforming growth factor beta 2 (TGF$$2; 10 ng/mL) alone or in the presence of the broad-spectrum histone deacetylase (HDAC) inhibitor,trichostatin A (TSA; 0.1 $$M),were assessed for contraction and migration through collagen contraction and scratch assays,respectively. Western blotting and immunofluorescence analysis were performed to assess $$-smooth muscle actin ($$-SMA) and $$-catenin expression after TGF$$2 treatment alone or in combination with TSA. RESULTS TGF$$2 significantly increased RPE cell contraction in collagen matrix and this effect was inhibited in the presence of TSA (0.1 $$M). In agreement with these data,immunofluorescence analysis of TSA-treated iPS-RPE wounded monolayers revealed decreased $$-SMA as compared with control. Scratch assays to assess wound healing revealed TSA inhibited TGF$$2-mediated iPS-RPE cell migration. CONCLUSIONS Our findings indicate a role of acetylation in RPE activation. Specifically,the HDAC inhibitor TSA decreased RPE cell proliferation and TGF$$2-mediated cell contraction and migration. Further investigation of pharmacological compounds that modulate acetylation may hold promise as therapeutic agents for PVR. View Publication

HIV-1 relies on the host-cell machinery to accomplish its replication cycle,and characterization of these helper factors contributes to a better understanding of HIV-host interactions and can identify potential novel antiviral targets. Here we explored the contribution of CIB2,previously identified by RNAi screening as a potential helper factor,and its homolog,CIB1. Knockdown of either CIB1 or CIB2 strongly impaired viral replication in Jurkat cells and in primary CD4+ T-lymphocytes,identifying these proteins as non-redundant helper factors. Knockdown of CIB1 and CIB2 impaired envelope-mediated viral entry for both for X4- and R5-tropic HIV-1,and both cell-free and cell-associated entry pathways were affected. In contrast,the level of CIB1 and CIB2 expression did not influence cell viability,cell proliferation,receptor-independent viral binding to the cell surface,or later steps in the viral replication cycle. CIB1 and CIB2 knockdown was found to reduce the expression of surface molecules implicated in HIV-1 infection,including CXCR4,CCR5 and integrin α4β7,suggesting at least one mechanism through which these proteins promote viral infection. Thus,this study identifies CIB1 and CIB2 as host helper factors for HIV-1 replication that are required for optimal receptor-mediated viral entry. View Publication

ALS is a rapidly progressive,devastating neurodegenerative illness of adults that produces disabling weakness and spasticity arising from death of lower and upper motor neurons. No meaningful therapies exist to slow ALS progression,and molecular insights into pathogenesis and progression are sorely needed. In that context,we used high-depth,next generation RNA sequencing (RNAseq,Illumina) to define gene network abnormalities in RNA samples depleted of rRNA and isolated from cervical spinal cord sections of 7 ALS and 8 CTL samples. We aligned textgreater50 million 2X150 bp paired-end sequences/sample to the hg19 human genome and applied three different algorithms (Cuffdiff2,DEseq2,EdgeR) for identification of differentially expressed genes (DEG's). Ingenuity Pathways Analysis (IPA) and Weighted Gene Co-expression Network Analysis (WGCNA) identified inflammatory processes as significantly elevated in our ALS samples,with tumor necrosis factor (TNF) found to be a major pathway regulator (IPA) and TNF$$-induced protein 2 (TNFAIP2) as a major network hub" gene (WGCNA). Using the oPOSSUM algorithm� View Publication

Pluripotent human embryonic stem cells (hESCs) are a potential renewable cell source for regenerative medicine and drug testing. To obtain adequate cell numbers for these applications,there is a need to develop scalable cell culture platforms to propagate hESCs. In this study,we encapsulated hESCs in calcium alginate microfibers as single cells,for expansion and differentiation under chemically defined conditions. hESCs were suspended in 1% (w/v) alginate solution at high cell density (textgreater10(7) cells/mL) and extruded at 5 m/min into a low calcium concentration bath (10 mM) for gelation. Mild citrate buffer (2.5 mM),which did not affect hESCs viability,was used to release the cells from the calcium alginate hydrogel. Encapsulation as single cells was critical,as this allowed the hESCs to grow in the form of relatively small and uniform aggregates. This alginate microfiber system allowed for expansion of an hESC line,HUES7,for up to five passages while maintaining pluripotency. Immunohistochemistry,polymerase chain reaction,and other analyses showed that passage 5 (P5) HUES7 cells expressed proteins and genes characteristic of pluripotent stem cells,possessed normal karyotype,and were able to form representative tissues of the three embryonic germ layers in vitro and in vivo. Encapsulated HUES7 cells at P5 could also be induced to directly differentiate into liver-like cells. Collectively,our experiments show that the alginate microfiber system can be used as a three-dimensional cell culture platform for long-term expansion and differentiation of hESCs under defined conditions. View Publication

Genomic imprinting is an epigenetic phenomenon resulting in parent-of-origin-specific gene expression that is regulated by a differentially methylated region. Gene mutations or failures in the imprinting process lead to the development of imprinting disorders,such as Angelman syndrome. The symptoms of Angelman syndrome are caused by the absence of functional UBE3A protein in neurons of the brain. To create a human neuronal model for Angelman syndrome,we reprogrammed dermal fibroblasts of a patient carrying a defined three-base pair deletion in UBE3A into induced pluripotent stem cells (iPSCs). In these iPSCs,both parental alleles are present,distinguishable by the mutation,and express UBE3A. Detailed characterization of these iPSCs demonstrated their pluripotency and exceptional stability of the differentially methylated region regulating imprinted UBE3A expression. We observed strong induction of SNHG14 and silencing of paternal UBE3A expression only late during neuronal differentiation,in vitro. This new Angelman syndrome iPSC line allows to study imprinted gene regulation on both parental alleles and to dissect molecular pathways affected by the absence of UBE3A protein. View Publication

Inflammation is characterized by the recruitment of leukocytes from the bloodstream. The rapid arrival of neutrophils is followed by a wave of inflammatory lymphocyte antigen 6 complex (Ly6C)-positive monocytes. In contrast Ly6C(low) monocytes survey the endothelium in the steady state,but their role in inflammation is still unclear. Here,using confocal intravital microscopy,we show that upon Toll-like receptor 7/8 (TLR7/8)-mediated inflammation of mesenteric veins,platelet activation drives the rapid mobilization of Ly6C(low) monocytes to the luminal side of the endothelium. After repeatedly interacting with platelets,Ly6C(low) monocytes commit to a meticulous patrolling of the endothelial wall and orchestrate the subsequent arrival and extravasation of neutrophils through the production of proinflammatory cytokines and chemokines. At a molecular level,we show that cysteine-rich protein 61 (CYR61)/CYR61 connective tissue growth factor nephroblastoma overexpressed 1 (CCN1) protein is released by activated platelets and enables the recruitment of Ly6C(low) monocytes upon vascular inflammation. In addition endothelium-bound CCN1 sustains the adequate patrolling of Ly6C(low) monocytes both in the steady state and under inflammatory conditions. Blocking CCN1 or platelets with specific antibodies impaired the early arrival of Ly6C(low) monocytes and abolished the recruitment of neutrophils. These results refine the leukocyte recruitment cascade model by introducing endothelium-bound CCN1 as an inflammation mediator and by demonstrating a role for platelets and patrolling Ly6C(low) monocytes in acute vascular inflammation. View Publication

Enterotoxigenic Escherichia coli (ETEC) causes 20% of the acute infectious diarrhea (AID) episodes worldwide,often by producing heat-stable enterotoxins (STs),which are peptides structurally homologous to paracrine hormones of the intestinal guanylate cyclase C (GUCY2C) receptor. While molecular mechanisms mediating ST-induced intestinal secretion have been defined,advancements in therapeutics have been hampered for decades by the paucity of disease models that integrate molecular and functional endpoints amenable to high-throughput screening. Here,we reveal that mouse and human intestinal enteroids in three-dimensional ex vivo cultures express the components of the GUCY2C secretory signaling axis. ST and its structural analog,linaclotide,an FDA-approved oral secretagog,induced fluid accumulation quantified simultaneously in scores of enteroid lumens,recapitulating ETEC-induced intestinal secretion. Enteroid secretion depended on canonical molecular signaling events responsible for ETEC-induced diarrhea,including cyclic GMP (cGMP) produced by GUCY2C,activation of cGMP-dependent protein kinase (PKG),and opening of the cystic fibrosis transmembrane conductance regulator (CFTR). Importantly,pharmacological inhibition of CFTR abrogated enteroid fluid secretion,providing proof of concept for the utility of this model to screen antidiarrheal agents. Intestinal enteroids offer a unique model,integrating the GUCY2C signaling axis and luminal fluid secretion,to explore the pathophysiology of,and develop platforms for,high-throughput drug screening to identify novel compounds to prevent and treat ETEC diarrheal disease. View Publication

When SUCNR1/GPR91-expressing macrophages are activated by inflammatory signals,they change their metabolism and accumulate succinate. In this study,we show that during this activation,macrophages release succinate into the extracellular milieu. They simultaneously up-regulate GPR91,which functions as an autocrine and paracrine sensor for extracellular succinate to enhance IL-1β production. GPR91-deficient mice lack this metabolic sensor and show reduced macrophage activation and production of IL-1β during antigen-induced arthritis. Succinate is abundant in synovial fluids from rheumatoid arthritis (RA) patients,and these fluids elicit IL-1β release from macrophages in a GPR91-dependent manner. Together,we reveal a GPR91/succinate-dependent feed-forward loop of macrophage activation and propose GPR91 antagonists as novel therapeutic principles to treat RA. View Publication