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Gunn KH, Gutgsell AR, Xu Y, Johnson CV, Liu J, Neher SB. Comparison of angiopoietin-like protein 3 and 4 reveals structural and mechanistic similarities. J Biol Chem 2021; 296:100312. [PMID: 33482195 PMCID: PMC7949051 DOI: 10.1016/j.jbc.2021.100312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 09/22/2020] [Revised: 01/07/2021] [Accepted: 01/15/2021] [Indexed: 12/17/2022] Open
Abstract
Elevated plasma triglycerides are a risk factor for coronary artery disease, which is the leading cause of death worldwide. Lipoprotein lipase (LPL) reduces triglycerides in the blood by hydrolyzing them from triglyceride-rich lipoproteins to release free fatty acids. LPL activity is regulated in a nutritionally responsive manner by macromolecular inhibitors including angiopoietin-like proteins 3 and 4 (ANGPTL3 and ANGPTL4). However, the mechanism by which ANGPTL3 inhibits LPL is unclear, in part due to challenges in obtaining pure protein for study. We used a new purification protocol for the N-terminal domain of ANGPTL3, removing a DNA contaminant, and found DNA-free ANGPTL3 showed enhanced inhibition of LPL. Structural analysis showed that ANGPTL3 formed elongated, flexible trimers and hexamers that did not interconvert. ANGPTL4 formed only elongated flexible trimers. We compared the inhibition of ANGPTL3 and ANGPTL4 using human very-low-density lipoproteins as a substrate and found both were noncompetitive inhibitors. The inhibition constants for the trimeric ANGPTL3 (7.5 ± 0.7 nM) and ANGPTL4 (3.6 ± 1.0 nM) were only 2-fold different. Heparin has previously been reported to interfere with ANGPTL3 binding to LPL, so we questioned if the negatively charged heparin was acting in a similar fashion to the DNA contaminant. We found that ANGPTL3 inhibition is abolished by binding to low-molecular-weight heparin, whereas ANGPTL4 inhibition is not. Our data show new similarities and differences in how ANGPTL3 and ANGPTL4 regulate LPL and opens new avenues of investigating the effect of heparin on LPL inhibition by ANGPTL3.
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Affiliation(s)
- Kathryn H Gunn
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Aspen R Gutgsell
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Yongmei Xu
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Caitlin V Johnson
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jian Liu
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Saskia B Neher
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA.
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Lee HC, Lin HT, Ke LY, Wei C, Hsiao YL, Chu CS, Lai WT, Shin SJ, Chen CH, Sheu SH, Wu BN. VLDL from Metabolic Syndrome Individuals Enhanced Lipid Accumulation in Atria with Association of Susceptibility to Atrial Fibrillation. Int J Mol Sci 2016; 17:ijms17010134. [PMID: 26805814 PMCID: PMC4730373 DOI: 10.3390/ijms17010134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/29/2015] [Accepted: 01/15/2016] [Indexed: 12/12/2022] Open
Abstract
Metabolic syndrome (MetS) represents a cluster of metabolic derangements. Dyslipidemia is an important factor in MetS and is related to atrial fibrillation (AF). We hypothesized that very low density lipoproteins (VLDL) in MetS (MetS-VLDL) may induce atrial dilatation and vulnerability to AF. VLDL was therefore separated from normal (normal-VLDL) and MetS individuals. Wild type C57BL/6 male mice were divided into control, normal-VLDL (nVLDL), and MetS-VLDL (msVLDL) groups. VLDL (15 µg/g) and equivalent volumes of saline were injected via tail vein three times a week for six consecutive weeks. Cardiac chamber size and function were measured by echocardiography. MetS-VLDL significantly caused left atrial dilation (control, n = 10, 1.64 ± 0.23 mm; nVLDL, n = 7, 1.84 ± 0.13 mm; msVLDL, n = 10, 2.18 ± 0.24 mm; p < 0.0001) at week 6, associated with decreased ejection fraction (control, n = 10, 62.5% ± 7.7%, vs. msVLDL, n = 10, 52.9% ± 9.6%; p < 0.05). Isoproterenol-challenge experiment resulted in AF in young msVLDL mice. Unprovoked AF occurred only in elderly msVLDL mice. Immunohistochemistry showed excess lipid accumulation and apoptosis in msVLDL mice atria. These findings suggest a pivotal role of VLDL in AF pathogenesis for MetS individuals.
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Affiliation(s)
- Hsiang-Chun Lee
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Hsin-Ting Lin
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Liang-Yin Ke
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chi Wei
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
| | - Yi-Lin Hsiao
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chih-Sheng Chu
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Wen-Ter Lai
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Shyi-Jang Shin
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chu-Huang Chen
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Vascular and Medicinal Research, Texas Heart Institute, Houston, TX 77030, USA.
- New York Heart Research Foundation, Mineola, NY 11501, USA.
- Lipid and Glycoimmune Research Center, Changhua Christian Hospital, Changhua 500, Taiwan.
| | - Sheng-Hsiung Sheu
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Bin-Nan Wu
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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Nagano T, Seki N, Tomita Y, Sugita T, Aida Y, Itagaki M, Sutoh S, Abe H, Tsubota A, Aizawa Y. Impact of Chronic Hepatitis C Virus Genotype 1b Infection on Triglyceride Concentration in Serum Lipoprotein Fractions. Int J Mol Sci 2015; 16:20576-94. [PMID: 26334270 PMCID: PMC4613219 DOI: 10.3390/ijms160920576] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/13/2015] [Accepted: 08/20/2015] [Indexed: 12/14/2022] Open
Abstract
Reduced low-density lipoprotein (LDL) cholesterol level is a characteristic feature of dyslipidemia in chronic hepatitis C virus (HCV) infection. However, abnormality in serum triglyceride (TG) has not been fully investigated. To clarify the impact of HCV genotype 1b (G1b) infection and advanced fibrosis on serum TG profiles, TG concentrations in lipoprotein fractions were examined in fasting sera from 185 subjects with active or cleared HCV infection by high-performance liquid chromatography. Serum lipoproteins were fractionated into four classes: chylomicron, very low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL). Then, the significance of HCV G1b infection on TG levels in each lipoprotein fraction was determined using multiple regression models. We found that active HCV G1b infection was positively associated with high HDL-TG levels and low VLDL-TG levels, independent of other factors included in the regression model. In VLDL sub-fractions, active HCV infection was only found to be associated with low levels of large VLDL-TG. Similarly, advanced liver fibrosis in chronic HCV G1b infection was associated with high levels of LDL-TG, HDL-TG, and small VLDL-TG, independent of other clinical factors. These findings indicate that active HCV G1b infection and advanced fibrosis are closely associated with abnormal serum TG profiles.
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Affiliation(s)
- Tomohisa Nagano
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Nobuyoshi Seki
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Yoichi Tomita
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Tomonori Sugita
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Yuta Aida
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Munenori Itagaki
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Satoshi Sutoh
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Hiroshi Abe
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
| | - Akihito Tsubota
- Core Research Facilities for Basic Science, Research Center for Medical Science, Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan.
| | - Yoshio Aizawa
- Department of Gastroenterology and Hepatology Internal Medicine, Jikei University Katsushika Medical Center, 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506, Japan.
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