Pathogen-driven modulation of eight STATs in Cromileptes altivelis: Comparative analysis from homeostasis to immune...

Signal transducer and activator of transcription (STAT) family members, which serve as transcription activators, play a central role in regulating inflammatory responses. While STATs have been well-characterized in mammals, systematic studies in fish remain scarce. In the present study, eight STATs in Cromileptes altivelis-CaSTAT1a, CaSTAT1b, CaSTAT2, CaSTAT3, CaSTAT4, CaSTAT5a, CaSTAT5b, and CaSTAT6-were characterized using PCR cloning and bioinformatics approaches. Phylogenetic analysis indicated that STATs have undergone significant evolutionary conservation throughout their lineage. Tissue expression patterns in healthy fish revealed that the eight CaSTATs displayed spatiotemporal specificity, with greater expression observed in gill, blood, and muscle. In response to bacterial (Vibrio harveyi, Streptococcus agalactiae) or viral (nervous necrosis virus, NNV) challenge, CaSTATs were robustly expressed and exhibited pathogen-, tissue-, and time-dependent expression divergence. In summary, our data highlight the indispensable roles of eight CaSTATs in modulating host immune responses.