RNA interference provides insights into the multi-functional profiles of Es-MSTN gene in Eriocheir sinensis

Myostatin (MSTN) is a negative regulation factor involved in skeletal muscle growth and development in vertebrates. In order to understand the multi-functional roles of MSTN in crustaceans, we assessed the molting / growth characters, analyzed the tissues composition and investigated the expression levels of lipid metabolism and immune related genes in Chinese mitten crab (Eriocheir sinensis) after injection of Es-MSTN dsRNA during one molt cycle of 49 days. We found the RNAi group displayed shorter molting interval, higher specific growth rate, and lower hepatosomatic index compared with the control group, evidencing MSTN may also be a negative regulator of muscle growth and development in E. sinensis. In the RNAi group, the expression levels were upregulated for lipid metabolism-related genes of pancreatic lipase (LP), carnitine palmitoyl transferases 1β (CPT1β) and fatty acid-binding protein 3 (FABP3) in muscles, but were downregulated for these three genes and fatty acid-binding protein 9 (FABP9) in hepatopancreas. Meanwhile, the expression levels were all upregulated for immune-related genes of prophenoloxidase (PHE), anti-lipopolysaccharide factor (ALF), Lectin H (LecH), and prophenoloxidase-activating factor (PPAF) in both muscle and hepatopancreas in the RNAi group. Further tissue composition analysis showed that there were no significant differences in amino acid composition between the RNAi and control groups in muscle and hepatopancreas, but most of significant differences in fatty acid composition were detected between the two groups in both muscle and hepatopancreas. This study demonstrated that Es-MSTN is a vital muscle growth inhibition factor and displayed diverse function in participating in energy metabolism and immune response in E. sinensis.