A complement component C3a-like peptide stimulates chemotaxis by hemocytes from an invertebrate chordate - The tunicate, Pyura stolonifera

David A. Raftos*, Jennifer Robbins, Rebecca A. Newton, Sham V. Nair

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    33 Citations (Scopus)

    Abstract

    Recent evidence suggests that the complement system evolved as a critical host defence mechanism among invertebrates, long before the origin among vertebrates of adaptive immune responses mediated by somatically re-arranging antibodies. The current study supports that contention by identifying a complement component C3a-like peptide in the tunicate, Pyura stolonifera. Activation of P. stolonifera serum with common inflammatory elicitors (lipopolysaccharide and zymosan) resulted in the proteolytic generation of an 8.5 kDa peptide, and concomitantly conferred chemoattractant activity on the serum. The 8.5 kDa peptide shares substantial amino acid sequence homology with a previously characterised tunicate complement component C3-like protein (72% amino acid identity in an 18 amino acid overlap). It is also recognised by an anti-C3 antiserum that is known to cross react with tunicate C3 homologues. Hemocyte migration assays performed with the 8.5 kDa peptide that had been partially purified by gel filtration confirmed that the molecule acts as a powerful chemotactic agent. This suggests that the proteolytic activation of tunicate C3-like molecules can initiate inflammatory responses involving cellular recruitment by liberating a pro-inflammatory peptide akin to the vertebrate anaphylatoxin, C3a.

    Original languageEnglish
    Pages (from-to)377-386
    Number of pages10
    JournalComparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology
    Volume134
    Issue number2
    DOIs
    Publication statusPublished - 1 Feb 2003

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