Transcriptional control of skeletal muscle insulin resistance

骨骼肌胰岛素抵抗的转录控制

• 批准号: 8463513
• 负责人: Donald E Ayer
• 金额: $ 28.81万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-24 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8463513
• 关键词: Accounting; Affect; Alleles; Attenuated; Binding; Bioenergetics; Carbon; Cell Line; Cell Lineage; Cell Nucleus; Cells; ChIP-seq; Communication; Complex; Data; Development; Diabetes Mellitus; Disease; Epithelial Cells; Family; Gene Expression Profile; Genetic Transcription; Genomics; Glucose; Glucose-6-Phosphate; Helix-Turn-Helix Motifs; Hyperglycemia; Insulin; Insulin Resistance; Knock-out; Lead; Malignant Neoplasms; Mammals; Mediating; Mitochondria; Modeling; Molecular; Mus; Muscle Cells; Non-Insulin-Dependent Diabetes Mellitus; Nuclear; Nuclear Proteins; Organelles; Organism; Outer Mitochondrial Membrane; Peripheral; Physiological; Play; Proteins; Publishing; Regulation; Role; Severities; Site; Skeletal Muscle; Source; Techniques; Testing; Therapeutic Intervention; Thioredoxin; Transcription Coactivator; Transcriptional Activation; Transcriptional Regulation; Transgenic Organisms; blood glucose regulation; genome-wide; genome-wide analysis; glucose disposal; glucose sensor; glucose uptake; in vivo; insight; member; mitochondrial dysfunction; mouse model; novel; novel diagnostics; prognostic; programs; promoter; protein expression; protein function; public health relevance; research study; tissue culture; transcription factor

DESCRIPTION (provided by applicant): Understanding the earliest molecular changes that drive the genesis of type 2 diabetes may lead to the development of new diagnostics, prognostics, and potentially new targets for therapeutic intervention. We have discovered a new member of the basic-helix-loop-helix-zipper family of transcription factors called MondoA that we propose plays a critical role in skeletal muscle glucose homeostasis and insulin resistance. MondoA functions primarily as a transcriptional activator, binding to CACGTG genomic targets with its obligate heterodimeric partner Mlx. Several lines of evidence indicate that MondoA:Mlx complexes are key regulators of cellular bioenergetics. First, MondoA:Mlx complexes are not constitutively nuclear proteins, rather they shuttle between the outer mitochondrial membrane and the nucleus, suggesting that they facilitate communication between these two essential organelles. Second, MondoA:Mlx complexes accumulate in the nucleus, binding their target promoters to activate their expression under hyperglycemic conditions by sensing glucose-6-phosphate levels. Third, MondoA:Mlx complexes are required for transcriptional activation of at least 75 percent of glucose-induced targets, indicating that they are major regulators of the glucose-dependent transcriptome. Finally, MondoA is very highly expressed in skeletal muscle, which is a major site of glucose disposal and is transcriptionally active in a number of muscle cell lines. Together, we suggest that skeletal muscle is one of MondoA's primary sites of action. We hypothesize a critical function for MondoA in how skeletal muscle senses and responds to changes in glucose levels. One critical MondoA target is thioredoxin interacting protein (TXNIP). TXNIP has pleiotropic roles in glucose homeostasis and insulin resistance, which are mediated in part by its function as a negative regulator of peripheral glucose disposal. Consistent with TXNIP being a critical MondoA effector, MondoA is also a potent negative regulator of glucose uptake. As such, we hypothesize that the nuclear activity MondoA and its transcriptional targets may also drive skeletal muscle insulin resistance by negatively regulating glucose uptake. TXNIP is not the sole MondoA effector in attenuating glucose uptake, indicating that other MondoA transcriptional targets must also contribute. We propose to employ a conditional deletion allele of murine MondoA to specifically inactivate MondoA in skeletal muscle. In Aims 1, we will use this mouse model to determine MondoA's in vivo function in skeletal muscle glucose homeostasis and whether MondoA activity is required for skeletal muscle insulin resistance as our preliminary data suggest. Further, we propose comprehensive genomic approaches in Aim 2 to discover the direct and MondoA-dependent transcriptome in skeletal muscle. Finally, our preliminary data indicate that MondoA transcriptional activity is controlled by mitochondrial overload. We will test this model in Aim 3 and determine how MondoA and TXNIP function as potent negative regulators of glucose uptake.

描述（由申请人提供）：了解驱动2型糖尿病发生的早期分子变化可能会导致新的诊断、预后和治疗干预的潜在新靶点的发展。我们发现了一个名为MondoA的碱性螺旋-环-螺旋-拉链转录因子家族的新成员，我们认为它在骨骼肌葡萄糖稳态和胰岛素抵抗中起着关键作用。MondoA主要作为转录激活因子，与其专性异二聚体伙伴Mlx结合到CACGTG基因组靶点。一些证据表明，MondoA:Mlx复合物是细胞生物能量学的关键调节因子。首先，MondoA:Mlx复合物不是核蛋白的组成部分，而是在线粒体外膜和细胞核之间穿梭，这表明它们促进了这两个基本细胞器之间的通信。其次，MondoA:Mlx复合物在细胞核中积累，结合其靶启动子，通过感知葡萄糖-6-磷酸水平激活其在高血糖条件下的表达。第三，MondoA:Mlx复合物是至少75%的葡萄糖诱导靶标转录激活所必需的，这表明它们是葡萄糖依赖性转录组的主要调节因子。最后，MondoA在骨骼肌中非常高表达，骨骼肌是葡萄糖处理的主要部位，在许多肌肉细胞系中转录活跃。总之，我们认为骨骼肌是MondoA的主要作用部位之一。我们假设MondoA在骨骼肌如何感知和响应葡萄糖水平变化方面具有关键功能。一个关键的MondoA靶点是硫氧还蛋白相互作用蛋白（TXNIP）。TXNIP在葡萄糖稳态和胰岛素抵抗中具有多效性作用，部分是通过其作为外周葡萄糖处理的负调节因子的功能介导的。与TXNIP是一个关键的MondoA效应一致，MondoA也是一个有效的葡萄糖摄取负调节因子。因此，我们假设核活性MondoA及其转录靶点也可能通过负性调节葡萄糖摄取来驱动骨骼肌胰岛素抵抗。TXNIP并不是唯一的MondoA抑制葡萄糖摄取的效应物，这表明其他的MondoA转录靶点也有一定的作用。我们建议使用小鼠MondoA的条件缺失等位基因特异性灭活骨骼肌中的MondoA。在Aims 1中，我们将使用该小鼠模型来确定MondoA在骨骼肌葡萄糖稳态中的体内功能，以及我们的初步数据表明，MondoA活性是否需要骨骼肌胰岛素抵抗。此外，我们在Aim 2中提出了全面的基因组方法来发现骨骼肌中直接和依赖mondoa的转录组。最后，我们的初步数据表明，MondoA转录活性受线粒体过载控制。我们将在Aim 3中测试该模型，并确定MondoA和TXNIP如何作为葡萄糖摄取的有效负调节因子发挥作用。