REGULATION OF MUSCLE GENE EXPRESSION

在肌生成过程中， 肌节发育所必需的肌肉特异性蛋白质。 至少 这种增加部分反映了基因编码的转录激活 对于这些蛋白质。 生物学的一个中心问题是细胞如何转录 只有他们基因组的某一部分， 状态 这项研究的长期目标是确定 成肌细胞发育过程中调控信号如何调控肌肉基因表达 分化 这些研究的先决条件是分离相关基因， 在肌生成过程中差异表达。 我们将重点关注一个家庭， 编码中间丝蛋白、结蛋白和 波形蛋白 结蛋白是一种肌肉特异性蛋白， 与肌细胞分化有关。 然而，波形蛋白的合成 并不局限于肌肉，它的表达并不反映 肌肉特异性调节 这两个基因的克隆提供了至少两个 确定基因调控基本机制的方法 在肌肉中的表达。 DNA测序允许人们寻找同源的 基因内的序列元件和周围环境中的差异 监管区域。 此外，结蛋白基因的序列（5英尺 end）将与其他表现出肌肉特异性调控的基因进行比较 这可能揭示了受监管的组织所需的共同结构要素， 表情 这些假定监管区域的功能将 通过引入正常和修饰的基因进行测试， 真核病毒载体进入前体细胞（成肌细胞）。 成肌细胞将 被刺激分化和导入基因的表达 通过S1作图实验对寄主基因进行定量比较。 肌肉特异性基因（结蛋白）应该只在分化的 细胞 通过修饰推定的调节区中的结蛋白基因 将采用缺失作图或位点特异性诱变来鉴定 正确调节所需的序列。 长期目标是 建议的研究是实现对分子的理解 影响肌肉特异性基因转录的机制。 这可能 包括识别和分离调节因素， 与染色质相互作用并控制基因表达。

During myogenesis there is a coordinate increase in the synthesis of muscle-specific proteins essential for sarcomeric development. At least in part this increase reflects transcriptional activation of the genes coding for these proteins. A central question in biology is how cells transcribe only a certain part of their genome thereby achieving a differentiated state. The long-term objective of this proposed research is to determine how regulatory singals govern muscle gene expression during myoblast differentiation. A prerequisite for these studies is to isolate related genes which are differentially expressed during myogenesis. We shall focus on a family of genes which code for the intermediate filament proteins, desmin and vimentin. Desmin is a muscle-specific protein which is synthesized concommitant with muscle cell differentiation. However, vimentin synthesis is not restricted to muscle and its expression does not reflect muscle-specific regulation. Clones of these two genes provide at least two approaches for determining fundamental control mechanisms governing gene expression in muscle. DNA sequencing allows one to search for homologous sequence elements within the genes and differences within the surrounding regulatory regions. In addition, the sequence of the desmin gene (5 feet end) will be compared to other genes exhibiting muscle-specific regulation which may reveal common structural elements required for regulated expression. The functionality of these presumptive regulatory regions will be tested by the introduction of both normal and modified genes via eukaryotic viral vectors into precursor cells (myoblasts). Myoblasts will be stimulated to differentiate and the expression of the introduced genes and host genes will be quantitated and comapred by S1 mapping experiments. Muscle-specific genes (desmin) should be expressed only in differentiated cells. Modification of the desmin gene in putative regulatory regions by deletion mapping or site-specific mutagenesis will be employed to identify sequences required for correct regulation. The long range goal of this proposed research is to achieve an understanding of the molecular mechanisms affecting transcription of a muscle-specific gene. This may involve the identification, and isolation of regulatory factors which interact with chromatin and control gene expression.