The role of Sox6 in skeletal muscle fiber type differentiation

Sox6在骨骼肌纤维类型分化中的作用

• 批准号: 7640581
• 负责人: NOBUKO HAGIWARA
• 金额: $ 32.26万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7640581
• 关键词: Adult; Binding Sites; Biological Assay; Birth; Calcineurin; Classification; Complex; Data; Degenerative Disorder; Development; Electrophoretic Mobility Shift Assay; Embryo; Environment; Family; Fiber; Future; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Goals; Knockout Mice; Knowledge; Mammals; Maps; Metabolic; Modeling; Molecular; Mus; Muscle; Muscle Development; Muscle Fibers; Mutant Strains Mice; Myoblasts; Myosin Heavy Chains; NFAT Pathway; Nuclear Protein; Nuclear Proteins; Pathway interactions; Phenotype; Physiological; Play; Post-Translational Protein Processing; Protein Isoforms; Proteins; Repression; Role; Screening procedure; Skeletal Muscle; Specific qualifier value; Staging; Striated Muscles; Testing; Transcription Repressor/Corepressor; Transcriptional Regulation; Two-Hybrid System Techniques; Yeasts; chromatin immunoprecipitation; cofactor; design; fetal; member; mutant; myogenesis; postnatal; protein protein interaction; recombinase; skeletal; transcription factor; yeast two hybrid system

DESCRIPTION (provided by applicant): The formation of slow and fast twitch fibers in skeletal muscle is a hallmark of functional maturity, enabling muscles to respond to complex physiological demands. Although striated muscles are exquisitely designed to execute diverse physical and metabolic tasks beginning immediately after birth, an understanding of how slow and fast skeletal muscle fibers initially form during fetal skeletal muscle development is still limited. It is our long-term goal to uncover the mechanisms of fiber type differentiation in the fetal skeletal muscle. Our recent data suggest that during fetal skeletal muscle development, Sox6 is required for normal fiber type-specific gene expression. In Sox6-null skeletal muscle, suppression of slow fiber-specific gene expression fails to occur in late fetal stages and slow fiber-specific genes maintain high levels of expression in the future fast fiber muscles, even in the postnatal stages. Sox6 is a member of the Sox transcription factor family. Although it is highly expressed in skeletal muscle, Sox6's role in muscle development is unknown. In this proposal, we will investigate the role of Sox6 in fiber type-specific gene expression during the fetal skeletal muscle development. Our central hypothesis is that Sox6 functions as a transcriptional repressor of slow fiber type-specific genes in the future fast fibers of the fetal skeletal muscle. The three aims proposed to test our hypothesis are: Aim1. Test the hypothesis that Sox6 expression in muscle is required for the initial fiber type differentiation in fetal skeletal muscle. Aim 2. Determine the mechanisms that regulate fiber type-specific Sox6 activity by testing two hypotheses: modulations by protein-protein interactions and post-translational modifications. Aim 3. Test the hypothesis that Sox6 coordinately regulates transcription of multiple genes which specify fiber types by: (1) identifying primary Sox6 targets using ChIP on chip assays and (2) determining how Sox6 represses the MyHC-2 gene These aims will be achieved by determining the phenotype of skeletal muscle specific Sox6 conditional knockout mice (Aim 1), by identifying Sox6 co-factors using yeast two-hybrid assays and determining post-translational modification of the Sox6 protein in skeletal muscle (Aim 2), and by identifying primary targets of the Sox6 protein using ChIP on chip assays and determining the molecular mechanism of transcriptional suppression of the MyHC-2 gene by Sox6. Completion of the proposed aims will advance our knowledge in the terminal differentiation of fetal skeletal muscle and aid us in gaining important information for treating muscle degenerative diseases. Project Narrative In this A1 resubmission, we investigate the role of the Sox6 transcription factor in the fetal muscle fiber type specification. Our central hypothesis is that Sox6 functions as a transcriptional repressor of slow fiber type-specific genes in the future fast fibers of the fetal skeletal muscle. To test this, we will ask following questions in three specific aims: when and where, during myogenesis, does Sox6 function? (Aim 1); what are the cellular mechanisms to limit the repression of slow fiber type-specific genes by Sox6 to fast fibers? (Aim 2); and finally, how does Sox6 achieve transcriptional suppression of slow fiber type-specific genes at the molecular level? (Aim 3).

描述（由申请人提供）：骨骼肌中慢肌纤维和快肌纤维的形成是功能成熟的标志，使肌肉能够对复杂的生理需求做出反应。尽管横纹肌经过精心设计，可以在出生后立即执行各种身体和代谢任务，但对胎儿骨骼肌发育过程中慢速和快速骨骼肌纤维最初形成的了解仍然有限。我们的长期目标是揭示胎儿骨骼肌纤维类型分化的机制。我们最近的数据表明，在胎儿骨骼肌发育过程中，Sox6 是正常纤维类型特异性基因表达所必需的。在 Sox6 缺失的骨骼肌中，慢纤维特异性基因表达的抑制在胎儿晚期不会发生，并且慢纤维特异性基因在未来的快纤维肌肉中保持高水平表达，甚至在出生后阶段也是如此。 Sox6 是 Sox 转录因子家族的成员。尽管 Sox6 在骨骼肌中高表达，但其在肌肉发育中的作用尚不清楚。在本提案中，我们将研究 Sox6 在胎儿骨骼肌发育过程中纤维类型特异性基因表达中的作用。我们的中心假设是，Sox6 在胎儿骨骼肌未来的快纤维中充当慢纤维类型特异性基因的转录抑制因子。为检验我们的假设而提出的三个目标是： 目标1。检验以下假设：肌肉中的 Sox6 表达是胎儿骨骼肌初始纤维类型分化所必需的。目标 2. 通过测试两个假设来确定调节纤维类型特异性 Sox6 活性的机制：蛋白质-蛋白质相互作用的调节和翻译后修饰。目标 3. 通过以下方式测试 Sox6 协调调节指定纤维类型的多个基因转录的假设：(1) 使用 ChIP 芯片分析确定主要 Sox6 靶标，以及 (2) 确定 Sox6 如何抑制 MyHC-2 基因 这些目标将通过确定骨骼肌特异性 Sox6 条件性敲除小鼠的表型（目标 1）、使用酵母双杂交测定鉴定 Sox6 辅助因子并确定骨骼肌中 Sox6 蛋白的翻译后修饰（目标 2）、使用 ChIP 芯片测定确定 Sox6 蛋白的主要靶标并确定其分子机制来实现。 Sox6 对 MyHC-2 基因的转录抑制。完成所提出的目标将增进我们对胎儿骨骼肌终末分化的了解，并帮助我们获得治疗肌肉退行性疾病的重要信息。项目叙述 在这次 A1 重新提交中，我们研究了 Sox6 转录因子在胎儿肌纤维类型规范中的作用。我们的中心假设是，Sox6 在胎儿骨骼肌未来的快纤维中充当慢纤维类型特异性基因的转录抑制因子。为了测试这一点，我们将针对三个具体目标提出以下问题：在肌生成过程中，Sox6 何时何地发挥作用？ （目标 1）；限制 Sox6 对快纤维对慢纤维类型特异性基因的抑制的细胞机制是什么？ （目标 2）；最后，Sox6如何在分子水平上实现慢纤维类型特异性基因的转录抑制？ （目标 3）。