Rab10 GTPase from the mud crab Scylla paramamosain is involved in the host immune response against V. parahaemolyticus infection.

Rab GTPases are pivotal regulators of organelle trafficking and host immune responses, which are critical for bacterial defense. However, little is known of the function of Rab in crustacean responses to bacterial infection. In this study, a Rab10 gene (Sp-Rab10) was identified from the mud crab Scylla paramamosain. The full open reading frame of consisted of 612 bp, encoding a 203-amino acid polypeptide that shared 98% sequence identity with Portunus trituberculatus Rab10. Quantitative real-time PCR (qRT-PCR) analysis showed that Sp-Rab10 exhibited broad tissue distribution, with the highest expression detected in the hepatopancreas. Notably, Sp-Rab10 expression was markedly up-regulated following V. parahaemolyticus infection, implying its potential involvement in the innate immune response against bacterial challenge. To explore the regulatory mechanism of Sp-Rab10, an RNA interference (RNAi) experiment was conducted. Silencing of Sp-Rab10 resulted in significant down regulation of 3 phagocytosis-related genes (c-type lysozyme, crustin and anti-lipopolysaccharide factor). Additionally, in vivo knockdown of Sp-Rab10 increased bacterial load in the hemolymph and mortality of mud crabs after V. parahaemolyticus infection. Collectively, these findings demonstrated that Sp-Rab10 played a critical role in antimicrobial defense in crustaceans.