| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 100 === There are two Akirin genes, Akirin1 and Akirin2, in vertebrates. Akirin1 is a nuclear factor negatively regulated by myostatin and has been shown to be a promyogenic factor in skeletal myogenesis. Akirin1 can regulate the basic helix-loop-helix myogenic regulator factor (MRF) family, MyoD and Myogenin. Drosophila Akirin and mouse Akirin2 are highly conserved nuclear proteins required for NF-kappaB-dependent innate immune responsive gene expression. In zebrafish, Akirin1 and Akirin2 are expressed in all examined tissues and abundantly expressed in the brain and muscle. In this study, we established Akirin1 and Akirin2 transgenic zebrafish lines by muscle-specific promoter combined with TetOff regulatory system, respectively to study the function and molecular mechanism of Akirin gene family on the muscle growth of zebrafish. Real-time quantitative PCR analysis for F1 offspring of Akirin1 transgenic zebrafish revealed that the Akirin1 can activate the MRFs genes, including MyoD, Myf5, Mrf4, Myogenin and IGF2 gene in zebrafish. Furthermore, we observed the phenotype of hypertrophy in the muscle of adult Akirin1-overexpressed transgenic zebrafish. In contrast to Akirin1, Akirin2 transgenic zebrafish showed MyoD, Myogenin and IGF2 were down-regulated. Knockdown of Akirin2 by using antisense morpholino caused muscle hypertrophy and increased MyoD, Myogenin and IGF2 mRNA expression. Our results indicate that Akirin gene family may play an important role in the regulation of muscle growth with an antagonistic function between Akirin1 and Akirin2 in zebrafish.
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