STEROID INTERACTIONS WITH P GLYCOPROTEINS

描述(改编自申请人的摘要)：MDR1 P-糖蛋白可能调节小鼠T淋巴瘤细胞对药物的敏感性 糖皮质激素。P-糖蛋白是一种依赖于ATP的转运蛋白，可以清除 疏水性药物从细胞中释放出来，从而导致多药耐药性。一些人 类固醇，如黄体酮，会抑制P-糖蛋白对药物的转运。 P-糖蛋白具有高度的选择性 运输皮质类固醇，类固醇的特殊结构特征是 与P-糖蛋白结合和转运的识别决定因素。 本申请提出了小鼠多药耐药基因mdr1的结构-功能分析 与其结合和运输皮质类固醇的能力有关的蛋白质。一个 已开发出一种筛选WEHI-7小鼠T细胞变异体的方法 含有MDR1突变的淋巴瘤株影响蛋白质的能力 运输地塞米松。其他通常抑制多药耐药的类固醇有 在这些变种中减少了这样做的能力。这些选择旨在 确保MDR1保留其运输其他药物的大部分能力。它 推测mdr1基因突变会影响人类对多药耐药基因的识别 作为结合的决定因素的特定类固醇结构特征 MDR1。使用多种类固醇MDR1抑制剂的检测将确定 这些类固醇结构决定因素中的哪一个(最初，3-和 20-酮基)不再被突变的mdr1识别。离体 突变mdr1蛋白的诱变和表达将证实 每个突变的功能效应。

DESCRIPTION (Adapted from the applicant's abstract): The mdr1 P-glycoprotein may regulate the sensitivity of murine T lymphoma cells to glucocorticoids. P-glycoproteins are ATP-dependent transporters that remove hydrophobic drugs from cells and thus cause multidrug resistance. Some steroids such as progesterone inhibit transport of drugs by P-glycoproteins. There is a high degree of selectivity in the ability of P-glycoproteins to transport corticosteroids, and specific structural features of steroids are recognition determinants for binding to and transport by P-glycoproteins. This application proposes a structure-function analysis of the murine mdr1 protein concerning its ability to bind to and transport corticosteroids. A method has been developed to select for variants of the WEHI-7 murine T lymphoma line that contain mdr1 mutations affecting the protein's ability to transport dexamethasone. Other steroids that normally inhibit mdr1 have a reduced capacity to do so in such variants. The selections are designed to ensure that mdr1 retains most of its capacity to transport other drugs. It is proposed that the putative mdr1 mutations affect the recognition of specific steroid structural features that are determinants for binding to mdr1. Assays using a variety of steroidal mdr1 inhibitors will determine which of these steroid structural determinants (initially, the 3- and 20-keto groups) are no longer recognized by the mutated mdr1. In vitro mutagenesis and expression of mutant mdr1 proteins will confirm the functional effects of each mutation.