An invertebrate-specific and immune-responsive microRNA augments oyster haemocyte phagocytosis by targeting CgI kappa B2

• Published in: Scientific Reports
• Main Authors: Chen, Hao, Zhou, Zhi, Wang, Hao, Wang, Lingling, Wang, Weilin, Liu, Rui, Qiu, Limei, Song, Linsheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Crassostrea gigas
• Online Access: http://ir.qdio.ac.cn/handle/337002/130961; https://doi.org/10.1038/srep29591

Nuclear factor (NF)-kappa B pathway is an evolutionally conserved pathway in activating immune response, in which I kappa Bs can repress the activation. In the present study, cgi-miR-2d, an invertebrate-specific microRNA, was proved to regulate CgI kappa B2 expression and haemocyte phagocytosis during bacterial infection in oyster Crassostrea gigas. The expression of cgi-miR-2d was significantly up-regulated after Vibrio splendidus challenge, while CgI kappa B2 transcripts decreased. Significant decreases in both luminescence and CgI kappa B2 3'UTR level was observed after transfection of cgi-miR-2d in CgI kappa B2 3'UTR luciferase reporter assay. CgI kappa B2 mRNA level decreased significantly (0.51-fold of control group, p < 0.05) in gain-of-function assay of cgi-miR-2d in vivo while it increased markedly (1.27-fold, p < 0.05) when cgi-miR-2d was repressed (0.10-fold, p < 0.01). A significant increase of haemocyte phagocytosis rate was observed in cgi-miR-2d overexpression group (p < 0.01), consistent with results in CgI kappa B2 knock-down group (p < 0.01). Moreover, the apoptosis rate of haemocytes was found significantly declined (28.57%, p < 0.01) in gain-of-function assay of cgi-miR-2d. Together, those results not only depicted the functional conservation of miR-2d family in anti-apoptosis of oysters but also highlighted its interaction with phagocytosis by modulating NF-kappa B pathway, which might dedicate critically to the well-balance of host immune response.