Muscle Development Transition and Myogenic Regulatory Factors Expression Profiling During Rapid Growth in Silver Pomfret (Pampus argenteus)

Myogenic regulatory factors (MRFs) serve as crucial transcription factors that regulate muscle development and differentiation. Although MRFs have been extensively studied across various species, their specific role in the muscle development of silver pomfret (Pampus argenteus) has not been fully understood. To elucidate the role of MRFs in the muscle development of silver pomfret, we characterized the muscle growth pattern during the rapid growth phase of this organism (60–120 days post-hatching, Dph). The analysis revealed a distinct transition in growth mechanisms: Hyperplasia dominated muscle development before 90 Dph, whereas hypertrophy became predominant thereafter. The period between 80–90 Dph was a critical transition stage in the muscle growth pattern. Subsequently, five MRF family members, namely, myogenic determination 1 (MyoD1), MyoD2, myogenic factor 5 (Myf5), Myf6, and myogenin (MyoG), were initially identified in silver pomfret. MRFs exhibited evolutionary conservation and were specifically expressed in the muscle of the silver pomfret. Differential expressions of MRFs were observed across various stages of rapid growth and among individuals with differing growth rates. Upon the addition of exogenous regulatory factors, insulin-like growth factor 1 (IGF)-1 and transforming growth factor beta 1 (TGF-β1) in vitro, MRFs exhibited the most significant upregulation in response to 100 ng/mL of IGF-1. Conversely, Myf5 demonstrated the most pronounced down-regulation at 100 ng/mL of TGF-β1. For the remaining genes, the most effective suppression was achieved with 1 ng/mL of TGF-β1. These findings indicate the crucial role played by MRFs in the regulation of muscle growth and development. This study not only provides new insights into the functional roles of MRFs in fish muscle development but also establishes a foundation for the optimization of silver pomfret aquaculture strategies through the modulation of these factors.