Nuclear Receptor Coactivators GRIP1, CoCoA and Flil

描述（由申请人提供）：激素激活的核受体（NR）与靶基因启动子结合，并募集辅激活因子复合物以帮助激活转录。p160辅激活因子复合物由直接与活化的NR结合的p160蛋白和几种次级辅激活因子组成。我们的全球战略是表征辅激活因子的功能结构域，并寻找与其激活结构域结合并介导辅激活因子信号通路下游事件的蛋白质。通过这一过程的反复应用，我们将发现p160共激活因子在染色质或基础转录机制中的最终靶点。p160蛋白先前被证明具有两个用于信号传递的C末端激活结构域：AD 1结合CBP/p300，而AD 2结合CARM 1。我们最近在p160共激活因子的N-末端区域（AD 3）中鉴定了一个新的激活结构域，并鉴定了两种与p160 N-末端结合并与p160蛋白协同作用的蛋白质作为NR的共激活因子：卷曲螺旋共激活因子（可可）和Flightless I（Flil）。在这里，我们将确定的机制，这些蛋白质的每一个合作与其他NR共激活因子，并有助于转录激活的NR。我们将通过定义可可和Flil与NR、p160共激活因子和/或其他已知蛋白质相互作用伴侣的相互作用位点来定义它们的功能亚结构域。我们还将定义它们的激活结构域，其用于将激活信号传递到转录机制，并鉴定与激活结构域结合的蛋白质，从而在激活信号通路中处于下游。还将研究可可酸和Flil作为与其他类型的转录因子的共激活剂的参与。最后，我们将研究可可酸和Flil的可变需求及其在A549细胞系中的多种类固醇激素调节的启动子（一些激素诱导型和一些激素抑制型）上的各种功能结构域，以研究共激活因子功能机制与启动子结构之间的关系。

DESCRIPTION (provided by applicant): Hormone-activated nuclear receptors (NR) bind to target gene promoters and recruit complexes of coactivators to help activate transcription. The p160 coactivator complex consists of a p160 protein, which binds directly to activated NRs, and several secondary coactivators. Our global strategy is to characterize the functional domains of coactivators and search for proteins that bind to their activation domains and mediate downstream events in the coactivator signaling pathway. By reiterative application of this process, we will find the ultimate targets of the p160 coactivators in the chromatin or basal transcription machinery. The p160 proteins were previously shown to have two C-terminal activation domains for signal transmission: AD1 binds CBP/p300, while AD2 binds CARM1. We recently identified a new activation domain in the N-terminal region of p160 coactivators (AD3) and identified two proteins which bind to the p160 N-terminus and cooperate synergistically with p160 proteins as coactivators for NRs: Coiled-coil Coactivator (CoCoA) and Flightless I (Flil). Here, we will determine the mechanisms by which each of these proteins cooperates with other NR coactivators and contributes to transcriptional activation by NRs. We will define the functional subdomains of CoCoA and Flil by defining their sites of interaction with NRs, p160 coactivators, and/or other known protein interaction partners. We will also define their activation domains, which are used to transmit the activating signal to the transcription machinery, and identify proteins that bind to the activation domains and are thus downstream in the activation signaling pathway. The involvement of CoCoA and Flil as coactivators with other classes of transcription factors will also be investigated. Finally, we will study the variable requirements for CoCoA and Flil and their various functional domains on multiple steroid hormone-regulated promoters (some hormone inducible and some hormone repressible) in the A549 cell line to investigate the relationship between mechanism of coactivator function and promoter architecture.