Beclin-1 is involved in tongue sole Cynoglossus semilaevis immune defense against bacterial infection

In mammals, beclin-1 is a key player that regulates autophagic activity. In fish, the immune function of beclin-1 is essentially unknown. In this study, we analyzed the involvement of tongue sole (Cynoglossus semilaevis) beclin-1 (named CsBECN1) in antibacterial immunity. CsBECN1 is composed of 451 amino acid residues and shares 84.5-95.1% overall sequence identities with other teleost beclin-1. CsBECN1 possesses a typical Bcl-2 homology domain 3 and an Atg6 domain. Expression of CsBECN1 occurred in multiple tissues and was upregulated during bacterial infection. Knockdown of CsBECN1 significantly enhanced bacterial dissemination in the tissues of tongue sole, whereas overexpression of CsBECN1 significantly reduced bacterial dissemination. Taken together, these results indicate that CsBECN1 is required for the antibacterial immunity of tongue sole.