title: Lipopolysaccharide and beta-1, 3-glucan binding protein (LGBP) stimulates prophenoloxidase activating system in Chinese mitten crab (Eriocheir sinensis).
abstract: Melanization mediated by prophenoloxidase (proPO) activating system play an essential role in killing invading microorganisms in invertebrates. Lipopolysaccharide and β-1, 3-glucan binding protein (LGBP) as a pattern recognition protein have been demonstrated to active the proPO cascade in insect and shrimp. In this study, we investigated the role of LGBP in prophenoloxidase cascade-induced melanization in Chinese mitten crab (Eriocheir sinensis). By RT-PCR analysis, EsLGBP was detected in all tested tissues, and showed highest expression in hemocytes, gill, intestine and brain. The expression of EsLGBP was up-regulated in the hemocytes following injections of LPS and β-1, 3-glucan. The recombinant EsLGBP protein (rEsLGBP) was produced via prokaryotic expression system and affinity chromatography. By western blotting, rEsLGBP was discovered to exhibit the ability to bind to all tested microorganisms, including Gram-negative bacteria, Gram-positive bacteria and yeast (Pichia pastoris). Meanwhile we found rEsLGBP has a high binding activity towards microbial immune elicitors such as LPS and β-1, 3-glucan whereas no binding activity is detected with peptidoglycan. Moreover, the effects of RNAi-mediated blockade of EsLGBP were investigated on bacterial counts in the hemolymph and cumulative mortality rate of crabs infected with Vibrio parahaemolyticus in vivo. Further experiments demonstrate that rEsLGBP can trigger the whole hemolymph dependent melanization and stimulate to proPO cascade in vitro. Taken together, these results provide experimental evidence for role of LGBP in innate immunity, especially in the activation of prophenoloxidase activating system.
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China.
authors.forename: You-Ting
authors.initials: YT
authors.lastname: Zhu
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China.
authors.forename: Xue-Jie
authors.initials: XJ
authors.lastname: Li
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China.
authors.forename: Shi-Chuang
authors.initials: SC
authors.lastname: Wang
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China. Electronic address: wwli@bio.ecnu.edu.cn.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Li
authors.affiliation: Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai 200241, China. Electronic address: qwang@bio.ecnu.edu.cn.
authors.forename: Qun
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D058491:Bacterial Load; D003386:Brachyura / Q000276:immunology*; D004156:Catechol Oxidase / Q000378:metabolism*; D004792:Enzyme Precursors / Q000378:metabolism*; D006434:Hemocytes / Q000276:immunology*; D006458:Hemolymph / Q000276:immunology; D007113:Immunity, Innate; D037102:Lectins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology; D008543:Melanins / Q000378:metabolism*; D010802:Phylogeny; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D014735:Vibrio Infections / Q000276:immunology*; D014736:Vibrio parahaemolyticus / Q000276:immunology*
chemical_list: D004792:Enzyme Precursors; D037102:Lectins; D008070:Lipopolysaccharides; D008543:Melanins; D034741:RNA, Small Interfering; C038451:pro-phenoloxidase; D004156:Catechol Oxidase
keywords: Eriocheir sinensis; LGBP; Melanization; Prophenoloxidase activating system