title: Immunocompetent molecules and their response network in horseshoe crabs.
abstract: Horseshoe crab hemocyte selectively responds to bacterial lipopolysaccharides (LPS), which depends critically on the proteolytic activity of the LPS-responsive serine protease zymogen factor C. In response to stimulation by LPS, the hemocyte secretes several kinds of immunocompetent proteins. The coagulation cascade triggered by LPS or beta-1,3-D-glucans (BDG) results in the formation of coagulin fibrils that are subsequently stabilized by transglutaminase (TGase)-dependent cross-linking. Invading pathogens are recognized and agglutinated by lectins and then killed by antimicrobial peptides. Moreover, LPS-triggered hemocyte exocytosis is enhanced by a feedback mechanism in which the antimicrobial peptides serve as endogenous mediators. Factor C also acts as an LPS-sensitive complement C3 convertase. In addition, a sub-cuticular epidermis-derived protein forms a TGase-stabilized mesh at sites of injury. Horseshoe crabs have a sophisticated innate immune response network that coordinately effects pathogen recognition and killing, prophenoloxidase activation, complement activation and TGase-dependent wound healing.
authors.affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan. skawascb@kyudai.jp
authors.forename: Shun-ichiro
authors.initials: S
authors.lastname: Kawabata
mesh_terms: D000818:Animals; D060829:Arthropod Proteins; D004792:Enzyme Precursors / Q000276:immunology*; D006434:Hemocytes / Q000276:immunology; D006737:Horseshoe Crabs / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology; D012697:Serine Endopeptidases / Q000276:immunology*
chemical_list: D060829:Arthropod Proteins; D004792:Enzyme Precursors; D008070:Lipopolysaccharides; D012697:Serine Endopeptidases; C057151:Limulus clotting factor C