Regulation of Nuclear Receptor Expression and Function

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Recent Progress. The overall goal of my research program is to increase our understanding of the chemical biology and the intricate network of cellular and molecular factors that govern the expression and function of members of the superfamily of nuclear receptors, such as pregnane X receptor (PXR), constitutive androstane receptor (CAR), and vitamin D receptor (VDR). These receptors regulate the expression of genes involved in the transport, bioactivation, and detoxification of many chemicals, including drugs, environmental chemicals, and those present in our body, such as steroid hormones and vitamins. My studies in the past five years have focused on studying chemical regulation of PXR, CAR, and VDR, elucidating post-transcriptional mechanism of PXR expression, and discovering novel biological actions of PXR and CAR. Results from these studies provide a scientific foundation for my NSERC Discovery Grant renewal application. Objectives. The objectives will be to study co-regulation of PXR and VDR by investigating the role of specific microRNAs involved in controlling the expression and function of PXR and VDR, identify and delineate the contribution of coactivators to the regulation of PXR and CAR, and investigate the regulation of PXR and CAR by other receptors. The longer-term objective of my research program is to enhance our fundamental knowledge of the systems biology of nuclear receptors. Methodology. Primary cultures of human hepatocytes, primary cultures of human intestinal cells, and LS180 human adenocarcinoma cells will be the experimental models. Experimental approaches will include the use of a mimic and an inhibitor of a microRNA, pharmacological antagonism and inverse agonism, gene editing, cell-based luciferase reporter gene assays, time-resolved fluorescence resonance energy transfer competitive ligand binding assay, fluorescence microscopy, co-immunoprecipitation, pull down assays, mammalian two-hybrid assay, chromatin immunoprecipitation assay, real-time polymerase chain reaction, and immunoblot analyses. HQP. My proposed research program will provide learning opportunities for 2 MSc students, 2 PhD students, and 5 undergraduate summer students. The research will form the basis of each graduate student's thesis and provide research experience to undergraduate students. Impact. The fundamental scientific knowledge generated will help increase our understanding of the various factors that influence PXR and CAR expression and function. The information will predict and explain inter-individual differences in how we respond to endogenous substances, drugs, and other chemicals. My proposed research program will provide training to the next generation of scientists in the field of receptor biology. Equipped with skills and experiences in biochemistry, cell biology, and pharmacology, my HQP will contribute their expertise to the research and development efforts in the life sciences/biotechnology/pharmaceutical sectors in Canada.