Function of lamp2 Gene Response to Vibrio vulnificus Infection and LPS Stimulation in the Half-Smooth Tongue Sole (Cynoglossus semilaevis)

Lysosome-associated membrane glycoproteins (LAMPs), including lysosomal membrane protein 1 (Lamp1) and lysosomal membrane protein 2 (Lamp2), are involved in phagocytosis, chaperone-mediated autophagy (CMA), and other pathways that interact with lysosomal activity. However, the role of Lamp2 in teleosts has not been clarified. In this study, we investigated the functions of lamp2 genes during Vibrio vulnificus infection. We achieved subcellular localization of the lamp2 gene at the cellular level and performed overexpression and RNA interference experiments followed by Lipopolysaccharides (LPS) stimulation to probe the expression changes of related genes. Ultrapathology analysis of the head-kidney revealed an increase in lysosomes and the formation of autophagosomal vesicles after V. vulnificus infection, suggesting that lysosomes bind to autophagosomes. The lamp2 gene, encoding 401 amino acids in Cynoglossus semilaevis, was constitutively expressed in all examined tissues of healthy half-smooth tongue sole, with the highest expression in blood. A challenge test was conducted to assess the response of half-smooth tongue sole (Cynoglossus semilaevis) to different concentrations of V. vulnificus. The results showed that the relative expression of lamp2 and its related genes-lc3, rab7, vamp8, atg14, stx17, snap29, ctsb, and ctsd-varied with time and concentration in the gill, spleen, head-kidney, blood, liver, and gut tissues. From the results of lamp2 gene overexpression and RNA interference experiments, it is hypothesized that lamp2 positively regulates lc3, rab7, vamp8, snap29, and stx17, and negatively regulates ctsd and ctsb. Our findings provide new primary data for the function of lamp2 gene in the half-smooth tongue sole., particularly its role in regulating the immune response against V. vulnificus.