Elucidation of the mechanisms by which cells recognize and respond to different levels of androgens

男科学中一个尚未回答的基本问题是细胞如何以不同的方式识别和响应 不同水平的生理和合成雄激素。据推测，由于雄激素主要在以下方面不同， 它们对雄激素受体（AR）的相对结合亲和力，它们的区别在于它们使 类似的受体辅调节复合物的形成，这表现为一个定量的连续体， 同样的答案。然而，利用引人注目的新数据，我们提出了替代方案，尽管不是相互的。 排除雄激素剂量调节细胞中AR单体和二聚体相对丰度的可能性 并且这些形式的受体具有不同的辅调节因子结合偏好，导致不同的生物学特性。 产出事实上，使用体外系统模拟从去势（低剂量; LD）到真性腺水平的暴露， 和以上（高剂量; HD），我们已经确定，在染色质结构，转录的整体变化， LD诱导的细胞内顺式因子和基因表达的变化有实质性的不同， 雄激素（单体AR）与细胞增殖相关，HD雄激素（二聚体AR）诱导细胞增殖。 与分化表型相关的程序。对雄激素水平的反应也有类似的区别， 在体内观察。此外，我们发现LD和HD雄激素都促进AR， mTOR的依赖性、非基因组激活，但所得翻译输出不同， LD而不是HD雄激素促进编码关键细胞周期蛋白（即E2 F1， FOXM1）。重要的是，我们已经鉴定了不允许受体二聚化的高亲和力AR配体， 表明它们的作用与LD雄激素的作用表型相似。因此，通过使用受体寡聚化状态作为 生物传感器细胞能够对不同水平的雄激素做出不同的反应;这一过程可以被利用 用于治疗癌症和其他雄激素病的新AR调节剂的开发。 假设：雄激素受体表达细胞具有生化机制，使它们能够 对不同暴露水平的雄激素表现出不同的生物学反应， 激素在同一细胞中表现出不同的活性。 目的：（1）定义使细胞能够感知和响应不同水平雄激素的机制，（2） 阐明雄激素激活mTOR和调节mRNA翻译特异性的机制， (3)使用基于小分子的方法来探索通路的生理和病理重要性 以及使细胞对不同水平的雄激素做出不同反应的过程。 影响：除了探索AR的药理学外，这项研究还将正式检验“协同调节因子假说”。 功能不同的辅助调节因子的差异参与允许相同的配体表现出不同的功能， 细胞内和细胞间的活动。这也将有助于建立一个概念框架， 确定其他配体调节的核受体的分子药理学的机制。

An unanswered fundamental question in andrology is how cells recognize and respond in a different manner to different levels of physiological and synthetic androgens. It is assumed that since androgens differ primarily in their relative binding affinity for the androgen receptor (AR) that they are distinguished by how well they enable the formation of similar receptor-coregulator complexes and that this manifests as a quantitative continuum of the same responses. However, leveraging compelling new data we propose the alternate, albeit not mutually exclusive, possibility that androgen dose regulates the relative abundance of AR monomers and dimers in cells and that these forms of the receptor have different coregulator binding preferences resulting in different biological outputs. Indeed, using in vitro systems that model exposure from castrate (low dose; LD) to eugonadal levels and above (high dose; HD), we have determined that the global changes in chromatin architecture, transcription factor cistrome, and gene expression in cells are substantially different, with the changes induced by LD androgens (monomeric AR) being associated with cell proliferation and HD androgens (dimeric AR) inducing a program associated with a differentiated phenotype. A similar distinction in response to androgen levels was observed in vivo. Further, we made the surprising observation that both LD and HD androgens facilitate an AR dependent, non-genomic activation of mTOR but that the resulting translational outputs are different, such that LD but not HD androgens facilitate increased translation of mRNAs encoding key cell cycle proteins (i.e. E2F1, FOXM1). Importantly, we have identified high affinity AR ligands that do not allow receptor dimerization and have shown that their actions phenocopy those of LD androgens. Thus, by using receptor oligomerization state as a biosensor cells are able to respond differently to different levels of androgens; a process that can be exploited in the development of new AR modulators for the treatment of cancer and other androgenopathies. Hypothesis: Androgen receptor expressing cells possess biochemical mechanisms that enable them to manifest qualitatively distinct biological responses to different exposure levels of androgens enabling the same hormone to exhibit different activities in the same cell. Aims: (1) Define the mechanism(s) that enable cells to sense and respond to different levels of androgens, (2) Elucidate the mechanisms by which androgens activate mTOR and regulate mRNA translational specificity, and (3) Use small molecule-based approaches to explore the physiological and pathological importance of pathways and processes that enable cells to respond differently to different levels of androgens. Impact: In addition to probing the pharmacology of AR this study will formally test the “coregulator hypothesis” that differential engagement of functionally distinct coregulators allows the same ligand to exhibit different activities in and between cells. This will also enable the establishment of a conceptual framework that will inform the mechanisms that determine the molecular pharmacology of other ligand-regulated nuclear receptors.