Identification of myomaker in yellowfin seabream (Acanthopagrus latus) (Hottuyn, 1782) and its transcriptional regulation by Two MyoDs

Abstract

Myomaker is a muscle-specific membrane protein that is essential for myoblast fusion. Myomaker is regulated by myoblast determination protein (MyoD), a muscle-specific basic helix-loop-helix (bHLH) transcription factor in higher vertebrates. However, the transcriptional regulatory mechanism of the myomaker gene has not been explored in marine fishes. In the present study, molecular cloning, bioinformatic analysis and transcriptional analysis of Acanthopagrus latus myomaker (Almyomaker) were performed. The open reading frame (ORF) sequence of Almyomaker is 858 bp, which encodes a polypeptide of 285 amino acids. Moreover, phylogenetic and gene structure analysis indicates that Almyomaker is highly conserved among vertebrates. The tissue distribution pattern shows that Almyomaker is more highly expressed in white muscle than in other tissues. Furthermore, to explore whether two MyoDs are modulators of Almyomaker, a promoter analysis was performed using progressive deletion mutations of Almyomaker. The results of promoter activity assays show that Almyomaker expression is notably activated by two MyoDs. Transcriptional activity of the Almyomaker promoter was observed to dramatically decrease after targeted mutation of the MyoD1 M1 and MyoD2 M2 binding sites. In summary, MyoD1 and MyoD2 play an important role in the regulation of Almyomaker expression and may promote myoblast fusion during muscle development and growth by modulating Almyomaker expression.