Myogenic Regulatory Factors Expression in Muscle Tissue

这一建议解决了几个关键问题，关于分子机制的调控选择骨骼肌基因。识别调节肌肉特异性基因的网络将对产生替代因退行性疾病或损伤而受损的肌肉类型的策略具有根本性意义，并且与组织转分化机制具有广泛的相关性。在硬骨鱼脊椎动物S. macrurus中，骨骼肌纤维完全分化，只经过融合和随后转化为电细胞，即电器官的非收缩电流产生细胞。成熟的电器官与肌源性细胞共享许多但不是全部的细胞特征，仅维持一小部分收缩蛋白的表达。我们的长期目标是确定大鼠肌生成程序的遗传、细胞和分子因素。该研究的主要目的是确定MyoD家族的肌生成调节因子（MRFs）如何调节电细胞中的肌肉基因。提出的研究验证了假设，即肌肉和电器官之间的mrf对肌肉基因的调节是不同的。我们的具体目标是：(1)在细胞水平上确定成熟肌肉和电器官中MRF转录本和蛋白产物的表达；(2)表征肌肉向电器官转分化过程中MRF的表达模式；(3)鉴定肌肉与电器官中MRF调控的基因。为了实现这些目标，一组适用于实验的工具已经组装好了。

This proposal addresses several key questions regarding the molecular mechanisms underlying the regulation of select skeletal muscle genes. Identification of networks that regulate muscle-specific genes would have fundamental implications for the generation of strategies to replace muscle types damaged by degenerative diseases or injury, and have broad relevance to mechanisms of tissue transdifferentiation. In the teleost vertebrate S. macrurus, skeletal muscle fibers fully differentiate only to undergo fusion and subsequent conversion into electrocytes, i.e, the noncontractile currentproducing cells of the electric organ. The mature electric organ shares many but not all cellular features with myogenic cells maintaining the expression of only a subset of the contractile protein profile. Our long term goal is to characterize the genetic, cellular and molecular factors that define the myogenic program in S. macrurus. The main objective of the proposed research is to determine how muscle genes in electrocytes are regulated by the MyoD family of myogenic regulatory factors (MRFs). The proposed studies test the hypothesis that the regulation of muscle genes by MRFs differs between muscle and electric organ. Our specific aims are: (1) to define the expression of MRF transcripts and protein products in mature muscle and electric organ at the cellular level, (2) characterize the expression pattern of MRFs during the transdifferentiation of muscle to electric organ, and (3) identify genes regulated by MRFs in muscle versus electric organ. To accomplish these aims, a collection of tools that is amenable to experimentation with S. macrurus has been assembled. Importantly, we can easily induce the transdifferentiation of muscle to electric organ, and we know the changes that occur in muscle protein expression. These studies use a novel but simple model system to further our current understanding of the molecular mechanisms involving MRFs in the maintenance of the differentiated muscle phenotype.