Torafugu myosin heavy chain gene, MYHM2528-1, is specifically expressed in neonatal slow and fast muscle fibers, suggesting its functional role in indeterminate muscle growth in fish. However, the transcriptional regulatory mechanisms of MYHM2528-1 involved in indeterminate muscle growth in fish remained unknown. We previously isolated a 2100 bp 5'- flanking sequence of torafugu MYHM2528-1 that showed sufficient promoter activity to allow specific gene expression in neonatal muscle fibers of zebrafish. Here, we examined the cis-regulatory mechanism of 2100 bp 5'-flanking region of torafugu MYHM2528-1 using deletion-mutation analysis in zebrafish embryo. We discovered that myoblast determining factor (MyoD) binding elements play a key role and participate in the transcriptional regulation of MYHM2528-1 expression in zebrafish embryos. We further discovered that paired box protein (Pax3) are required for promoting MYHM2528-1 expression and myocyte enhancer factor-2 (MEF2) binding sites participate in the transcriptional regulation of MYHM2528-1 expression in slow/fast skeletal muscles. Our study also confirmed that the nuclear factor of activated T-cell (NFAT) binding sites take part in the transcriptional regulation of MYHM2528-1 expression in slow and fast muscles fiber in relation to indeterminate muscle growth. These results obviously confirmed that multiple cis-elements in the 5'-flanking region of MYHM2528-1 function in the transcriptional regulation of its expression.
Keywords: MYH(M2528–1); Torafugu; Transcription factor; Transcriptional regulation; Zebrafish.
Copyright © 2018. Published by Elsevier B.V.