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Tang SY, Ma HP, Lin C, Lo MT, Lin LY, Chen TY, Wu CK, Chiang JY, Lee JK, Hung CS, Liu LYD, Chiu YW, Tsai CH, Lin YT, Peng CK, Lin YH. Heart rhythm complexity analysis in patients with inferior ST-elevation myocardial infarction. Sci Rep 2023; 13:20861. [PMID: 38012168 PMCID: PMC10681979 DOI: 10.1038/s41598-023-41261-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 08/23/2023] [Indexed: 11/29/2023] Open
Abstract
Heart rhythm complexity (HRC), a subtype of heart rate variability (HRV), is an important tool to investigate cardiovascular disease. In this study, we aimed to analyze serial changes in HRV and HRC metrics in patients with inferior ST-elevation myocardial infarction (STEMI) within 1 year postinfarct and explore the association between HRC and postinfarct left ventricular (LV) systolic impairment. We prospectively enrolled 33 inferior STEMI patients and 74 control subjects and analyzed traditional linear HRV and HRC metrics in both groups, including detrended fluctuation analysis (DFA) and multiscale entropy (MSE). We also analyzed follow-up postinfarct echocardiography for 1 year. The STEMI group had significantly lower standard deviation of RR interval (SDNN), and DFAα2 within 7 days postinfarct (acute stage) comparing to control subjects. LF power was consistently higher in STEMI group during follow up. The MSE scale 5 was higher at acute stage comparing to control subjects and had a trend of decrease during 1-year postinfarct. The MSE area under scale 1-5 showed persistently lower than control subjects and progressively decreased during 1-year postinfarct. To predict long-term postinfarct LV systolic impairment, the slope between MSE scale 1 to 5 (slope 1-5) had the best predictive value. MSE slope 1-5 also increased the predictive ability of the linear HRV metrics in both the net reclassification index and integrated discrimination index models. In conclusion, HRC and LV contractility decreased 1 year postinfarct in inferior STEMI patients, and MSE slope 1-5 was a good predictor of postinfarct LV systolic impairment.
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Affiliation(s)
- Shu-Yu Tang
- Department of Internal Medicine, National Taiwan University Hospital Yunlin Branch, Yunlin, Taiwan
| | - Hsi-Pin Ma
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Chen Lin
- Department of Biomedical Sciences and Engineering, National Central University, No. 300, Zhongda Road, Taoyuan, Taiwan.
| | - Men-Tzung Lo
- Department of Biomedical Sciences and Engineering, National Central University, No. 300, Zhongda Road, Taoyuan, Taiwan
| | - Lian-Yu Lin
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Tsung-Yan Chen
- Department of Internal Medicine, National Taiwan University Hospital Hsinchu Branch, Hsinchu, Taiwan
| | - Cho-Kai Wu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jiun-Yang Chiang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jen-Kuang Lee
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chi-Sheng Hung
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Li-Yu Daisy Liu
- Department of Agronomy, Biometry Division, National Taiwan University, Taipei, Taiwan
| | - Yu-Wei Chiu
- Department of Computer Science and Engineering, Yuan Ze university, Taoyuan, Taiwan
- Cardiology Division of Cardiovascular Medical Center, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Cheng-Hsuan Tsai
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
- Department of Internal Medicine, Division of Cardiology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei, Taiwan.
| | - Yen-Tin Lin
- Department of Internal Medicine, Taoyuan General Hospital, Taoyuan, Taiwan.
- Department of Inderal Medicine, Division of Cardiology, Taoyuan General Hospital, 1492 Zhongshan Road, Taoyuan, 33004, Taiwan.
| | - Chung-Kang Peng
- Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, USA
| | - Yen-Hung Lin
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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Wu VC, Chan CK, Wu WC, Peng KY, Chang YS, Yeh FY, Chiang JY, Lee YJ, Liu KL, Wang SM, Lin YH, Chueh JS, Chueh SCJ, Yang SY, Liu KL, Chang CC, Lee BC, Wang SM, Huang KH, Lin PC, Lin YH, Lin LY, Liao SC, Yen RF, Lu CC, Er LK, Hu YH, Chang CH, Wu CH, Tsai YC, Ho CH, Huang WC, Chen YY, Wu VC. New-onset diabetes mellitus risk associated with concurrent autonomous cortisol secretion in patients with primary aldosteronism. Hypertens Res 2023; 46:445-455. [PMID: 36481967 DOI: 10.1038/s41440-022-01086-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/03/2022] [Accepted: 10/04/2022] [Indexed: 12/14/2022]
Abstract
Concurrent autonomous cortisol secretion (ACS) in patients with primary aldosteronism (PA patients) is not uncommon. This work aimed to determine the effect of cortisol levels on incident new-onset type 2 diabetes mellitus (NODM) in PA patients. Using the prospectively designed observational TAIPAI cohort, the PA patients were grouped by cortisol level after an overnight low-dose dexamethasone suppression test (1-mg DST). Of the 476 PA patients, 387 (43.7% men; mean age 52.8 years) did not have baseline DM. After a mean follow-up of 4.3 ± 2.9 years, 32 patients (8.3%) developed NODM. The cutoff value obtained via a generalized additive model showed that a serum cortisol level ≥ 2.65 µg/dL after 1-mg DST was a risk factor for developing NODM (HR, 3.5, p = 0.031) by Cox proportional- hazards model.. In PA patients with a higher body mass index (>25 kg/m2; HR, 3.16), lower estimated glomerular filtration rate (<90 ml/min/1.73 m2; HR, 3.18), longer hypertension duration (>7 years; HR, 3.34), and higher waist-to-hip ratio (>0.9; HR, 3.07), a concomitant cortisol level ≥ 2.65 μg/dL after 1-mg DST were more likely to develop NODM. The high-cortisol group of patients with aldosterone-producing adenoma (APA) using mineralocorticoid receptor antagonist (MRA) was associated with an increased risk of NODM (HR, 5.72). Our results showed that PA patients with a concomitant cortisol level ≥ 2.65 µg/dL after 1-mg DST, independent of the aldosterone level, had a higher incidence of NODM. Such PA patients should be carefully evaluated and managed to achieve better glucose control and prevent metabolic syndrome.
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Affiliation(s)
- Vin-Cent Wu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chieh-Kai Chan
- Division of Nephrology, Department of Internal Medicine, National Taiwan University Hospital, Hsin-Chu Branch, Hsinchu City, Taiwan
| | - Wan-Chen Wu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Kang-Yung Peng
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Yuan-Shian Chang
- Department of Internal Medicine, Postal Hospital, Taipei, Taiwan
| | - Fang-Yu Yeh
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jiun-Yang Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Yuan-Ju Lee
- Department of Urology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kao-Lang Liu
- Medical Imaging, National Taiwan University Cancer Center, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shuo-Meng Wang
- Department of Urology, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Yen-Hung Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jeff S Chueh
- Department of Urology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Cheng JF, Lee CL, Chiang JY, Wu CK, Wang YC, Tsai CT, Liu SC, Tsai CT, Chang CJ, Hwang JJ. Impact of Selection Preference on Longer-Term Outcomes between Bioresorbable Vascular Scaffold versus Everolimus-Eluting Stent for True Lumen Tracking-Recanalized Chronic Total Occlusion. Int Heart J 2023; 64:154-163. [PMID: 37005311 DOI: 10.1536/ihj.22-581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
Creation of sizable subintima during intervention for chronic total occlusions (CTO) could lead to the key selection preference of metallic stents rather than bioresorbable vascular scaffolds (BVS) and then possibly deviate the outcome comparisons in real-world studies. By including recanalized CTO with true lumen tracking, we tested if any selection preference remained and compared the outcomes between everolimus-eluting stent (EES) and BVS implantation.Among 211 consecutive CTO interventions with true lumen tracking from August 2014 to April 2018 when BVS was available, we compared the clinical and interventional features between 28 patients with BVS and 77 patients with EES implantation. With propensity score matching and a median follow-up of 50.5 (37.3-60.3) months, we further assessed 25 patients with BVS and 25 with EES for target vessel failure (TVF: cardiac death, target vessel myocardial infarction, and target lesion revascularization).Multivariate analyses showed that BVS was still favored in the presence of LAD CTO (odds ratio (OR) = 3.4, 95% confidence interval (CI) = 1.0-11.7) and an average scaffold/stent size ≥ 3 mm (OR = 10.5, 95% CI = 3.0-37.3). EES was preferred for lesions with a J-CTO score ≥ 3 (OR = 19.3, 95% CI = 3.4-110.8) and multivessel intervention necessary at index procedure (OR = 11.3, 95% CI = 1.9-67.3). With matched comparisons, the TVF-free survival of EES was better than that of BVS for CTO recanalization (P = 0.049 by log-rank test) at long-term follow-up.Even with true lumen tracking techniques, selection bias remained substantial when determining either device for CTO implantation. The matched comparison of outcomes suggested the unfavorable longer-term impacts of the first generation of BVS on CTO lesions.
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Affiliation(s)
- Jen-Fang Cheng
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
| | - Chien-Lin Lee
- Division of Cardiovascular, Department of Internal Medicine, Far Eastern Memorial Hospital
| | - Jiun-Yang Chiang
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
| | - Cho-Kai Wu
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
| | - Yi-Chih Wang
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
| | - Chia-Ti Tsai
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
| | - Shih-Chi Liu
- Division of Cardiovascular, Department of Internal Medicine, Fu Jen Catholic University Hospital
| | - Cheng-Ting Tsai
- Division of Cardiovascular, Department of Internal Medicine, MacKay Memorial Hospital
| | - Chi-Jen Chang
- Division of Cardiovascular, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou
| | - Juey-Jen Hwang
- Division of Cardiovascular, Department of Internal Medicine, National Taiwan University Hospital
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Chiang JY, Lin L, Wu CC, Hwang JJ, Yang WS, Wu YW. Serum myostatin level is associated with myocardial scar burden by SPECT myocardial perfusion imaging. Clin Chim Acta 2022; 537:9-15. [DOI: 10.1016/j.cca.2022.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/29/2022] [Accepted: 09/26/2022] [Indexed: 11/29/2022]
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Lien CW, Hsien-Li Kao P, Chiang JY. TCTAP C-087 Revascularization in Patient With Left Main Coronary Artery Chronic Total Occlusion and Left Ventricular Dysfunction. J Am Coll Cardiol 2022. [DOI: 10.1016/j.jacc.2022.03.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lee CK, Liao CW, Meng SW, Wu WK, Chiang JY, Wu MS. Lipids and Lipoproteins in Health and Disease: Focus on Targeting Atherosclerosis. Biomedicines 2021; 9:biomedicines9080985. [PMID: 34440189 PMCID: PMC8393881 DOI: 10.3390/biomedicines9080985] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/01/2021] [Accepted: 08/04/2021] [Indexed: 12/15/2022] Open
Abstract
Despite advances in pharmacotherapy, intervention devices and techniques, residual cardiovascular risks still cause a large burden on public health. Whilst most guidelines encourage achieving target levels of specific lipids and lipoproteins to reduce these risks, increasing evidence has shown that molecular modification of these lipoproteins also has a critical impact on their atherogenicity. Modification of low-density lipoprotein (LDL) by oxidation, glycation, peroxidation, apolipoprotein C-III adhesion, and the small dense subtype largely augment its atherogenicity. Post-translational modification by oxidation, carbamylation, glycation, and imbalance of molecular components can reduce the capacity of high-density lipoprotein (HDL) for reverse cholesterol transport. Elevated levels of triglycerides (TGs), apolipoprotein C-III and lipoprotein(a), and a decreased level of apolipoprotein A-I are closely associated with atherosclerotic cardiovascular disease. Pharmacotherapies aimed at reducing TGs, lipoprotein(a), and apolipoprotein C-III, and enhancing apolipoprotein A-1 are undergoing trials, and promising preliminary results have been reported. In this review, we aim to update the evidence on modifications of major lipid and lipoprotein components, including LDL, HDL, TG, apolipoprotein, and lipoprotein(a). We also discuss examples of translating findings from basic research to potential therapeutic targets for drug development.
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Affiliation(s)
- Chih-Kuo Lee
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu 300, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Che-Wei Liao
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Department of Internal Medicine, National Taiwan University Cancer Center, Taipei 106, Taiwan
| | - Shih-Wei Meng
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu 300, Taiwan
| | - Wei-Kai Wu
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei 100, Taiwan
| | - Jiun-Yang Chiang
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Division of Cardiology, Department of Internal Medicine and Cardiovascular Center, National Taiwan University Hospital, Taipei 100, Taiwan
- Correspondence: (J.-Y.C.); (M.-S.W.)
| | - Ming-Shiang Wu
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei 100, Taiwan
- Correspondence: (J.-Y.C.); (M.-S.W.)
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Chiu WC, Chiang JY, Chiang FT. Small chemical compounds Y16 and Rhosin can inhibit calcium sensitization pathway in vascular smooth muscle cells of spontaneously hypertensive rats. J Formos Med Assoc 2021; 120:1863-1868. [PMID: 33893012 DOI: 10.1016/j.jfma.2021.03.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/22/2021] [Accepted: 03/28/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND/PURPOSE The small-molecule compounds Y16 and Rhosin can inhibit the activation of leukemia-associated Rho guanine nucleotide exchange factor (LARG) and small G-protein RhoA, respectively, in breast cancer cells and inhibit their growth and migration. However, it remains unclear whether they have inhibitory effects on the vascular smooth muscle cells (VSMCs) of spontaneously hypertensive rats (SHRs). METHODS Primary cultured VSMCs from SHRs were treated with different concentrations of Y16 or Y16 plus Rhosin for 24 h, followed by 10-min stimulation with 10-7 M angiotensin II (Ang II). The cells were then harvested, and the total protein was extracted. The co-immunoprecipitation method, Western blot analysis, and MTT assay were performed to determine the LARG-RhoA interaction, the protein levels of RhoA and MYPT1, and cell viability, respectively. RESULTS Y16 dose-dependently inhibited the LARG-RhoA complex formation induced by Ang II. With 50 μM of Y16, the effect of inhibition was statistically significant. Y16 also reduced the formation of phospho-MYPT1 stimulated by Ang II. With 5 μM of Y16, the inhibitory effect was statistically significant. When 25 μM of Y16 and 25 μM of Rhosin were combined, the inhibitory effect on LARG-RhoA interaction was statistically significant. When Y16 and Rhosin were combined, a significantly reduced concentration could effectively inhibit MYPT1 phosphorylation (2.5 μM compared with 5 μM for Y16 alone). CONCLUSION Treating SHR VSMCs with Y16 can suppress the activation of LARG, prevent LARG binding to RhoA, and decrease the phosphorylation of MYPT1, thus weakening the activation of the calcium (Ca2+) sensitization pathway in SHR VSMCs.
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Affiliation(s)
- Wei-Chiao Chiu
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jiun-Yang Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Fu-Tien Chiang
- Division of Cardiology, Department of Internal Medicine, Fu Jen Catholic University Hospital, New Taipei, Taiwan; Fu Jen Catholic University, Taiwan.
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Chiu WC, Chiang JY, Juang JM, Wu CK, Tsai CT, Tseng YZ, Su MJ, Chiang FT. Reduction of blood pressure elevation by losartan in spontaneously hypertensive rats through suppression of LARG expression in vascular smooth muscle cells. J Formos Med Assoc 2020; 119:164-172. [DOI: 10.1016/j.jfma.2019.03.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/22/2018] [Accepted: 03/21/2019] [Indexed: 10/27/2022] Open
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Chiang JY, Lee SH, Chen YC, Wu CK, Chuang JY, Lo SC, Yeh HM, Yeh SFS, Hsu CA, Lin BB, Chang PC, Chang CH, Liang HJ, Chiang FT, Lin CY, Juang JMJ. Metabolomic Analysis of Platelets of Patients With Aspirin Non-Response. Front Pharmacol 2019; 10:1107. [PMID: 31680941 PMCID: PMC6797853 DOI: 10.3389/fphar.2019.01107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 08/28/2019] [Indexed: 12/20/2022] Open
Abstract
Background: Aspirin is the most commonly used antiplatelet agent for the prevention of cardiovascular diseases. However, a certain proportion of patients do not respond to aspirin therapy. The mechanisms of aspirin non-response remain unknown. The unique metabolomes in platelets of patients with coronary artery disease (CAD) with aspirin non-response may be one of the causes of aspirin resistance. Materials and Methods: We enrolled 29 patients with CAD who were aspirin non-responders, defined as a study subject who were taking aspirin with a platelet aggregation time less than 193 s by PFA-100, and 31 age- and sex-matched patients with CAD who were responders. All subjects had been taking 100 mg of aspirin per day for more than 1 month. Hydrophilic metabolites from the platelet samples were extracted and analyzed by nuclear magnetic resonance (NMR). Both 1D 1H and 2D J-resolved NMR spectra were obtained followed by spectral processing and multivariate statistical analysis, such as partial least squares discriminant analysis (PLS-DA). Results: Eleven metabolites were identified. The PLS-DA model could not distinguish aspirin non-responders from responders. Those with low serum glycine level had significantly shorter platelet aggregation time (mean, 175.0 s) compared with those with high serum glycine level (259.5 s). However, this association became non-significant after correction for multiple tests. Conclusions: The hydrophilic metabolic profile of platelets was not different between aspirin non-responders and responders. An association between lower glycine levels and higher platelet activity in patients younger than 65 years suggests an important role of glycine in the pathophysiology of aspirin non-response.
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Affiliation(s)
- Jiun-Yang Chiang
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Sheng-Han Lee
- Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Yen-Ching Chen
- College of Public Health, Institute of Epidemiology and Preventive Medicine, National Taiwan University, Taipei, Taiwan
| | - Cho-Kai Wu
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Jing-Yuan Chuang
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, Taiwan
| | - Shyh-Chyi Lo
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Huei-Ming Yeh
- Department of Anesthesiology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shih-Fan Sherri Yeh
- Department of Environmental and Occupational Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Cheng-An Hsu
- Division of Haematology, Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Bin-Bin Lin
- Division of Haematology, Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Pi-Chu Chang
- Division of Haematology, Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chih-Hsin Chang
- Division of Haematology, Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Hao-Jan Liang
- Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Fu-Tien Chiang
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.,Cardiovascular Center, Fu-Jen Catholic University Hospital, New Taipei, Taiwan
| | - Ching-Yu Lin
- Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Jyh-Ming Jimmy Juang
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
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Chiang JY, Fu CM, Lin YC, Ku BW, Hsu SU, Wu CK, Lin LY, Lin JL, Chiang FT, Juang JM. P1880Entropy-based algorithm for atrial fibrillation detection using photoplethysomgraphic signal recorded by a smart watch. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz748.0628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Atrial fibrillation (AF) is the most common arrhythmia, and its paroxysmal and short duration nature makes its detection challenging. The most important limitation of current smartwatches is that patients need to touch to the sensor of the watch to record signals when patients feel discomfort. We developed a wearable smart watch and evaluated its accuracy to differentiate AF from sinus rhythm, which can continuously detecting heart rhythm without hand touching the device.
Methods and results
A wearable smart watch with PPG sensor and electrocardiogram (ECG) recording function was used for signal acquisition. A total 399 patients with a mean age of 67 years old were enrolled in the study, of whom 237 (81.5%) were male, and 101 have been diagnosed with AF. Pulse wave extracted from the green light spectrum of the signal and ECG were recorded for about 10 minutes for each patient. Pulse-to-pulse intervals (PPI) were automatically identified. All ECG signals were verified by two cardiologists. The correlation between R-to-R interval on ECG and PPI were excellent, with a correlation coefficient R >0.99 (p<0.05). An entropy-based algorithm which combined Shannon entropy of successive difference of PPI and sample entropy of PPI was used to discriminate between AF and sinus rhythm. This method had high sensitivity and specificity (96% and 98%, respectively), the area under receiver operating characteristic curve reached 0.98.
Conclusions
We developed an entropy-based algorithm for AF detection with PPG signal recorded by a wearable smart watch. This algorithm discriminates AF from sinus rhythm accurately. This advance in technology overcomes an important clinical obstacle and can increase the AF detection rate tremendously.
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Affiliation(s)
- J Y Chiang
- National Taiwan University Hospital, Internal medicine, Taipei, Taiwan
| | - C M Fu
- MediaTek Inc, Taipei, Taiwan
| | - Y C Lin
- MediaTek Inc, Taipei, Taiwan
| | - B W Ku
- MediaTek Inc, Taipei, Taiwan
| | - S U Hsu
- MediaTek Inc, Taipei, Taiwan
| | - C K Wu
- MediaTek Inc, Taipei, Taiwan
| | - L Y Lin
- National Taiwan University Hospital, Division of Cardiology, Department of Internal Medicine, Taipei, Taiwan
| | - J L Lin
- National Taiwan University Hospital, Division of Cardiology, Department of Internal Medicine, Taipei, Taiwan
| | - F T Chiang
- National Taiwan University Hospital, Division of Cardiology, Department of Internal Medicine, Taipei, Taiwan
| | - J M Juang
- National Taiwan University Hospital, Division of Cardiology, Department of Internal Medicine, Taipei, Taiwan
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11
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Wu CK, Yeh CF, Chiang JY, Lin TT, Wu YF, Chiang CK, Kao TW, Hung KY, Huang JW. Effects of atorvastatin treatment on left ventricular diastolic function in peritoneal dialysis patients—The ALEVENT clinical trial. J Clin Lipidol 2017; 11:657-666. [DOI: 10.1016/j.jacl.2017.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/12/2017] [Accepted: 02/28/2017] [Indexed: 12/31/2022]
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Chiu HC, Ma HP, Lin C, Lo MT, Lin LY, Wu CK, Chiang JY, Lee JK, Hung CS, Wang TD, Daisy Liu LY, Ho YL, Lin YH, Peng CK. Serial heart rhythm complexity changes in patients with anterior wall ST segment elevation myocardial infarction. Sci Rep 2017; 7:43507. [PMID: 28252107 PMCID: PMC5333143 DOI: 10.1038/srep43507] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 01/27/2017] [Indexed: 12/19/2022] Open
Abstract
Heart rhythm complexity analysis has been shown to have good prognostic power in patients with cardiovascular disease. The aim of this study was to analyze serial changes in heart rhythm complexity from the acute to chronic phase of acute myocardial infarction (MI). We prospectively enrolled 27 patients with anterior wall ST segment elevation myocardial infarction (STEMI) and 42 control subjects. In detrended fluctuation analysis (DFA), the patients had significantly lower DFAα2 in the acute stage (within 72 hours) and lower DFAα1 at 3 months and 12 months after MI. In multiscale entropy (MSE) analysis, the patients had a lower slope 5 in the acute stage, which then gradually increased during the follow-up period. The areas under the MSE curves for scale 1 to 5 (area 1–5) and 6 to 20 (area 6–20) were lower throughout the chronic stage. Area 6–20 had the greatest discriminatory power to differentiate the post-MI patients (at 1 year) from the controls. In both the net reclassification improvement and integrated discrimination improvement models, MSE parameters significantly improved the discriminatory power of the linear parameters to differentiate the post-MI patients from the controls. In conclusion, the patients with STEMI had serial changes in cardiac complexity.
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Affiliation(s)
- Hung-Chih Chiu
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Hsi-Pin Ma
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Chen Lin
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan
| | - Men-Tzung Lo
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan
| | - Lian-Yu Lin
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Cho-Kai Wu
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Jiun-Yang Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Jen-Kuang Lee
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Chi-Sheng Hung
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tzung-Dau Wang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Li-Yu Daisy Liu
- Department of Agronomy, Biometry Division, National Taiwan University, Taipei, Taiwan
| | - Yi-Lwun Ho
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yen-Hung Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.,Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
| | - Chung-Kang Peng
- Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
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Chiang JY, Huang JW, Lin LY, Chang CH, Chu FY, Lin YH, Wu CK, Lee JK, Hwang JJ, Lin JL, Chiang FT. Detrended Fluctuation Analysis of Heart Rate Dynamics Is an Important Prognostic Factor in Patients with End-Stage Renal Disease Receiving Peritoneal Dialysis. PLoS One 2016; 11:e0147282. [PMID: 26828209 PMCID: PMC4734614 DOI: 10.1371/journal.pone.0147282] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 01/02/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Patients with severe kidney function impairment often have autonomic dysfunction, which could be evaluated noninvasively by heart rate variability (HRV) analysis. Nonlinear HRV parameters such as detrended fluctuation analysis (DFA) has been demonstrated to be an important outcome predictor in patients with cardiovascular diseases. Whether cardiac autonomic dysfunction measured by DFA is also a useful prognostic factor in patients with end-stage renal disease (ESRD) receiving peritoneal dialysis (PD) remains unclear. The purpose of the present study was designed to test the hypothesis. MATERIALS AND METHODS Patients with ESRD receiving PD were included for the study. Twenty-four hour Holter monitor was obtained from each patient together with other important traditional prognostic makers such as underlying diseases, left ventricular ejection fraction (LVEF) and serum biochemistry profiles. Short-term (DFAα1) and long-term (DFAα2) DFA as well as other linear HRV parameters were calculated. RESULTS A total of 132 patients (62 men, 72 women) with a mean age of 53.7±12.5 years were recruited from July 2007 to March 2009. During a median follow-up period of around 34 months, eight cardiac and six non-cardiac deaths were observed. Competing risk analysis demonstrated that decreased DFAα1 was a strong prognostic predictor for increased cardiac and total mortality. ROC analysis showed that the AUC of DFAα1 (<0.95) to predict mortality was 0.761 (95% confidence interval (CI). = 0.617-0.905). DFAα1≧ 0.95 was associated with lower cardiac mortality (Hazard ratio (HR) 0.062, 95% CI = 0.007-0.571, P = 0.014) and total mortality (HR = 0.109, 95% CI = 0.033-0.362, P = 0.0003). CONCLUSION Cardiac autonomic dysfunction evaluated by DFAα1 is an independent predictor for cardiac and total mortality in patients with ESRD receiving PD.
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Affiliation(s)
- Jiun-Yang Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Jenq-Wen Huang
- Division of Nephrology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Lian-Yu Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Chin-Hao Chang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Fang-Ying Chu
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Yen-Hung Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Cho-Kai Wu
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Jen-Kuang Lee
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Juei-Jen Hwang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Jiunn-Lee Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Fu-Tien Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
- * E-mail:
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14
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Lin TT, Chiang JY, Liao MT, Tsai CT, Hwang JJ, Chiang FT, Lin JL, Lin LY. Primary prevention of atrial fibrillation with beta-blockers in patients with end-stage renal disease undergoing dialysis. Sci Rep 2015; 5:17731. [PMID: 26643783 PMCID: PMC4672347 DOI: 10.1038/srep17731] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 11/05/2015] [Indexed: 01/19/2023] Open
Abstract
Current evidence suggests that beta-blocker lower the risk of development of atrial fibrillation (AF) and in-hospital stroke after cardiac surgery. This study was to assess whether beta-blockers could decrease incidence of new-onset AF in patients with end stage renal disease (ESRD). We identified patients from a nation-wide database called Registry for Catastrophic Illness, which encompassed almost 100% of the patients receiving dialysis therapy in Taiwan from 1995 to 2008. Propensity score matching and Cox’s proportional hazards regression model were used to estimate hazard ratios (HRs) for new-onset AF. Among 100066 patients, 41.7% received beta-blockers. After a median follow-up of 1500 days, the incidence of new-onset AF significantly decreased in patients treated with beta-blockers (HR = 0.483, 95% confidence interval = 0.437-0.534). The prevention of new-onset AF was significantly better in patients taking longer duration of beta-blockers therapy (P for time trend <0.001). The AF prevention effect remains robust in subgroup analyses. In conclusion, beta-blockers seem effective in the primary prevention of AF in ESRD patients. Hence, beta-blockers may be the target about upstream treatment of AF.
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Affiliation(s)
- Ting-Tse Lin
- Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Jiun-Yang Chiang
- Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Min-Tsun Liao
- Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Chia-Ti Tsai
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Juey Jen Hwang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Fu-Tien Chiang
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan.,Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jiunn-Lee Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Lian-Yu Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
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15
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Chiang JY, Huang CC, Chen YH, Lin MS, Kao PHL. TCTAP C-005 An Winding Road Toward Revascularization. J Am Coll Cardiol 2015. [DOI: 10.1016/j.jacc.2015.03.274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Chung WS, Chen YF, Hsu JC, Yang WT, Chen SC, Chiang JY. Inhaled corticosteroids and the increased risk of pulmonary tuberculosis: a population-based case-control study. Int J Clin Pract 2014; 68:1193-9. [PMID: 24838040 DOI: 10.1111/ijcp.12459] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
AIMS The association between inhaled corticosteroid (ICS) use and pulmonary tuberculosis (TB) development is uncertain. We conducted a population-based case-control study to investigate whether ICS use increases the risk of developing TB. METHODS Tuberculosis patients aged 18 years and older were identified using the National Health Insurance Research Database (NHIRD) in Taiwan between 2002 and 2010. Each TB patient was frequency matched to four control patients according to age, sex and index year. We retrospectively followed up the medications and comorbid medical conditions for the 5 years prior to the index date. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) of TB development using multiple logistic regression models. RESULTS Most of the study participants were men (68.7%), and the mean age among the 8091 TB patients and 32,364 comparison participants was 61.3 ± 18.6 years. After adjusting for potential covariates, ICS use caused a 2.04-fold increased risk of developing TB (adjusted OR: 2.04, 95% CI: 1.78-2.33). When considering dose-response and adjusting for potential covariates, ICS and oral corticosteroids (OCS) use remained independent risk factors and exhibited a dose-response relationship of TB development. The multiplicative increased risk of TB was also significant in patients using ICS and OCS compared with patients not using ICS and OCS (adjusted OR: 4.31, 95% CI: 3.39-5.49). Previous TB history exhibited the greatest risk of TB development among the comorbidities (adjusted OR: 8.50, 95% CI: 7.52-9.61). CONCLUSION Long-term ICS use may increase the risk of TB.
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Affiliation(s)
- W-S Chung
- Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; Department of Healthcare Administration, Central Taiwan University of Science and Technology, Taichung, Taiwan
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17
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Chiang JY, Kao HL. TCTAP C-181 A Novel Technique for Percutaneous Transluminal Angioplasty to Subclavian Artery Occlusion. J Am Coll Cardiol 2014. [DOI: 10.1016/j.jacc.2014.02.457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Zhang M, Chiang JY. Transcriptional regulation of the human sterol 12alpha-hydroxylase gene (CYP8B1): roles of heaptocyte nuclear factor 4alpha in mediating bile acid repression. J Biol Chem 2001; 276:41690-9. [PMID: 11535594 DOI: 10.1074/jbc.m105117200] [Citation(s) in RCA: 180] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sterol 12alpha-hydroxylase catalyzes the synthesis of cholic acid and controls the ratio of cholic acid over chenodeoxycholic acid in the bile. Transcription of CYP8B1 is inhibited by bile acids, cholesterol, and insulin. To study the mechanism of CYP8B1 transcription by bile acids, we have cloned and determined 3389 base pairs of the 5'-upstream nucleotide sequences of the human CYP8B1. Deletion analysis of CYP8B1/luciferase reporter activity in HepG2 cells revealed that the sequences from -57 to +300 were important for basal and liver-specific promoter activities. Hepatocyte nuclear factor 4alpha (HNF4alpha) strongly activated human CYP8B1 promoter activities, whereas cholesterol 7alpha-hydroxylase promoter factor (CPF), an NR5A2 family of nuclear receptors, had much less effect. Electrophoretic mobility shift assay identified an overlapping HNF4alpha- and CPF-binding site in the +198/+227 region. The human CYP8B1 promoter activities were strongly repressed by bile acids, and the bile acid response element was localized between +137 and +220. Site-directed mutagenesis of the HNF4alpha-binding site markedly reduced promoter activity and its response to bile acid repression. On the other hand, mutation of the CPF-binding site had little effect on promoter activity and bile acid inhibition. A negative nuclear receptor, small heterodimer partner markedly inhibited transactivation of CYP8B1 by HNF4alpha. Mammalian two-hybrid assay confirmed that HNF4alpha interacted with small heterodimer partner. Furthermore, bile acids and farnesoid X receptor reduced the expression of nuclear HNF4alpha in HepG2 cells and rat livers and its binding to DNA. Bile acids and farnesoid X receptor also inhibited mouse HNF4alpha gene transcription. In summary, our data revealed the critical roles HNF4alpha play on CYP8B1 transcription and its repression by bile acids. Bile acids repress human CYP8B1 transcription by reducing the transactivation activity of HNF4alpha through interaction of HNF4alpha with SHP and reduction of HNF4alpha expression in the liver.
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Affiliation(s)
- M Zhang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown, Ohio 44272, USA
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19
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Chen W, Owsley E, Yang Y, Stroup D, Chiang JY. Nuclear receptor-mediated repression of human cholesterol 7alpha-hydroxylase gene transcription by bile acids. J Lipid Res 2001; 42:1402-12. [PMID: 11518759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Hydrophobic bile acids strongly repressed transcription of the human cholesterol 7alpha-hydroxylase gene (CYP7A1) in the bile acid biosynthetic pathway in the liver. Farnesoid X receptor (FXR) repressed CYP7A1/Luc reporter activity in a transfection assay in human liver-derived HepG2 cells, but not in human embryonic kidney (HEK) 293 cells. FXR-binding activity was required for bile acid repression of CYP7A1 transcription despite the fact that FXR did not bind to the CYP7A1 promoter. FXR-induced liver-specific factors must be required for mediating bile acid repression. Bile acids and FXR repressed endogenous CYP7A1 but stimulated alpha-fetoprotein transcription factor (FTF) and small heterodimer partner (SHP) mRNA expression in HepG2 cells. Feeding of rats with chenodeoxycholic acid repressed CYP7A1, induced FTF, but had no effect on SHP mRNA expression in the liver. FTF strongly repressed CYP7A1 transcription in a dose-dependent manner, and SHP further inhibited CYP7A1 in HepG2 cells, but not in HEK 293 cells. FXR only moderately stimulated SHP transcription, whereas FTF strongly inhibited SHP transcription in HepG2 cells. Results revealed that FTF was a dominant negative factor that was induced by bile acid-activated FXR to inhibit both CYP7A1 and SHP transcription. Differential regulation of FTF and SHP expression by bile acids may explain the wide variation in CYP7A1 expression and the rate of bile acid synthesis and regulation in different species.
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Affiliation(s)
- W Chen
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA
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20
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Abstract
Oxysterol 7 alpha-hydroxylase catalyzes hydroxylation of oxysterols and neurosterols and plays a role in the alternative bile acid synthesis pathway. This gene is widely expressed in many organs and peripheral tissues and may protect tissues from the toxicity of oxysterols. Mutation in CYP7B1 caused neonatal cholestasis. To examine the regulatory mechanisms governing CYP7B1 expression, the 5' flanking sequence of the CYP7B1 was analyzed and revealed a CpG island of about 1.2 kb. Transient transfection assays of deletion mutants of the CYP7B1 promoter-luciferase reporter gene in human liver-derived HepG2, fibroblast NT1088, and human embryonic kidney 293 cell lines revealed that the region from -291 to +189 was critical for gene transcription. Three GC box sequences located between -25 and +10 were essential for basal transcription because mutations of these sequences markedly reduced promoter activity. Sp1 and Sp3 bound to these sequences as demonstrated by DNase I footprinting assays and electrophoretic mobility shift assay. Thus, regulation of CYP7B1 transcription by Sp1 may play a pivotal role in regulating oxysterol levels, which regulate cholesterol metabolism.
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Affiliation(s)
- Z Wu
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P.O. Box 95, Rootstown, OH 44272, USA
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21
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Abstract
The cholesterol 7alpha-hydroxylase gene (CYP7A1) plays an important role in regulation of bile acid biosynthesis and cholesterol homeostasis. Oxysterol receptor, LXR, stimulates, whereas the bile acid receptor, FXR, inhibits CYP7A1 transcription. The goal of this study was to investigate the role of LXRalpha on the regulation of rat, human and hamster CYP7A1 transcription in its native promoter and cellular context. Cotransfection with LXRalpha and RXRalpha expression plasmids strongly stimulated rat CYP7A1/luciferase reporter activity in HepG2 cells and oxysterol was not required. However, LXRalpha had much less effect on hamster and no significant effect on human CYP7A1 promoter activity in HepG2 cells. In Chinese hamster ovary cells, cotransfection with LXRalpha stimulated reporter activity by less than 2-fold and addition of 22(R)-hydroxycholesterol caused a small but significant stimulation of rat, human and hamster CYP7A1 promoter activity. At least two direct repeats of AGGTCA-like sequences with 4-base spacing (DR4) and five-base spacing (DR5), in previously identified bile acid response elements of the rat CYP7A1 were able to bind LXRalpha/RXRalpha and confer LXRalpha stimulation. However, LXRalpha did not bind to the corresponding sequences of the human gene and bound weakly to hamster and mouse DR4 sequences. Therefore, rats and mice have the unusual capacity to convert cholesterol to bile acids by LXRalpha-mediated stimulation of CYP7A1 transcription, whereas other species do not respond to cholesterol and develop hypercholesterolemia on a diet high in cholesterol.
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Affiliation(s)
- J Y Chiang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P.O. Box 95, Rootstown, OH 44272, USA.
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22
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Chiang JY, Kimmel R, Weinberger C, Stroup D. Farnesoid X receptor responds to bile acids and represses cholesterol 7alpha-hydroxylase gene (CYP7A1) transcription. J Biol Chem 2000; 275:10918-24. [PMID: 10753890 DOI: 10.1074/jbc.275.15.10918] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Cholesterol 7alpha-hydroxylase gene (CYP7A1) transcription is repressed by bile acids. The goal of this study is to elucidate the mechanism of CYP7A1 transcription by bile acid-activated farnesoid X receptor (FXR) in its native promoter and cellular context and to identify FXR response elements in the gene. In Chinese hamster ovary cells transfected with retinoid X receptor alpha (RXRalpha)/FXR, only chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) were able to stimulate a heterologous promoter/reporter containing an ecdysone response element. In HepG2 cells, all bile acids (25 microM) were able to repress CYP7A1/luciferase reporter activity, and only CDCA and DCA further repressed reporter activity when cotransfected with RXRalpha/FXR. The concentration of CDCA required to inhibit 50% of reporter activity (IC(50)) was determined to be approximately 25 microM without FXR and 10 microM with FXR. Deletion analysis revealed that the bile acid response element located between nucleotides -148 and -128 was the FXR response element, but RXRalpha/FXR did not bind to this sequence. These results suggest that bile acid-activated FXR exerts its inhibitory effect on CYP7A1 transcription by an indirect mechanism, in contrast to the stimulation and binding of FXR to intestinal bile acid-binding protein gene promoter. Results also reveal that bile acid receptors other than FXR are present in HepG2 cells.
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Affiliation(s)
- J Y Chiang
- Department of Biochemistry, Northeastern Ohio Universities College of Medicine, Rootstown, Ohio 44272, USA.
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Marrapodi M, Chiang JY. Peroxisome proliferator-activated receptor alpha (PPARalpha) and agonist inhibit cholesterol 7alpha-hydroxylase gene (CYP7A1) transcription. J Lipid Res 2000; 41:514-20. [PMID: 10744771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Fibrates are widely used hypolipidemic drugs that regulate the expression of many genes involved in lipid metabolism by activating the peroxisome proliferator-activated receptor alpha (PPARalpha). The objective of this study was to investigate the mechanism of action of peroxisome proliferators and PPARalpha on the transcription of cholesterol 7alpha-hydroxylase, the rate-limiting enzyme in the conversion of cholesterol to bile acids in the liver. When cotransfected with the expression vectors for PPARalpha and RXRalpha, Wy14,643 reduced human and rat cholesterol 7alpha-hydroxylase gene (CYP7A1)/luciferase reporter activities by 88% and 43%, respectively, in HepG2 cells, but not in CV-1 or CHO cells. We have mapped the peroxisome proliferator response element (PPRE) to a conserved sequence containing the canonical AGGTCA direct repeats separated by one nucleotide (DR1). This DR1 sequence was mapped previously as a binding site for the hepatocyte nuclear factor 4 (HNF-4) which stimulates CYP7A1 transcription. Electrophoretic mobility shift assay (EMSA) showed no direct binding of in vitro synthesized PPARalpha/RXRalpha heterodimer to the DR1 sequence. PPARalpha and Wy14,643 did not affect HNF-4 binding to the DR1. However, Wy14,643 and PPARalpha/RXRalpha significantly reduced HNF-4 expression in HepG2 cells. These results suggest that PPARalpha and agonist repress cholesterol 7alpha-hydroxylase activity by reducing the availability of HNF-4 for binding to the DR-1 sequence and therefore attenuates the transactivation of CYP7A1 by HNF-4.
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Affiliation(s)
- M Marrapodi
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P.O. Box 95, Rootstown, OH 44272-0095, USA
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Stroup D, Chiang JY. HNF4 and COUP-TFII interact to modulate transcription of the cholesterol 7alpha-hydroxylase gene (CYP7A1). J Lipid Res 2000; 41:1-11. [PMID: 10627496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
The gene for cholesterol 7alpha-hydroxylase (CYP7A1) contains a sequence at nt -149 to -118 that was found to play a large role in determining the overall transcriptional activity and regulation of the promoter. Hepatocyte nuclear factor 4 (HNF4) and chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) synergistically activate transcription of the CYP7A1 promoter. Transactivation of CYP7A1 by HNF4 in the human hepatoma cell line, HepG2, was enhanced by cotransfection with COUP-TFII or the basal transcription element binding protein (BTEB). HNF4 prepared from rat liver nuclear extracts bound to oligomers homologous to the nt -146 to -134 sequences in electrophoretic mobility shift assays (EMSA), which corresponded to a conserved region containing a direct repeat of hormone response elements spaced by one nucleotide (DR1). The sequences surrounding this DR1 were found to be essential for the HNF4 transactivation. In vitro-translated COUP-TFII was found to bind the adjacent sequences from nt -139 to -128 (DR0), but COUP-TFII interacted with this region at a much lower affinity than to the COUP-TFII-site at nt -72 to -57 (DR4). Mutations at nt -139 to -128 or nt -72 to -57 reduced the COUP-TFII and HNF4 synergy; however, these COUP-TFII-binding sequences were not absolutely required for the cooperative effect of HNF4 and COUP-TFII on transactivation. These results indicated that the observed transactivation was the result of protein/protein interactions facilitated by the juxtaposition of the binding elements.
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Affiliation(s)
- D Stroup
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P. O. Box 95, Rootstown, OH 44272-0095, USA
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Wu Z, Martin KO, Javitt NB, Chiang JY. Structure and functions of human oxysterol 7alpha-hydroxylase cDNAs and gene CYP7B1. J Lipid Res 1999; 40:2195-203. [PMID: 10588945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Oxysterol 7alpha-hydroxylase has broad substrate specificity for sterol metabolites and may be involved in many metabolic processes including bile acid synthesis and neurosteroid metabolism. The cloned human oxysterol 7alpha-hydroxylase (CYP7B1) cDNA encodes a polypeptide of 506 amino acid residues that shares 40% sequence identity to human cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids in the liver. In contrast to the liver-specific expression of CYP7A1, CYP7B1 mRNA transcripts were detected in human tissues involved in steroid genesis (brain, testes, ovary, and prostate) and in bile acid synthesis (liver) and reabsorption (colon, kidney, and small intestine). The human oxysterol 7alpha-hydroxylase transiently expressed in 293/T cells was able to catalyze 7alpha-hydroxylation of 27-hydroxycholesterol and dehydroepiandrosterone (DHEA). The human CYP7A1 and CYP7B1 both contain six exons and five introns. However, CYP7B1 spans at least 65 kb of the genome and is about 6-fold longer than CYP7A1. The transcription start site (+1) was localized 204 bp upstream of the initiation codon. No TATA box-like sequence was found near the transcription start site. Transient transfection assays of CYP7B1 promoter/luciferase reporter constructs in HepG2 cells revealed that the promoter was highly active. The 5' upstream region from nt -83 to +189 is the core promoter of the gene.
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Affiliation(s)
- Z Wu
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P. O. Box 95, Rootstown, OH 44272, USA
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Foti D, Stroup D, Chiang JY. Basic transcription element binding protein (BTEB) transactivates the cholesterol 7 alpha-hydroxylase gene (CYP7A). Biochem Biophys Res Commun 1998; 253:109-13. [PMID: 9875228 DOI: 10.1006/bbrc.1998.9759] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholesterol 7 alpha-hydroxylase catalyzes the first and rate-limiting step in the conversion of cholesterol to bile acids in the liver. Previously, we have identified two bile acid response elements located in nt -74 to -54 (BARE-I) and -148 to -118 (BARE-II) regions. The nucleotide sequences in these BAREs are highly conserved and shared a novel sequence, AGTTCAAG. To identify and isolate nuclear protein factors that bind to these BAREs, we have screened a human liver cDNA expression library with oligonucleotide probes containing the sequence from nt -149 to -127. Twenty positive clones were selected and purified. Partial nucleotide sequences of these clones were determined. Nucleotide homology search of DNA databases of the sequences of these clones revealed that sequence of one clone, G13, is identical to basic transcription element binding protein (BTEB), a GC box-binding protein of Sp1 family transcription factors known to regulate many cytochrome P450 genes. Electrophoretic mobility shift assays have identified a basic transcription element (BTE) in BARE-II and a Sp1 binding site located in the nt -100/-82 region of the CYP7A promoter. Transient transfection assays have confirmed that BTEB was able to transactivate the CYP7A promoter/luciferase chimergic gene.
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Affiliation(s)
- D Foti
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272, USA
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Crestani M, Sadeghpour A, Stroup D, Galli G, Chiang JY. Transcriptional activation of the cholesterol 7alpha-hydroxylase gene (CYP7A) by nuclear hormone receptors. J Lipid Res 1998; 39:2192-200. [PMID: 9799805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
The gene encoding cholesterol 7alpha-hydroxylase (CYP7A), the rate-limiting enzyme in bile acid synthesis, is transcriptionally regulated by bile acids and hormones. Previously, we have identified two bile acid response elements (BARE) in the promoter of the CYP7A gene. The BARE II is located in nt -149/-118 region and contains three hormone response element (HRE)-like sequences that form two overlapping nuclear receptor binding sites. One is a direct repeat separated by one nucleotide DR1 (-146- TGGACTtAGTTCA-134) and the other is a direct repeat separated by five nucleotides DR5 (-139-AGTTCAaggccGGG TAA-123). Mutagenesis of these HRE sequences resulted in lower transcriptional activity of the CYP7A promoter/reporter genes in transient transfection assay in HepG2 cells. The orphan nuclear receptor, hepatocyte nuclear factor 4 (HNF-4)1, binds to the DR1 sequence as assessed by electrophoretic mobility shift assay, and activates the CYP7A promoter/reporter activity by about 9-fold. Cotransfection of HNF-4 plasmid with another orphan nuclear receptor, chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII), synergistically activated the CYP7A transcription by 80-fold. The DR5 binds the RXR/RAR heterodimer. A hepatocyte nuclear factor-3 (HNF-3) binding site (-175-TGTTTGTTCT-166) was identified. HNF-3 was required for both basal transcriptional activity and stimulation of the rat CYP7A promoter activity by retinoic acid. Combinatorial interactions and binding of these transcription factors to BAREs may modulate the promoter activity and also mediate bile acid repression of CYP7A gene transcription.
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Affiliation(s)
- M Crestani
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, PO Box 95, Rootstown Ohio 44272-0095, USA
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Abstract
Bile acids are important physiological agents required for disposal of cholesterol and absorption of vitamins and fats. Bile acids are synthesized from cholesterol in the liver. Enterohepatic circulation of bile acids is very efficient and plays an important physiological role in lipid absorption and secretion, and regulation of bile acid biosynthesis and cholesterol homeostasis. Conversion of cholesterol to bile acids requires 15 different enzymatic steps. Four cytochrome P450 enzymes play important roles in bile acid biosynthesis. The classic bile acid biosynthesis pathway starts with modification of the sterol ring and followed by side chain cleavage reactions to synthesize cholic acid (CA) and chenodeoxycholic acid (CDCA), the primary bile acids in most species. The first and rate-limiting enzyme in this pathway is cholesterol 7alpha -hydroxylase, a microsomal cytochrome P450, CYP7A. Another microsomal cytochrome P450 sterol 12alpha-hydroxylase (CYP12) is required for the synthesis of cholic acid. Mitochondrial cytochrome P450 sterol 27-hydroxylase (CYP27) catalyzes sterol side chain oxidation to convert C27 sterol to C24 bile acids. An alternative bile acid biosynthesis pathway (acidic) has been known for sometime but only recently has attracted much attention. In this pathway, side chain oxidation precedes modification of the sterol ring. Mitochondrial sterol 27-hydroxylase (CYP27) catalyzes the first reaction and followed by 7alpha-hydroxylation catalyzed by a microsomal oxysterol 7alpha-hydroxylase (CYP7B). Recent advances in purification and cloning of these major enzymes in the pathways have led to better understanding the molecular basis of regulation of bile acid synthesis and physiological role of the alternative pathways.
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Affiliation(s)
- J Y Chiang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, P. O. Box 95, Rootstown, OH 44272, USA
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Pandak WM, Heuman DM, Redford K, Stravitz RT, Chiang JY, Hylemon PB, Vlahcevic ZR. Hormonal regulation of cholesterol 7alpha-hydroxylase specific activity, mRNA levels, and transcriptional activity in vivo in the rat. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)30033-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Pandak WM, Heuman DM, Redford K, Stravitz RT, Chiang JY, Hylemon PB, Vlahcevic ZR. Hormonal regulation of cholesterol 7alpha-hydroxylase specific activity, mRNA levels, and transcriptional activity in vivo in the rat. J Lipid Res 1997; 38:2483-91. [PMID: 9458272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In primary cultures of rat hepatocytes, transcription of the cholesterol 7alpha-hydroxylase gene is induced synergistically by glucocorticoid and thyroid hormones. The objective of the present study was to evaluate the role of endogenous glucocorticoid and thyroid hormones in the maintenance of cholesterol 7alpha-hydroxylase gene expression in vivo. Male Sprague-Dawley rats underwent adrenalectomy (A), thyroidectomy (T), adrenalectomy + thyroidectomy (A + T), hypophysectomy (H), or sham surgery (paired controls). Ten days post surgery, livers were harvested and choles terol 7alpha-hydroxylase specific activity, steady-state mRNA levels, and transcriptional activity were determined. Serum corticosterone levels were <2% of paired controls in A, A + T, and H rats. Free thyroxine index was <32% of paired controls in rats with T and H. When compared to sham-operated controls, A + T and H led to decreases in cholesterol 7alpha-hydroxylase specific activities of 44 +/- 8% and 57 +/- 3%, respectively (P < 0.03 and < 0.05). Similar changes were observed in cholesterol 7alpha-hydroxylase steady-state mRNA levels, which decreased by 43 +/- 10% (P < 0.001) and 56 +/- 19% (P < 0.05), respectively. Cholesterol 7alpha-hydroxylase transcriptional activity in A + T and H rats decreased by 34 +/- 11% (P < 0.01) and 61 +/- 4% (P < 0.001), respectively. The observed decreases were greater after H than after A + T, suggesting the possibility that another pituitary hormone plays a role in regulation of cholesterol 7alpha-hydroxylase. Thyroidectomy alone led to a decrease in cholesterol 7alpha-hydroxylase specific activity of 37 +/- 7% (P < 0.05) and a trend toward decreased steady-state mRNA levels (21 +/- 12%; P = ns). Adrenalectomy did not significantly decrease cholesterol 7alpha-hydroxylase specific activity or mRNA levels. Neither thyroidectomy nor adrenalectomy alone affected transcriptional activity. We conclude that under physiologic circumstances, full expression of the cholesterol 7alpha-hydroxylase gene requires synergistic action of glucocorticoids and thyroid hormone.
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Affiliation(s)
- W M Pandak
- Department of Medicine, Veterans Affairs Medical Center and Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA
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Abstract
The transcriptional activity of the cholesterol 7 alpha-hydroxylase gene CYP7A is repressed by bile acids. Taurine conjugates of chenodeoxycholate and deoxycholate, but not cholate and ursodeoxycholate, inhibited the CYP7A promoter/luciferase reporter activity in transient transfection assays in Hep G2 cells. A region from nucleotide (nt) -74 to -55 was found to mediate bile acid response. However, deletion of this bile acid response element (BARE-I) enhanced reporter activity but did not eliminate the bile acid response. This is due to the presence of another BARE-II located in a conserved region between nt -149 and -128. Deletion or mutations of these sequences reduced promoter activity and abolished bile acid repression. This BARE-II shares an identical AGTTCAAG core sequence with BARE-I. Electrophoretic mobility shift assays of BARE-I and BARE-II probes using Hep G2 nuclear extract and the partially purified binding activity of nt -65/-54 DNA-affinity column revealed that the same or a similar nuclear protein might bind to both BAREs. BARE-II is the major BARE involved in the transcriptional repression of the CYP7A gene by hydrophobic bile acids.
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Affiliation(s)
- D Stroup
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272-0095, USA
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Stroup D, Crestani M, Chiang JY. Orphan receptors chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) and retinoid X receptor (RXR) activate and bind the rat cholesterol 7alpha-hydroxylase gene (CYP7A). J Biol Chem 1997; 272:9833-9. [PMID: 9092518 DOI: 10.1074/jbc.272.15.9833] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The cholesterol 7alpha-hydroxylase gene (CYP7A) is transcriptionally regulated by a number of factors, including hormones, bile acids, and diurnal rhythm. Previous studies have identified a region from nucleotides (nt) -74 to -55 of the rat CYP7A promoter that enhanced bile acid repression of the SV40 early promoter, as assayed with a luciferase reporter gene in transiently transfected HepG2 cells. The rat CYP7A promoter/reporter activity was strongly stimulated by cotransfection with an expression plasmid encoding the nuclear hormone receptor chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) in a dose-dependent manner. Site-directed mutagenesis in the region of nt -74 to -55 altered this stimulation. Recombinant COUP-TFII expressed in HepG2 or COS-1 cells were found to bind to nt -74 -55 and nt -149 -128 probes by electrophoretic mobility shift assay (EMSA) and by supershifting the corresponding band with COUP-TFII-specific antibodies. The region of nt -176 -117 was previously mapped as a retinoic acid response region and was found to bind retinoid X receptor (RXR). EMSA supershift assays of wild-type and mutant oligomers using antibody against RXR revealed that the sequences between nt -145 and -134 were important for RXR binding. We conclude that COUP-TFII stimulates the transcriptional activity of the rat CYP7A promoter by binding to the sequences between nt -74 to -54 and nt -149 to -128. RXR may stimulate CYP7A gene transcription by binding to a direct repeat of the hormone response element separated by one nucleotide located at nt -146 -134.
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Affiliation(s)
- D Stroup
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown, Ohio 44272-0095, USA
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Nguyen LB, Shefer S, Salen G, Chiang JY, Patel M. Cholesterol 7alpha-hydroxylase activities from human and rat liver are modulated in vitro posttranslationally by phosphorylation/dephosphorylation. Hepatology 1996; 24:1468-74. [PMID: 8938182 DOI: 10.1002/hep.510240628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Purified cholesterol 7alpha-hydroxylases (C7alphaH) from human and rat liver microsomes, and from transformed Escherichia coli expression systems, were incubated with 0.3 mmol/L [gamma-32P] adenosine triphosphate (ATP) in the presence and absence of bacterial alkaline phosphatase (AP) or rabbit muscle adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase. The amounts of 32P incorporation after separation of human and rat C7alphaH proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were related to C7alphaH catalytic activities (determined by a radioisotope incorporation method) and enzyme protein mass (determined by Western blotting and laser densitometry). Both human and rat C7alphaH activities significantly decreased after dephosphorylation by AP (-57% - -72%) and increased up to twofold with phosphorylation by rabbit muscle cAMP-dependent protein kinase. The increases in C7alphaH activities were proportional to the amounts of cAMP-dependent protein kinase used, and were coupled to 32P incorporation into the purified enzymes. Both the activation of C7alphaH and the amounts of 32P incorporation were time-dependent and reached a maximum after 1 hour of incubation with 5 U of cAMP-dependent protein kinase. In a second set of experiments, purified human and rat liver C7alphaH were dephosphorylated by 30-minute incubation with AP, followed by inactivation of the phosphatase by the inhibitor NaF, and rephosphorylation of C7alphaH by 30-minute incubation with rabbit muscle cAMP-dependent protein kinase or bovine heart cAMP-independent protein kinase. Rephosphorylation of the dephosphorylated C7alphaH proteins by cAMP-dependent protein kinase increased C7alphaH catalytic activities up to fourfold, and the stimulation in catalytic activities paralleled the increases in 32P incorporation into the purified enzymes. Bovine heart protein kinase was as potent as rabbit muscle cAMP-dependent protein kinase in stimulating catalytic activity and 32P incorporation into the human C7alphaH protein. Because the protein mass of these purified enzymes did not change, the short-term regulation or catalytic efficiency of C7alphaH (activity per protein mass unit) is modulated, in vitro, posttranslationally by a phosphorylation/dephosphorylation mechanism in both the human and the rat enzymes.
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Affiliation(s)
- L B Nguyen
- Department of Medicine and the Liver Center, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark 07103, USA
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De Fabiani E, Crestani M, Marrapodi M, Pinelli A, Chiang JY, Galli G. Regulation of the hamster cholesterol 7 alpha-hydroxylase gene (CYP7A): prevalence of negative over positive transcriptional control. Biochem Biophys Res Commun 1996; 226:663-71. [PMID: 8831673 DOI: 10.1006/bbrc.1996.1412] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cholesterol 7 alpha-hydroxylase plays a crucial role in cholesterol homeostasis. We investigated the regulation of this enzyme in the hamster, a suitable animal model for studying cholesterol metabolism. DNase I hypersensitivity assay revealed the presence of a hypersensitive region in the proximal promoter. Both negative (bile acids, phorbol esters and insulin) and positive (glucocorticoid hormones) effects were mediated through sequences in the region 318 bp upstream of the ATG codon. All-trans-retinoic acid, cAMP, and LDL did not affect transcriptional activity. These findings show that the hamster cholesterol 7 alpha-hydroxylase gene undergoes a predominant negative regulation, as opposed to the rat CYP7A homologous gene.
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Affiliation(s)
- E De Fabiani
- Istituto di Scienze Farmacologiche, Universit degli Studi di Milano, Italy
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35
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Wang DP, Stroup D, Marrapodi M, Crestani M, Galli G, Chiang JY. Transcriptional regulation of the human cholesterol 7 alpha-hydroxylase gene (CYP7A) in HepG2 cells. J Lipid Res 1996. [DOI: 10.1016/s0022-2275(20)37548-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Wang DP, Stroup D, Marrapodi M, Crestani M, Galli G, Chiang JY. Transcriptional regulation of the human cholesterol 7 alpha-hydroxylase gene (CYP7A) in HepG2 cells. J Lipid Res 1996; 37:1831-41. [PMID: 8895049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A stable HepG2 cell line harboring a human cholesterol 7 alpha-hydroxylase (CYP7A) minigene/luciferase reporter gene construct was selected for studying transcriptional regulation of CYP7A gene promoter. Insulin and phorbol 12-myristate-13-acetate (PMA) strongly repressed the promoter activity as measured with luciferase activity expressed in the cells. The promoter activity of the 5' progressive deletion/luciferase reporter gene constructs was studied in a transient transfection assay in HepG2 cells. PMA represses the promoter activity and the response elements were localized in the -184/-151 and -134/-81 regions. Insulin also represses the promoter activity and response element was mapped in the -298/-81 region. Surprisingly, glucocorticoid receptor (GR) strongly inhibited promoter activity in the presence of dexamethasone, and response elements were localized in the -298/-151 and the -150/+24 regions. Thyroid hormone receptor also repressed promoter activity and response elements were localized in the -150/+24 and upstream regions. Cotransfection of CYP7A chimeric constructs with an expression vector carrying liver-enriched transcription factor HNF3 alpha stimulated the reporter gene activity, but cotransfection with GR plasmid interfered with the HNF3 alpha-stimulated activity possibly through competition for binding to overlapping GR/HNF3 binding sites. Thus, human cholesterol 7 alpha-hydroxylase gene promoter is strongly repressed by insulin, PMA, and steroid/thyroid hormones and results in the low level of cholesterol 7 alpha-hydroxylase expression in the human liver.
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Affiliation(s)
- D P Wang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272, USA
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Crestani M, Sadeghpour A, Stroup D, Galli G, Chiang JY. The opposing effects of retinoic acid and phorbol esters converge to a common response element in the promoter of the rat cholesterol 7 alpha-hydroxylase gene (CYP7A). Biochem Biophys Res Commun 1996; 225:585-92. [PMID: 8753804 DOI: 10.1006/bbrc.1996.1215] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The activity of the rat CYP7A/luciferase reporter gene was increased five-fold by all-trans retinoic acid (atRA) or 9-cis retinoic acid (9cRA) in transient transfection assay in HepG2 cells. Cotransfection with retinoid X receptor (RXR) stimulated the promoter activity in the absence of ligand, however, addition of atRA inhibited the transcriptional activity. Cotransfection with retinoic acid receptor (RAR) did not have much effect on CYP7A promoter activity. The CYP7A promoter, when linked upstream to the SV40/ luciferase reporter gene, strongly repressed the phorbol 12-myristate 13-acetate (PMA)-stimulated SV40/ luciferase reporter gene activity. The regions conferring the effects of RA and PMA were mapped to nt-176/ -117 and nt-148/-129, respectively. Several direct repeats of hormone response element (AGTTCA) in this region are required for RA response. AP-1 like sequences are located within the region responding to both RA and PMA. Site-directed mutagenesis of the AP-1 site abolished the effects of both RA and phorbol esters. Retinoic acid effect was antagonized by PMA. Moreover, cotransfection of Fos and Jun expression vectors blunted the stimulatory effect of retinoic acid on the CYP7A/luciferase gene activity. Therefore, effects of two different signal transduction pathways converge to a common response element. This regulatory cross-talk may be involved in bile acid repression and regulates CYP7 gene transcription in the liver.
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Affiliation(s)
- M Crestani
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272-0095, USA
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Pandak WM, Stravitz RT, Lucas V, Heuman DM, Chiang JY. Hep G2 cells: a model for studies on regulation of human cholesterol 7alpha-hydroxylase at the molecular level. Am J Physiol 1996; 270:G401-10. [PMID: 8638705 DOI: 10.1152/ajpgi.1996.270.3.g401] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The present study examines the feedback control governing human cholesterol 7alpha-hydroxylase mRNA expression in the human hepatoblastoma cell line, Hep G2. Glycochenodeoxycholate (GCDC) and glycodeoxycholate, hydrophobic bile salts, decreased cholesterol 7alpha-hydroxylase mRNA levels and bile acid synthesis in a concentration-dependent (76 +/- 8%, P<0.001, and 48 +/- 3%, P<0.01, respectively) and time-dependent manner. Cholesterol 7alpha-hydroxylase mRNA levels were repressed with a half-maximal inhibitory concentration of <12.5 microM by GCDC and a half-life of 30 min by 100 microM of the bile acid. The addition of actinomycin D (10 microgram/ml) alone or in combination with GCDC (100 microM) led to similar concentration-and time-dependent suppression of cholesterol 7alpha-hydroxylase mRNA. Glycocholate (100 microM), not internalized based on lack of uptake of a fluorescent cholate analogue, had no effect on cholesterol 7alpha-hydroxylase mRNA or total bile acid synthesis. In cultures transfected with a rat cholesterol 7alpha-hydroxylase promoter construct, reporter gene activity was decreased (31%, P<0.01) by GCDC (100 microM). Hep G2 cells maintain the intracellular machinery to express and rapidly regulate human cholesterol 7alpha-hydroxylase by hydrophobic bile acids. These data suggest that Hep G2 cells will support functional studies of the human cholesterol 7alpha-hydroxylase gene.
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Affiliation(s)
- W M Pandak
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0711
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Crestani M, Stroup D, Chiang JY. Hormonal regulation of the cholesterol 7 alpha-hydroxylase gene (CYP7). J Lipid Res 1995; 36:2419-32. [PMID: 8656080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The transcriptional regulation of the rat cholesterol 7 alpha-hydroxylase gene (CYP7) by hormones and signal transduction pathways was studied by transient transfection assay of the promoter activity. HepG2 cells were transfected with deletion mutants of the CYP7 upstream region linked to the luciferase reporter gene. The transcription of CYP7/luciferase chimeric genes was higher in confluent than in subconfluent cultures of HepG2 cells. Glucocorticoid receptors, in the presence of dexamethasone, up-regulated the CYP7 gene through two regions located between -3262 and -2803, and between -344 and -222, respectively. Thyroid hormones did not have any effect on the promoter activity. Insulin inhibited the promoter activity through sequences located between -344 and -222, and abolished the stimulation by dexamethasone. Hence, the insulin effect was dominant over that of glucocorticoids. Treatment of transfected HepG2 cells with phorbol 12-myristate 13-acetate (PMA), a known activator of protein kinase C (PKC), resulted in a time-dependent inhibition of the CYP7 promoter activity. The negative phorbol ester-response sequences were mapped between -344 and -222, and between -200 and -161, respectively. The CYP7 promoter activity was induced nearly 5-fold by all-trans-retinoic acid through sequences in the region from -200 to -129. Finally, cyclic AMP and protein kinase A (PKA) stimulated the expression of the CYP7/luciferase gene through multiple sequences in the distal and proximal regions, and both positive and negative response regions were mapped. Our results revealed that the -416 fragment of the rat CYP7 gene confers the activation by glucocorticoids and retinoic acid, and inhibition by insulin, phorbol esters and cAMP. It appears that this proximal promoter may contain a pleiotropic domain that regulates the effects of multiple signals.
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Affiliation(s)
- M Crestani
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272-0095, USA
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Pandak WM, Heuman DM, Hylemon PB, Chiang JY, Vlahcevic ZR. Failure of intravenous infusion of taurocholate to down-regulate cholesterol 7 alpha-hydroxylase in rats with biliary fistulas. Gastroenterology 1995; 108:533-44. [PMID: 7835596 DOI: 10.1016/0016-5085(95)90083-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND/AIMS The decrease in cholesterol 7 alpha-hydroxylase induced by intraduodenal infusion of taurocholate in bile fistula rats may be indirect, i.e., mediated through release or absorption of an intestinal factor in response to the presence of bile salts in the intestine. The aim of this study was to determine if negative feedback regulation of cholesterol 7 alpha-hydroxylase can be shown when equimolar concentrations of taurocholate are administered intravenously, thus bypassing the intestine. METHODS After 96 hours of biliary diversion, taurocholate (36 mumol.h-1.100 g, rat-1) was infused into the rats either intravenously or intraduodenally for the final 24 hours. Livers were then harvested for analysis of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase specific activity, cholesterol 7 alpha-hydroxylase specific activity, messenger RNA levels, and transcriptional activity. RESULTS Intraduodenally administered taurocholate significantly decreased HMG-CoA reductase and cholesterol 7 alpha-hydroxylase specific activity by more than 50% and cholesterol 7 alpha-hydroxylase steady-state messenger RNA levels and transcriptional activity by 50%-75%. In contrast, intravenous administration of taurocholate failed to down-regulate either cholesterol 7 alpha-hydroxylase or HMG-CoA reductase. CONCLUSIONS Passage of taurocholate through the intestine strongly potentiates negative feedback regulation of cholesterol 7 alpha-hydroxylase. A putative intestinal factor, released or absorbed in the presence of bile acids in the intestinal lumen, may play a role in the regulation of bile acid synthesis.
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Affiliation(s)
- W M Pandak
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond
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Chiang JY, Stroup D. Identification and characterization of a putative bile acid-responsive element in cholesterol 7 alpha-hydroxylase gene promoter. J Biol Chem 1994; 269:17502-7. [PMID: 8021257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Nucleotide sequences of a 7997-base pair SacI fragment spanning 3643 base pairs of the upstream promoter region to exon 4 of the rat cholesterol 7 alpha-hydroxylase gene (CYP7) have been determined. DNase I footprinting and electrophoretic mobility shift assay of the proximal promoter from nucleotides -346 to +36 revealed two protected regions which specifically shifted proteins in rat liver nuclear extracts. Footprint A (nucleotides -81 to -35) contained a cluster of overlapping sequence motifs of TGT3, steroid/thyroid hormone response elements (7 alpha TRE), hepatocyte nuclear factors 1 and 4, and CAAT/enhancer-binding protein alpha and has been shown to confer bile acid repression of the CYP7 gene promoter activity. Footprint B (nucleotides -148 to -129) contained a sequence motif HNF4. When footprint A (-101 to -49) or 7 alpha TRE (-73 to -55) sequence was linked upstream to a heterologous SV40 promoter/luciferase plasmid and transiently transfected into HepG2 cells, taurodeoxycholate suppressed the SV40 promoter activity. Electrophoretic mobility shift assays revealed that one or two bands shifted by the 7 alpha TRE or by a direct repeat sequence in 7 alpha TRE were absent when liver nuclear extracts of deoxycholic acid-treated rats were used. Similar gel shift patterns were also observed when human 7 alpha TRE or human liver nuclear extracts were used. The rat direct repeat sequence interacted with two polypeptides (M(r) = 57,000 and 116,000) in both rat and human liver nuclear extracts. These results suggest that hydrophobic bile acids may suppress the CYP7 gene expression by binding to a bile acid receptor which interacts with and prevents the binding of liver nuclear protein(s) to a bile acid-responsive element and that the core of bile acid-responsive element is a direct repeat.
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Affiliation(s)
- J Y Chiang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272
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Karam WG, Chiang JY. Expression and purification of human cholesterol 7 alpha-hydroxylase in Escherichia coli. J Lipid Res 1994; 35:1222-31. [PMID: 7964183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cholesterol 7 alpha-hydroxylase (P450c7) is the first and rate-limiting enzyme in bile acid biosynthesis and is the product of a cytochrome P450 gene, CYP7. We have previously reported the cloning of a full-length human cholesterol 7 alpha-hydroxylase cDNA (Karam, W. G., and J. Y. L. Chiang. 1992. Biochem. Biophys. Res. Commun. 185: 588-595). Using this clone in a polymerase chain reaction, we have generated a cDNA (H7 alpha 1.5) in which the codons for the N-terminal 24 amino acid residues were deleted. The translational product of this cDNA would be a truncated protein, P450c7(delta 2-24) with a hydrophilic NH2-terminal sequence, Met-Ala-Arg-Arg-Arg-Gln... This cDNA was cloned into the expression vector pJL and the construct pJL/H7 alpha 1.5 was transformed into E. coli strain TOPP3. We have also ligated a truncated rat cholesterol 7 alpha-hydroxylase cDNA obtained previously (Li, Y. C., and J. Y. L. Chiang. 1991. J. Biol. Chem. 266: 19186-19191) into the pJL vector and have transformed this construct (pJL/R7 alpha 1.5) into E. coli strain MV1304. Both of these systems expressed functional cholesterol 7 alpha-hydroxylase in E. coli. A fivefold improvement in the expression of rat enzyme over the previous expression system was obtained. About 70-80% of the truncated human P450 in the clear lysate was localized in the cytosol. The truncated human and rat P450c7(delta 2-24) were purified to homogeneity. Reconstitution of cholesterol 7 alpha-hydroxylase activity using purified rat or human P450c7(delta 2-24) showed a similar Km of 6 and 7 microM for cholesterol, a Vmax of 0.13 and 0.14 nmol/min, and a turnover number of 1.3 and 1.5 per min, respectively. Immunoblotting experiment revealed that a polyclonal antibody raised against rat microsomal cholesterol 7 alpha-hydroxylase recognized both rat and human P450c7(delta 2-24). This expression system provides a method for isolation of a large quantity of purified and catalytically active cholesterol 7 alpha-hydroxylase for the study of structure and function of this important enzyme in bile acid synthesis and cholesterol homeostasis.
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Affiliation(s)
- W G Karam
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272
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Pandak WM, Vlahcevic ZR, Heuman DM, Redford KS, Chiang JY, Hylemon PB. Effects of different bile salts on steady-state mRNA levels and transcriptional activity of cholesterol 7 alpha-hydroxylase. Hepatology 1994; 19:941-7. [PMID: 8138269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme in the bile acid synthesis pathway, is down-regulated by taurocholate by way of negative feedback control at the level of gene transcription. The molecular basis of regulation of cholesterol 7 alpha-hydroxylase by other hydrophobic bile salts and under more physiological conditions is not known. The aim of this study was to investigate the molecular basis of regulation of cholesterol 7 alpha-hydroxylase by several naturally occurring bile salts in rats with intact enterohepatic circulation. Male Sprague-Dawley rats were pair-fed for 14 days normal chow (control), cholestyramine (5% of diet), cholic acid (1%), chenodeoxycholic acid (1%) or deoxycholic acid (0.25%). When rats were killed, livers were harvested and HMG-CoA reductase specific activity and cholesterol 7 alpha-hydroxylase specific activities, steady-state mRNA levels and transcriptional activity were determined and compared with those of control rats fed normal chow. Compared with results in paired controls, cholestyramine feeding led to an approximate threefold increase in HMG-CoA reductase specific activity. Feeding of hydrophobic bile salts profoundly decreased the specific activity of HMG-CoA reductase. Cholestyramine led to a three-fold increase in cholesterol 7 alpha-hydroxylase specific activity, steady-state mRNA levels and gene transcriptional activity. The feeding of cholic (1%), chenodeoxycholic (1%) and deoxycholic acid (0.25%) led to significant decreases in cholesterol 7 alpha-hydroxylase specific activities (62%, 84% and 97%, respectively), steady-state mRNA levels (72%, 29% and 61%, respectively) and transcriptional activities (44%, 43% and 54%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W M Pandak
- Section of Gastroenterology, McGuire Veterans Administration Medical Center, Richmond, Virginia
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Abstract
The human cholesterol 7 alpha-hydroxylase gene (CYP7) spans about 11 kb of the genome and contains six exons and five introns. Nucleotide sequences of a 5'-upstream region to exon III (5535 bp), a 5'-upstream EcoRI fragment (2575 bp), and an EcoRI fragment covering intron V to exon VI (2319 bp) have been determined. A comparison of our sequences with those reported previously unveiled numerous sequencing discrepancies that are apparently due to sequencing errors. There are only one confirmed and one possible genetic polymorphism in the promoter of this highly conserved human gene. The proximal promoter contained many consensus recognition sequences for liver-enriched transcription factors and steroid hormone receptors that may play important roles in regulation of the CYP7 gene transcription by bile acids, cholesterol, and hormones.
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Affiliation(s)
- D P Wang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272
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Crestani M, Karam WG, Chiang JY. Effects of bile acids and steroid/thyroid hormones on the expression of cholesterol 7 alpha-hydroxylase mRNA and the CYP7 gene in HepG2 cells. Biochem Biophys Res Commun 1994; 198:546-53. [PMID: 8297364 DOI: 10.1006/bbrc.1994.1080] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The expression of cholesterol 7 alpha-hydroxylase mRNA levels in confluent HepG2 cultures was reduced by tauro- or glyco-conjugates of deoxycholate and chenodeoxycholate, but not by cholate. Ursodeoxycholates, on the other hand, stimulated the mRNA level. The 5'-upstream regions of rat cholesterol 7 alpha-hydroxylase gene (CYP7) were fused to luciferase reporter gene and the constructs, p-3616/Luc, p-224/Luc and p-160/Luc, were transiently transfected into HepG2 cells. Tauro-conjugates of deoxycholate and chenodeoxycholate inhibited the transcriptional activities of the gene constructs in the confluent cells, but not in subconfluent cells. These results reveal that bile acid responsive elements are located in the -160 fragment and also between nt -3616 and -224. Thyroid and steroid hormones stimulated transcriptional activity expressed in the confluent cells and their responsive elements are located upstream of nt -224. It appears that adult phenotypes are responsible for bile acid feedback and hormone response in HepG2 cells.
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Affiliation(s)
- M Crestani
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio University, College of Medicine, Rootstown 44272
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Abstract
Cholesterol 7 alpha-hydroxylase is the rate limiting enzyme in bile acid biosynthesis and plays an important role in cholesterol homeostasis. The Golden Syrian hamster has been used as an animal model for the study of atherosclerosis and cholesterol gallstone disease. We have screened a lambda DASH II hamster liver genomic library using a rat cDNA as a hybridization probe. A 14-kb genomic clone has been isolated and characterized by restriction mapping and Southern blot hybridization. The clone contained the full-length gene encoding cholesterol 7 alpha-hydroxylase together with an upstream sequence of approximately 5 kb. DNA sequencing and analysis of about 11 kb of the gene revealed that the hamster CYP7 gene consists of six exons and five introns, which have the same structures and sizes as predicted in the rat and human CYP7 genes. The nucleotide and deduced amino acid sequences of the hamster cholesterol 7 alpha-hydroxylase have a high sequence identity of about 90% to the rat and 82% to the human sequences. Particularly, exons 2, 5, and 6 are highly conserved among these species, thus reflecting the presence of some domains that are crucial for the activity of this unique enzyme. The putative cholesterol-binding region, an aromatic amino acid region, and the P450 heme-binding region are completely conserved. Comparison of the 250-bp 5'-flanking sequence to the corresponding region in the rat and human genes revealed a high degree of homology ranging between 71% and 82%. Next to the canonical TATA and CCAAT boxes are many consensus sequences (LF-A1, LF-B1, TGT3) for liver-specific or -enriched transcription factors (HNF4, HNF1, and HNF5, respectively) and an imperfect direct repeat of thyroid hormone responsive element (TRE), which is located between TGT3 and LF-B1. These sequence motifs are completely conserved among the rat, human, and hamster CYP7 genes. Several modified sterol regulatory element (SRE)-like sequences are located in the upstream flanking region and in the first intron. This highly conserved proximal promoter may play important roles in the transcription activity and in the regulation of the CYP7 gene by physiological agents, such as bile acids and steroid/thyroid hormones. This is the first report describing the complete nucleotide sequence and confirming the structure of a CYP7 gene.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M Crestani
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio University College of Medicine, Rootstown 44272
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Breuer O, Sudjana-Sugiaman E, Eggertsen G, Chiang JY, Björkhem I. Cholesterol 7 alpha-hydroxylase is up-regulated by the competitive inhibitor 7-oxocholesterol in rat liver. Eur J Biochem 1993; 215:705-10. [PMID: 8354276 DOI: 10.1111/j.1432-1033.1993.tb18082.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Rats of the Sprague-Dawley strain were infused intravenously with a fat emulsion (Intralipid, trademark of Kabi Pharmacia, Uppsala, Sweden) containing 7-oxocholesterol. This resulted in an increased cholesterol 7 alpha-hydroxylase activity in liver microsomes as compared to controls and was accompanied by increased levels of cholesterol 7 alpha-hydroxylase mRNA and microsomal cholesterol 7 alpha-hydroxylase protein. Rats were also fed a cholestyramine-supplemented diet and infused with 7-oxocholesterol. These animals excreted about half as much bile acids in faeces as cholestyramine-fed controls. Addition of 7-oxocholesterol to liver microsomes from normal rats in amounts corresponding to those present in microsomes from 7-oxocholesterol-treated rats inhibited the cholesterol 7 alpha-hydroxylase activity by about 75%. Cholesterol induced a type-I binding spectrum when added to a purified bacterial-expressed cholesterol 7 alpha-hydroxylase (P-450c7 delta 2-24). 7-Oxocholesterol competitively inhibited the cholesterol binding spectrum, while 7 beta-hydroxycholesterol did not interfere with binding of cholesterol to the enzyme. It is concluded that treatment with the competitive inhibitor 7-oxocholesterol leads to a reduced bile acid biosynthesis and, as a consequence of reduced bile acid inhibition, a compensatory increase in cholesterol 7 alpha-hydroxylase synthesis. The high enzyme activity measured in microsomal preparations from 7-oxocholesterol-treated rats may be due to a continuous conversion of 7-oxocholesterol into less inhibitory metabolites, e.g. 7 beta-hydroxycholesterol. The latter compound was found in high concentrations in liver microsomes from rats treated with 7-oxocholesterol. The physiological importance of these results is discussed in relation to the previous findings that 7-oxocholesterol is accumulated in liver after cholesterol feeding and that 7-oxocholesterol is formed from cholesterol during lipid peroxidation.
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Affiliation(s)
- O Breuer
- Karolinska Institutet, Department of Clinical Chemistry, Huddinge University Hospital, Sweden
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Jones MP, Pandak WM, Heuman DM, Chiang JY, Hylemon PB, Vlahcevic ZR. Cholesterol 7 alpha-hydroxylase: evidence for transcriptional regulation by cholesterol or metabolic products of cholesterol in the rat. J Lipid Res 1993. [DOI: 10.1016/s0022-2275(20)39675-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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