Genetic mechanisms controlling serotonergic function across life span

描述(申请者提供)：该项目旨在研究在整个生命周期内调节5-羟色胺系统功能的遗传机制，并确定这些机制如何影响出生后5-羟色胺调节的行为。这些研究的基础是发现了调节5-羟色胺调节行为的依赖于Pet-1的转录程序，以及新开发的5-羟色胺神经元特异性和时间控制的条件靶向方法。我们的方法使我们能够研究纯化的5-羟色胺神经元中5-羟色胺神经元的特异性转录机制，并通过可靠的基因消融的空间和时间控制来研究生命任何阶段的5-羟色胺能基因的功能。关于Pet-1控制5-羟色胺神经元发育并最终调节5-羟色胺行为的机制，许多问题仍未得到解答。例如，尽管我们以前的研究表明，Pet-1在直接与5-羟色胺合成、重摄取、自身抑制和代谢有关的基因(Tph2、Aadc、Sert、VMAT2、Htr1A、Htr1B、MaoB)的协调诱导中是必需的，但尚不清楚Pet-1‘S的功能是否仅限于这些基因。Pet-1是否在不同的5-羟色胺神经元群体中调节不同的基因集合，它是否仅仅是5-羟色胺能基因表达的激活剂，或者它是否同时抑制5-羟色胺神经元发育过程中某些基因的表达，也尚不清楚。尽管我们已经证明，成年5-羟色胺神经元需要Pet-1来维持TPH2和SERT，但对于5-羟色胺神经元的重要功能，如5-羟色胺神经元放电和5-羟色胺调节行为，Pet-1调控转录的关键时期还知之甚少。我们将研究在生命的不同阶段，包括新生儿到青春期，5-羟色胺信号的调控是否需要Pet-1的转录调控。新生儿期(P5-P20)是5-羟色胺信号被证明对正常成人情绪行为至关重要的时期，而青春期恰好是5-羟色胺相关疾病(如精神分裂症和应激相关情绪障碍)的发病时期。最后，由于缺乏合适的方法，新生和成年5-羟色胺神经元中5-羟色胺合成对5-羟色胺调节行为的重要性一直没有得到充分的研究。我们将使用我们的新的时间条件靶向方法来测试关于行为小鼠出生后和成年期对5-羟色胺合成的早期需求的具体假设。我们的新目标将共同研究Pet-1调节基因的下游网络，对内在转录机制的要求，以及可塑性发育过渡期的5-羟色胺合成，这些时期被认为是确定心理健康相关行为的关键时期。

DESCRIPTION (provided by applicant): This project is aimed at investigating the genetic mechanisms that act across lifespan to regulate 5-HT system function and determine how these mechanisms impact postnatal 5-HT modulated behaviors. The basis of these studies is the discovery of a Pet-1 dependent transcriptional program that regulates 5-HT-modulated behaviors and newly developed 5-HT neuron-specific and temporally controlled conditional targeting approaches. Our approaches have enabled an investigation of 5-HT neuron-specific transcriptional mechanisms in purified 5-HT neurons and functional studies of serotonergic genes at any stage of life with reliable spatial and temporal control of gene ablation. Many questions remain unanswered about the mechanisms through which Pet-1 controls 5-HT neuron development and ultimately 5-HT modulated behaviors. For example, although our previous studies have shown that Pet-1 is needed for the coordinate induction of genes (Tph2, AADC, Sert, Vmat2, Htr1A, Htr1B, MaoB) directly responsible for 5-HT synthesis, reuptake, autoinhibition and metabolism it is not known whether Pet-1's function is restricted to these genes. It is also not known whether Pet-1 regulates different sets of genes in different populations of 5-HT neurons and whether it is solely an activator of serotonergic gene expression or whether it, perhaps, also simultaneously represses expression of some genes during the development of 5-HT neurons. Although we have shown that Pet-1 is needed in adult 5-HT neurons for maintenance of Tph2 and Sert the critical periods for Pet-1-directed transcription in essential 5-HT neuron functions such as 5-HT neuron firing and 5-HT modulated behaviors are poorly understood. We will investigate whether transcriptional regulation by Pet-1 is required for control of 5-HT signaling at different stages of life including the neonatal to adolescent period. The neonatal period (P5-P20) is a period in which 5-HT signaling has been shown to be critical for normal adult emotional behaviors while the adolescent period coincides with the onset of 5-HT related disorders such as schizophrenia and stress-related emotional disturbances. Finally, the importance of 5-HT synthesis in neonatal and adult 5-HT neurons for 5-HT modulated behaviors has never been adequately addressed because of the lack of suitable methods. We will use our new temporal conditional targeting approaches to test specific hypotheses about the early postnatal and adulthood requirements for 5-HT synthesis in the behaving mouse. Together, our new aims will investigate the downstream network of Pet-1 regulated genes, the requirements for intrinsic transcriptional mechanisms, and 5-HT synthesis at malleable developmental transition periods that are known to be critical periods for the determination of mental health relevant behaviors.