Cholesterol homeostasis is maintained through the coordinate regulation of cholesterol uptake, synthesis, transport, degradation, and secretion. Loss of cholesterol homeostasis causes diseases, such as atherosclerosis and cholesterol gallstones. Atherosclerosis and its clinical sequelae are a major cause of premature death and disability in the United States and in the industrialized would. We recently discovered and characterized a novel nuclear sulfated oxysterol, 5-cholesten-3b, 25-diol 3- sulphate, which increased dramatically with increased cholesterol delivery to mitochondria in primary hepatocytes. This oxysterol was found in high concentrations in the mitochondria and nuclei of these cells, and appears capable of activating the genes encoding cholesterol 7a-hydroxylase (CYP7A1), and cholesterol transporters (ABCA1, ABCG5, ABCG8). Our preliminary data indicate that cholesterol can be hydroxylated at 25-position first, and then sulfated at 3-hydroxy position in mitochondria. The water-soluble product is then transported out of the mitochondria and enters to the nucleus. This sulfated 25-OH cholesterol seems to activate nuclear receptor(s) and upregulates bile acid synthesis and cholesterol secretion. We hypothesize that this sulfated cholesterol derivative is an intermediate in a novel cholesterol metabolism pathway. The overall objective of this application is to characterize the intermediates in this novel pathway, determine the cellular location of the key enzymes in the pathway, and explore the role this pathway may play in cellular cholesterol homeostasis.
the specific aims are: 1. To characterize and determine the chemical structures of the novel sulfated oxysterol(s) in nuclei, mitochondria, and culture media; to chemically synthesize this nuclear sulfated oxysterol; 2.To elucidate the metabolic pathway of this novel nuclear sulfated oxysterol in primary hepatocytes; and 3. To explore the role that this novel sulfated oxysterol plays in the maintenance of cholesterol homeostasis using the chemically synthesized nuclear oxysterol. The successful completion of this study will provide fundamental information regarding intracellular oxysterols regulate intracellular cholesterol and lipids metabolism, which may represent new therapeutic approaches to treatment of hypercholesterolemia and hyperlipidemia. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL078898-03
Application #
7479766
Study Section
Hepatobiliary Pathophysiology Study Section (HBPP)
Program Officer
Liu, Lijuan
Project Start
2006-09-18
Project End
2011-07-31
Budget Start
2008-08-01
Budget End
2009-07-31
Support Year
3
Fiscal Year
2008
Total Cost
$284,174
Indirect Cost
Name
Mcguire Research Institute, Inc.
Department
Type
DUNS #
785883331
City
Richmond
State
VA
Country
United States
Zip Code
23249
Ren, Shunlin; Ning, Yanxia (2014) Sulfation of 25-hydroxycholesterol regulates lipid metabolism, inflammatory responses, and cell proliferation. Am J Physiol Endocrinol Metab 306:E123-30
Xu, Leyuan; Kim, Jin Koung; Bai, Qianming et al. (2013) 5-cholesten-3?,25-diol 3-sulfate decreases lipid accumulation in diet-induced nonalcoholic fatty liver disease mouse model. Mol Pharmacol 83:648-58
Xu, Leyuan; Shen, Shanwei; Ma, Yongjie et al. (2012) 25-Hydroxycholesterol-3-sulfate attenuates inflammatory response via PPAR? signaling in human THP-1 macrophages. Am J Physiol Endocrinol Metab 302:E788-99
Zhang, Xin; Bai, Qianming; Xu, Leyuan et al. (2012) Cytosolic sulfotransferase 2B1b promotes hepatocyte proliferation gene expression in vivo and in vitro. Am J Physiol Gastrointest Liver Physiol 303:G344-55
Zhang, Xin; Bai, Qianming; Kakiyama, Genta et al. (2012) Cholesterol metabolite, 5-cholesten-3?-25-diol-3-sulfate, promotes hepatic proliferation in mice. J Steroid Biochem Mol Biol 132:262-70
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Xu, Leyuan; Bai, Qianming; Rodriguez-Agudo, Daniel et al. (2010) Regulation of hepatocyte lipid metabolism and inflammatory response by 25-hydroxycholesterol and 25-hydroxycholesterol-3-sulfate. Lipids 45:821-32
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Ning, Yanxia; Xu, Leyuan; Ren, Shunlin et al. (2009) StAR overexpression decreases serum and tissue lipids in apolipoprotein E-deficient mice. Lipids 44:511-9

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