Signaling of the Pregnane X Receptor

孕烷 X 受体的信号传导

• 批准号: 7831855
• 负责人: Bingfang Yan
• 金额: $ 10.29万
• 依托单位: UNIVERSITY OF RHODE ISLAND
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7831855
• 关键词: Attenuated; Base Sequence; Be++ element; Beryllium; Cardiovascular Diseases; Cells; Cytochrome P450 3A4; Disease; Elements; Event; Experimental Designs; Functional RNA; Funding; Gene Expression; Genes; Hand; Human; Individual; Inflammation; Inflammation Mediators; Interleukin-6; Kinetics; Ligands; Lipopolysaccharides; Location; Malignant Neoplasms; Mediating; Messenger RNA; MicroRNAs; Molecular; Monitor; Nucleotides; Pharmaceutical Preparations; Play; RNA Polymerase II; Rattus; Recovery; Repression; Research Design; Research Project Grants; Role; Signal Transduction; Site; TATA Box; Testing; To specify; Transactivation; Transcript; Transcription Initiation Site; Translations; United States National Institutes of Health; Work; abstracting; attenuation; base; chemical elimination; cytokine; design; drug metabolism; expectation; mutant; parent grant; pregnane X receptor; promoter; public health relevance; rat CYP3A23 protein; receptor expression; response

DESCRIPTION (provided by applicant): Yan, Bingfang ABSTRACT This is a revision application in response to the announcement NOT-OD-09-058: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications This revision application proposes a set of studies to extend the specific aims of the parent grant. The focus of the parent grant, presented as two specific aims, is to elucidate signaling events associated with the pregnane X receptor (PXR), a master regulator on the expression of many chemical elimination genes such as cytochrome P450 3A4 (CYP3A4) in humans and CYP3A23 in rats. Interestingly, the CYP3A23 but not the CYP3A4 proximal promoter responds robustly to a PXR ligand, although a functional PXR element is present in both CYP3A4 and CYP3A23 proximal promoters. Instead, the CYP3A4 proximal promoter coordinates with other upstream PXR elements and confers transactivation activity. Sequence comparison reveals that the CYP3A4 promoter, compared with CYP3A23, has the PXR element 30 bases farther from the transcription starting site. In addition, the CYP3A4 but not CYP3A23 promoter has an HNF3/CEBP site in front of the PXR element. The PXR-mediated trans- activation, on the other hand, is markedly attenuated by cytokines such as interleukin-6 (IL-6). microRNA-511 (miR-511), highly induced by IL-6, diminishes PXR transactivation. miRs are known to silence gene expression through sequence pairing with their target mRNAs. The proposed studies are designed to test the hypotheses that the PXR transcript is a sequence-specific target of miR-511, and the physical location of the PXR element and the presence of the HNF3/CEBP site contribute significantly to the inability of the CYP3A4 proximal promoter to effectively respond to PXR-transactivation. To define the potential role of the physical location or the interference of the HNF3/CEBP site, mutants will be prepared to disrupt the HNF3/CEBP site, relocate the PXR element closer to the transcription starting site, or both. These mutants will be tested for increased ability to respond to PXR transactivation. To determine the molecular action of miR-511 to decrease PXR expression, cells will be transfected with miR-511 and the levels of PXR mRNA and its translation efficiency will be monitored. In addition, the sequence supporting the action of miR-511 will be located and the role of miR-511 in the suppression of PXR by IL-6 will be established. Overall, the studies in the revision application represent significant expansion of the original aims in the parent grant. Importantly, these studies are closely integrated into the studies in the parent grant, and together, they will provide more comprehensive understanding on the expression of drug elimination genes regarding species-dependent transactivation and altered expression during inflammation. PUBLIC HEALTH RELEVANCE: The capacity of drug elimination is altered by co-administration of other drugs and disease status such as inflammation. The revision application proposes a set of studies to reveal the underlying mechanisms on how and to which extent the drug-eliminating capacity of an individual is altered by co-administered drugs or inflammatory mediators.

描述（由申请人提供）：Yan，Bingfang 摘要这是针对公告 NOT-OD-09-058 的修订申请：NIH 宣布恢复法案资金可用于竞争性修订申请 该修订申请提出了一系列研究，以扩展母基金的具体目标。母基金的重点有两个具体目标，即阐明与孕烷 X 受体 (PXR) 相关的信号转导事件，PXR 是许多化学消除基因（例如人类细胞色素 P450 3A4 (CYP3A4) 和大鼠 CYP3A23）表达的主要调节因子。有趣的是，尽管 CYP3A4 和 CYP3A23 近端启动子中均存在功能性 PXR 元件，但 CYP3A23 而不是 CYP3A4 近端启动子对 PXR 配体有强烈响应。相反，CYP3A4 近端启动子与其他上游 PXR 元件协调并赋予反式激活活性。序列比对发现，CYP3A4启动子与CYP3A23相比，PXR元件距离转录起始位点较远30个碱基。此外，CYP3A4（而非 CYP3A23）启动子在 PXR 元件前面有一个 HNF3/CEBP 位点。另一方面，PXR 介导的反式激活会被白细胞介素 6 (IL-6) 等细胞因子显着减弱。 IL-6 高度诱导的 microRNA-511 (miR-511) 可减少 PXR 反式激活。已知 miR 通过与其目标 mRNA 进行序列配对来沉默基因表达。拟议的研究旨在测试以下假设：PXR 转录物是 miR-511 的序列特异性靶标，PXR 元件的物理位置和 HNF3/CEBP 位点的存在显着导致 CYP3A4 近端启动子无法有效响应 PXR 反式激活。为了确定物理位置或 HNF3/CEBP 位点干扰的潜在作用，将制备突变体来破坏 HNF3/CEBP 位点，将 PXR 元件重新定位到更靠近转录起始位点，或两者兼而有之。将测试这些突变体对 PXR 反式激活的反应能力的增强。为了确定 miR-511 降低 PXR 表达的分子作用，将用 miR-511 转染细胞，并监测 PXR mRNA 的水平及其翻译效率。此外，将定位支持miR-511作用的序列，并确定miR-511在IL-6抑制PXR中的作用。总体而言，修订申请中的研究代表了母基金原始目标的显着扩展。重要的是，这些研究与母基金的研究紧密结合，共同提供对药物消除基因表达的更全面的理解，这些基因涉及物种依赖性反式激活和炎症期间表达的改变。 公共健康相关性：药物消除的能力会因其他药物的共同给药和炎症等疾病状态而改变。修订申请提出了一系列研究，以揭示共同给药的药物或炎症介质如何以及在多大程度上改变个体的药物消除能力的潜在机制。