The long-term objectives of my laboratory are to improve our understanding of the basic regulatory mechanisms that govern drug disposition and drug metabolism. There is a clear recognition that the frequency of adverse drug reactions (ADRs) is increased in patients affected with an underlying systemic inflammation. In these individuals, variable drug responses are not necessarily related to genetic polymorphisms but are due to the rapid and dramatic reduction in the expression of key genes that encode important drug metabolizing enzymes (DMEs) and drug transporter proteins. In liver, the pregnane x receptor (PXR) is the master- xenobiotic 'sensor'. Ligand-dependent activation of PXR increases the overall uptake, metabolism, transport and eventual elimination of a myriad of xenobiotics and prescription drugs. Based upon strong preliminary data, we hypothesize that the immunosuppressive effects that occur in patients following Rifampicin therapy occurs via the post-translational modification of the PXR protein. We provide evidence that TNFalpha promotes poly-sumoylation of liganded-PXR to feedback repress NF-kappa B-target genes.
Aim 1 will define the specific sites of ligand-activated PXR SUMOylation sequentially in vitro, in cultured cells, and then in hepatocytes using a novel and innovative mass spectrometry-based approach.
Aim 2 will test the hypothesis that the mechanism of selective repression of the inflammatory response is due to SUMO-modified PXR preventing clearance of nuclear receptor corepressor/NF-kappa B complexes using biochemical methods. Understanding the biochemical details and molecular mechanisms of how PXR is converted from a positive regulator of hepatic DMEs into a transcriptional suppressor of inflammation in liver tissue will provide a new molecular paradigm for understanding drug-mediated repression of the hepatic inflammatory response. New molecular insights regarding the biology of PXR SUMOylation will provide new opportunities to develop novel pharmacological strategies for addressing ADRs, and will eventually help to identify small molecules that will be used to treat inflammatory liver diseases.
The information gathered from the successful completion of this research proposal represents the key first step in developing novel pharmaceutical strategies that could be used to prevent ADRs in patients on combination therapy that are experiencing acute or systemic inflammation. This information will help to predict and prevent ADRs in patients experiencing acute or systemic inflammation.
|Cui, Wenqi; Sun, Mengxi; Zhang, Shupei et al. (2016) A SUMO-acetyl switch in PXR biology. Biochim Biophys Acta 1859:1170-82|
|Bossaller, Lukas; Christ, Anette; Pelka, Karin et al. (2016) TLR9 Deficiency Leads to Accelerated Renal Disease and Myeloid Lineage Abnormalities in Pristane-Induced Murine Lupus. J Immunol 197:1044-53|
|Sun, Mengxi; Cui, Wenqi; Woody, Sarah K et al. (2015) Pregnane X receptor modulates the inflammatory response in primary cultures of hepatocytes. Drug Metab Dispos 43:335-43|
|Cui, Wenqi; Sun, Mengxi; Galeva, Nadezhda et al. (2015) SUMOylation and Ubiquitylation Circuitry Controls Pregnane X Receptor Biology in Hepatocytes. Drug Metab Dispos 43:1316-25|
|Watkins, Amanda A; Yasuda, Kei; Wilson, Gabriella E et al. (2015) IRF5 deficiency ameliorates lupus but promotes atherosclerosis and metabolic dysfunction in a mouse model of lupus-associated atherosclerosis. J Immunol 194:1467-79|
|Watkins, Amanda A; Bonegio, Ramon G B; Rifkin, Ian R (2014) Evaluating the role of nucleic acid antigens in murine models of systemic lupus erythematosus. Methods Mol Biol 1169:143-58|
|Yasuda, Kei; Watkins, Amanda A; Kochar, Guneet S et al. (2014) Interferon regulatory factor-5 deficiency ameliorates disease severity in the MRL/lpr mouse model of lupus in the absence of a mutation in DOCK2. PLoS One 9:e103478|
|Staudinger, Jeffrey L (2013) Disease, drug metabolism, and transporter interactions. Pharm Res 30:2171-3|
|Wang, Zhiyong; Gall, Jonathan M; Bonegio, Ramon et al. (2013) Nucleophosmin, a critical Bax cofactor in ischemia-induced cell death. Mol Cell Biol 33:1916-24|
|Staudinger, Jeff L; Woody, Sarah; Sun, Mengxi et al. (2013) Nuclear-receptor-mediated regulation of drug- and bile-acid-transporter proteins in gut and liver. Drug Metab Rev 45:48-59|
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