Disease relevance of C3

• In addition, continuous exposure of embryos, beginning with the hatched blastula stage, to heat killed Vibrio diazatrophicus, a marine pathogen of sea urchins, significantly increased Sp064 message content in plutei compared to unexposed controls [1].

High impact information on C3

• Phylogenetic analysis of SpC3 compared with other members of the thioester protein family, which includes C3, C4, C5, and alpha2-macroglobulin, shows that SpC3 is the first divergent complement protein, falling at the base of the complement protein clade [2].
• There are five consensus N-linked glycosylation sites, and putative cleavage sites for factor I and C3 convertase [2].
• Genome blots suggest that SpC3 is encoded by a single copy gene per haploid genome [2].
• Purple sea urchin, Strongylocentrotus purpuratus, homologues of complement C3 (SpC3) and factor B (SpBf) have been identified, suggesting the presence of an alternative complement pathway [3].
• Confocal microscopy showed that opsonized yeast were phagocytosed by a single coelomocyte type (polygonal phagocytes), presumably because these cells express SpC3 receptors [4].

Biological context of C3

• This indicates that SpC3 promotes phagocytosis by physically tagging target cells for ingestion [4].
• In this study, transcript levels from the gene, Sp064, which encodes SpC3, were examined in developing embryos and found to be present in unfertilized eggs and throughout embryogenesis with a peak in transcript levels just prior to and during gastrulation [1].
• Although the changes in SpC3 were not as great as those identified previously for human C3 expressed in macrophages, the kinetics of the response are similar to that of acute-phase reactants in mammals [5].

Associations of C3 with chemical compounds

• A homologue of complement C3, SpC3, has been identified in adult Strongylocentrotus purpuratus and is expressed in coelomocytes [1].
• Expression of SpC3, the sea urchin complement component, in response to lipopolysaccharide [5].

Analytical, diagnostic and therapeutic context of C3

• Changes in the amounts of SpC3 in coelomic fluid and in coelomocytes were then followed over time by Western blots and ELISA [5].
• To determine which of these subpopulations expresses Sp064 and produces SpC3, coelomocytes were separated by discontinuous gradient density centrifugation [6].

References