Functional Analysis of Nuclear Receptors

核受体超家族成员是进化相关的DNA结合转录因子。目前的研究建议的重点是结构性雄烷受体(CAR；基因命名为NR1I3)，它不仅调控特定基因的表达，涉及葡萄糖稳态、脂肪代谢和骨骼稳态，而且还调控外源物质(也称为外来化学品，如药物、草药和环境污染物)和内源性物质(如激素、维生素和脂肪酸)的转运、生物激活和解毒。我的研究计划的长期目标是加强我们对各种分子和细胞因子的了解，这些分子和细胞因子调节核受体(例如CAR)的功能和表达，这些受体参与控制基因的表达，这些基因在外源物质和内源性物质的运输、生物激活和解毒中发挥重要作用。具体的短期目标是：1)确定调控人类CAR野生型异构体(HCAR-WT)表达和功能的microRNAs；以及2)描述特定的HCAR剪接变异体(例如HCAR-SV22和HCAR-SV26)的功能，并确定HCAR异构体的功能是否受到其他核受体的调节。在目标1下，需要解决的实验问题包括：1)microRNA对HCAR-WT表达和功能的影响及其对HCAR-WT靶基因表达的影响；2)视黄酸X受体-α(RXR-α)的microRNA调节对HCAR转录活性的影响；以及3)HCAR-WT的配体对microRNAs表达的影响，包括调节HCAR-WT表达和功能的配体。在目标2下，实验问题是：1)确定特定HCAR剪接变异体(例如HCAR-SV22和HCAR-SV26)的功能；以及2)确定各种HCAR异构体(例如HCAR-WT、HCAR-SV23、HCAR-SV24)与其他核受体(如小异二聚体伙伴(SHP)和肝X受体-α(LXR-α))之间是否存在功能相互作用(即串扰)。我们提出的研究计划将加强我们对表观遗传学对HCAR表达和功能的影响，人类CAR的各种剪接变体的功能，以及它们是否受到其他核受体的调控的基本理解。产生的信息将帮助我们预测和解释我们对内源性物质和外源物质(包括药物)的反应方式的个体间差异，并增加我们对调节HCAR表达和功能的各种因素的理解。

Members of the superfamily of nuclear receptors are evolutionarily-related DNA-binding transcription factors. The focus of the current research proposal is on the constitutive androstane receptor (CAR; gene designation NR1I3), which regulates the expression of specific genes involved not only in glucose homeostasis, lipid metabolism, and bone homeostasis, but also transport, bioactivation, and detoxification of xenobiotics (also referred to as foreign chemicals; e.g. drugs, herbal medicines, and environmental pollutants) and endogenous substances (e.g. hormones, vitamins, and fatty acids). The longer-term objective of my research program is to enhance our understanding of the various molecular and cellular factors that regulate the function and expression of nuclear receptors (e.g. CAR) involved in controlling the expression of genes that play an important role in the transport, bioactivation, and detoxification of xenobiotics and endogenous substances. The specific short-term aims are to: 1) identify microRNAs in regulating the expression and function of the wild-type isoform of human CAR (hCAR-WT); and 2) delineate the function of specific hCAR splice variants (e.g. hCAR-SV22 and hCAR-SV26) and determine whether the function of hCAR isoforms is subject to regulation by other nuclear receptors. Under Aim #1, the experimental issues to be addressed will include: 1) the effect of microRNA on expression and function of hCAR-WT and the consequence on hCAR-WT target gene expression; 2) the consequences of microRNA regulation of retinoic X receptor-alpha (RXR-alpha) on hCAR transcriptional activity; and 3) the effect of ligands of hCAR-WT on expression of microRNAs, including the ones that regulate the expression and function of hCAR-WT. Under Aim #2, the experimental issues are to: 1) to characterize the functionality of specific hCAR splice variants (e.g. hCAR-SV22 and hCAR-SV26); and 2) determine whether there is functional interaction (i.e. cross-talk) between the various hCAR isoforms (e.g. hCAR-WT, hCAR-SV23, hCAR-SV24) and other nuclear receptors, such as small heterodimer partner (SHP) and liver X receptor-alpha (LXR-alpha). Our proposed research program will enhance our fundamental understanding of the influence of epigenetics on the expression and function of hCAR, the functionality of the various splice variants of human CAR, and whether they are subject to regulation by other nuclear receptors. The information generated will help us to predict and explain inter-individual differences in how we respond to endogenous substances and xenobiotics, including drugs, and increase our understanding of the various factors that regulate hCAR expression and function.