15-Deoxy-D12, 14-PGE, J2 as a ligand of RXRalpha

描述（由申请人提供）：15-Deoxy-？12,14 -前列腺素J2 （15d-PGJ2）是前列腺素D2 （PGD2）的天然代谢物，在癌细胞中具有强大的促凋亡活性。虽然15d-PGJ2是对过氧化物酶体增殖物激活受体（PPAR）亲和力最高的天然配体，但15d-PGJ2诱导细胞凋亡的实际分子靶点仍有待鉴定和表征。最近，我们在癌细胞中发现了一种新的凋亡途径，即孤儿核受体TR3从细胞核易位到线粒体，诱导细胞色素c （cyt c）的释放和凋亡。在我们的初步研究中，我们观察到TR3必须与类视黄醇X受体异二聚。（RXR?）从细胞核转移到细胞质，在那里TR3结合线粒体Bcl-2诱导cyt c释放和凋亡。此外，我们发现15d- PGJ2结合RXR？诱导RXR？从细胞核到细胞质的易位，导致TR3的共易位。这些令人兴奋的发现使我们提出15d-PGJ2是一种天然的RXR？配体，它通过诱导RXR？15d-PGJ2通过诱导RXR？/TR3细胞质定位和线粒体靶向。本多学科研究应用的主要目的是研究15d-PGJ2如何与RXR结合？调节RXR吗?核输出和tr3依赖性细胞凋亡，并在这些发现的基础上开发有效的合成类似物，选择性地调节RXR？细胞质作用（记者）。为实现我们的目标，提出了四个目标：在体外和体内研究RXR介导15d-PGJ2细胞凋亡的作用。稳定转染和RNAi方法。2. 探讨15d-PGJ2结合调控受体二聚化和RXR核输出的分子机制。及其异源二聚体，以及Akt对TR3的磷酸化如何调节RXR?？TR3二聚化与核出口。3. 为了检验15d-PGJ2结合对RXR？/TR3异源二聚体和Bcl-2及其对线粒体活性的影响4. 利用计算方法结合生物评价结果，设计并合成具有增强RXR选择性和活性的15d-PGJ2类似物。我们的研究结果将确定15d-PGJ2是天然的RXR？这将有助于我们进一步了解15d-PGJ2诱导细胞凋亡的分子机制，并有助于发现更有效的具有癌症预防价值的合成报告基因。

DESCRIPTION (provided by applicant): 15-Deoxy-?12, 14-prostaglandin J2 (15d-PGJ2), a natural metabolite of prostaglandin D2 (PGD2), has potent pro-apoptotic activity in cancer cells. Although 15d-PGJ2 is the highest affinity natural ligand for peroxisome proliferator-activated receptor ??(PPAR?), the actual molecular target of 15d-PGJ2 for inducing apoptosis remains to be identified and characterized. Recently, we discovered a novel apoptotic pathway in cancer cells, in which orphan nuclear receptor TR3 translocates from the nucleus to the mitochondrion to induce cytochrome c (cyt c) release and apoptosis. In our preliminary studies, we observed that TR3 must heterodimerize with retinoid X receptor ? (RXR?) to translocate from the nucleus to the cytoplasm, where TR3 binds mitochondrial Bcl-2 to induce cyt c release and apoptosis. In addition, we discovered that 15d- PGJ2 binds RXR? and induces RXR? translocation from the nucleus to the cytoplasm, resulting in cotranslocation of TR3. These exciting findings lead us to propose that 15d-PGJ2 is a natural RXR? ligand, which acts by inducing RXR? cytoplasmic activity, and that 15d-PGJ2 promotes cancer cell apoptosis by inducing RXR?/TR3 cytoplasmic localization and mitochondrial targeting. The major objectives of this multidisciplinary research application are to study how binding of 15d-PGJ2 to RXR? regulates RXR? nuclear export and TR3-dependent apoptosis and on the basis of these findings develop efficient synthetic analogs that selectively modulate RXR? cytoplasmic action (rexporters). Four Aims are proposed to accomplish our goals: 1. To determine the role of RXRs in mediating the apoptotic effects of 15d-PGJ2 in vitro and in vivo using RXR? stable transfection and RNAi approaches. 2. To investigate the molecular mechanisms by which 15d-PGJ2 binding modulates receptor dimerization and nuclear export of RXR? and its heterodimers, as well as how TR3 phosphorylation by Akt regulates RXR??TR3 dimerization and nuclear export. 3. To examine the effect of 15d-PGJ2 binding on the interaction of the RXR?/TR3 heterodimer and Bcl-2 and its impact on mitochondrial activities. 4. To design and synthesize 15d-PGJ2 analogs with enhanced RXR selectivity and activity using computational approaches coupled with the results of bioevaluation. Results obtained from our studies will establish 15d-PGJ2 as a natural RXR? ligand regulating a novel RXR signaling pathway, enhance our understanding of the molecular mechanism by which 15d-PGJ2 induces apoptosis, and lead to the identification of more effective synthetic rexporters with cancer preventive value.