Molecular characterization and expression of the teleost cytosolic DNA sensor genes cGAS, LSm14A, DHX9, and DHX36 in Japanese medaka, Oryzias latipes.

Numerous cytosolic DNA sensors (CDSs), which are very important for recognizing cytosolic dsDNA derived from intracellular viruses and bacteria, exist in mammals. However, teleost CDSs are poorly understood. In this study, four CDSs, including the cyclic GMP-AMP synthase (cGAS), Sm-like protein 14 homolog A (LSm14A), DEAH-box helicase (DHX) 9, and DHX36 genes were identified in Japanese medaka, Oryzias latipes, and their expression patterns were elucidated. The expression of these genes was upregulated in the intestines and kidney of CpG-ODN-stimulated medaka. The cGAS and LSm14A genes were significantly induced in the intestines, kidney, and spleen of formalin-killed Edwardsiella tarda-treated medaka; the DHX9 and DHX36 genes were not. cGAS gene expression was induced only in the intestines of live E. tarda-treated medaka. These results suggest that the transcription of four CDS genes of medaka responds to dsDNA stimulation, and cGAS is probably more important for the immune response against E. tarda infection.