Structural Studies of the Vitamin D Receptor

描述（由申请人提供）：类固醇和核激素受体 是已知最大的一类真核转录调节因子， 响应非肽亲脂信号调节转录。的 该超家族的成员包括维生素D受体（VDR）， 调节与钙稳态相关的基因，并在 造血和皮肤细胞的分化，以及雄激素受体 (AR)，直接调节前列腺特异性基因的表达， 他人 激素受体通过作为同源或异源二聚体结合到 DNA靶-称为反应元件-由两个六核苷酸组成 半位点，通过半位点的序列彼此区分， 位置以及一半位置相对于另一半位置的方向和间距。 VDR与由两个半位点组成的反应元件结合， 重复，中间间隔三个碱基对（DR-3）。AR与反向 重复，三间隔响应元件（IR-3），虽然最近一种新的AR 识别出与DR-3型非常相似的反应元件， 用于区分AR响应基因与那些响应于 糖皮质激素和其他类固醇。 理解VDR和AR在以下方面的作用的潜在立体化学： 转录激活和DNA靶选择需要结构上的 相关大分子物质和复合物的分析。我们计划解决 用X射线晶体学分析DNA结合的结构 VDR同源二聚体和RXR-VDR异源二聚体的结构域与多种 DNA靶标，以及与其复合的AR DNA结合结构域的结构， 新的直接重复DNA靶标。这些研究旨在阐明 VDR和AR DNA靶标识别的结构基础，它们共享的 DR-3型反应元件的偏好，以及用于 区分正确和不正确的DNA目标。我们将把我们的 结构结果与蛋白质的结合亲和力的测量， 共有和野生型应答元件。将使用NMR和晶体学 并行和协同地检查全长VDR的结构， 以了解DNA和配体结合域之间的相互作用。 这些分析可能会导致设计新的抗癌或治疗药物， 化合物.

DESCRIPTION (provided by applicant): The steroid and nuclear hormone receptors are the largest known class of eukaryotic transcriptional regulators and modulate transcription in response to non-peptide lipophillic signals. The members of this superfamily include the vitamin D receptor (VDR), which regulates genes related to calcium homeostasis and plays a role in the differentiation of hematopoietic and skin cells, and the androgen receptor (AR), which directly regulates the expression of prostate-specific genes, among others. Hormone receptors exert their effects by binding as homo- or hetero-dimers to DNA targets - called response elements - composed of two hexanucleotide half-sites that are distinguished from one another by the sequence of the half site and the orientation and spacing of one half site relative to the other. VDR binds to response elements composed of two half-sites arranged as a direct repeat with three base pairs of spacer in between (DR-3). AR binds to inverted repeat, three-spacer response elements (IR-3), although recently a novel AR response element was identified that closely resembles the DR-3 type and may serve to distinguish AR responsive genes from those responsive to glucocorticoids and other steroids. An understanding of the underlying stereochemistry of the role of VDR and AR in transcriptional activation and DNA target selection requires the structural analysis of the relevant macromolecular species and complexes. We plan to solve and analyze, using X-ray crystallography, the structures of the DNA binding domain of VDR homodimers and RXR-VDR heterodimers in complex with a variety of DNA targets, and the structure of the AR DNA binding domain in complex with its novel direct repeat DNA target. These studies are aimed at elucidating the structural basis for both VDR and AR DNA target recognition, their shared preference for DR-3 type response elements, and the mechanisms employed to distinguish correct from incorrect DNA targets. We will correlate our structural results with measurements of the protein's binding affinity to consensus and wild-type response elements. NMR and crystallography will be used in parallel and synergistically to examine the structure of full-length VDR, in order to understand the interplay between the DNA and ligand binding domains. These analyses may lead to the design of novel anti-cancer or therapeutic compounds.