技术资料

During pancreatic development,proliferating pancreatic progenitors activate the proendocrine transcription factor neurogenin 3 (NEUROG3),exit the cell cycle,and differentiate into islet cells. The mechanisms that direct robust NEUROG3 expression within a subset of progenitor cells control the size of the endocrine population. Here we demonstrate that NEUROG3 is phosphorylated within the nucleus on serine 183,which catalyzes its hyperphosphorylation and proteosomal degradation. During progression through the progenitor cell cycle,NEUROG3 phosphorylation is driven by the actions of cyclin-dependent kinases 2 and 4/6 at G1/S cell-cycle checkpoint. Using models of mouse and human pancreas development,we show that lengthening of the G1 phase of the pancreatic progenitor cell cycle is essential for proper induction of NEUROG3 and initiation of endocrine cell differentiation. In sum,these studies demonstrate that progenitor cell-cycle G1 lengthening,through its actions on stabilization of NEUROG3,is an essential variable in normal endocrine cell genesis. View Publication

Molluscum contagiosum poxvirus (MCV) type 1 and type 2 encode two chemokine-like proteins MC148R1 and MC148R2. It is believed that MC148R proteins function by blocking the inflammatory response. However,the mechanism of the proposed biological activities of MC148R proteins and the role of the additional C-terminal cysteines that do not exist in other chemokines are not understood. Here,we demonstrated in two different assay systems that His-tagged MC148R1 displaces the interaction between CXCL12α and CXCR4. The N-terminal cysteines but not the additional C-terminal cysteines modulate this displacement. His-tagged MC148R1 blocked both CXCL12α-mediated and MIP-1α-mediated chemotaxis. In contrast,MC148R2 blocked MIP-1α-mediated but not CXCL12α-mediated chemotaxis. Immunoprecipitation by antibodies to MC148R1 or CXCL12α followed by immunoblotting and detection by antibodies to the other protein demonstrated physical interaction of His-tagged CXCL12α and His-tagged MC148R1. Interaction with chemokines might mask the receptor interaction site resulting in decreased binding and impairment of the biological activities. View Publication

Most patients with acute myelogenous leukemia (AML) relapse and die of their disease. Increasing evidence indicates that AML relapse is driven by the inability to eradicate leukemia stem cells (LSC). Thus,it is imperative to identify novel therapies that can ablate LSCs. Using an in silico gene expression-based screen for compounds evoking transcriptional effects similar to the previously described anti-LSC agent parthenolide,we identified AR-42 (OSU-HDAC42),a novel histone deacetylase inhibitor that is structurally similar to phenylbutyrate,but with improved activity at submicromolar concentrations. Here,we report that AR-42 induces NF-κB inhibition,disrupts the ability of Hsp90 to stabilize its oncogenic clients,and causes potent and specific cell death of LSCs but not normal hematopoietic stem and progenitor cells. Unlike parthenolide,the caspase-dependent apoptosis caused by AR-42 occurs without activation of Nrf-2-driven cytoprotective pathways. As AR-42 is already being tested in early clinical trials,we expect that our results can be extended to the clinic. View Publication

Cryopreservation is the use of low temperatures to preserve structurally intact living cells. The cells that survive the thermodynamic journey from the 37 °C incubator to the -196 °C liquid nitrogen storage tank are free from the influences of time. Thus,cryopreservation is a critical component of cell culture and cell manufacturing protocols. Successful cryopreservation of human cells requires that the cells be derived from patient samples that are collected in a standardized manner,and carefully handled from blood draw through cell isolation. Furthermore,proper equipment must be in place to ensure consistency,reproducibility,and sterility. In addition,the correct choice and amount of cryoprotectant agent must be added at the correct temperature,and a controlled rate of freezing (most commonly 1 °C/min) must be applied prior to a standardized method of cryogenic storage. This appendix describes how human primary cells can be frozen for long-term storage and thawed for growth in a tissue culture vessel. View Publication

PURPOSE Recent advances in immunotherapy of advanced human cancers underscored the need to address and eliminate tumor immune evasion. The myeloid-derived suppressor cells (MDSC) are important inhibitors of T-cell responses in solid tumors,such as prostate cancers. However,targeting MDSCs proved challenging due to their phenotypic heterogeneity. EXPERIMENTAL DESIGN Myeloid cell populations were evaluated using flow cytometry on blood samples,functional assays,and immunohistochemical/immunofluorescent stainings on specimens from healthy subjects,localized and metastatic castration-resistant prostate cancer patients. RESULTS Here,we identify a population of Lin(-)CD15(HI)CD33(LO) granulocytic MDSCs that accumulate in patients' circulation during prostate cancer progression from localized to metastatic disease. The prostate cancer-associated MDSCs potently inhibit autologous CD8(+) T cells' proliferation and production of IFNγ and granzyme-B. The circulating MDSCs have high levels of activated STAT3,which is a central immune checkpoint regulator. The granulocytic pSTAT3(+) cells are also detectable in patients' prostate tissues. We previously generated an original strategy to silence genes specifically in Toll-like Receptor-9 (TLR9) positive myeloid cells using CpG-siRNA conjugates. We demonstrate that human granulocytic MDSCs express TLR9 and rapidly internalize naked CpG-STAT3siRNA,thereby silencing STAT3 expression. STAT3 blocking abrogates immunosuppressive effects of patients-derived MDSCs on effector CD8(+) T cells. These effects depended on reduced expression and enzymatic activity of Arginase-1,a downstream STAT3 target gene and a potent T-cell inhibitor. CONCLUSIONS Overall,we demonstrate the accumulation of granulocytic MDSCs with prostate cancer progression and the feasibility of using TLR9-targeted STAT3siRNA delivery strategy to alleviate MDSC-mediated immunosuppression. View Publication

The impact of shipping temperatures and preservation media used during transport of either peripheral blood mononuclear cells (PBMCs) or Jurkat cells was assessed,in view of implementing of a proficiency testing scheme on mononuclear cell viability. Samples were analyzed before and after shipment at different temperatures (ambient temperature,dry ice,and liquid nitrogen) and in different preservation media (serum with cryoprotectant,commercial cryopreservation solution,and room temperature transport medium). Sample quality was assessed by viability assays (Trypan Blue dye exclusion,flow cytometry,Cell Analysis System cell counting (CASY)),and by ELISpot functional assay. The liquid nitrogen storage and shipment were found to be the most stable conditions to preserve cell viability and functionality. However,we show that alternative high quality shipment conditions for viable cells are dry ice shipment and commercial cryopreservation solution. These were also cost-efficient shipment conditions,satisfying the requirements of a proficiency testing scheme for viable mononuclear cells. Room temperature transport medium dramatically and adversely affected the integrity of mononuclear cells. View Publication

We present a simple microfluidic system that generates water-in-water,aqueous two phase system (ATPS) droplets,by passive flow focusing. ATPS droplet formation is achieved by applying weak hydrostatic pressures,with liquid-filled pipette tips as fluid columns at the inlets,to introduce low speed flows to the flow focusing junction. To control the size of the droplets,we systematically vary the interfacial tension and viscosity of the ATPS fluids and adjust the fluid column height at the fluid inlets. The size of the droplets scales with a power law of the ratio of viscous stresses in the two ATPS phases. Overall,we find a drop size coefficient of variation (CV; i.e.,polydispersity) of about 10%. We also find that when drops form very close to the flow focusing junction,the drops have a CV of less than 1%. Our droplet generation method is easily scalable: we demonstrate a parallel system that generates droplets simultaneously and improves the droplet production rate by up to one order of magnitude. Finally,we show the potential application of our system for encapsulating cells in water-in-water emulsions by encapsulating microparticles and cells. To the best of our knowledge,our microfluidic technique is the first that forms low interfacial tension ATPS droplets without applying external perturbations. We anticipate that this simple approach will find utility in drug and cell delivery applications because of the all-biocompatible nature of the water-in-water ATPS environment. View Publication

INTRODUCTION The control of differentiation of mesenchymal stromal/stem cells (MSCs) is crucial for tissue engineering strategies employing MSCs. The purpose of this study was to investigate whether the transcriptional co-factor Yes-associated protein (YAP) regulates chondrogenic differentiation of MSCs. METHODS Expression of total YAP,its paralogue transcriptional co-activator with PDZ-binding motif (TAZ),and individual YAP transcript variants during in vitro chondrogenesis of human MSCs was determined by quantitative reverse transcription polymerase chain reaction (RT-PCR). YAP expression was confirmed by western blotting. To determine the effect of high YAP activity on chondrogenesis,C3H10T1/2 MSC-like cells were transduced with human (h)YAP and treated in micromass with bone morphogenetic protein-2 (BMP-2). Chondrogenic differentiation was assessed by alcian blue staining and expression of chondrocyte-lineage genes. BMP signalling was determined by detection of pSmad1,5,8 by western blotting and expression of BMP target genes by quantitative RT-PCR. Finally,YAP and pYAP were detected in mouse embryo hindlimbs by immunohistochemistry. RESULTS YAP,but not TAZ,was downregulated during in vitro chondrogenesis of human MSCs. One of the YAP transcript variants,however,was upregulated in high-density micromass culture. Overexpression of hYAP in murine C3H10T1/2 MSCs inhibited chondrogenic differentiation. High YAP activity in these cells decreased Smad1,5,8 phosphorylation and expression of the BMP target genes Inhibitor of DNA binding/differentiation (Id)1,Id2 and Id3 in response to BMP-2. In developing mouse limbs,Yap was nuclear in the perichondrium while mostly phosphorylated and cytosolic in cells of the cartilage anlage,suggesting downregulation of Yap co-transcriptional activity during physiological chondrogenesis in vivo. CONCLUSIONS Our findings indicate that YAP is a negative regulator of chondrogenic differentiation of MSCs. Downregulation of YAP is required for chondrogenesis through derepression of chondrogenic signalling. Therapeutic targeting of YAP to promote cartilage repair and prevent secondary osteoarthritis is an exciting prospect in rheumatology. View Publication