Dynamics of activity-induced transcription in single dentate granule cells

项目摘要 对于神经网络来说，要通过经验来完善和塑造，新基因的表达是对基因表达的一种反应。 活动至关重要。神经活动触发即时早期基因（IEGs）的表达，如arc、fos和 egr 1在几分钟内，但许多IEGs是转录因子，反过来触发随后的波 转录。这些后期的转录波对于巩固稳定的、持久的、 记忆，但身份和功能的基因在这些后来的波仍然是未知的。此外，它是未知的 如果回路中所有激活的神经元都受到相同的调节，或者如果细胞特异性转录变化可以驱动 出现功能差异。在单个神经元水平上的这种异质性的程度已经被证明是 完全未被探索过直到现在，随着单细胞测序技术的最新进展， 跟踪单个激活神经元中的基因表达变化。该项目将跟踪活动相关基因 海马齿状回单个神经元的变化，这是学习和记忆的关键区域， 第一次提供了单个神经元中活动的转录“签名”。完成这项工作的方法是 通过检查齿状颗粒细胞的三个目标;第一，长期的转录波将是 在转录和翻译抑制剂已经被研究的整个时间跨度期间， 会损害记忆力第二，每个转录波的影响将在以下方面进行探讨： 细胞兴奋性的变化以及体内或体外随后事件的激活概率。 最后，齿状回是少数几个在成年期合并新神经元的大脑区域之一， 哺乳动物未成熟的齿状颗粒细胞与成熟的齿状颗粒细胞高度相似，除了它们 具有独特的电生理特性，有助于控制整个齿状回的功能。 因此，这一独特的未成熟细胞群体的活性相关转录也将被表征 因为它们对成熟细胞的功能和转录影响。该项目的发现将揭示新的联系 在单个神经元中基因表达和功能之间的关系，确定新的目标， 在健康人的记忆中，以及在衰老或疾病状态下恢复记忆功能。

Project Summary For neural networks to be refined and shaped by experience, the expression of new genes in response to activity is critical. Neural activity triggers the expression of immediate early genes (IEGs) such as arc, fos, and egr1 within minutes, but many IEGs are transcription factors that in turn trigger subsequent waves of transcription. These later waves of transcription are necessary for the consolidation of stable, persistent memories, yet identity and function of the genes in these later waves remains unknown. Further, it is unknown if all activated neurons in a circuit are identically modulated, or if cell-specific transcriptional changes can drive emerging functional differences. The extent of this heterogeneity at the level of the individual neuron has been completely unexplored. Only now, with recent advances in single-cell sequencing technologies, is it possible to track gene expression changes in individual activated neurons. This project will track activity-related gene changes in single neurons of the hippocampal dentate gyrus, a region critical for learning and memory, providing for the first time a transcriptional `signature' of the activity in individual neurons. This will be achieved by examining dentate granule cells in three aims; First, the long-term waves of transcription will be characterized during the full time span during which transcription and translation inhibitors have been demonstrated to impair memory. Second, the impact of each transcriptional wave will be explored in terms of changes in cell excitability and the probability of activation to a subsequent event either in vivo or in vitro. Finally, the dentate gyrus is one of the few brain regions that incorporates new neurons during adulthood in mammals. Immature dentate granule cells are highly similar to their mature counterparts, except that they possess distinct electrophysiological properties which help to control function across the entire dentate gyrus. Therefore activity-related transcription of this unique population of immature cells will be characterized, as well as their functional and transcriptional impact on mature cells. Findings from this project will reveal novel links between gene expression and function in individual neurons, identifying novel targets for the maintenance of memory in healthy humans and in restoring memory function in aging or disease states.