Myogenic Regulatory Factors Expression in Muscle Tissue

这项建议解决了几个关键问题，涉及调控选定的骨骼肌基因的分子机制。识别调控肌肉特异性基因的网络将对制定替代因退行性疾病或损伤而受损的肌肉类型的策略具有重要意义，并与组织转分化的机制具有广泛的相关性。在硬骨脊椎动物S.macrurus中，骨骼肌纤维完全分化，只经历融合和随后转换成电细胞，即产生电子器官的非收缩电流的细胞。成熟的电器官具有许多但不是全部的细胞特征，肌源性细胞仅维持收缩蛋白图谱的一部分表达。我们的长期目标是确定定义大沙门氏菌成肌程序的遗传、细胞和分子因素的特征。这项拟议研究的主要目的是确定肌细胞中的肌肉基因如何受到MyoD家族的生肌调节因子(MRF)的调控。这项拟议的研究验证了这样一种假设，即磁共振波谱对肌肉基因的调控在肌肉和电子器官之间是不同的。我们的具体目标是：(1)在细胞水平上确定MRF转录本和蛋白产物在成熟肌肉和电子器官中的表达；(2)研究MRF在肌肉向电子器官转化过程中的表达模式；(3)识别在肌肉和电子器官中受MRF调控的基因。为了实现这些目标，已经组装了一系列可以用大斑潜蝇进行实验的工具。 重要的是，我们可以很容易地诱导肌肉向电器官的转分化，我们知道肌肉蛋白质表达的变化。这些研究使用一种新颖而简单的模型系统来加深我们目前对MRF在维持分化的肌肉表型中的分子机制的理解。

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.