The significant regulatory role of cytochrome P450 in the innate immune response of the Zhikong scallop (Chlamys farreri).

Cytochrome P450 (CYP450) enzymes represent a critical class of detoxification enzymes that play essential roles in antioxidant defense, xenobiotic metabolism, and innate immune responses in animals. However, knowledge regarding the gene sequences and functional characteristics of CYP450 genes in mollusks remains limited. In this study, a novel CYP450 gene, designated Cf-CYP450, was cloned from the Zhikong scallop (Chlamys farreri). The open reading frame (ORF) of Cf-CYP450 spans 1497 bp and encodes a polypeptide of 498 amino acids. The N-terminus of the Cf-CYP450 protein contains a transmembrane domain, whereas the C-terminus harbors a conserved P450 domain. Phylogenetic analysis indicates that Cf-CYP450 is a newly identified member of the molluscan CYP450 family. Quantitative real-time PCR analysis revealed that Cf-CYP450 mRNA is ubiquitously expressed across various scallop tissues, with the highest expression observed in gill tissue. Furthermore, the expression of Cf-CYP450 is inducible by multiple stimuli, including pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS), peptidoglycan (PGN), and poly (I:C). As anticipated, infections with bacteria (including various Vibrio species) and viruses (e.g., acute viral necrosis virus) significantly alter Cf-CYP450 expression levels, suggesting its involvement in scallop innate immunity. Dual-luciferase reporter (DLR) assays further demonstrated that overexpression of Cf-CYP450 in HEK293T cells markedly suppresses the activity of multiple immune-related reporter genes. Additionally, Cf-CYP450 dose-dependently inhibits the activation of ISRE (Interferon stimulated response element) reporter genes induced by poly (I:C) or scallop IRF1 (Interferon regulatory factor 1). Notably, Cf-CYP450 expression in HEK293T cells also induces significant phosphorylation of MAPK (Mitogen-activated protein kinase) signaling proteins, such as JNK (c-Jun N-terminal kinase) and Erk1/2 (Extracellular regulated protein kinases 1/2). These findings collectively indicate that Cf-CYP450 plays a pivotal role in scallop defense against exogenous pathogens and may mediate diverse immune responses through participation in distinct signaling pathways or regulation of specific effector genes.