Isoform-specific effects of MeCP2 isoforms on neuronal viability

MeCP2 亚型对神经元活力的亚型特异性影响

• 批准号: 8374277
• 负责人: Santosh R D'Mello
• 金额: $ 21.94万
• 依托单位: UNIVERSITY OF TEXAS DALLAS
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8374277
• 关键词: Accounting; Apoptosis; BDNF gene; Binding; Biology; Birth; Brain; Brain-Derived Neurotrophic Factor; Cell Cycle; Cessation of life; Development; Down-Regulation; Event; Gene Duplication; Genes; Genetic Transcription; Human; Link; Methyl-CpG-Binding Protein 2; Modeling; Molecular; Mus; Mutation; Nerve Degeneration; Neurodevelopmental Disorder; Neurologic; Neurologic Dysfunctions; Neurons; Organism; Pathogenesis; Pattern; Phosphorylation; Physiological; Protein Isoforms; Proteins; RNA Splicing; Regulation; Rett Syndrome; Role; Specific qualifier value; Testing; Time; Transgenic Mice; Work; forkhead protein; insight; interest; nervous system development; nervous system disorder; neurobehavioral; neurodevelopment; neuronal survival; neurotoxic; neurotoxicity; novel; overexpression; research study; selective expression; tissue culture; transcription factor

DESCRIPTION (provided by applicant): Ever since mutations in the methyl-CpG binding protein 2 (MeCP2) gene were found to be the primary cause of Rett syndrome, there has been a tremendous level of interest in understanding the biology and normal function of MeCP2. The MeCP2 gene is alternatively spliced to generated two isoforms commonly referred to as MeCP2-e1 and MeCP2-e2. The significance of these two isoforms is not known and it is widely believed that there is no functional difference. Indeed, most studies in which MeCP2 is ectopically expressed do not specify which isoforms is being used, and expression studies of MeCP2 rarely distinguish between the two. We find that the two isoforms are differentially regulated in postmitotic neurons that are degenerating. Moreover, the enhanced expression of MeCP2-e2 promotes neuronal death while elevated MeCP2-e1 expression has no such effect. In addition to the differential expression pattern and effect on neuronal viability, the two isofors bind the FoxG1 with dramatically different efficiency. FoxG1 is a transcription factor which promotes neuronal survival and whose mutations have also been linked to Rett syndrome. The specific aims of the proposal are (1) To understand the mechanisms underlying MeCP2-e2-induced neurotoxicity, (2) To define the relationship between MeCP2 and FoxG1 in the regulation of neuronal survival, and (3) If time permits, we will analyze neuronal death in MeCP2-expressing transgenic mice. It is noteworthy that while both MeCP2 and FoxG1 proteins are widely and abundantly expressed in neurons of the mature brain, studies on them have so far focused overwhelmingly on their roles in the context of neurodevelopment. Our proposed work will fill this void. As described above, MeCP2 gene duplication in humans causes neurological dysfunction along with cerebellar neurodegeneration. The neurotoxic effect of elevated MeCP2-e2 that we observe in tissue culture models recapitulates this neurodegeneration and will shed insight into the molecular mechanisms underlying it. PUBLIC HEALTH RELEVANCE: Our proposal focuses on MeCP2, mutations of which account for over 90% of the cases of Rett syndrome, a neurodevelopmental disorder. While the role of MeCP2 during nervous system development has been studied, its function in mature neurons is not clear. In addition, the functional differences of the two different MeCP2 isoforms that are expressed in vertebrate organisms is not known. We show that the two MeCP2 isoforms do have separate functions which include the regulation of neuronal death. We propose to study how MeCP2 regulates the death of mature neurons and understand its relationship with FoxG1, another protein that has been linked to Rett syndrome. It is noteworthy that humans and mice with elevated levels of MeCP2 suffer a neurological disorder distinct from Rett syndrome. Besides helping us understand the basic biology of how the survival and death of neurons is controlled, our studies could shed insight into how elevated MeCP2 causes neurological dysfunction in humans.

描述（由申请人提供）：自从发现甲基-CpG结合蛋白2（MeCP2）基因突变是Rett综合征的主要原因以来，人们对了解MeCP2的生物学和正常功能产生了极大的兴趣。MeCP2基因选择性剪接产生两种亚型，通常称为MeCP2-e1和MeCP2-e2。这两种亚型的意义尚不清楚，人们普遍认为它们没有功能差异。事实上，大多数研究中，MeCP2异位表达没有具体说明哪种亚型正在使用，和表达研究的MeCP2很少区分两者。我们发现，这两种亚型的差异调节有丝分裂后的神经元退化。此外，MeCP2-e2表达增强促进神经元死亡，而MeCP2-e1表达升高则没有这种作用。除了差异表达模式和对神经元活力的影响外，两种亚型以显著不同的效率结合FoxG1。FoxG1是一种促进神经元存活的转录因子，其突变也与Rett综合征有关。该提案的具体目的是（1）了解MeCP2-e2诱导神经毒性的机制，（2）确定MeCP2和FoxG1在神经元存活调节中的关系，以及（3）如果时间允许，我们将分析MeCP2表达转基因小鼠的神经元死亡。值得注意的是，虽然MeCP2和FoxG1蛋白在成熟大脑的神经元中广泛而丰富地表达，但迄今为止对它们的研究主要集中在它们在神经发育背景下的作用。我们拟议的工作将填补这一空白。如上所述，人类中的MeCP 2基因复制导致神经功能障碍沿着小脑神经变性。我们在组织培养模型中观察到的MeCP2-e2升高的神经毒性作用重现了这种神经变性，并将深入了解其分子机制。 公共卫生相关性：我们的建议集中在MeCP2上，其突变占Rett综合征（一种神经发育障碍）病例的90%以上。虽然已经研究了MeCP2在神经系统发育过程中的作用，但其在成熟神经元中的功能尚不清楚。此外，在脊椎动物生物体中表达的两种不同MeCP2同种型的功能差异尚不清楚。我们表明，这两个MeCP2亚型确实有不同的功能，其中包括神经元死亡的调节。我们建议研究MeCP2如何调节成熟神经元的死亡，并了解其与FoxG1的关系，FoxG1是另一种与Rett综合征有关的蛋白质。值得注意的是，MeCP2水平升高的人和小鼠患有与Rett综合征不同的神经障碍。除了帮助我们了解神经元的生存和死亡是如何控制的基本生物学，我们的研究还可以深入了解MeCP2升高如何导致人类神经功能障碍。