The SpTrf genes are strongly upregulated in response to immune challenge. These genes encode homologues of the complement cascade, lectins, a Tie receptor homologue (a putative growth factor receptor), antimicrobial peptides called SpStrongelocins, and a set of unique genes that are members of the SpTransformer (SpTrf formerly Sp185/333) gene family that are only found in sea urchins. A number of immune genes are upregulated in activated coelomocytes in response to lipopolysaccharide (LPS), other pathogen associated molecular patterns, and heat-killed Vibrio diazotrophicus (a marine bacterium). Many of the immune response genes are expressed in the immune cells, or coelomocytes, that become activated in response to infection or injury. Annotation of the sea urchin genome and the identification of genes encoding proteins that function in immunity demonstrated that innate immune system of this long-lived invertebrate is complex, robust, and sophisticated.
The scientific question that has focused the research in the lab for many years has been ‘how do immune systems function in marine invertebrates?’ and is centered the innate immune system of the purple sea urchin, Strongylocentrotus purpuratus.