Lu Zhao

Tianjin Normal University, T’ien-ching-shih, Tianjin Shi, China

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Publications (4)10.84 Total impact

  • Jin-sheng Sun · Lu Zhao · Li Sun
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    ABSTRACT: Interleukin-8 (IL-8), or CXCL8, is a member of the CXC chemokine family that in mammals is known to mediate inflammatory response. In this study, we identified and analyzed an IL-8 orthologue, CsIL8, from half-smooth tongue sole (Cynoglossus semilaevis). The deduced amino acid sequence of CsIL8 contains 100 residues and is closely related to the lineage 1 IL-8 of a number of fish species. In silico analysis identified in CsIL8 a CXC chemokine domain that contains four conserved cysteine residues, two of which form the CXC signature motif of CXC chemokines. Expression of CsIL8 as determined by quantitative real time RT-PCR was detected in a wide range of tissues under normal physiological conditions and was upregulated by bacterial challenge and by vaccination with a subunit vaccine. Purified recombinant CsIL8 (rCsIL8) induced migration of peripheral blood leukocytes and head kidney (HK) lymphocytes and stimulated the proliferation of these cells in a dose-dependent manner. When rCsIL8 was added to the cell culture of HK lymphocytes, it upregulated the expression of interleukin-1β and CsIL8 in a time-dependent fashion. These results indicate that CsIL8 is a biologically active CXC chemokine with immunoregulatory activity and that CsIL8 is involved in pathogen-induced inflammatory response.
    No preview · Article · Jun 2011 · Fish & Shellfish Immunology
  • Lu Zhao · Yong-Hua Hu · Jin-Sheng Sun · Li Sun
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    ABSTRACT: High mobility group box 1 protein (HMGB1) is a chromatin-associated nonhistone protein that is involved in nucleosome formation and transcriptional regulation. In addition, HMGB1 is also known as an extracellular cytokine that triggers inflammation and immune responses. HMGB1-like sequences have been identified in a number of fish species, however, the function of piscine HMGB1 remains uninvestigated. In this study, we reported the identification and analysis of SoHMGB1, an HMGB1 homologue from red drum (Sciaenops ocellatus). SoHMGB1 is 206 residues in length and contains two basic HMG boxes and a highly acidic C-terminal domain. SoHMGB1 shares 71-87% overall sequence identities with the HMGB1 counterparts from human, rat, and several fish species. Quantitative real time RT-PCR analysis showed that constitutive SoHMGB1 expression was detected in various tissues, with the lowest and highest levels found in kidney and muscle respectively. Bacterial challenge upregulated SoHMGB1 expression in head kidney (HK) and HK macrophages and induced extracellular secretion of SoHMGB1 by the activated macrophages. Recombinant SoHMGB1 (rSoHMGB1) purified from yeast exhibited no direct antimicrobial effect but was significantly stimulatory on the proliferation, activation, and bactericidal activity of HK macrophages. Taken together, these results indicate for the first time that a fish HMGB1, SoHMGB1, can function as a secreted cytokine in the event of bacterial infection and promote innate defense through the activation of macrophages.
    No preview · Article · Apr 2011 · Developmental and comparative immunology
  • Lu Zhao · Jin-Sheng Sun · Li Sun
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    ABSTRACT: Lysozyme is a muramidase that inflicts damage on bacterial cell wall by catalyzing the cleavage of the beta-1,4-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan. Lysozymes are classified into several types, one of which is the goose-type (g-type). In this study, we identified and analyzed a g-type lysozyme (SmLysG) from turbot Scophthalmus maximus. The deduced amino acid sequence of SmLysG contains 193 residues and is most closely related to that of the g-type lysozyme of Scophthalmus rhombus (94% overall identity). SmLysG possesses a Goose Egg White Lysozyme (GEWL) domain with conserved residues essential for catalytic activity. Recombinant SmLysG (rSmLysG) purified from yeast exhibits strong lysozyme activity against Micrococcus luteus. Enzyme assays showed that the optimal temperature and pH of rSmLysG are 30°C and pH 7.0, respectively. Substrate spectrum analysis indicated that rSmLysG inhibited the growth of a number of important fish pathogens of both Gram-negative and Gram-positive natures. SmLysG transcription was detected in multiple tissues and was upregulated in kidney and spleen by experimental challenges with lipopolysaccharide and bacterial pathogens that are, respectively, sensitive to and resistant against the lytic effect of rSmLysG. Comparative analysis showed that although bacterial infection also induced the expression of c-type lysozyme, the induction levels were much lower than those of SmLysG. Taken together, these results indicate that SmLysG is a functional g-type lysozyme with a wide working range and is involved in innate immune defense against general bacterial infection.
    No preview · Article · Feb 2011 · Fish & Shellfish Immunology
  • Lu Zhao · Yong-hua Hu · Li Sun · Jin-sheng Sun
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    ABSTRACT: C2 domains are protein structural modules found in many eukaryotic proteins involved in signal transduction, membrane trafficking, and immune defense. Most of the studied C2 domain-containing proteins are multi-domained in structure, in which the C2 domain is an independently folded motif and plays an essential role in calcium-dependent membrane-targeting. Although C2 domains isolated from intact proteins have been studied for biological functions, no study on natural proteins containing C2 domain only has been documented. In this study, we identified a Scophthalmus maximus protein SmC2P1 that is comprised of a single C2 domain and lacks any other apparent domain structures. The deduced amino acid sequence of SmC2P1 contains 129 residues and shares 36-38% identities with the C2 domains of the perforins of several fish species. Like typical C2 domains, SmC2P1 is predicted to organize into eight beta-strands with a Ca(2+)-binding site located in inter-strand loops. SmC2P1 expression was detected, in deceasing order, in liver, spleen, blood, brain, muscle, kidney, gill, and heart. Experimental challenge of turbot with a bacterial pathogen significantly upregulated SmC2P1 expression in kidney in a time-dependent manner. Recombinant SmC2P1 purified from yeast exhibits no hemolytic activity but binds to pathogen-infected kidney lymphocytes in the presence of calcium. Furthermore, interaction of recombinant SmC2P1 with bacterium-infected lymphocytes reduced bacterial survival. These results indicate that SmC2P1 is a functional protein that is involved in host immune defense against bacterial infection.
    No preview · Article · Nov 2010 · Fish & Shellfish Immunology