ATG12 contributes to antibacterial immunity against Aeromonas veronii in Macrobrachium rosenbergii

Autophagy is a central component of host immune defense against various infections. Autophagy-related protein 12 (ATG12) is a key regulator of autophagy, but its role in antibacterial immunity remains unclear. In this study, Macrobrachium rosenbergii ATG12 (MrATG12) was cloned, and its role in response to Aeromonas veronii challenge was investigated. The open reading frame of MrATG12 was 360 bp in length and encoded a polypeptide of 119 amino acids. Sequence comparison revealed that MrATG12 from M. rosenbergii shared the highest sequence identity with Palaemon carinicauda. Tissue distribution analysis showed that MrATG12 was highly expressed in the hemocytes of M. rosenbergii. Upon A. veronii challenge, MrATG12 mRNA expression in the gill and hepatopancreas was significantly increased. MrATG12 was distributed in both the cytoplasm and nucleus of HEK-293T cells and co-localized with MrATG5. MrATG12 knockdown was associated with reduced expression of several autophagy-related genes and increased expression of several antimicrobial peptide (AMP)-related genes. In addition, bacterial load and mortality were elevated following MrATG12 knockdown. These findings support a role for MrATG12 in the immune response of M. rosenbergii to A. veronii infection and expand our understanding of antibacterial immunity in crustaceans.