The regulatory function of GATA3 on immune response in Japanese flounder (Paralichthys olivaceus).

GATA3 belongs to the GATA family, and it could interact with the target gene promoter. It has been reported to play a central role in regulating lymphocyte differentiation. In this study, the GATA3 cDNA sequence was identified by a homologous clone and the RACE technology from Japanese flounder (Paralichthys olivaceus). The full-length of the GATA3 cDNA sequence was 2904 bp, including 1332 bp open reading frame (ORF), 265 bp 5 ′-untranslated region (5′ UTR), and 1308 bp 3 ′-UTR, encoding 443 amino acids. GATA3 protein sequence was conserved in vertebrates and invertebrates, including two zinc finger domains. qRT-PCR showed that the expression of GATA3 was high in the gill, kidney, and spleen. Expression of GATA3 slowly increased at the earlier stages and culminated at the late gastrula and somatic stages. Immunohistochemistry (IHC) results showed that the GATA3 protein was expressed in lymphocyte cells, undifferentiated basal and pillar cells of the gills, as well as lymphocyte cells and melanin macrophages of the kidney. The expression of GATA3 was significantly regulated in tissues and different types of lymphocytes after stimulation with Edwardsiella tarda. Dual-luciferase reporter assay indicated that the GATA3 protein could directly interact with promoters of target genes involved in the immune response. These findings suggested that GATA3 plays a major role in regulating the immune response. This study provided a theoretical basis for the immune response mechanism of teleost and a useful reference for later research on fish immunology. • The full-length of GATA3 cDNA was identified from Japanese flounder. • GATA3 was highly expressed in the gill. • A positive signal of GATA3 was detected in lymphocyte-like cells of the gill and kidney. • GATA3 was significantly down-regulated after being challenged with Edwardsiella tarda in tissues and lymphocytes. • GATA3 could interact with target genes involved in immune response as a transcription factor. [ABSTRACT FROM AUTHOR]