Nuclear Transport of Androgen Receptor

这个项目的中心假设是，控制分隔化和功能的机制 雄激素受体(AR)在前列腺癌中调节不当。核进出口已经成为 控制转录因子活性的关键机制。核进口AR被认为与 雄激素结合，由此提出AR的构象变化导致伴侣释放和暴露 向核进口机器发出核定位信号(NLS)。关于这种进口的分子细节很少 已经在正常细胞或癌细胞中直接分析了通路，包括哪些导入受体与NLS联系， 以及AR是如何经历雄激素非依赖性输入的。AR的核出口也鲜为人知，尽管我们 已经确定了AR的核出口信号，在我们的初步研究中，我们发现 AR受到严格控制。我们发现AR铰链区Ser650的雄激素依赖的磷酸化是 输出到细胞质所必需的。我们还有一种从LNCaP细胞核输出AR的生化分析方法。 AR在体外的输出是冈田酸敏感和胞浆因子依赖的。在目标1和目标2中，我们将确定 调节细胞质和细胞核之间AR运输的成分，并决定是否 AR的核转运与雄激素非依赖性的进展有关。在《目标3》中，我们将 描述信号转导通路如何调节AR的核输出。AR调节基因表达 在前列腺中处于正常和病理生理状态，是化疗的重要靶点。 前列腺癌从雄激素依赖到雄激素非依赖的进展与 增强了对AR的生长因子信号，我们认为这通过一个或多个基于转运蛋白的途径影响AR的活动 机械装置。

The central hypothesis of this Project is that the mechanisms that control compartmentalization and function of the androgen receptor (AR) are improperly regulated in prostate cancer. Nuclear import and export have emerged as key mechanisms for controlling the activity of transcription factors. Nuclear import of AR is thought to be linked to androgen binding, whereby a conformational change in AR is proposed to cause chaperone release and exposure of the nuclear localization signal (NLS) to the nuclear import machinery. Few molecular details about this import pathway have been directly analyzed in normal or cancer cells, including what import receptor contacts the NLS, and how AR undergoes androgen-independent import. Nuclear export of AR is also poorly understood, though we have identified a nuclear export signal for AR, and in our preliminary studies we have found that nuclear export of AR is tightly controlled. We found that androgen-dependent phosphorylation of Ser650 in the hinge region of AR is necessary for export to the cytoplasm. We also have a biochemical assay for AR export from LNCaP cell nuclei. AR export in vitro is okadaic acid-sensitive and cytosolic factor-dependent. In Aims 1 and 2 we will identify the components that mediate AR trafficking between the cytoplasm and nucleus, and determine if alterations in the nuclear transport of AR is correlated with the progression to androgen-independence. In Aim 3 we will characterize how signal transduction pathways regulate nuclear export of AR. The AR regulates gene expression in the prostate in both normal and pathophysiological states and serves as an important target for chemotherapy. The progression of prostate cancer from androgen-dependence to androgen-independence is correlated with enhanced growth factor signaling to AR, which we propose influences AR activity through one or more transportbased mechanisms.