Hepatitis B Virus Polymerase Blocks Pattern Recognition Receptor Signaling via Interaction with DDX3: Implications for Immune Evasion

Viral infection leads to induction of pattern-recognition receptor signaling, which leads to interferon regulatory factor (IRF) activation and ultimately interferon (IFN) production. To establish infection, many viruses have strategies to evade the innate immunity. For the hepatitis B virus (HBV), which causes chronic infection in the liver, the evasion strategy remains uncertain. We now show that HBV polymerase (Pol) blocks IRF signaling, indicating that HBV Pol is the viral molecule that effectively counteracts host innate immune response. In particular, HBV Pol inhibits TANK-binding kinase 1 (TBK1)/IκB kinase-ε (IKKε), the effector kinases of IRF signaling. Intriguingly, HBV Pol inhibits TBK1/IKKε activity by disrupting the interaction between IKKε and DDX3 DEAD box RNA helicase, which was recently shown to augment TBK1/IKKε activity. This unexpected role of HBV Pol may explain how HBV evades innate immune response in the early phase of the infection. A therapeutic implication of this work is that a strategy to interfere with the HBV Pol-DDX3 interaction might lead to the resolution of life-long persistent infection.     

Membrane‐bound HSP70‐engineered myeloma cell‐derived exosomes stimulate more efficient CD8+ CTL‐ and NK‐mediated antitumour immunity than exosomes released from heat‐shocked tumour cells expressing cytoplasmic HSP70

Exosomes (EXO) derived from tumour cells have been used to stimulate antitumour immune responses, but only resulting in prophylatic immunity. Tumour‐derived heat shock protein 70 (HSP70) molecules are molecular chaperones with a broad repertoire of tumour antigen peptides capable of stimulating dendritic cell (DC) maturation and T‐cell immune responses. To enhance EXO‐based antitumour immunity, we generated an engineered myeloma cell line J558_HSP expressing endogenous P1A tumour antigen and transgenic form of membrane‐bound HSP70 and heat‐shocked J558_HS expressing cytoplasmic HSP70, and purified EXO_HSP and EXO_HS from J558_HSP and J558_HS tumour cell culture supernatants by ultracentrifugation. We found that EXO_HSP were able to more efficiently stimulate maturation of DCs with up‐regulation of Ia^b, CD40, CD80 and inflammatory cytokines than EXO_HS after overnight incubation of immature bone‐marrow‐derived DCs (5 × 10⁶ cells) with EXO (100 μg), respectively. We also i.v. immunized BALB/c mice with EXO (30 μg/mouse) and assessed P1A‐specific T‐cell responses after immunization. We demonstrate that EXO_HSP are able to stimulate type 1 CD4⁺ helper T (Th1) cell responses, and more efficient P1A‐specific CD8⁺ cytotoxic T lymphocyte (CTL) responses and antitumour immunity than EXO_HS. In addition, we further elucidate that EXO_HSP‐stimulated antitumour immunity is mediated by both P1A‐specific CD8⁺ CTL and non‐P1A‐specific natural killer (NK) responses. Therefore, membrane‐bound HSP70‐expressing tumour cell‐released EXO may represent a more effective EXO‐based vaccine in induction of antitumour immunity.     

Discovering likely invariants of distributed transaction systems for autonomic system management

Large amount of monitoring data can be collected from distributed systems as the observables to analyze system behaviors. However, without reasonable models to characterize systems, we can hardly interpret such monitoring data effectively for system management. In this paper, a new concept named flow intensity is introduced to measure the intensity with which internal monitoring data reacts to the volume of user requests in distributed transaction systems. We propose a novel approach to automatically model and search relationships between the flow intensities measured at various points across the system. If the modeled relationships hold all the time, they are regarded as invariants of the underlying system. Experimental results from a real system demonstrate that such invariants widely exist in distributed transaction systems. Further we discuss how such invariants can be used to characterize complex systems and support autonomic system management. Guofei Jiang received the B.S. and Ph.D. degrees in electrical and computer engineering from Beijing Institute of Technology, China, in 1993 and 1998, respectively. During 1998–2000, he was a postdoctoral fellow in computer engineering at Dartmouth College, NH. He is currently a research staff member with the Robust and Secure Systems Group in NEC Laboratories America at Princeton, NJ. During 2000–2004, he was a research scientist in the Institute for Security Technology Studies at Dartmouth College. His current research focus is on distributed system, dependable and secure computing, system and information theory. He has published over 50 technical papers in these areas. He is an associate editor of IEEE Security and Privacy magazine and has served in the program committees of many conferences. Haifeng Chen received the BEng and MEng degrees, both in automation, from Southeast University, China, in 1994 and 1997 respectively, and the PhD degree in computer engineering from Rutgers University, New Jersey, in 2004. He has worked as a researcher in the Chinese national research institute of power automation. He is currently a research staff member at NEC laboratory America, Princeton, NJ. His research interests include data mining, autonomic computing, pattern recognition and robust statistics. Kenji Yoshihira received the B.E. in EE at University of Tokyo in 1996 and designed processor chips for enterprise computer at Hitachi Ltd. for five years. He employed himself in CTO at Investoria Inc. in Japan to develop an Internet service system for financial information distribution through 2002 and received the M.S. in CS at New York University in 2004. He is currently a research staff member with the Robust and Secure Systems Group in NEC Laboratories America, inc. in NJ. His current research focus is on distributed system and autonomic computing.     

SOCS1 inhibits tumor necrosis factor-induced activation of ASK1-JNK inflammatory signaling by mediating ASK1 degradation

We have previously shown that ASK1 undergoes ubiquitination and degradation in resting endothelial cells (EC) and that proinflammatory cytokine tumor necrosis factor (TNF) induces deubiquitination and stabilization, leading to ASK1 activation. However, the mechanism for the regulation of ASK1 stability is not known. In the present study, we have shown that SOCS1, a member of suppressor of cytokine signaling, induces ASK1 degradation. SOCS1 was constitutively expressed in EC and formed a labile complex with ASK1 that can be stabilized by proteasomal inhibitors. The phosphotyrosine-binding SH2 domain of SOCS1 was critical for its association with ASK1. Thus a SOCS1 mutant defective in phosphotyrosine binding failed to bind to and induce ASK1 degradation. Phosphotyrosine of ASK1 was induced in response to growth factors, and TNF induced dephosphorylation and dissociation of ASK1 from SOCS1. ASK1 with a mutation at Tyr-718 diminished the binding to SOCS1, suggesting that the phosphotyrosine-718 of ASK1 is critical for SOCS1 binding. Moreover, ASK1 expression and activity were up-regulated in SOCS1-deficient mice and derived EC, resulting in enhanced TNF-induced activation of JNK, expression of proinflammatory molecules, and apoptotic responses. We concluded that SOCS1 functions as a negative regulator in TNF-induced inflammation in EC, in part, by inducing ASK1 degradation.     

Self-assembled gold nanoshells on biodegradable chitosan fibers

A novel chitosan fiber core/gold shell structural organic-inorganic composite was presented via a facile and eco-friendly approach. The chitosan fiber and gold/chitosan composites were characterized with the assistance of scanning electron microscopy and transmission electron microscopy observations. The chitosan fibers used in this study were 50 nm to 5 microm in diameter and up to hundreds of micrometers in length. The gold shells were typically 20-50 nm in depth, and their lattice fringes obliquely intersecting at an angle of 60 degrees were displayed. The formation mechanism of the as-fabricated chitosan fiber core with gold as the shell structural composites was also schematically discussed.     

Innovative Approach for Improvement of an Antibiotic-Overproducing Industrial Strain of Streptomyces albus

Working with a Streptomyces albus strain that had previously been bred to produce industrial amounts (10 mg/ml) of salinomycin, we demonstrated the efficacy of introducing drug resistance-producing mutations for further strain improvement. Mutants with enhanced salinomycin production were detected at a high incidence (7 to 12%) among spontaneous isolates resistant to streptomycin (Str^r), gentamicin, or rifampin (Rif^r). Finally, we successfully demonstrated improvement of the salinomycin productivity of the industrial strain by 2.3-fold by introducing a triple mutation. The Str^r mutant was shown to have a point mutation within the rpsL gene (encoding ribosomal protein S12). Likewise, the Rif^r mutant possessed a mutation in the rpoB gene (encoding the RNA polymerase β subunit). Increased productivity of salinomycin in the Str^r mutant (containing the K88R mutation in the S12 protein) may be a result of an aberrant protein synthesis mechanism. This aberration may manifest itself as enhanced translation activity in stationary-phase cells, as we have observed with the poly(U)-directed cell-free translation system. The K88R mutant ribosome was characterized by increased 70S complex stability in low Mg²⁺ concentrations. We conclude that this aberrant protein synthesis ability in the Str^r mutant, which is a result of increased stability of the 70S complex, is responsible for the remarkable salinomycin production enhancement obtained.     

Purification and Characterization of an Extracellular Alkaline Serine Protease with Dehairing Function from <Emphasis Type="Italic">Bacillus pumilus</Emphasis>

An extracellular alkaline serine protease (called DHAP), produced by a Bacillus pumilus strain, demonstrates significant dehairing function. This protease is purified by hydrophobic interaction chromatography, ion exchange, and gel filtration. DHAP had a pI of 9.0 and a molecular weight of approximately 32,000 Dalton. It shows maximal activity at pH 10 and with a temperature of 55°C; the enzyme activity can be completely inhibited by phenylmethylsulfonyl fluoride (PMSF) and diisopropyl fluorophosphates (DFP). The first 20 amino acid residues of the purified DHAP have been determined with a sequence of AQTVPYGIPQIKAPAVHAQG. Alignment of this sequence with other alkaline protease demonstrates its high homology with protease from another B. pumilus strain. Received: 17 April 2002 / Accepted: 24 May 2002     

细菌群体感应LuxR solos蛋白研究进展

N-酰基高丝氨酸内酯(N-acyl-L-homoserine lactones,AHLs)信号分子介导的群体感应(quorum sensing,QS)是一种普遍的革兰氏阴性细菌信息交流方式。AHL-QS系统包括Lux I型AHLs合成酶和LuxR型受体蛋白。然而,部分革兰氏阴性菌缺失1个或多个LuxI型AHLs合成酶,仅有未配对的LuxR型受体蛋白,该LuxR型受体蛋白称为LuxR solo或Orphan蛋白。LuxR solos蛋白在细菌窃听、种间和种内的信号交流中起重要作用,为群体感应研究领域的热点。本文主要综述细菌LuxR solos蛋白的发现、基本概念、蛋白结构及类型,阐述感应AHLs和非AHLs信号分子的重要LuxR solos蛋白及功能,并对群体感应LuxR solos蛋白的研究前景和意义进行了展望。     

利用卫星追踪颈圈对圈养野生双峰驼野化放归的监测

2012-2014年,通过对甘肃敦煌西湖国家级自然保护区野化放归的两峰野生双峰驼（Camelus ferus）佩带卫星追踪颈圈进行跟踪监测,利用最小凸多边形法和内核法开展了放归生境中野骆驼的活动范围和空间利用研究。研究期间,分别进行了22个月(ID:108444)和9个月(ID:108445)的跟踪监测,获得了3403个(ID:108444) 和1573个(ID:108445)定位成功的GPS位点。野骆驼放归后的前两个月仍存在一定的对圈养环境的依赖,两个月后野骆驼的活动范围开始向外扩展,直至四个月后,基本扩展至整个放养的围栏,活动范围分别从9.5109 km²增加到19.3694 km2 (ID:108444),8.8943 km² 增加到19.4192 km² (ID:108445)。整个监测期间,95% Kernel活动范围分别为7.7181km² (ID:108444) 和 3.0321 km² (ID:108445)。从整个监测期间(ID:108444)的50% Kernel活动范围（0.2811 km²）来看,野骆驼整个放归期间仍然比较依赖原先的圈养环境;野骆驼存在对胡杨疏林的偏好;同时,放归的野骆驼仍然保持了对人的亲近行为。从2013年整年来看,放归野骆驼实际生境利用,春、秋两季范围大,夏、冬两季范围较小。放归的野骆驼不同季节对主要生境的利用也有所不同,最为明显的是夏季,野骆驼活动范围集中在荒漠地区,避开植被多的区域以避免蚊虫叮咬。本研究进一步了解了野骆驼的行为习性及其适应环境的行为对策,为野骆驼圈养种群的科学管理和进一步野化放归提供了理论依据。