Metabolic Effects of Thyroid Hormone

描述(申请人提供)：核受体(NRs)通过与辅助激活因子和辅助抑制因子相互作用来调节转录。大量的研究已经用滴注/陷阱和p160/SRC家族的共激活子，以及SMRT/N-COR共抑制子进行。在最后一次授予期间，我们实验室克隆并鉴定了四个新的转录因子(NRC、NIF-1、NRIF3和PSF-A)，它们似乎在调节NRS和其他转录因子的活性方面发挥了重要作用。核受体共调节蛋白(NRC)是一个含有两个LxxL1基序的2063个氨基酸的新核蛋白。LxxLL-1与所有NRs相互作用，而LxxLL-2与ERbeta和LXR beta相互作用。配体受体与LxxLL-1的结合导致NRC的构象变化，从而导致转录激活。NRC在体内与CBP相互作用，并激活其他转录因子，如CFos和cJun。NIF-1(NRC相互作用因子-I)是一种新的1,342个氨基酸的核蛋白，它在体内和体外与NRC相互作用，并通过与NRC的结合增强NRs、CFos和cJun对配体依赖的转录激活。核受体相互作用因子3(NRIF3)是一个由177个氨基酸组成的核蛋白，它只与TRs和RXRs相互作用，同时含有激活和抑制结构域。抑制依赖于Ser28的磷酸化。因此，根据磷酸化状态的不同，NRIF3可以作为激活物或抑制物。在许多乳腺癌细胞中，NRIF3不是一个激活剂，它的表达迅速导致caspase-2介导的细胞凋亡。PSF-A是一种707个氨基酸的核蛋白，与许多NRs的DBD相关，并通过与Sin3、HDAC1和HDAC2的结合而发挥阻遏作用。这项建议的重点是通过酵母双杂交筛选和质谱学确定与NRC、NIF-1和NRIF3的活性形成络合物并调节其活性的新因子。我们还计划进一步阐明PSF在多种NRs调控基因表达中的作用。我们建立了NRIF3-/-小鼠来研究NRIF3的生理作用。虽然NRC+/-小鼠表现出胚胎致死性，而NRC+/-小鼠是正常的，但我们培育了一种与NRC单倍体缺陷相关的有趣表型的NRC+/-小鼠。识别与这些调控因子相关的因素并研究这些“基因敲除小鼠”，应该能提供这些因素如何调节细胞中受体功能和其他重要生物学过程的全面图景。

DESCRIPTION (provided by applicant): Nuclear receptors (NRs) modulate transcription through interaction with co-activators and co-repressors. A wide body of research has been carried out with the DRIP/TRAPs and the p160/SRC family of co-activators, and with SMRT/N-CoR co-repressors. During the last granting period, our laboratory cloned and characterized four novel factors (NRC, NIF-1, NRIF3, and PSF-A) that appear to play an important role in mediating the activity of NRs and other transcription factors. NRC (Nuclear Receptor Co-regulation) is a novel 2063 amino acid nuclear protein with two LxxLL motifs. LxxLL-1 interacts with all NRs while LxxLL-2 interacts with ERbeta and LXRbeta. The binding of liganded-receptor with LxxLL-1 results in a conformational change in NRC leading to transcriptional activation. NRC interacts with CBP in vivo and also activates other transcription factors such as cFos and cJun. NIF-1 (NRC Interacting Factor-I) is a novel 1,342 amino acid nuclear protein that interacts in vivo and in vitro with NRC and enhances ligand-dependent transcriptional activation by NRs and cFos and cJun through association with NRC. NRIF3 (Nuclear Receptor Interacting Factor 3) is a 177 amino acid nuclear protein that only interacts with TRs and RXRs and contains both activation and repression domains. Repression is dependent on phosphorylation of Ser28. Thus, NRIF3 could act as an activator or repressor depending on the state of phosphorylation. In a number of breast cancer cells, NRIF3 is not an activator and its expression rapidly leads to caspase-2 mediated apoptosis. PSF-A is a 707 amino acid nuclear protein that associates with the DBD of many NRs and acts as a repressor through its association with Sin3 and HDAC1 and HDAC2. The focus of this proposal is to identify novel factors, through yeast two-hybrid screens and mass spectroscopy, that complex with and modulate the activity of NRC, NIF-1, and NRIF3. We also plan to further clarify the role of PSF on modulating gene expression by a variety of NRs. We developed NRIF3 -/- mice to study the physiological role of NRIF3. Although NRC +/- mice exhibit embryonic lethality, and NRC +/- mice are normal, we developed a strain of NRC +/- mice that exhibit interesting phenotypes related to NRC haploid deficiency. Identification of factors that associate with these regulators and study of these "knockout mice", should provide a comprehensive picture of how these factors modulate receptor function and other important biological processes in cells.