Myf5 and MyoD Play Distinct Roles in Craniofacial Development of Zebrafish

• Main Authors: Rong-Feng Yung, 楊榮峯
• Other Authors: 蔡懷楨
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/35725399295977098231

碩士 === 國立臺灣大學 === 分子與細胞生物學研究所 === 93 === The myogenic regulatory factors Myf5 and MyoD are essential for muscle cell fate specification. The function of Myf5 and MyoD are known on the trunk myogenesis. However, the roles of Myf5 and MyoD during head myogenesis are largely unknown. In this study, I used whole mount in situ hybridization to observe the expression patterns of myf5 and myoD in the head of zebrafish. Results showed that myf5 was expressed in the precursors of two obliques, lateral rectus and pharyngeal muscles. On contrast, myoD transcripts were detected in all of the head muscle precursors. Specifically knockdown of myf5 revealed that myf5 was required for the formation of two obliques, lateral rectus, sternohyoideus and all of the pharyngeal muscle. Myf5 was also required for the expressions of myoD and myogenin in these muscles. However, specifically knockdown of myoD revealed that myoD was required for the formation of the superior rectus, inferior rectus, medial rectus and ventral pharyngeal muscles. MyoD was also required for the expression of myogenin in these muscles. In addition, we also observed that the two myf5-positive oblique precursors migrated from posterior to anterior by whole mount in situ hybridization experiment. This observation was also supported by using myf5:EGFP transgenic zebrafish that carries the reporter EGFP driven by the upstream regulatory fragment of myf5. Since the myf5-expressing cells with GFP can be traced in vivo, the migration of two egfp-positive oblique precursors were observed. Loss-of-function experiments also revealed that myf5 was required for superior oblique and inferior oblique migration. Furthermore, we found that inhibition of myf5 translation result in abnormal head and reduction of the number in cranial neural crest cells and cartilage, and induce apoptosis in the head cells. But these defectives did not occur in the myoD-morpholino-injected embryos. Taken together, our results revealed that myf5 and myoD play distinct roles during head myogenesis and cartilage formation in zebrafish.