IFN-γ2 enhances proliferation and differentiation of muscle cells: a novel target of natural grass feeding mode improving muscle quality in grass carp (Ctenopharyngodon idella).

Grass carp (Ctenopharyngodon idella), as the highest-yielding freshwater species in China, has become a focus of muscle quality research. Previous studies have shown that natural grass feeding (GF) mode can improve the muscle quality of grass carp compared with artificial feeding (AF) mode, but its mechanism has not been revealed. In this study, we identified that interferon-γ2 (IFN-γ2) can be induced in the muscle tissues under GF mode. Therefore, recombinant IFN-γ2 protein was obtained to study its effect on grass carp muscle cells (GCMCs). We found that IFN-γ2 can facilitate the proliferation of GCMCs, and promote the myotube enlargement of GCMCs. Meanwhile, mRNA level investigations indicated that IFN-γ2 can regulate the expression of genes related to cell physiological processes. By transcriptome analysis, we screened a series of genes related to cell proliferation, differentiation, and migration. Using STAT1 inhibitor fludarabine in vitro, we confirmed that IFN-γ2 regulates the physiological development of GCMCs through JAK/STAT1. Finally, by knocking down IFN-γ2 in grass carp individuals, we verified that IFN-γ2 has an effective regulatory effect in vivo. This study provides novel target for improving the muscle quality of grass carp and provides inspiration for the development of aquaculture feeding mode. HIGHLIGHTS: 1. Natural grass feeding mode induces IFN-γ2 expression in grass carp muscle. 2. IFN-γ2 promotes the proliferation of grass carp muscle cells via JAK/STAT1. 3. IFN-γ2 regulates the expression of genes related to muscle proliferation in vivo.