Gene Cloning, Expression And Immunological Actities Of CD9 From Japanese Lamprey

CD9 is a member of the tetraspanin superfamily and is involved in various cellular processes. Lamprey, the living representative of jawless vertebrates, has been a focal point in the search for the evolutionary origins of adaptive immunity due to its unique position in chordate phylogeny. There are large numbers of homologous genes have been identified in lamprey which associated with immune response, cell differentiation, proliferation, migration and signal transduction. The expression of these abundant genes means a lot in the research of early adaptive immune system. On the contrary, there have been no defined reports on the immune function related CD9 in Japanese lamprey.In this study, we cloned the CD9 gene from Japanese lamprey after screening a leucocyte cDNA library. The CD9 gene contains 684 bp open read frame encoding 228 amino acids. Both real-time PCR and immunohistochemical assays showed wide distribution to the CD9 in Japanese lamprey tissues. In addition, the expression level of the CD9 mRNA was up-regulated in liver and heart after stimulation by LPS. An interaction between CD29 and CD9 in the Japanese lamprey intestine has been found with co-immunoprecipitation assays. Flow cytometric analysis demonstrated that CD9 was detected on the leucocytes, and the expression level was higher on the granulocytes than that on the lymphocytes. The aforementioned research will provide reference for further study of Japanese lamprey CD9 and the immunologic mechanism in jawless vertebrates.