RNA interference in Haliotis rufescens myostatin evidences upregulation of insulin signaling pathway

Muscle growth rate is a critical issue for abalone aquaculture due to impacts on production costs. However, knowledge of the molecular mechanisms involved in molluscan myogenesis is limited. Therefore, the myostatin gene in the red abalone Haliotis rufescens (Hr-MSTN) was characterized and evaluated at the transcriptional level using RNA interference and gene silencing correlated with the insulin pathway as a proxy for somatic growth. Hr-MSTN cDNA was comprised of 2346 base pairs that encoded 489 amino acids and that contained structural characteristics typical of the transforming growth factor-β superfamily, including C-terminal signal peptide, propeptide domain, and transforming growth factor-β regions. Gene expression analysis revealed ubiquitous transcript expression in all tested red abalone tissues, but the muscle and mantle evidenced the highest transcriptional activity. RNA interference against MSTN mRNA significantly downregulated MSTN at 14 days post-injection, correlating with an upregulation of the insulin-related genes Insulin receptor, Growth factor receptor bound 2, and Proto-oncogene serine/threonine-protein kinase. These results suggest that MSTN silencing can promote activation of the insulin transcription pathway and consequently trigger somatic growth in the red abalone. This study is the first to evaluate the role of MSTN in gastropods using RNA interference, thus providing new perspectives for genetic improvement programs in abalone aquaculture.