A novel nuclear receptor, termed the steroid and xenobiotic receptor (SXR), a broad-specificity sensing receptor that is a novel branch of the nuclear receptor superfamily, has been discovered. SXR forms a heterodimer with RXR that can bind to and induce transcription from response elements present in steroid-inducible cytochrome P450 genes in response to hundreds of natural and synthetic compounds with biological activity, including therapeutic steroids as well as dietary steroids and lipids. Instead of hundreds of receptors, one for each inducing compound, the invention SXR receptors monitor aggregate levels of inducers to trigger production of metabolizing enzymes in a coordinated metabolic pathway. Agonists and antagonists of SXR are administered to subjects to achieve a variety of therapeutic goals dependent upon modulating metabolism of one or more endogenous steroids or xenobiotics to establish homeostasis. An assay is provided for identifying steroid drugs that are likely to cause drug interaction if administered to a subject in therapeutic amounts. Transgenic animals are also provided which express human SXR, thereby serving as useful models for human response to various agents which potentially impact P450-dependent metabolic processes. Also provided are expression systems and expression vectors having SXR receptors and the like operably linked to target genes of interest.
人们发现了一种新型核受体,称为类
固醇和异
生物受体(SXR),它是一种广特异性感应受体,是核受体超家族的一个新分支。SXR 与 RXR 形成异源二聚体,能与类
固醇诱导的细胞色素 P450
基因中的反应元件结合并诱导其转录,从而对数百种具有
生物活性的天然和合成化合物(包括治疗性类
固醇以及膳食类
固醇和脂质)做出反应。本发明的 SXR 受体不需要数百种受体(每种诱导化合物一种受体),而是监测诱导剂的总体
水平,从而在协调的代谢途径中触发代谢酶的产生。对受试者施用 SXR 的激动剂和拮抗剂,以实现各种治疗目标,这些目标取决于调节一种或多种内源性类
固醇或异
生物的代谢,从而建立体内平衡。本研究还提供了一种检测方法,用于确定以治疗量给受试者用药时可能引起药物相互作用的类
固醇药物。还提供了表达人类 SXR 的转
基因动物,从而作为人类对可能影响 P450 依赖性代谢过程的各种制剂的反应的有用模型。此外,还提供了表达系统和表达载体,这些系统和载体具有可与感兴趣的靶
基因连接的 SXR 受体等。