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Articles by Q Zhao
Total Records ( 6 ) for Q Zhao
  Q Zhao and H. Kurata
 

Motivation: Gene deletion and overexpression are critical technologies for designing or improving the metabolic flux distribution of microbes. Some algorithms including flux balance analysis (FBA) and minimization of metabolic adjustment (MOMA) predict a flux distribution from a stoichiometric matrix in the mutants in which some metabolic genes are deleted or non-functional, but there are few algorithms that predict how a broad range of genetic modifications, such as over- and underexpression of metabolic genes, alters the phenotypes of the mutants at the metabolic flux level.

Results: To overcome such existing limitations, we develop a novel algorithm that predicts the flux distribution of the mutants with a broad range of genetic modification, based on elementary mode analysis. It is denoted as genetic modification of flux (GMF), which couples two algorithms that we have developed: modified control effective flux (mCEF) and enzyme control flux (ECF). mCEF is proposed based on CEF to estimate the gene expression patterns in genetically modified mutants in terms of specific biological functions. GMF is demonstrated to predict the flux distribution of not only gene deletion mutants, but also the mutants with underexpressed and overexpressed genes in Escherichia coli and Corynebacterium glutamicum. This achieves breakthrough in the a priori flux prediction of a broad range of genetically modified mutants.

  C. F Lee , M Qiao , K Schroder , Q Zhao and R. Asmis
 

Rationale: The enhanced formation of intracellular reactive oxygen species (ROS) induced by oxidized low-density lipoprotein (OxLDL) promotes macrophage death, a process likely to contribute to the formation of necrotic cores and the progression of atherosclerotic lesions. Yet macrophage deficiency of phagocytic NADPH oxidase (Nox2), the primary source of ROS in macrophages, does not reduce atherosclerotic lesion development in mice. This suggests an as yet unidentified NADPH oxidase may be present in macrophages and responsible for the intracellular ROS formation induced by OxLDL.

Objective: The aim of this study was to identify the source of intracellular ROS involved in macrophage death.

Methods and Results: Nox4 was expressed in human monocytes and mature macrophages, and was localized to the endoplasmic reticulum and to defined foci within the nucleus. Nox4 colocalized with p22phox, and both proteins were upregulated in response to OxLDL stimulation, whereas Nox2/gp91phox levels remained unchanged. Induction of Nox4 expression, intracellular ROS formation and macrophage cytotoxicity induced by OxLDL were blocked by MEK1/2 inhibition, but not by inhibitors of p38-MAPK (mitogen-activated protein kinase), JNK (Jun N-terminal kinase), or JAK2 (Janus kinase 2). Small interfering RNA knockdown of Nox4 inhibited both intracellular ROS production and macrophage cytotoxicity induced by OxLDL, whereas Nox4 overexpression enhanced both OxLDL-stimulated ROS formation and macrophage death.

Conclusions: Nox4 is a novel source of intracellular ROS in human monocytes and macrophages. Induction of Nox4 by OxLDL is mediated by the MEK1/ERK pathway and required for OxLDL cytotoxicity in human macrophages, implicating monocytic Nox4 in atherogenesis.

  X Huang , Q Feng , Q Qian , Q Zhao , L Wang , A Wang , J Guan , D Fan , Q Weng , T Huang , G Dong , T Sang and B. Han
 

The next-generation sequencing technology coupled with the growing number of genome sequences opens the opportunity to redesign genotyping strategies for more effective genetic mapping and genome analysis. We have developed a high-throughput method for genotyping recombinant populations utilizing whole-genome resequencing data generated by the Illumina Genome Analyzer. A sliding window approach is designed to collectively examine genome-wide single nucleotide polymorphisms for genotype calling and recombination breakpoint determination. Using this method, we constructed a genetic map for 150 rice recombinant inbred lines with an expected genotype calling accuracy of 99.94% and a resolution of recombination breakpoints within an average of 40 kb. In comparison to the genetic map constructed with 287 PCR-based markers for the rice population, the sequencing-based method was ~20x faster in data collection and 35x more precise in recombination breakpoint determination. Using the sequencing-based genetic map, we located a quantitative trait locus of large effect on plant height in a 100-kb region containing the rice "green revolution" gene. Through computer simulation, we demonstrate that the method is robust for different types of mapping populations derived from organisms with variable quality of genome sequences and is feasible for organisms with large genome sizes and low polymorphisms. With continuous advances in sequencing technologies, this genome-based method may replace the conventional marker-based genotyping approach to provide a powerful tool for large-scale gene discovery and for addressing a wide range of biological questions.

  Q Zhao , J. H Shen , Z. Y Shen , Z. Y Wu , X. E Xu , J. J Xie , J. Y Wu , Q Huang , X. F Lu , E. M Li and L. Y. Xu
 

Phosphorylation of fascin at serine 39 (phospho-S39-fascin) could inhibit its actin-binding and actin-bundling activities and decrease filopodia formation. However, the relationship between phospho-S39-fascin expression and clinicopathological parameters in tumors is still unknown. Here, Western blot analysis and IHC applied to tissue microarray technology were performed to examine the expression status of non-phosphorylated fascin (fascin) and phospho-S39-fascin and their impacts on the prognosis of patients with esophageal squamous cell carcinoma (ESCC). Fascin and phospho-S39-fascin expressions were tested by cytoplasmic staining. Among the 254 patients, 90 cases showed high expression of fascin and 87 cases showed high expression of phospho-S39-fascin. Survival analysis showed that high expression of fascin was significantly associated with a poor prognosis of the patients with ESCC (p=0.004). In contrast, high expression of phospho-S39-fascin correlated significantly with an improved outcome of patients (p=0.020). Multivariate analysis showed that both fascin and phospho-S39-fascin were independent prognostic factors. In a combined analysis, the patients with high expression of fascin and low expression of phospho-S39-fascin tumors had a shorter overall survival than those with high expression of both fascin and phospho-S39-fascin tumors (5-year overall survival rate: 28.7% vs 48.3%, p=0.068). Our results suggest that high expression of fascin correlates with poor outcome and that high expression of phospho-S39-fascin decreases the risk of poor prognosis in ESCC. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. (J Histochem Cytochem 58:979–988, 2010)

  H Bayir , A. A Kapralov , J Jiang , Z Huang , Y. Y Tyurina , V. A Tyurin , Q Zhao , N. A Belikova , I. I Vlasova , A Maeda , J Zhu , H. M Na , P. G Mastroberardino , L. J Sparvero , A. A Amoscato , C. T Chu , J. T Greenamyre and V. E. Kagan
 

Damage of presynaptic mitochondria could result in release of proapoptotic factors that threaten the integrity of the entire neuron. We discovered that -synuclein (Syn) forms a triple complex with anionic lipids (such as cardiolipin) and cytochrome c, which exerts a peroxidase activity. The latter catalyzes covalent hetero-oligomerization of Syn with cytochrome c into high molecular weight aggregates. Syn is a preferred substrate of this reaction and is oxidized more readily than cardiolipin, dopamine, and other phenolic substrates. Co-localization of Syn with cytochrome c was detected in aggregates formed upon proapoptotic stimulation of SH-SY5Y and HeLa cells and in dopaminergic substantia nigra neurons of rotenone-treated rats. Syn-cardiolipin exerted protection against cytochrome c-induced caspase-3 activation in a cell-free system, particularly in the presence of H2O2. Direct delivery of Syn into mouse embryonic cells conferred resistance to proapoptotic caspase-3 activation. Conversely, small interfering RNA depletion of Syn in HeLa cells made them more sensitive to dopamine-induced apoptosis. In human Parkinson disease substantia nigra neurons, two-thirds of co-localized Syn-cytochrome c complexes occurred in Lewy neurites. Taken together, these results indicate that Syn may prevent execution of apoptosis in neurons through covalent hetero-oligomerization of cytochrome c. This immediate protective function of Syn is associated with the formation of the peroxidase complex representing a source of oxidative stress and postponed damage.

  D. M Kuang , Q Zhao , C Peng , J Xu , J. P Zhang , C Wu and L. Zheng
 

Macrophages (M) are prominent components of solid tumors and exhibit distinct phenotypes in different microenvironments. We have recently found that tumors can alter the normal developmental process of M to trigger transient activation of monocytes in peritumoral stroma. We showed that a fraction of monocytes/M in peritumoral stroma, but not in cancer nests, expresses surface PD-L1 (also termed B7-H1) molecules in tumors from patients with hepatocellular carcinoma (HCC). Monocytes activated by tumors strongly express PD-L1 proteins with kinetics similar to their activation status, and significant correlations were found between the levels of PD-L1+ and HLA-DRhigh on tumor-infiltrating monocytes. Autocrine tumor necrosis factor and interleukin 10 released from activated monocytes stimulated monocyte expression of PD-L1. The PD-L1+ monocytes effectively suppressed tumor-specific T cell immunity and contributed to the growth of human tumors in vivo; the effect could be reversed by blocking PD-L1 on those monocytes. Moreover, we found that PD-L1 expression on tumor-infiltrating monocytes increased with disease progression, and the intensity of the protein was associated with high mortality and reduced survival in the HCC patients. Thus, expression of PD-L1 on activated monocytes/M may represent a novel mechanism that links the proinflammatory response to immune tolerance in the tumor milieu.

 
 
 
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