Molecular characterization of a novel tetraspanin from the oyster, Crassostrea ariakensis: Variation, localization and relationship to oyster host defense

We identified a tetraspanin family member gene, named Ca-TSP, in the oyster Crassostrea ariakensis and found that the transcription profiles of Ca-TSP were variable in the oyster hemocytes. Three distinct patterns of variation of Ca-TSP were observed. Using immunofluorescence and immunoelectron microscopy, we show that Ca-TSP was present in granules and in vesicular structures of the oyster hemocyte. Sequence analysis, structural features and immunogold electron microscopy showed that Ca-TSP is an integral membrane glycoprotein of granules of hemocyte and may be a novel CD63-like gene of the tetraspanin family of molluscs. The gene expression analysis of Ca-TSP using isolated oyster hemocytes, was done following challenge of the oysters with LPS and Poly I:C. The Ca-TSP mRNA levels increased in hemocytes in the first 12 h after LPS and Poly I:C stimulation, and decreased after the addition of H2O2. Western blot analysis using anti-Ca-TSP antibody indicated that gene expression and protein levels were similar. The recombinant Ca-TSP was found to significantly inhibit hemocytes aggregation. Our results suggested that Ca-TSP participates in the innate immunity of the oyster.

► A novel tetraspanin family member gene, namely Ca-TSP, identified from mollusc oyster.
► Ca-TSP was enriched in granules of hemocytes.
►  Ca-TSP has variable transcription profiles, responded to stimulus challenge.
► Recombinant Ca-TSP significantly inhibited the hemocyte aggregation.