Characterization of Caspase Gene Family Members in Spotted Sea Bass (Lateolabrax maculatus) and Their Expression Profiles in Response to Vibrio harveyi Infection

The caspase gene family is a crucial gene cluster that regulates apoptosis which contribute to programmed cell death, cell proliferation and differentiation, and several immune responses. In our study, a complete set of 12 caspase genes were identified in spotted sea bass Lateolabrax maculatus . These genes were divided into three subfamilies: 2 inflammatory caspases ( casp-1 and casp-14-like ), 5 apoptosis initiators ( casp-2, casp-8a, casp-8b, casp-9 , and casp-10 ), and 5 apoptosis executioners ( casp-3a, casp-3b, casp-3-like, casp-6 , and casp-7 ). Their phylogenetic relationships, synteny and gene structures were systematically analyzed. Furthermore, the relative expression profiles of the caspase family members in the liver, intestine, head kidney, and spleen were measured by qPCR after infection with Vibrio harveyi . The results showed that the overall mRNA levels of the caspase genes were dramatically increased after V. harveyi infection, and the expression patterns varied among genes and tissues. More caspase genes underwent pronounced expression changes in the head kidney and spleen than in the liver or intestine, mainly after 48 h of the challenge. Specifically, casp-3a, casp-3b, casp-3-like, casp-6, casp-7, casp-8a, casp-8b, casp-10 , and casp-14-like in the head kidney, and casp-3-like, casp-6, casp-7 , and casp-14-like in the spleen, were the most responsive caspase genes which may contribute significantly to immune regulation in spotted sea bass. Additionally, the apoptosis level in head kidney and spleen after infection were examined using the Caspase assay. Our study provides a systemic overview of the caspase gene family in spotted sea bass after V. harveyi infection and lays a foundation for further deciphering the biological roles of these caspase genes.