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Articles by B Zheng
Total Records ( 5 ) for B Zheng
  S Yu , B Zheng , X Zhao and Y. Feng
 

A bioinformatic screening of the genome of the thermophilic bacterium Fervidobacterium nodosum Rt17-B1 for ester-hydrolyzing enzymes revealed a putative bacterial esterase (FNE) encoded by Fond_1301 with typical GDSL family motifs. To confirm its putative esterase function, the FNE gene was cloned, functionally expressed in Escherichia coli, and purified to homogeneity. Recombinant FNE exhibited the highest esterase activity of 14,000 U/mg with p-nitrophenyl acetate (pNPC2) as substrate. The catalytic efficiency (kcat/Km) toward p-nitrophenyl acetate (C2) was approximately 120-fold higher than toward p-nitrophenyl butyrate (C4). No significant esterase activity was observed for the substrates with a chain length ≥C8. The monomeric enzyme has a molecular mass of 27.5 kDa and exhibits optimal activity around 75°C, at pH 8.5. Its thermostability is relatively high with a half-life of 80 min at 70°C, but less stable compared with some other hyperthermophilic esterases. A structural model was constructed using acetylesterase from Aspergillus aculeatus as a template. The structure showed an /β-hydrolase fold and indicated the presence of a typical catalytic triad consisting of a serine, aspartate, and histidine, which was verified by site-directed mutagenesis. Sequence analysis showed that FNE was only distantly related to other esterases. A comparison of the conserved motifs shared with GDSL proteins revealed that FNE could be grouped into GDSL family and was further classified as SGNH hydrolase.

  L Zhou , B Zheng , A Wei , B Geller and J. Cui
 

The support for multiple high-definition video streams in wireless home networks requires appropriate routing and rate control measures, ascertaining the reasonable links for transmitting each stream and the rate of the video to be delivered over the chosen links. In this paper, we invest the combination of the routing and rate control in a united convex optimization formulation and propose a distributed joint solution based on cross-layer design. We first develop a distortion model which captures both the impact of encoder quantization and packet loss due to network congestion on the overall video quality. Then, the optimal joint rate control and routing scheme is realized by adapting its rate to the time-varying traffic and minimizing the overall network congestion. Furthermore, simulation results are provided, which demonstrate the effectiveness of our proposed joint routing and rate control scheme in the context of wireless home networks.

  B Zheng , Z Wang , S Li , B Yu , J. Y Liu and X. Chen
 

Intergenic transcription by RNA Polymerase II (Pol II) is widespread in plant and animal genomes, but the functions of intergenic transcription or the resulting noncoding transcripts are poorly understood. Here, we show that Arabidopsis Pol II is indispensable for endogenous siRNA-mediated transcriptional gene silencing (TGS) at intergenic low-copy-number loci, despite the presence of two other polymerases—Pol IV and Pol V—that specialize in TGS through siRNAs. We show that Pol II produces noncoding scaffold transcripts that originate outside of heterochromatic, siRNA-generating loci. Through these transcripts and physical interactions with the siRNA effector protein ARGONAUTE4 (AGO4), Pol II recruits AGO4/siRNAs to homologous loci to result in TGS. Meanwhile, Pol II transcription also recruits Pol IV and Pol V to different locations at heterochromatic loci to promote siRNA biogenesis and siRNA-mediated TGS, respectively. This study establishes that intergenic transcription by Pol II is required for siRNA-mediated TGS, and reveals an intricate collaboration and division of labor among the three polymerases in gene silencing.

  X Zhang , B Han , J Huang , B Zheng , Q Geng , F Aziz and Q. Dong
  Objective

The purpose of this study was to detect the presence of cancer stem-like cells with bronchioalveolar stem cells (BASCs) properties and investigate the clinicopathological role of expression of OCT4 as well as the correlation with clinical outcomes in adenocarcinoma of the lung.

Methods

Specimens of 112 cases of Stage IB–IIIA lung adenocarcinoma after radical surgery were collected from June 1999 to June 2002. The putative cancer stem cells in tumor sections were visualized immunofluorescently by using the antibodies against three bronchioalveolar stem cells markers: surfactant protein C (SPC), Clara cell secretary protein (CCSP) and Octamer-4 (OCT4). Cancer stem-like cells with bronchioalveolar stem cell properties in human lung adenocarcinoma were subdivided into two phenotypes: OCT4+BASC (SPC+CCSP+OCT4+) and OCT4BASC (SPC+CCSP+OCT4).

Results

Cancer cells with CCSP+SPC+BASC phenotype were detected in 107 cases, 80 cases with OCT4+BASC phenotype (SPC+CCSP+OCT4+) and 27 cases with SPC+CCSP+OCT4. There was a correlation between differentiation and OCT4 expression (P = 0.047). The pattern of survival curves shows the expected trend of decreasing survival with increasing stage at diagnosis (P = 0.015) and with OCT4+BASC expression (P = 0.019). Multivariate Cox's analysis reveals that pathological stages of TNM (P = 0.008) and bronchioalveolar stem cells phenotypes (P = 0.015) are the independent prognostic factors.

Conclusions

The cancer cells with bronchioalveolar stem cells phenotype are detectable in adenocarcinoma of the lung and the expression of self-renewal regulatory gene OCT4 in these cells indicated the worse clinical outcomes.

  M He , M Han , B Zheng , Y. N Shu and J. K. Wen
 

Krüppel-like factor 5 (KLF5) and c-Jun are involved in angiotensin II (Ang II)-induced cell proliferation and play an important role in p21 expression. But the direct and functional implications of KLF5 and c-Jun in regulating p21 expression in vascular smooth muscle cells (VSMCs) are unclear. Here, we show that Ang II upregulated KLF5 and c-Jun expression and inhibited p21 expression in VSMCs, and silencing of KLF5 expression by KLF5-specific small interfering RNA (siRNA) neutralized the inhibitory effects of Ang II on p21 expression. Exposure of VSMCs to Ang II rapidly and strongly stimulated KLF5 phosphorylation, which results in an increase of the interaction of KLF5 with c-Jun. Treating VSMCs with PD98059, the ERK inhibitor, inhibited ERK activation and KLF5 phosphorylation as well as the interaction between KLF5 and c-Jun. Reporter analysis showed that both KLF5 and c-Jun cooperatively repressed the promoter of p21. Furthermore, KLF5 bound to its cis-elements in the p21 promoter, and meanwhile interacted with c-Jun in Ang II-induced VSMCs. These results suggest that Ang II induces KLF5 phosphorylation mediated by the ERK signalling in VSMCs, which in turn stimulates the interaction of KLF5 with c-Jun, subsequently leads to the suppression of p21 expression.

 
 
 
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