PGC-1 functions as a transcriptional coactivator for the retinoid X receptors
PGC-1 functions as a transcriptional coactivator for the retinoid X receptors
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DOI：
10.1074/jbc.m109409200
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发表时间：
2002-02-08
影响因子：
4.8
通讯作者：
Suen, CS
中科院分区：
文献类型：
--
作者：
Delerive, P;Wu, YF;Suen, CS
由核受体介导的配体依赖性基因转录涉及将转录共激活子募集到配体结合域 (LBD)，从而导致与基础转录机制相互作用，并最终与 RNA 聚合酶 II 相互作用。尽管大多数共激活因子普遍表达，但组织选择性共激活因子 PGC-1 最近已得到表征。由于 PGC-1 和类视黄醇 X 受体 (RXR) 具有重叠的组织分布，因此我们研究了 PGC-1 是否是类视黄醇 X 受体的共激活剂。在瞬时转染测定中，PGC-1 增强配体刺激的 RXR 转录。此外，PGC-1 通过所有三种 RXR 异构体有效增强 RXR 元件驱动的报告基因转录。免疫沉淀分析表明 PGC-1 和 RXRalpha 在体内相互作用。此外，谷胱甘肽 S-转移酶 Pull-down 测定表明，这种相互作用需要 PGC-1 的 LXXLL 基序的存在。我们进一步证明，在哺乳动物双杂交测定中，这种物理相互作用还需要 RXR 的 AF-2 区域的存在才能与 PGC-1 的 LXXLL 基序相互作用，这与我们的蛋白质-蛋白质相互作用结果一致。时间分辨荧光测定表明，PGC-1 NR 盒内的肽在体外被配体结合的 RXRalpha 有效招募。最后，PGC-1 和 TIF2 协同增强配体激活的 RXRα 转录活性。总而言之，这些结果表明 PGC-1 是 RXRalpha 的真正共激活剂。
Ligand-dependent gene transcription mediated by the nuclear receptors involves the recruitment of transcriptional coactivators to the ligand-binding domain (LBD), which leads to interaction with the basal transcription machinery, and ultimately with RNA polymerase II. Although most of these coactivators are ubiquitously expressed, a tissue-selective coactivator, PGC-1, has recently been characterized. Because PGC-1 and the retinoid X receptors (RXRs) possess an overlapping tissue distribution, we investigated whether PGC-1 is a coactivator for the retinoid X receptors. In a transient transfection assay, PGC-1 augments ligand-stimulated RXR transcription. Furthermore, PGC-1 efficiently enhances the RXR element-driven reporter gene transcription by all three RXR isoforms. An immunoprecipitation assay reveals that PGC-1 and RXRalpha interact in vivo. In addition, a glutathione S-transferase pull-down assay showed that this interaction requires the presence of the LXXLL motif of PGC-1. We demonstrate further, in a mammalian two-hybrid assay, that this physical interaction also requires the presence of the AF-2 region of RXR to interact with the LXXLL motif of PGC-1, which is consistent with our protein-protein interaction results. A time-resolved fluorescence assay shows that a peptide within the NR box of PGC-1 is efficiently recruited by a ligand-bound RXRalpha in vitro. Finally, PGC-1 and TIF2 synergistically enhance ligand-activated RXRalpha transcriptional activity. Taken together, these results indicate that PGC-1 is a bona fide coactivator for RXRalpha.