title: Exocytosis of a complement component C3-like protein by tunicate hemocytes.
abstract: This study investigates the exocytic responses of invertebrate hemocytes to pathogen-associated antigens. It demonstrates that a homologue of complement component C3, a key defensive protein of the innate immune system, is expressed by phagocytic hemocytes (non-refractile vacuolated cells) of the tunicate, Styela plicata. C3-like molecules are localized in sub-cellular vesicles and are rapidly exocytosed after stimulation with bacterial, fungal or algal cell surface molecules. Signal transduction analysis indicated that the induced secretion of C3-like molecules is mediated by a G-protein dependent signaling pathway, which modulates tubulin microtubules. All of this evidence indicates that hemocytes can contribute to host defense responses by rapidly exocytosing C3-like proteins at sites of infection.
authors.affiliation: Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia. draftos@rna.bio.mq.edu.au
authors.forename: David A
authors.initials: DA
authors.lastname: Raftos
authors.forename: Megan
authors.initials: M
authors.lastname: Fabbro
authors.forename: Sham V
authors.initials: SV
authors.lastname: Nair
mesh_terms: D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D015153:Blotting, Western; D000001:Calcimycin / Q000494:pharmacology; D002351:Carrageenan / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002772:Cholera Toxin / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D003176:Complement C3 / Q000032:analysis / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D022162:Cytoplasmic Vesicles / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D006434:Hemocytes / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D007150:Immunohistochemistry; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008351:Mannans / Q000494:pharmacology; D008854:Microscopy, Electron; D010617:Phenanthridines / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014561:Urochordata / Q000166:cytology / Q000276:immunology / Q000502:physiology*
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D003176:Complement C3; D008070:Lipopolysaccharides; D008351:Mannans; D010617:Phenanthridines; C433788:lipopolysaccharide, E. coli O26-B6; D005576:Colforsin; D015638:Cytochalasin D; D000001:Calcimycin; D019284:Thapsigargin; D002351:Carrageenan; D002772:Cholera Toxin; C016299:chelerythrine; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D003078:Colchicine