Oscillatory gene expression and the maintenance of temporal patterning

项目摘要： 发育基因调控是一个多维问题，信号汇聚在一起产生模式 在适当的位置(空间调节)和正确的时间(时间调节)转录。一个同等重要的 这一调节过程的重要特征包括在过程中产生正确数量的转录 发展许多关键调控基因以剂量敏感的方式发挥作用，在太多或太少的情况下 表达会导致发育缺陷或疾病。目前，我们只有一个原始的认识。 关于发育调节基因的转录输出是如何建立的。中概述的实验 这项建议旨在通过在线虫幼虫体内使用成像系统来直接解决这个问题 GFP分子直接与新生的RNA捆绑在一起，同时它们在 原子核。这一新平台使我们能够直接对实时表达动态进行量化和建模 最终决定了个体基因在整个发育过程中的转录输出。在目标1中，我们将使用以下内容 系统剖析两个转录因子BLMP-1和LIN-42调节 转录突发(包括突发频率、持续时间和幅度)以调整关键字的转录水平 MicroRNAs(包括LIN-4和LET-7)，它决定了细胞命运指定的序列模式。然后我们将调查 BLMP-1通过重塑启动未来转录的基因组和分子机制 目的基因座附近染色质的可及性。在最终目标中，我们将描述物理和功能 LIN-42与几种保守的核激素受体(NHR-23RORg和NHR-85Rev-R)的相互作用 ErbB)，介导LIN-4和LET-7转录激活的时间方面。这一研究途径将揭示 染色质重塑的原理及其对周期性转录输出的影响 表达的基因确保了发育过程中细胞命运指定的精确度和稳健性。

Project Abstract: Developmental gene regulation is a multidimensional problem where signals converge to generate patterns of transcription at the proper location (spatial regulation) and correct time (temporal regulation). An equally important feature of this regulatory process involves generating the correct amount of transcription during development as many key regulatory genes function in dosage sensitive manners where too much or too little expression can lead to developmental defects or disease. At present, we have only a primitive understanding about how the transcriptional output of developmentally regulated genes is established. Experiments outlined in this proposal aim to directly address this problem by employing an in vivo imaging system in C. elegans larva where GFP molecules are directly tethered to nascent RNAs while they are being actively transcribed in the nucleus. This new platform enables us to directly quantify and model the real-time expression dynamics that ultimately dictate transcriptional output of individual genes throughout development. In Aim 1, we will use this system to dissect the mechanisms by which two transcription factors, BLMP-1 and LIN-42, modulate features of transcriptional bursting (including burst frequency, duration, and amplitude) to tune transcriptional levels of key microRNAs (including lin-4 and let-7) that dictate sequential patterns of cell fate specification. We will then probe the genomic and molecular mechanisms that BLMP-1 employs to prime future transcription by remodeling chromatin accessibility near target gene loci. In the final Aim, we will characterize the physical and functional interactions between LIN-42 and several conserved nuclear hormone receptors (NHR-23RORg and NHR-85Rev- erbb) that mediate temporal aspects of lin-4 and let-7 transcriptional activation. This avenue of research will reveal the principles by which chromatin remodeling and its impact on modulating the transcriptional output of cyclically expressed genes ensures the precision and robustness of cell fate specification during development.