The nuclear hormone receptor CAR (NR1I3) mediates increased drug metabolism in response to diverse xenobiotics. These include the well known inducer phenobarbital (PB), which functions as an indirect CAR activator, and a number of species-specific agonist or inverse agonist ligands. We have found that CAR also directs a protective response to elevated levels of endogenous toxic metabolites. Both published reports and our preliminary results demonstrate that CAR activation can alter glucose and lipid metabolism, and indicate that metabolic dysregulation in diabetes and other disorders affects drug metabolism. These results expand the physiologic functions of CAR well beyond drug metabolism and raise important questions regarding its impact on basic metabolic pathways. Moreover, we have also shown that CAR activation directly induces hepatocyte growth and DNA replication and blocks apoptosis. In the short term this is an adaptive response that protects the liver, but chronic CAR activation induces liver tumors, raising key issues regarding the role of this xenobiotic receptor in hepatocarcinogenesis. The continuing long term goal of this project is to understand the specific regulatory functions of CAR. The current proposal addresses two specific hypotheses: 1. CAR is both a modulator of basic metabolic pathways and a target of the pathologic consequences of metabolic dysregulation. 2. CAR is both a modulator of early stages of hepatocarcinogenesis and a therapeutic target in the later stages of this process. The two broad specific aims are to: 1. Define the impact of CAR on basic metabolic pathways and target genes, and characterize the effects of the dysregulation of such pathways on the xenobiotic responses mediated by CAR. 2. Characterize the role of CAR in the early stages of hepatocarcinogenesis, test the therapeutic potential of CAR inverse agonists in inhibition of liver tumor growth, and examine the functional interaction of CAR with the Retinoblastoma gene product and p-catenin. These studies could have specific and direct impact on human health by providing new insights into alterations in drug metabolism in metabolic disease, particularly Type I diabetes, and a new therapeutic avenues to intervene in both Type 2 diabetes and liver cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK046546-16
Application #
7622613
Study Section
Molecular and Cellular Endocrinology Study Section (MCE)
Program Officer
Margolis, Ronald N
Project Start
1995-02-01
Project End
2011-05-31
Budget Start
2009-06-01
Budget End
2010-05-31
Support Year
16
Fiscal Year
2009
Total Cost
$338,468
Indirect Cost
Name
Baylor College of Medicine
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
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Dong, Bingning; Lee, Ju-Seog; Park, Yun-Yong et al. (2015) Activating CAR and ?-catenin induces uncontrolled liver growth and tumorigenesis. Nat Commun 6:5944
Kim, Kang Ho; Sederstrom, Joel M (2015) Assaying Cell Cycle Status Using Flow Cytometry. Curr Protoc Mol Biol 111:28.6.1-11
Moore, David D (2012) Nuclear receptors reverse McGarry's vicious cycle to insulin resistance. Cell Metab 15:615-22
Chen, Wei-Dong; Fu, Xianghui; Dong, Bingning et al. (2012) Neonatal activation of the nuclear receptor CAR results in epigenetic memory and permanent change of drug metabolism in mouse liver. Hepatology 56:1499-509
Xiao, Rui; Sun, Deqiang; Ayers, Stephen et al. (2012) Research resource: The estrogen receptor ? cistrome defined by DamIP. Mol Endocrinol 26:349-57
Park, Young Joo; Lee, Eun Kyung; Lee, Yoon Kwang et al. (2012) Opposing regulation of cytochrome P450 expression by CAR and PXR in hypothyroid mice. Toxicol Appl Pharmacol 263:131-7
Wagner, Martin; Moore, David D (2011) Endoplasmic reticulum stress and glucose homeostasis. Curr Opin Clin Nutr Metab Care 14:367-73
Smetanina, Mariya A; Pakharukova, Mariya Y; Kurinna, Svitlana M et al. (2011) Ortho-aminoazotoluene activates mouse constitutive androstane receptor (mCAR) and increases expression of mCAR target genes. Toxicol Appl Pharmacol 255:76-85
Sberna, Anne-Laure; Assem, Mahfoud; Xiao, Rui et al. (2011) Constitutive androstane receptor activation decreases plasma apolipoprotein B-containing lipoproteins and atherosclerosis in low-density lipoprotein receptor-deficient mice. Arterioscler Thromb Vasc Biol 31:2232-9

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