技术资料

The pathogenesis of malarial anemia is multifactorial,and the mechanisms responsible for its high mortality are poorly understood. Studies indicate that host mediators produced during malaria infection may suppress erythroid progenitor development (Miller,K.L.,J.C. Schooley,K.L. Smith,B. Kullgren,L.J. Mahlmann,and P.H. Silverman. 1989. Exp. Hematol. 17:379-385; Yap,G.S.,and M.M. Stevenson. 1991. Ann. NY Acad. Sci. 628:279-281). We describe an intrinsic role for macrophage migration inhibitory factor (MIF) in the development of the anemic complications and bone marrow suppression that are associated with malaria infection. At concentrations found in the circulation of malaria-infected patients,MIF suppressed erythropoietin-dependent erythroid colony formation. MIF synergized with tumor necrosis factor and gamma interferon,which are known antagonists of hematopoiesis,even when these cytokines were present in subinhibitory concentrations. MIF inhibited erythroid differentiation and hemoglobin production,and it antagonized the pattern of mitogen-activated protein kinase phosphorylation that normally occurs during erythroid progenitor differentiation. Infection of MIF knockout mice with Plasmodium chabaudi resulted in less severe anemia,improved erythroid progenitor development,and increased survival compared with wild-type controls. We also found that human mononuclear cells carrying highly expressed MIF alleles produced more MIF when stimulated with the malarial product hemozoin compared with cells carrying low expression MIF alleles. These data suggest that polymorphisms at the MIF locus may influence the levels of MIF produced in the innate response to malaria infection and the likelihood of anemic complications. View Publication

Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by ectopic expression of four transcription factors. However,the efficiency of human iPS cell generation is extremely low and therefore elucidating the mechanisms underlying cellular reprogramming is of prime importance. We demonstrate that 8-Bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) improves the reprogramming efficiency of human neonatal foreskin fibroblast (HFF1) cells transduced with the four transcription factors by 2-fold. The combination of 8-Br-cAMP and VPA synergistically increases the efficiency to 6.5-fold. The effect of 8-Br-cAMP or VPA may in part be due to the up-regulation of cytokine-related and inflammatory pathways. Remarkably,the synergistic effect of 8-Br-cAMP and VPA on cellular reprogramming may be due to the transient decrease of p53 protein during the early stages of reprogramming. However,it could also be due to additional differentially regulated genes and pathways such as the up-regulation of cytokine-related,inflammatory pathways and self-renewal supporting gene,namely cyclin-encoding CCND2,and the associated genes CCNA1 and CCNE1. Conversely,we also see the down-regulation of the p53 (CCNB2,GTSE1,SERPINE1) and cell cycle (PLK1,CCNB2) pathways. Our data demonstrates that a cyclic AMP analog,8-Br-cAMP,enhances the efficiency of cellular reprogramming. In addition,8-Br-cAMP and VPA have a synergistic effect on cellular reprogramming,which may be in part due to the transient down-regulation of the p53 signaling pathway during the early stages of reprogramming. View Publication

This study describes an OTULIN-related autoinflammatory syndrome (ORAS) patient with two rare heterozygous variants of OTULIN (p.P152L and p.R306Q); the latter is a de novo variant that acts in a dominant-negative manner to cause ORAS. OTULIN-related autoinflammatory syndrome (ORAS),a severe autoinflammatory disease,is caused by biallelic pathogenic variants of OTULIN,a linear ubiquitin-specific deubiquitinating enzyme. Loss of OTULIN attenuates linear ubiquitination by inhibiting the linear ubiquitin chain assembly complex (LUBAC). Here,we report a patient who harbors two rare heterozygous variants of OTULIN (p.P152L and p.R306Q). We demonstrated accumulation of linear ubiquitin chains upon TNF stimulation and augmented TNF-induced cell death in mesenchymal stem cells differentiated from patient-derived iPS cells,which confirms that the patient has ORAS. However,although the de novo p.R306Q variant exhibits attenuated deubiquitination activity without reducing the amount of OTULIN,the deubiquitination activity of the p.P152L variant inherited from the mother was equivalent to that of the wild-type. Patient-derived MSCs in which the p.P152L variant was replaced with wild-type also exhibited augmented TNF-induced cell death and accumulation of linear chains. The finding that ORAS can be caused by a dominant-negative p.R306Q variant of OTULIN furthers our understanding of disease pathogenesis. Graphical Abstract View Publication

Although aldehyde dehydrogenase (ALDH) activity has become a surrogate of hematopoietic stem and progenitor cells (HSPCs),its function during hematopoiesis was unclear. Here,we examined its role in zebrafish hematopoiesis based on pharmacological inhibition and morpholino (MO) knockdown. Zebrafish embryos were treated with diethylaminobenzaldehyde (DEAB,1 μmol/l) between 0- and 48 hour-post-fertilization (hpf). MOs targeting aldhs were injected between 1 and 4-cell stage. The effects on hematopoiesis were evaluated at different stages. DEAB treatment between 0 and 18 hpf increased gene expression associated with HSPC (scl,lmo2),erythropoiesis (gata1,α- and β-eHb) and myelopoiesis (spi1) as well as gfp(+) cells in dissociated Tg(gata1:gfp) embryos. The effects were ameliorated by all-trans retinoic acid (1 nmol/l). Definitive hematopoiesis and the erythromyeloid precursors were unaffected. In all,14 out of 15 zebrafish aldhs were detectable by reverse transcription PCR in 18 hpf embryos,of which only aldh1a2 and aldh16a1 were expressed in sites pertinent to hematopoiesis. Molecular targeting by MOs was demonstrated for 15 aldhs,but none of them,even in combined aldh1a2 and aldh1a3 knockdown,recapitulated the hematopoietic expansion in DEAB-treated embryos. In conclusion,DEAB expands HSPC population during primitive hematopoiesis through inhibition of aldh and retinoic acid synthesis. The specific aldh isoform(s) remains to be determined. View Publication

Retinoids play an important role in development,differentiation,and homeostasis. The discovery of retinoid receptors belonging to the superfamily of nuclear ligand-activated transcriptional regulators has revolutionized our molecular understanding as to how these structurally simple molecules exert their pleiotropic effects. Diversity in the control of gene expression by retinoid signals is generated through complexity at different levels of the signaling pathway. A major source of diversity originates from the existence of two families of retinoid acid (RA) receptors (R),the RAR isotypes (alpha,beta,and gamma) and the three RXR isotypes (alpha,beta,and gamma),and their numerous isoforms,which bind as RXR/RAR heterodimers to the polymorphic cis-acting response elements of RA target genes. The possibility of cross-modulation (cross-talk) with cell-surface receptors signaling pathways,as well as the finding that RARs and RXRs interact with multiple putative coactivators and/or corepressors,generates additional levels of complexity for the array of combinatorial effects that underlie the pleiotropic effects of retinoids. This review focuses on recent developments,particularly in the area of structure-function relationships. View Publication

The cell cycle (CC) underpins diverse cell processes like cell differentiation,cell expansion,and tumorigenesis but current single-cell (sc) strategies study CC as: coarse phases,rely on transcriptomic signatures,use imaging modalities limited to adherent cells,or lack high-throughput multiplexing. To solve this,we develop an expanded,Mass Cytometry (MC) approach with 48 CC-related molecules that deeply phenotypes the diversity of scCC states. Using Cytometry by Time of Flight,we quantify scCC states across suspension and adherent cell lines,and stimulated primary human T cells. Our approach captures the diversity of scCC states,including atypical CC states beyond canonical definitions. Pharmacologically-induced CC arrest reveals that perturbations exacerbate noncanonical states and induce previously unobserved states. Notably,primary cells escaping CC inhibition demonstrated aberrant CC states compared to untreated cells. Our approach enables deeper phenotyping of CC biology that generalizes to diverse cell systems with simultaneous multiplexing and integration with MC platforms. Subject terms: Assay systems,Proteomics,Cell biology,Immunology,Systems biology View Publication

A defect in cell trafficking and chemotaxis plays an important role in the immune deficiency observed in Wiskott-Aldrich syndrome (WAS). In this report,we show that marrow cells from WAS protein (WASP)-deficient mice also have a defect in chemotaxis. Serial transplantation and competitive reconstitution experiments demonstrated that marrow cells,including hematopoietic progenitors and stem cells (HSCs),have decreased homing capacities that were associated with a defect in adhesion to collagen. During development,HSCs migrate from the liver to the marrow and the spleen,prompting us to ask if a defect in HSC homing during development may explain the skewed X-chromosome inactivation in WAS carriers. Preliminary evidence has shown that,in contrast to marrow progenitor cells,fetal liver progenitor cells from heterozygous females had a random X-chromosome inactivation. When fetal liver cells from WASP-carrier females were injected into irradiated recipients,a nonrandom inactivation of the X-chromosome was found at the level of hematopoietic progenitors and HSCs responsible for the short- and long-term hematopoietic reconstitution. Therefore,the mechanism of the skewed X-chromosomal inactivation observed in WAS carriers may be related to a migration defect of WASP-deficient HSCs. View Publication

To exploit the full potential of human pluripotent stem cells for regenerative medicine,developmental biology and drug discovery,defined culture conditions are needed. Media of known composition that maintain human embryonic stem (hES) cells have been developed,but finding chemically defined,robust substrata has proven difficult. We used an array of self-assembled monolayers to identify peptide surfaces that sustain pluripotent stem cell self-renewal. The effective substrates displayed heparin-binding peptides,which can interact with cell-surface glycosaminoglycans and could be used with a defined medium to culture hES cells for more than 3 months. The resulting cells maintained a normal karyotype and had high levels of pluripotency markers. The peptides supported growth of eight pluripotent cell lines on a variety of scaffolds. Our results indicate that synthetic substrates that recognize cell-surface glycans can facilitate the long-term culture of pluripotent stem cells. View Publication

Human mesenchymal stromal cells (hMSCs) have generated significant interest due to their potential use in clinical applications. hMSCs are present at low frequency in vivo,but after isolation can be expanded considerably,generating clinically useful numbers of cells. In this study,we demonstrate the use of a defined embryonic stem cell expansion medium,mTeSR (Stem Cell Technologies),for the expansion of bone-marrow-derived hMSCs. The hMSCs grow at comparable rates,demonstrate tri-lineage differentiation potential,and show similar surface marker profiles (CD29(+),CD44(+),CD49a(+),CD73(+),CD90(+),CD105(+),CD146(+),CD166(+),CD34(-),and CD45(-)) in both the fetal bovine serum (FBS)-supplemented medium and mTeSR. However,expression of early differentiation transcription factors runt-related transcription factor 2,sex-determining region Y box 9,and peroxisome proliferator-activated receptor gamma changed significantly. Both runt-related transcription factor 2 and sex-determining region Y box 9 were upregulated,whereas peroxisome proliferator-activated receptor gamma was downregulated in mTeSR compared with FBS. Although osteogenic and chondrogenic differentiation was comparable in cells grown in mTeSR compared to FBS,adipogenic differentiation was significantly decreased in mTeSR-expanded cells,both in terms of gene expression and absolute numbers of adipocytes. The removal of the FBS from the medium and the provision of a defined medium with disclosed composition make mTeSR a superior study platform for hMSC biology in a controlled environment. Further,this provides a key step toward generating a clinical-grade medium for expansion of hMSCs for clinical applications that rely on osteo- and chondroinduction of MSCs,such as bone repair and cartilage generation. View Publication

A defined xeno-free system for patient-specific iPSC derivation and differentiation is required for translation to clinical applications. However,standard somatic cell reprogramming protocols rely on using MEFs and xenogeneic medium,imposing a significant obstacle to clinical translation. Here,we describe a well-defined culture system based on xeno-free media and LN521 substrate which supported i) efficient reprogramming of normal or diseased skin fibroblasts from human of different ages into hiPSCs with a 15-30 fold increase in efficiency over conventional viral vector-based method; ii) long-term self-renewal of hiPSCs; and iii) direct hiPSC lineage-specific differentiation. Using an excisable polycistronic vector and optimized culture conditions,we achieved up to 0.15%-0.3% reprogramming efficiencies. Subsequently,transgene-free hiPSCs were obtained by Cre-mediated excision of the reprogramming factors. The derived iPSCs maintained long-term self-renewal,normal karyotype and pluripotency,as demonstrated by the expression of stem cell markers and ability to form derivatives of three germ layers both in vitro and in vivo. Importantly,we demonstrated that Parkinson's patient transgene-free iPSCs derived using the same system could be directed towards differentiation into dopaminergic neurons under xeno-free culture conditions. Our approach provides a safe and robust platform for the generation of patient-specific iPSCs and derivatives for clinical and translational applications. textcopyright 2013 Elsevier Ltd. View Publication

Human ESC and iPSC are an attractive source of cells of high quantity and purity to be used to elucidate early human development processes,for drug discovery,and in clinical cell therapy applications. To efficiently differentiate pluripotent cells into a pure population of hematopoietic progenitors we have developed a new 2-dimensional,defined and highly efficient protocol that avoids the use of feeder cells,serum or embryoid body formation. Here we showed that a single matrix protein in combination with growth factors and a hypoxic environment is sufficient to generate from pluripotent cells hematopoietic progenitors capable of differentiating further in mature cell types of different lineages of the blood system. We tested the differentiation method using hESCs and 9 iPSC lines generated from different tissues. These data indicate the robustness of the protocol providing a valuable tool for the generation of clinical-grade hematopoietic cells from pluripotent cells. View Publication

Dravet Syndrome is an intractable form of childhood epilepsy associated with deleterious mutations in SCN1A,the gene encoding neuronal sodium channel Nav1.1. Earlier studies using human induced pluripotent stem cells (iPSCs) have produced mixed results regarding the importance of Nav1.1 in human inhibitory versus excitatory neurons. We studied a Nav1.1 mutation (p.S1328P) identified in a pair of twins with Dravet Syndrome and generated iPSC-derived neurons from these patients. Characterization of the mutant channel revealed a decrease in current amplitude and hypersensitivity to steady-state inactivation. We then differentiated Dravet-Syndrome and control iPSCs into telencephalic excitatory neurons or medial ganglionic eminence (MGE)-like inhibitory neurons. Dravet inhibitory neurons showed deficits in sodium currents and action potential firing,which were rescued by a Nav1.1 transgene,whereas Dravet excitatory neurons were normal. Our study identifies biophysical impairments underlying a deleterious Nav1.1 mutation and supports the hypothesis that Dravet Syndrome arises from defective inhibitory neurons. View Publication