Role of the ATP-dependent chromatin-remodeling enzyme BRG1 in inner ear morphogenesis

 描述（由申请人提供）：本项目的目标是表征驱动内耳神经感觉前体细胞发育和分化的调控网络。耳上皮前体细胞的分化和增殖以及分化为不同细胞类型的决定是内耳发育过程中的关键事件。这些过程的指令被编码在基因组中-在非编码调节序列中。这些基因通过与转录因子、辅因子和染色质调节因子相互作用，在时间和空间上控制基因表达程序，以产生和维持特定的细胞状态。虽然许多重要的基因已被确定在内耳，网络的因素和基因的相互作用，决定了分化细胞在内耳发育过程中的专门的表型还不清楚。我们发现，染色质重塑蛋白BRG 1，中央酶亚基在SWI/SNF染色质重塑机制，是必要的启动神经元发育程序，通过与内耳神经感觉细胞特异性转录因子EYA 1和SIX 1在耳蜗外植体和3 T3成纤维细胞的功能获得性研究。然而，还没有研究直接解决SWI/SNF染色质重塑在内耳中的发育作用。虽然染色质重塑提供了基因转录的重要机制，但调节内耳发育和功能的DNA调节元件/增强子尚未确定。我们的初步数据清楚地表明，Brg 1在内耳形态发生中起着关键作用。在本申请中，我们建议定义Brg 1在神经感觉前体细胞发育和分化中的发育作用，并解决Brg 1是否定义了促进神经元和感觉细胞身份所需的增强子。本研究中提出的实验有可能提供新的见解，了解因子和基因相互作用的网络如何构成驱动耳上皮细胞向功能性感觉神经元或毛细胞发育的程序。识别控制感觉或神经元细胞特异性基因表达程序的基因和调控网络应该为先天性感觉神经缺陷的遗传网络提供有价值的见解。

 DESCRIPTION (provided by applicant): The goal of this project is to characterize regulatory networks that drive neurosensory precursor cell development and differentiation in the inner ear. Specification and proliferation of otic epithelial precursor cells and the decision to become distinct cell types are crucial events during inner ear development. The instructions for these processes are encoded in the genome - in non-coding regulatory sequences. These control gene expression programs in time and space by interacting with transcription factors, cofactors and chromatin regulators to create and maintain specific cell states. Although many important genes have been identified in the inner ear, the network of factors and gene interactions that dictate the specialized phenotypes of differentiated cells during inner ear development are not understood. We found that the chromatin remodeling protein BRG1, the central enzymatic subunit in the SWI/SNF chromatin remodeling machinery, is necessary for initiating neuronal developmental program by interacting with inner ear neurosensory cell-specific transcription factors EYA1 and SIX1 in gain-of-function studies in cochlear explants and 3T3 fibroblast cells. However, no studies have yet been performed to directly address the developmental roles of SWI/SNF chromatin remodelers in the inner ear. While chromatin remodelers provide an important mechanism for gene transcription, the DNA regulatory elements/enhancers that regulate inner ear development and function are not defined. Our preliminary data clearly show that Brg1 plays a critical role in inner ear morphogenesis. In this application, we propose to define the developmental roles of Brg1 in neurosensory precursor cell development and differentiation and address whether Brg1 defines enhancers required to promote neuronal and sensory cell identity. The experiments proposed in this study have the potential to provide new insight into how a network of factors and gene interactions constitute the program that drives otic epithelial cell development towards functional sensory neurons or hair cells. Identifying genes and regulatory networks that control sensory or neuronal-cell specific gene expression program should provide valuable insights into the genetic networks that underlie congenital neurosensory deficits.