A novel intracellular signaling pathway elicited by DM9CP-6 regulates immune responses in oysters.

UNLABELLED

DM9 domain containing protein (DM9CP) is a recently discovered novel pattern recognition receptor (PRR) with the ability to recognize various microbes, but its role as a cytosolic PRR to track the invading microbes and trigger signaling pathway is still not clear. In the present study, a DM9CP (designated as DM9CP-6) and an intracellular regulatory molecule, 14-3-3 (designated as 14-3-3ε) were identified from oyster , which contained two tandem DM9 repeats and a 14-3-3ε domain, respectively. DM9CP-6 and 14-3-3ε were higher expressed in haemocytes, and their mRNA expression levels increased significantly after stimulation. DM9CP-6 could bind various polysaccharides (LPS, PGN, MAN, and D-mannose) and microbes (, , , , , and ) in vitro, and it was observed to be colocalized with the FITC-labeled , and in haemocytes in vivo. The pull-down, surface plasmon resonance (SPR) and Co-Immunoprecipitation (Co-IP) assays all demonstrated that 14-3-3ε was able to interact with DM9CP-6 in vitro or in vivo. After the expression of DM9CP-6 and 14-3-3ε was knocked down separately by RNAi, the nuclear translocation of Rel in haemocytes was inhibited, and the mRNA expressions of interleukin17-3 (IL17-3), IL17-6, Lysozyme and BigDef1 in haemocytes all decreased significantly after the oysters were stimulated with . The results collectively indicated that DM9CP-6 could function as an intracellular PRR to be associated with 14-3-3ε to trigger the NF-κB pathway, which eventually regulated the immune responses including the expressions of inflammatory cytokines and antimicrobial molecules in oysters.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s12964-025-02389-4.