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Karmazyn M, Gan XT. Molecular and Cellular Mechanisms Underlying the Cardiac Hypertrophic and Pro-Remodelling Effects of Leptin. Int J Mol Sci 2024; 25:1137. [PMID: 38256208 PMCID: PMC10816997 DOI: 10.3390/ijms25021137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Since its initial discovery in 1994, the adipokine leptin has received extensive interest as an important satiety factor and regulator of energy expenditure. Although produced primarily by white adipocytes, leptin can be synthesized by numerous tissues including those comprising the cardiovascular system. Cardiovascular function can thus be affected by locally produced leptin via an autocrine or paracrine manner but also by circulating leptin. Leptin exerts its effects by binding to and activating specific receptors, termed ObRs or LepRs, belonging to the Class I cytokine family of receptors of which six isoforms have been identified. Although all ObRs have identical intracellular domains, they differ substantially in length in terms of their extracellular domains, which determine their ability to activate cell signalling pathways. The most important of these receptors in terms of biological effects of leptin is the so-called long form (ObRb), which possesses the complete intracellular domain linked to full cell signalling processes. The heart has been shown to express ObRb as well as to produce leptin. Leptin exerts numerous cardiac effects including the development of hypertrophy likely through a number of cell signaling processes as well as mitochondrial dynamics, thus demonstrating substantial complex underlying mechanisms. Here, we discuss mechanisms that potentially mediate leptin-induced cardiac pathological hypertrophy, which may contribute to the development of heart failure.
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Mohr AE, Reiss RA, Beaudet M, Sena J, Naik JS, Walker BR, Sweazea KL. Short-term high fat diet alters genes associated with metabolic and vascular dysfunction during adolescence in rats: a pilot study. PeerJ 2021; 9:e11714. [PMID: 34285833 PMCID: PMC8274493 DOI: 10.7717/peerj.11714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 06/11/2021] [Indexed: 11/20/2022] Open
Abstract
Background Diet-induced metabolic dysfunction precedes multiple disease states including diabetes, heart disease, and vascular dysfunction. The critical role of the vasculature in disease progression is established, yet the details of how gene expression changes in early cardiovascular disease remain an enigma. The objective of the current pilot project was to evaluate whether a quantitative assessment of gene expression within the aorta of six-week old healthy male Sprague-Dawley rats compared to those exhibiting symptoms of metabolic dysfunction could reveal potential mediators of vascular dysfunction. Methods RNA was extracted from the aorta of eight rats from a larger experiment; four animals fed a high-fat diet (HFD) known to induce symptoms of metabolic dysfunction (hypertension, increased adiposity, fasting hyperglycemia) and four age-matched healthy animals fed a standard chow diet (CHOW). The bioinformatic workflow included Gene Ontology (GO) biological process enrichment and network analyses. Results The resulting network contained genes relevant to physiological processes including fat and protein metabolism, oxygen transport, hormone regulation, vascular regulation, thermoregulation, and circadian rhythm. The majority of differentially regulated genes were downregulated, including several associated with circadian clock function. In contrast, leptin and 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) were notably upregulated. Leptin is involved in several major energy balance signaling pathways and Hmgcs2 is a mitochondrial enzyme that catalyzes the first reaction of ketogenesis. Conclusion Together, these data describe changes in gene expression within the aortic wall of HFD rats with early metabolic dysfunction and highlight potential pathways and signaling intermediates that may impact the development of early vascular dysfunction.
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Affiliation(s)
- Alex E Mohr
- College of Health Solutions, Arizona State University, Phoenix, AZ, United States
| | - Rebecca A Reiss
- Biology Department, New Mexico Institute of Mining and Technology, Socorro, NM, United States
| | - Monique Beaudet
- Biology Department, New Mexico Institute of Mining and Technology, Socorro, NM, United States
| | - Johnny Sena
- National Center for Genome Resources, Santa Fe, NM, USA
| | - Jay S Naik
- The Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Benjimen R Walker
- The Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Karen L Sweazea
- College of Health Solutions & School of Life Sciences, Arizona State University, Tempe, AZ, USA
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Jing R, Pan W, Long T, Li Z, Li C. LINC00472 regulates vascular smooth muscle cell migration and proliferation via regulating miR-149-3p. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:12960-12967. [PMID: 33095897 DOI: 10.1007/s11356-020-10761-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
LncRNAs are one group of gene modulators functioning via several mechanisms in pathological and physiological conditions. We noted that LINC00472 expression level is elevated in atherosclerotic coronary tissues compared with normal coronary artery samples. LINC00472 is also upregulated in vascular smooth muscle cells (VSMCs) induced by TNF-α and PDGF-BB. Ectopic expression of LINC00472 induced VSMC migration and proliferation. The predicted binding sequence between miR-149-3p and LINC00472 was analyzed by LncBase Predicted. Overexpression of miR-149-3p decreases the luciferase activity of wild-type reporter plasmid, but not the mutant one. Ectopic expression of LINC00472 suppresses the expression of miR-149-3p in VSMCs. Furthermore, we demonstrated that miR-149-3p expression is decreased in atherosclerotic coronary tissues. MiR-149-3p was downregulated in VSMCs induced by TNF-α and PDGF-BB. Overexpression of LINC00472 induces VSMC migration and proliferation via regulating miR-149-3p. These data suggested that LINC00472 acts a critical role in the migration and proliferation of VSMCs partly via modulating miR-149-3p.
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Affiliation(s)
- Ran Jing
- Cardiovascular Department, Xiangya Hospital, Central South University, Changsha City, 410000, Hunan Province, China
| | - Wei Pan
- Cardiovascular Department, Xiangya Hospital, Central South University, Changsha City, 410000, Hunan Province, China
| | - Tianyi Long
- Cardiovascular Department, Xiangya Hospital, Central South University, Changsha City, 410000, Hunan Province, China
| | - Zhenyu Li
- Geriatric Department of Xiangya Hospital, Central South University, Changsha City, 410000, Hunan Province, China
| | - Chuanchang Li
- Geriatric Department of Xiangya Hospital, Central South University, Changsha City, 410000, Hunan Province, China.
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Shi X, Pan S, Li L, Li Y, Ma W, Wang H, Xu C, Li L, Wang D. HIX003209 promotes vascular smooth muscle cell migration and proliferation through modulating miR-6089. Aging (Albany NY) 2020; 12:8913-8922. [PMID: 32463793 PMCID: PMC7288934 DOI: 10.18632/aging.103079] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/24/2020] [Indexed: 12/14/2022]
Abstract
Accumulating references have showed that long noncoding RNAs (lncRNAs) act important roles in the development of human diseases. The role and expression of HIX003209 remains unclear in the pathogenesis of atherosclerosis. We showed that HIX003209 expression was upregulated in atherosclerotic coronary tissues compared to normal coronary artery samples. HIX003209 was overexpressed in vascular smooth muscle cells (VSMCs) induced by inflammatory mediators including tumor necrosis factor-α(TNF-α), ox-LDL and latelet-derived growth factor-BB (PDGF-BB). Ectopic expression of HIX003209 enhanced cell growth and migration and induced inflammatory mediators secretion such as interleukin 6 (IL-6), TNF-α and IL-1β in VSMCs. Furthermore, we showed that miR-6089 was downregulated in atherosclerotic coronary tissues compared to normal coronary artery samples. There was a negative association between expression of HIX003209 and miR-6089 in atherosclerotic coronary tissues. MiR-6089 expression was decreased in VSMCs induced by inflammatory mediators including TNF-α, ox-LDL and PDGF-BB. Dual luciferase analysis showed that miR-6089 overexpression decreased luciferase activity of HIX003209 WT-type 3’-UTR but not the mut-type 3’-UTR. Overexpression of HIX003209 suppressed the expression of miR-6089 in VSMCs. Ectopic expression of HIX003209 induced cell growth, migration and the secretion of inflammatory mediators via regulating miR-6089 expression. These data suggested that HIX003209 promoted VSMCs proliferation, migration and the secretion of inflammatory mediators partly via regulating miR-6089.
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Affiliation(s)
- Xiaofeng Shi
- Department of Emergency, Tianjin First Center Hospital, Tianjin 300192, People's Republic of China
| | - Shuang Pan
- Department of Physiology, School of Basic Medicine, Jinzhou Medicine University, Jinzhou 121000, Liaoning, People's Republic of China
| | - Li Li
- Clinical Nutrition Department, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, Liaoning, People's Republic of China
| | - Yongqi Li
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 3050005, Japan
| | - Wei Ma
- Department of Anatomy, Dalian Medical University, Dalian 116044, Liaoning, People's Republic of China
| | - Han Wang
- Department of Vascular Surgery, Dalian University Affiliated Xinhua Hospital, Dalian 116021, Liaoning, People's Republic of China
| | - Caiming Xu
- Department of General Surgery, The First Affiliated Hospital, Dalian Medical University, Dalian 116011, Liaoning, People's Republic of China
| | - Lei Li
- Department of Vascular Surgery, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, Liaoning, People's Republic of China
| | - Dong Wang
- Neurosurgery Department, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, Liaoning, People's Republic of China
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Zahner GJ, Ramirez JL, Spaulding KA, Khetani SA, Gasper WJ, Grunfeld C, Hills NK, Schafer AL, Grenon SM. Leptinemia is Associated With Peripheral Artery Disease. J Surg Res 2019; 238:48-56. [PMID: 30738358 DOI: 10.1016/j.jss.2019.01.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/25/2018] [Accepted: 01/08/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Leptin, adiponectin, and resistin are in a class of hormones called adipokines that are produced by adipocytes and have been implicated in the causal pathway of atherosclerosis. We examined the association between adipokine levels and peripheral artery disease (PAD), hypothesizing that after adjusting for fat mass, leptin and resistin would be higher, whereas adiponectin would be lower, in patients with PAD. METHODS A cross-sectional sample of 179 predominately male (97%) vascular surgery outpatients was recruited from the San Francisco Veterans Affairs Medical Center (SFVAMC). PAD was defined as either an ankle-brachial index < 0.9 plus symptoms of claudication or prior revascularization for symptomatic PAD (n = 141). Controls had an ankle-brachial index ≥0.9 and no history of atherosclerotic disease (n = 38). Adipokines were assayed using commercially available ELISA kits and values were log-transformed. Fat mass was measured using bioelectrical impedance. RESULTS In an analysis adjusting for body mass index (BMI) and atherosclerotic risk factors, higher serum leptin was associated with PAD (OR 2.54, 95% CI 1.07-6.01, P = 0.03), whereas high molecular weight adiponectin was inversely associated, though not significantly (OR 0.60, 95% CI 0.33-1.08, P = 0.09). Resistin was not associated with PAD. Sensitivity analyses using fat mass/height2 rather than BMI yielded similar results. CONCLUSIONS These results indicate that after adjusting for BMI or fat mass, serum leptin levels are positively and independently associated with PAD, whereas high molecular weight adiponectin might be inversely associated. Using a more representative, nonveteran sample, further investigations should focus on the potential role of adipokines in the pathophysiology of PAD as well as determine whether leptin levels have clinical utility in predicting PAD outcomes.
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Affiliation(s)
- Greg J Zahner
- Department of Surgery, University of California, San Francisco, San Francisco, California
| | - Joel L Ramirez
- Department of Surgery, University of California, San Francisco, San Francisco, California
| | - Kimberly A Spaulding
- Department of Surgery, University of California, San Francisco, San Francisco, California; Vascular Surgery Section, Veterans Affairs Medical Center, San Francisco, California
| | - Sukaynah A Khetani
- Department of Surgery, University of California, San Francisco, San Francisco, California; Vascular Surgery Section, Veterans Affairs Medical Center, San Francisco, California
| | - Warren J Gasper
- Department of Surgery, University of California, San Francisco, San Francisco, California; Vascular Surgery Section, Veterans Affairs Medical Center, San Francisco, California
| | - Carl Grunfeld
- Department of Medicine, University of California, San Francisco, San Francisco, California; Metabolism Section, Veterans Affairs Medical Center, San Francisco, California
| | - Nancy K Hills
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California
| | - Anne L Schafer
- Department of Medicine, University of California, San Francisco, San Francisco, California; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California; Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California
| | - S Marlene Grenon
- Department of Surgery, University of California, San Francisco, San Francisco, California.
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Effects of Qingshen granules on Janus Kinase/signal transducer and activator of transcription signaling pathway in rats with unilateral ureteral obstruction. J TRADIT CHIN MED 2018. [DOI: 10.1016/j.jtcm.2017.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Horimatsu T, Kim HW, Weintraub NL. The Role of Perivascular Adipose Tissue in Non-atherosclerotic Vascular Disease. Front Physiol 2017; 8:969. [PMID: 29234289 PMCID: PMC5712360 DOI: 10.3389/fphys.2017.00969] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/14/2017] [Indexed: 12/30/2022] Open
Abstract
Perivascular adipose tissue (PVAT) surrounds most large blood vessels and plays an important role in vascular homeostasis. PVAT releases various chemokines and adipocytokines, functioning in an endocrine and paracrine manner to regulate vascular signaling and inflammation. Mounting evidence suggests that PVAT plays an important role in atherosclerosis and hypertension; however, the role of PVAT in non-atherosclerotic vascular diseases, including neointimal formation, aortic aneurysm, arterial stiffness and vasculitis, has received far less attention. Increasing evidence suggests that PVAT responds to mechanical endovascular injury and regulates the subsequent formation of neointima via factors that promote smooth muscle cell growth, adventitial inflammation and neovascularization. Circumstantial evidence also links PVAT to the pathogenesis of aortic aneurysms and vasculitic syndromes, such as Takayasu's arteritis, where infiltration and migration of inflammatory cells from PVAT into the vascular wall may play a contributory role. Moreover, in obesity, PVAT has been implicated to promote stiffness of elastic arteries via the production of reactive oxygen species. This review will discuss the growing body of data and mechanisms linking PVAT to the pathogenesis of non-atherosclerotic vascular diseases in experimental animal models and in humans.
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Affiliation(s)
- Tetsuo Horimatsu
- Division of Cardiology, Department of Medicine, Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Ha Won Kim
- Division of Cardiology, Department of Medicine, Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Neal L Weintraub
- Division of Cardiology, Department of Medicine, Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
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Noblet JN, Goodwill AG, Sassoon DJ, Kiel AM, Tune JD. Leptin augments coronary vasoconstriction and smooth muscle proliferation via a Rho-kinase-dependent pathway. Basic Res Cardiol 2016; 111:25. [PMID: 26975316 PMCID: PMC5126981 DOI: 10.1007/s00395-016-0545-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/16/2016] [Accepted: 02/26/2016] [Indexed: 10/24/2022]
Abstract
Leptin has been implicated as a key upstream mediator of pathways associated with coronary vascular dysfunction and disease. The purpose of this investigation was to test the hypothesis that leptin modifies the coronary artery proteome and promotes increases in coronary smooth muscle contraction and proliferation via influences on Rho kinase signaling. Global proteomic assessment of coronary arteries from lean swine cultured with obese concentrations of leptin (30 ng/mL) for 3 days revealed significant alterations in the coronary artery proteome (68 proteins) and identified an association between leptin treatment and calcium signaling/contraction (four proteins) and cellular growth and proliferation (35 proteins). Isometric tension studies demonstrated that both acute (30 min) and chronic (3 days, serum-free media) exposure to obese concentrations of leptin potentiated depolarization-induced contraction of coronary arteries. Inhibition of Rho kinase significantly reduced leptin-mediated increases in coronary artery contractions. The effects of leptin on the functional expression of Rho kinase were time-dependent, as acute treatment increased Rho kinase activity while chronic (3 day) exposure was associated with increases in Rho kinase protein abundance. Proliferation assays following chronic leptin administration (8 day, serum-containing media) demonstrated that leptin augmented coronary vascular smooth muscle proliferation and increased Rho kinase activity. Inhibition of Rho kinase significantly reduced these effects of leptin. Taken together, these findings demonstrate that leptin promotes increases in coronary vasoconstriction and smooth muscle proliferation and indicate that these phenotypic effects are associated with alterations in the coronary artery proteome and dynamic effects on the Rho kinase pathway.
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Affiliation(s)
- Jillian N Noblet
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Daniel J Sassoon
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Alexander M Kiel
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA.
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Kim JK, Choi SR, Lee WY, Park MJ, Lee HS, Song YR, Kim HJ, Kim SG. Leptin, pre-existing vascular disease, and increased arteriovenous fistula maturation failure in dialysis patients. J Vasc Surg 2016; 64:402-410.e1. [PMID: 27134129 DOI: 10.1016/j.jvs.2016.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/01/2016] [Indexed: 11/18/2022]
Abstract
BACKGROUND The adipocytokine leptin is an independent cardiovascular risk factor and exerts proatherogenic effect. Pre-existing vascular disease is an important cause of arteriovenous fistula (AVF) maturation failure. We explored the association between serum leptin, pre-existing vascular disease, and AVF maturation failure in incident hemodialysis patients. METHODS Vein samples from 62 patients were collected at the time of AVF creation. Pre-existing vascular disease was evaluated with histologic changes and immunohistochemical characteristics of cellular phenotypes in intima. AVF maturation failure was defined as an AVF that could not be used successfully by the third month after its creation. RESULTS The prevalence of body mass index ≥30 kg/m2 was 17%, and AVF maturation failure occurred in 28 (45%) patients. Patients within the highest leptin tertile showed significantly higher maturation failure rate, independent of age, gender, diabetes, and body mass index. On histologic examination, significant differences in intimal hyperplasia (13.3 ± 4.5 vs 18.2 ± 5.2 vs 30.3 ± 14.3 μm) and medial thickening (76.8 ± 23.7 vs 103.9 ± 33.6 vs 109.3 ± 36.5 μm) were observed across leptin tertiles. Similarly, medial fibrosis was most severe in the highest tertile. According to the immunohistochemical staining, most intimal cells were α-smooth muscle actin-positive, vimentin-positive, desmin-negative myofibroblasts. However, in the lowest tertile, desmin-positive contractile smooth muscle cells were also frequently observed, suggesting relatively slow phenotypic changes in this group. Furthermore, as leptin tertiles increased, the expression of leptin receptor in the luminal border of intima was significantly decreased. CONCLUSIONS Obesity-related higher fistula maturation failure rate may be partly mediated by higher leptin level-associated pre-existing vascular diseases in end-stage renal disease patients. Decreased expression of leptin receptor may be related to this association.
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Affiliation(s)
- Jwa-Kyung Kim
- Department of Internal Medicine, Kidney Research Institute, Hallym University Sacred Heart Hospital, Anyang, Korea; Department of Clinical Immunology, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Sun Ryoung Choi
- Department of Nephrology, Sahmyook Medical Center, Seoul, Korea
| | - Won Yong Lee
- Department of Cardiovascular and Thoracic Surgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Mi Jin Park
- Department of Clinical Immunology, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Hyung Suk Lee
- Department of Nephrology, Sahmyook Medical Center, Seoul, Korea
| | - Young Rim Song
- Department of Internal Medicine, Kidney Research Institute, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Hyung Jik Kim
- Department of Internal Medicine, Kidney Research Institute, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Sung Gyun Kim
- Department of Internal Medicine, Kidney Research Institute, Hallym University Sacred Heart Hospital, Anyang, Korea; Department of Clinical Immunology, Hallym University Sacred Heart Hospital, Anyang, Korea.
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Ryan MJ, Coleman TT, Sasser JM, Pittman KM, Hankins MW, Stec DE. Vascular smooth muscle-specific deletion of the leptin receptor attenuates leptin-induced alterations in vascular relaxation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R960-7. [PMID: 26936780 DOI: 10.1152/ajpregu.00336.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 02/23/2016] [Indexed: 01/09/2023]
Abstract
Obesity is a risk factor for cardiovascular disease and is associated with increased plasma levels of the adipose-derived hormone leptin. Vascular smooth muscle cells (VSMC) express leptin receptors (LepR); however, their physiological role is unclear. We hypothesized that leptin, at levels to mimic morbid obesity, impairs vascular relaxation. To test this, we used control and VSM-LepR knockout mice (VSM-LepR KO) created with a tamoxifen-inducible specific Cre recombinase to delete the LepR gene in VSMC. Control (10-12 wk old) and VSM-LepR KO (10-12 wk old) mice were fed a diet containing tamoxifen (50 mg/kg) for 6 wk, after which vascular reactivity was studied in isolated carotid arteries using an organ chamber bath. Vessels were incubated with leptin (100 ng/ml) or vehicle (0.1 mM Tris·HCl) for 30 min. Leptin treatment resulted in significant impairment of vessel relaxation to the endothelial-specific agonist acetylcholine (ACh). When these experiments were repeated in the presence of the superoxide scavenger tempol, relaxation responses to ACh were restored. VSM-LepR deletion resulted in a significant attenuation of leptin-mediated impaired ACh-induced relaxation. These data show that leptin directly impairs vascular relaxation via a VSM-LepR-mediated mechanism, suggesting a potential pathogenic role for leptin to increase cardiovascular risk during obesity.
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Affiliation(s)
- Michael J Ryan
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, Jackson, Mississippi; and
| | - T Taylor Coleman
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, Jackson, Mississippi; and
| | - Jennifer M Sasser
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Katarina M Pittman
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, Jackson, Mississippi; and
| | - Michael W Hankins
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, Jackson, Mississippi; and
| | - David E Stec
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, Jackson, Mississippi; and
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Ghantous CM, Azrak Z, Hanache S, Abou-Kheir W, Zeidan A. Differential Role of Leptin and Adiponectin in Cardiovascular System. Int J Endocrinol 2015; 2015:534320. [PMID: 26064110 PMCID: PMC4433709 DOI: 10.1155/2015/534320] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 04/23/2015] [Indexed: 02/07/2023] Open
Abstract
Leptin and adiponectin are differentially expressed adipokines in obesity and cardiovascular diseases. Leptin levels are directly associated with adipose tissue mass, while adiponectin levels are downregulated in obesity. Although significantly produced by adipocytes, leptin is also produced by vascular smooth muscle cells and cardiomyocytes. Plasma leptin concentrations are elevated in cases of cardiovascular diseases, such as hypertension, congestive heart failure, and myocardial infarction. As for the event of left ventricular hypertrophy, researchers have been stirring controversy about the role of leptin in this form of cardiac remodeling. In this review, we discuss how leptin has been shown to play an antihypertrophic role in the development of left ventricular hypertrophy through in vitro experiments, population-based cross-sectional studies, and longitudinal cohort studies. Conversely, we also examine how leptin may actually promote left ventricular hypertrophy using in vitro analysis and human-based univariate and multiple linear stepwise regression analysis. On the other hand, as opposed to leptin's generally detrimental effects on the cardiovascular system, adiponectin is a cardioprotective hormone that reduces left ventricular and vascular hypertrophy, oxidative stress, and inflammation. In this review, we also highlight adiponectin signaling and its protective actions on the cardiovascular system.
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Affiliation(s)
- C. M. Ghantous
- Department of Anatomy, Cell biology and Physiology, American University of Beirut, DTS-255, P.O. Box 11-0236, Beirut 1107-2020, Lebanon
| | - Z. Azrak
- Department of Pharmacology and Toxicology, American University of Beirut, DTS-255, P.O. Box 11-0236, Beirut 1107-2020, Lebanon
| | - S. Hanache
- Department of Anatomy, Cell biology and Physiology, American University of Beirut, DTS-255, P.O. Box 11-0236, Beirut 1107-2020, Lebanon
| | - W. Abou-Kheir
- Department of Anatomy, Cell biology and Physiology, American University of Beirut, DTS-255, P.O. Box 11-0236, Beirut 1107-2020, Lebanon
| | - A. Zeidan
- Department of Anatomy, Cell biology and Physiology, American University of Beirut, DTS-255, P.O. Box 11-0236, Beirut 1107-2020, Lebanon
- *A. Zeidan:
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12
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Li H, Wang YP, Zhang LN, Tian G. Perivascular adipose tissue-derived leptin promotes vascular smooth muscle cell phenotypic switching via p38 mitogen-activated protein kinase in metabolic syndrome rats. Exp Biol Med (Maywood) 2014; 239:954-965. [PMID: 24719379 DOI: 10.1177/1535370214527903] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Perivascular adipose tissue (PVAT)-derived leptin is a detrimental adipocytokine and plays a critical role in the development of cardiovascular diseases in metabolic syndrome (MetS). During vascular remodeling, vascular smooth muscle cells (VSMCs) undergo phenotypic switching into a synthetic phenotype characterized by decreased expression of differentiation markers (smooth muscle myosin heavy chain, α-smooth muscle actin, and calponin) and increased proliferation. We aimed to determine whether PVAT-derived leptin influences VSMC phenotypic switching and to explore the underlying mechanisms in MetS rats. In vivo, 32 Wistar rats were divided into two groups that received either a normal diet (control rat) or a high-fat diet (MetS rats). After 16 weeks, rat aortas were stained using hematoxylin–eosin and imaged. VSMC differentiation markers and proliferating cell nuclear antigen (PCNA), PVAT-derived leptin, aortic leptin receptor (ObR), and p38 mitogen-activated protein kinase (MAPK) expression were detected. In vitro, aortic VSMCs were incubated with MetS rat PVAT conditioned medium (PVAT-CM) to mimic in vivo conditions and were pretreated with a p38 MAPK inhibitor (SB 203580) or leptin antagonist. Differentiation marker expression, including PCNA and p38 MAPK, was detected. MetS rats exhibited pronounced insulin resistance, hyperglycemia, hyperlipidemia, hypertension, obesity, and an associated increase in PVAT weight. VSMCs underwent phenotypic switching in MetS rat aorta and contributed to vascular remodeling. PVAT-derived leptin expression was higher in MetS rats than in control rats ( P < 0.01). ObRa expression and p38 MAPK phosphorylation were upregulated in MetS rat aorta. In vitro, VSMCs incubated with MetS rat PVAT-CM underwent phenotypic switching, associated with increased p38 MAPK phosphorylation. This VSMC phenotypic switching was inhibited by pretreatment with SB 203580 or a leptin antagonist. These results suggest that in MetS rats, PVAT-derived leptin promotes VSMC phenotypic switching via a p38 MAPK-dependent pathway to exacerbate vascular remodeling.
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Affiliation(s)
- Hao Li
- Department of Cardiovascular Medicine, the First Affiliated Hospital, Xi’an Jiaotong University College of Medicine, Xi’an, Shaanxi 710061, P.R. China
- Department of Critical Care Medicine, the First Affiliated Hospital, Xi’an Jiaotong University College of Medicine, Xi’an, Shaanxi 710061, P.R. China
| | - Ya-Ping Wang
- Geriatric Cardiology Department,Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi 710061, P.R. China
| | - Li-Na Zhang
- Department of Cardiovascular Medicine, the First Affiliated Hospital, Xi’an Jiaotong University College of Medicine, Xi’an, Shaanxi 710061, P.R. China
| | - Gang Tian
- Department of Cardiovascular Medicine, the First Affiliated Hospital, Xi’an Jiaotong University College of Medicine, Xi’an, Shaanxi 710061, P.R. China
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Pellegrino MJ, McCully BH, Habecker BA. Leptin stimulates sympathetic axon outgrowth. Neurosci Lett 2014; 566:1-5. [PMID: 24561183 DOI: 10.1016/j.neulet.2014.02.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/27/2014] [Accepted: 02/07/2014] [Indexed: 12/28/2022]
Abstract
The neurohormone leptin regulates energy homeostasis. Circulating levels of leptin secreted by adipose tissue act on hypothalamic neurons in the brain leading to decreased appetite and increased energy expenditure. Although leptin signaling in the central nervous system (CNS) is fundamental to its ability to regulate the body's metabolic balance, leptin also has a variety of effects in many peripheral tissues including the heart, the liver, and the sympathetic nervous system. Leptin stimulation of the hypothalamus can stimulate glucose uptake via the sympathetic nervous system in heart, muscle, and brown adipose tissue. Leptin receptors (Ob-Rb) are also expressed by peripheral sympathetic neurons, but their functional role is not clear. In this study, we found that leptin stimulates axonal growth of both adult and neonatal sympathetic neurons in vitro. Leptin stimulates acute activation of the transcription factor STAT3 via phosphorylation of tyrosine 705. STAT3 phosphorylation is required for leptin-stimulated sympathetic axon outgrowth. Thus, circulating levels of leptin may enhance sympathetic nerve innervation of peripheral tissues.
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Affiliation(s)
- Michael J Pellegrino
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Belinda H McCully
- Trauma Research Institute of Oregon, Division of Trauma, Critical Care & Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Beth A Habecker
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA.
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Chen J, Mo H, Guo R, You Q, Huang R, Wu K. Inhibition of the leptin-induced activation of the p38 MAPK pathway contributes to the protective effects of naringin against high glucose-induced injury in H9c2 cardiac cells. Int J Mol Med 2014; 33:605-12. [PMID: 24399619 DOI: 10.3892/ijmm.2014.1614] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 12/24/2013] [Indexed: 11/05/2022] Open
Abstract
Leptin, a product of the obese gene, has been reported to contribute to the development of cardiomyocyte hypertrophy in patients with diabetes and to activate the p38 mitogen-activated protein kinase (MAPK) pathway in cardiomyocytes. In this study, we demonstrate that naringin, a citrus flavonone, protects cardiomyoblasts (H9c2 cells) against high glucose (HG)-induced apoptosis by modulating the activation of the p38 MAPK pathway. We investigated the hypothesis that naringin prevents HG-induced injury by inhibiting the leptin-induced activation of the p38 MAPK pathway in H9c2 cells. Our results demonstrated that the exposure of H9c2 cells to HG (35 mmol/l) for a 24 h markedly upregulated the expression levels of both leptin and leptin receptors. However, the increase in the expression levels of leptin and leptin receptors was greatly attenuated by treatment of the H9c2 cells with 80 µmol/l naringin 2 h prior to exposure to HG. In addition, treatment of the cells with 50 ng/ml leptin antagonist (LA) for 24 h prior to exposure to HG markedly ameliorated the increased expression of phosphorylated (p)-p38 MAPK induced by HG. Of note, pre-treatment of the cells with either 80 µmol/l naringin or 50 ng/ml LA markedly inhibited the HG-induced injury, leading to an increase in cell viability and a decrease in the total number of apoptotic cells, preventing reactive oxygen species (ROS) generation, as well as the dissipation of mitochondrial membrane potential (MMP). In conclusion, the findings of the present study provide the first evidence that the leptin-induced activation of the p38 MAPK pathway is involved in HG-induced injury, including cytotoxicity, apoptosis, ROS generation and the dissipation of MMP in H9c2 cardiac cells. Our data demonstrate that naringin protects cardiac cells against HG-induced injury by inhibiting the leptin-induced activation of the p38 MAPK pathway.
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Affiliation(s)
- Jingfu Chen
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
| | - Hailiang Mo
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
| | - Runmin Guo
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
| | - Qiong You
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
| | - Ruina Huang
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
| | - Keng Wu
- Department of Cardiovasology, The Affiliated Hospital, Guangdong Medical College, Zhanjiang, Guangdong 524001, P.R. China
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15
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Moreira F, Corcini C, Mondadori R, Gevehr-Fernandes C, Mendes F, Araújo E, Lucia T. Leptin and mitogen-activated protein kinase (MAPK) in oocytes of sows and gilts. Anim Reprod Sci 2013; 139:89-94. [DOI: 10.1016/j.anireprosci.2013.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 03/15/2013] [Accepted: 03/21/2013] [Indexed: 12/21/2022]
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16
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Yamazaki Y, Emoto M, Morioka T, Kawano N, Lee E, Urata H, Tsuchikura S, Motoyama K, Mori K, Fukumoto S, Shoji T, Nishizawa Y, Inaba M. Clinical impact of the leptin to soluble leptin receptor ratio on subclinical carotid atherosclerosis in patients with type 2 diabetes. J Atheroscler Thromb 2012; 20:186-94. [PMID: 23124060 DOI: 10.5551/jat.14662] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM The adipocyte-derived hormone leptin plays a key role in the regulation of food intake and energy expenditure. Recent studies have suggested that leptin is also involved in the pathogenesis of obesity-associated atherosclerosis and cardiovascular disease. In this study, we investigated the associations of leptin and the soluble leptin receptor (sOb-R) with atherosclerosis in patients with type 2 diabetes. METHODS Three hundred seventeen type 2 diabetic subjects were enrolled in this cross-sectional study. Fasting plasma leptin and sOb-R concentrations were measured by enzyme-linked immunosorbent assays. The intima-media thickness (IMT) of the common carotid artery was measured by ultrasound. RESULTS The IMT was significantly associated with sOb-R concentrations, age, diabetes duration, serum creatinine (sCre) levels, and systolic blood pressure (SBP), but not with leptin concentrations or the leptin/sOb-R ratio. The concentrations of leptin (r=0.478, p<0.001) and the sOb-R (r= -0.404, p<0.001) and the leptin/sOb-R ratio (r=0.501, p<0.001) were strongly correlated with IMT in subjects treated with insulin for glycemic control, but not in those treated with diet alone or oral hypoglycemic agents. Multiple regression analysis, including age, sex, diabetes duration, body mass index, SBP, HbA1c, triglycerides, LDL-cholesterol, sCre, smoking, and insulin therapy, revealed that plasma leptin and the leptin/sOb-R ratio were independently associated with IMT in subjects treated with insulin. CONCLUSIONS Plasma leptin and the leptin/sOb-R ratio are associated with atherosclerosis in patients with type 2 diabetes on insulin therapy, and these associations were independent of obesity and other cardiovascular risk factors.
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Affiliation(s)
- Yuko Yamazaki
- Metabolism, Endocrinology, and Molecular Medicine, Osaka City University Graduate School of Medicine, Asahi-machi, Abeno-ku, Osaka, Japan.
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Northcott JM, Yeganeh A, Taylor CG, Zahradka P, Wigle JT. Adipokines and the cardiovascular system: mechanisms mediating health and disease. Can J Physiol Pharmacol 2012; 90:1029-59. [DOI: 10.1139/y2012-053] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review focuses on the role of adipokines in the maintenance of a healthy cardiovascular system, and the mechanisms by which these factors mediate the development of cardiovascular disease in obesity. Adipocytes are the major cell type comprising the adipose tissue. These cells secrete numerous factors, termed adipokines, into the blood, including adiponectin, leptin, resistin, chemerin, omentin, vaspin, and visfatin. Adipose tissue is a highly vascularised endocrine organ, and different adipose depots have distinct adipokine secretion profiles, which are altered with obesity. The ability of many adipokines to stimulate angiogenesis is crucial for adipose tissue expansion; however, excessive blood vessel growth is deleterious. As well, some adipokines induce inflammation, which promotes cardiovascular disease progression. We discuss how these 7 aforementioned adipokines act upon the various cardiovascular cell types (endothelial progenitor cells, endothelial cells, vascular smooth muscle cells, pericytes, cardiomyocytes, and cardiac fibroblasts), the direct effects of these actions, and their overall impact on the cardiovascular system. These were chosen, as these adipokines are secreted predominantly from adipocytes and have known effects on cardiovascular cells.
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Affiliation(s)
- Josette M. Northcott
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Institute of Cardiovascular Sciences, and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB R2H 2A6, Canada
| | - Azadeh Yeganeh
- Department of Physiology, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB R3T 2N2, Canada
| | - Carla G. Taylor
- Department of Physiology, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB R3T 2N2, Canada
| | - Peter Zahradka
- Department of Physiology, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB R3T 2N2, Canada
| | - Jeffrey T. Wigle
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3E OJ9, Canada
- Institute of Cardiovascular Sciences, and Medicine, St. Boniface Hospital Research Centre, Winnipeg, MB R2H 2A6, Canada
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Napoleone E, Cutrone A, Cugino D, Latella MC, Zurlo F, Iacoviello L, de Gaetano G, Donati MB, Lorenzet R. Leptin upregulates tissue factor expression in human breast cancer MCF-7 cells. Thromb Res 2011; 129:641-7. [PMID: 21840575 DOI: 10.1016/j.thromres.2011.07.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/26/2011] [Accepted: 07/20/2011] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Obesity is a risk factor for both cardiovascular disease and cancer development. Leptin, a cytokine produced by adipose tissue, controls different processes in peripheral tissues, including cancer development and thrombotic disorders in patients with a variety of clinical disorders. Tissue factor (TF), the trigger of blood clotting, is abundant in the adipose tissue. Since TF, often expressed by cancer cells, is considered a hallmark of cancer progression, we investigated whether leptin could modulate TF in the human metastatic breast carcinoma cell line MCF-7. MATERIALS AND METHODS MCF-7 cells were incubated with or without the different reagents at 37 °C. At the end of incubation, cells were tested for procoagulant activity by a one-stage clotting assay, TF and TNF-α antigen levels and mRNA by ELISA and real-time RT-PCR, respectively. Leptin receptor was studied by FACS. RESULTS Both TF activity and antigen constitutively expressed by MCF-7 were significantly increased by leptin in a dose-dependent fashion. TF mRNA levels were also enhanced indicating that leptin exerts its effect at the transcription level. The effect of leptin was specific and required binding to its receptor (Ob-R), which was found on the surface of the cells, since antibodies against leptin and Ob-R completely prevented TF expression upregulation. In addition, leptin enhanced both TNF-α mRNA synthesis and secretion from MCF7. An anti-TNF-α MoAb completely abolished the leptin-induced TF expression. CONCLUSIONS These data support the hypothesis that leptin, by its upregulation of TF, possibly mediated by TNF-α synthesis, may contribute to processes underlying both cancer and vascular cell disorders.
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Affiliation(s)
- Emanuela Napoleone
- Research Laboratories, Giovanni Paolo II Center for High Technology Research, and Education in Biomedical Sciences, Catholic University, Largo Gemelli 1, 86100 Campobasso, Italy
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Nagasu H, Satoh M, Kuwabara A, Yorimitsu D, Kidokoro K, Nishi Y, Tomita N, Sasaki T, Kashihara N. Overexpression of klotho protein modulates uninephrectomy-induced compensatory renal hypertrophy by suppressing IGF-I signals. Biochem Biophys Res Commun 2011; 407:39-43. [PMID: 21354104 DOI: 10.1016/j.bbrc.2011.02.089] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 02/18/2011] [Indexed: 10/18/2022]
Abstract
The klotho gene is highly expressed in the distal convoluted tubule of the kidney, while its encoded protein has many physiological and pathophysiological renal roles. We investigated the effect of klotho protein on physiological compensatory renal hypertrophy after nephrectomy in klotho transgenic (KLTG) mice. Renal hypertrophy was suppressed in KLTG mice compared with wild-type mice, and this was associated with suppression of insulin growth factor-1 (IGF-1) signaling by klotho protein. In vitro, IGF-1 signaling was suppressed in human proximal tubular cells transfected with the klotho plasmid. Our data suggest that klotho modulates compensatory renal hypertrophy after nephrectomy via suppression of the IGF-1 signaling pathway, indicating a novel physiological role for klotho protein in the kidney.
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Affiliation(s)
- Hajime Nagasu
- Department of Nephrology and Hypertension, Kawasaki Medical School, Kurashiki, Okayama, Japan.
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20
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mTOR mediates RhoA-dependent leptin-induced cardiomyocyte hypertrophy. Mol Cell Biochem 2011; 352:99-108. [PMID: 21318349 DOI: 10.1007/s11010-011-0744-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/28/2011] [Indexed: 01/29/2023]
Abstract
Obesity is associated with increased leptin production which may contribute to cardiac hypertrophy. However, the mechanism of leptin-induced cardiac hypertrophy remains incompletely understood. The Rho family (RhoA, Rac1, and Cdc42) and mammalian target of rapamycin (mTOR) have recently emerged as important regulators of cell growth. We therefore explored the roles and interrelationships of phosphatidylinositol 3-kinase (PI3K), mTOR, and the Rho family in the regulation of actin polymerization and leptin-induced hypertrophy in cultured neonatal rat ventricular myocytes. Five minutes treatment with leptin (3.1 nM) resulted in activation of RhoA and Rac1 (by 330 and 160%, respectively, P < 0.05) which was significantly attenuated by AG-490 (50 μM) and LY294002 (10 μM), specific inhibitors of JAK2 and PI3K, respectively. However, Cdc42 activity was unaffected by leptin. The hypertrophic effect of leptin was associated with an increase in phosphorylation of p70(S6K), the major target of mTOR, by 110% (P < 0.05). The specific mTOR inhibitor rapamycin (10 nM) attenuated leptin-induced RhoA and Rac1 activation. Furthermore, the leptin-induced decrease in the G/F-actin ratio, a measure of actin polymerization, was blunted by rapamycin. Leptin produced activation of the transcriptional factor GATA4 which was attenuated by the RhoA inhibitor C3, the p38 MAPK inhibitor SB203580 (10 μM) as well as rapamycin. Our results demonstrate a critical role for PI3K/mTOR/p70(S6K) in leptin-induced RhoA activation resulting in cardiomyocyte hypertrophy associated with GATA4 stimulation.
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Schram K, De Girolamo S, Madani S, Munoz D, Thong F, Sweeney G. Leptin regulates MMP-2, TIMP-1 and collagen synthesis via p38 MAPK in HL-1 murine cardiomyocytes. Cell Mol Biol Lett 2010; 15:551-63. [PMID: 20683677 PMCID: PMC6275652 DOI: 10.2478/s11658-010-0027-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 07/23/2010] [Indexed: 01/18/2023] Open
Abstract
A clear association between obesity and heart failure exists and a significant role for leptin, the product of the obese gene, has been suggested. One aspect of myocardial remodeling which characterizes heart failure is a disruption in the balance of extracellular matrix synthesis and degradation. Here we investigated the effects of leptin on matrix metalloproteinase (MMP) activity, tissue inhibitor of metalloproteinase (TIMP) expression, as well as collagen synthesis in HL-1 cardiac muscle cells. Gelatin zymographic analysis of MMP activity in conditioned media showed that leptin enhanced MMP-2 activity in a dose- and time-dependent manner. Leptin is known to stimulate phosphorylation of p38 MAPK in cardiac cells and utilization of the p38 MAPK inhibitor, SB203580, demonstrated that this kinase also plays a role in regulating several extracellular matrix components, such that inhibition of p38 MAPK signaling prevented the leptin-induced increase in MMP-2 activation. We also observed that leptin enhanced collagen synthesis determined by both proline incorporation and picrosirius red staining of conditioned media. Pro-collagen type-I and pro-collagen type-III expression, measured by real-time PCR and Western blotting were also increased by leptin, effects which were again attenuated by SB203580. In summary, these results demonstrate the potential for leptin to play a role in mediating myocardial ECM remodeling and that the p38 MAPK pathway plays an important role in mediating these effects.
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Affiliation(s)
- Kristin Schram
- Department of Biology, York University, Toronto, Canada M3J 1P3
| | | | - Siham Madani
- Department of Biology, York University, Toronto, Canada M3J 1P3
| | - Diana Munoz
- Department of Biology, York University, Toronto, Canada M3J 1P3
| | - Farah Thong
- Department of Biology, York University, Toronto, Canada M3J 1P3
| | - Gary Sweeney
- Department of Biology, York University, Toronto, Canada M3J 1P3
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23
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Abstract
Obesity results from an abnormal accumulation of fat in the white adipose tissue. Recent research utilizing genetic models of obesity in rodents has implicated a major role of leptin as a controller of obesity. Leptin is a 167-amino acid peptide hormone encoded by the obesity gene (ob), which is secreted by adipocytes and plays an important role in regulating food intake, energy expenditure and adiposity. Leptin receptors (OB-R) are expressed in the central nervous system mainly in afferent satiety centres of hypothalamus and in peripheral organs such as adipose tissues, skeletal muscles, pancreatic beta-cells and liver, thus indicating the autocrine and paracrine role of leptin in energy regulation. In human beings, a highly organized circadian pattern of leptin secretion is observed with peak levels in the midnight probably resulting from cumulative hyperinsulinemia of entire day. Leptin has a dual role in weight maintenance. Leptin reflects total body adipose tissue mass whereas in conditions of negative and positive energy balance, the dynamic changes in plasma leptin concentration function as a sensor of energy balance and influence the efferent energy regulation pathways. Many effects of leptin on metabolism are mediated by interaction with Insulin and also by synergistic action with cholecystokinin. Besides physiological roles, leptin may influence pathological conditions like obesity-associated atherosclerosis, oxidative stress and cancers. The purpose of the present review is to summarize the important aspects of the biology, actions, and regulation of leptin and to serve as an update of new information.
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Papaharalambus CA, Griendling KK. Basic mechanisms of oxidative stress and reactive oxygen species in cardiovascular injury. Trends Cardiovasc Med 2007; 17:48-54. [PMID: 17292046 PMCID: PMC1934425 DOI: 10.1016/j.tcm.2006.11.005] [Citation(s) in RCA: 249] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 11/16/2006] [Accepted: 11/22/2006] [Indexed: 11/25/2022]
Abstract
The development of vascular disease has its origins in an initial insult to the vessel wall by biological or mechanical factors. The disruption of homeostatic mechanisms leads to alteration of the original architecture of the vessel and its biological responsiveness, contributing to acute or chronic diseases such as stroke, hypertension, and atherosclerosis. Endothelial dysfunction, macrophage infiltration of the vessel wall, and proliferation and migration of smooth muscle cells all involve different types of reactive oxygen species produced by various vessel wall components. Although basic science and animal research have clearly established the role of reactive oxygen species in the progression of vascular disease, the failure of clinical trials with antioxidant compounds has underscored the need for better antioxidant therapies and a more thorough understanding of the role of reactive oxygen species in cardiovascular physiology and pathology.
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Wauman J, De Smet AS, Catteeuw D, Belsham D, Tavernier J. Insulin receptor substrate 4 couples the leptin receptor to multiple signaling pathways. Mol Endocrinol 2007; 22:965-77. [PMID: 18165436 DOI: 10.1210/me.2007-0414] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Leptin is an adipokine that regulates food intake and energy expenditure by activating its hypothalamic leptin receptor (LR). Members of the insulin receptor substrate (IRS) family serve as adaptor proteins in the signaling pathways of several cytokines and hormones and a role for IRS2 in central leptin physiology is well established. Using mammalian protein-protein interaction trap (MAPPIT), a cytokine receptor-based two-hybrid method, in the N38 hypothalamic cell line, we here demonstrate that also IRS4 interacts with the LR. This recruitment is leptin dependent and requires phosphorylation of the Y1077 motif of the LR. Domain mapping of IRS4 revealed the critical role of the pleckstrin homology domain for full interaction. In line with its function as an adaptor protein, IRS4 interacted with the regulatory p85 subunit of the phosphatidylinositol 3-kinase, phospholipase Cgamma, and the suppressor of cytokine signaling (SOCS) family members SOCS2, SOCS6, and SOCS7 and thus can modulate LR signaling.
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Affiliation(s)
- Joris Wauman
- Department of Medical Protein Research, University of Ghent, A. Baertsoenkaai 3, 9000 Ghent, Belgium
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26
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Koklu E, Ozturk MA, Kurtoglu S, Akcakus M, Yikilmaz A, Gunes T. Aortic intima-media thickness, serum IGF-I, IGFBP-3, and leptin levels in intrauterine growth-restricted newborns of healthy mothers. Pediatr Res 2007; 62:704-9. [PMID: 17957164 DOI: 10.1203/pdr.0b013e318157caaa] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neonates with intrauterine growth restriction (IUGR) are associated with reduced concentrations of IGF-I that might contribute to arterial wall thickening. Direct atherogenic effects of leptin have been described. We aimed to investigate the relationship among abdominal aortic intima-media thickness (aIMT), serum IGF-I, IGF binding protein-3, and leptin levels in neonates with IUGR. Abdominal aIMT was measured in 40 term neonates with IUGR and in 40 controls. Mean aIMT was significantly greater in neonates with IUGR (0.45 +/- 0.03 mm) than in controls (0.39 +/- 0.04 mm, p < 0.0001). Serum IGF-I and leptin levels were lower in neonates with IUGR than in controls. There was a significant positive correlation between aIMT and gestational age, whereas a significant negative correlation was determined between aIMT and IGF-I in the IUGR neonates. For aIMT, significant associations included serum IGF-I level (beta = -0.406, p = 0.006) and gestational age (beta = 0.331, p = 0.022) in a multiple stepwise linear regression analysis. In control neonates, serum IGF-I levels were negatively related to aIMT (beta = -0.750, p < 0.001). Neonates with IUGR have significant aIMT with decreased IGF-I. IGF-I levels determine aIMT not only in neonates with IUGR but also in healthy controls.
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Affiliation(s)
- Esad Koklu
- Department of Pediatrics, Division of Neonatology, Erciyes University, Kayseri, 38039, Turkey.
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27
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Abstract
Leptin, among the best known hormone markers for obesity, exerts pleiotropic actions on multiple organ systems. In this review, we summarize major leptin signaling pathways, namely Janus-activated kinase/signal transducers and activators of transcription and mitogen-activated protein kinase, including possible mechanisms of leptin resistance in obesity. The effects of leptin on the cardiovascular system are discussed in detail, including its contributions to hypertension, atherosclerosis, depressed myocardial contractile function, fatty acid metabolism, hypertrophic remodeling, and reduction of ischemic/reperfusion injury. The overall goal is to summarize current understanding of how altered leptin signaling in obesity contributes to obesity-related cardiovascular disease.
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Affiliation(s)
- Ronghua Yang
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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Schroeter MR, Schneiderman J, Schumann B, Glückermann R, Grimmas P, Buchwald AB, Tirilomis T, Schöndube FA, Konstantinides SV, Schäfer K. Expression of the leptin receptor in different types of vascular lesions. Histochem Cell Biol 2007; 128:323-33. [PMID: 17680264 DOI: 10.1007/s00418-007-0319-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2007] [Indexed: 12/21/2022]
Abstract
Clinical and experimental evidence suggests that the adipokine leptin may be important for the development of cardiovascular complications associated with obesity, possibly through interaction with its receptor on vascular cells. In the present study, we systematically analysed expression of the leptin receptor in normal and diseased vascular specimens using immunohistochemistry, immunofluorescence and quantitative real time-PCR. In particular, human atherosclerotic plaques as well as experimental vascular lesions induced in hypercholesterolemic mice and minipigs, respectively, were examined. Our results demonstrate the presence of the leptin receptor in normal vessel wall segments as well as neointimal or atherosclerotic lesions. In the latter, ObR expressing cells were predominantly localised on the luminal border and within the subintima, and coexpression of von Willebrand factor, VEGF receptor-2 or VE cadherin identified them as endothelial cells. Moreover, CD14-positive monocytes/macrophages were strongly positive for the leptin receptor. In contrast, only few ObR-expressing smooth muscle cells could be detected in human atherosclerotic plaques. The findings of the present study thus support a possible action of leptin on the cardiovascular system by demonstrating expression of the leptin receptor in different types of vascular lesions.
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Affiliation(s)
- Marco R Schroeter
- Department of Cardiology and Pulmonary Medicine, Georg August University of Göttingen, Göttingen, Germany
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29
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Louis H, Kakou A, Regnault V, Labat C, Bressenot A, Gao-Li J, Gardner H, Thornton SN, Challande P, Li Z, Lacolley P. Role of alpha1beta1-integrin in arterial stiffness and angiotensin-induced arterial wall hypertrophy in mice. Am J Physiol Heart Circ Physiol 2007; 293:H2597-604. [PMID: 17660399 DOI: 10.1152/ajpheart.00299.2007] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the arterial phenotype of mice lacking alpha(1)-integrin (alpha(1)(-/-)) at baseline and after 4 wk of ANG II or norepinephrine (NE) administration. Arterial mechanical properties were determined in the carotid artery (CA). Integrin expression, MAPK kinases, and focal adhesion kinase (FAK) were assessed in the aorta. No change in arterial pressure was observed in alpha(1)(-/-) mice. Elastic modulus-wall stress curves were similar in alpha(1)(-/-) and alpha(1)(+/+) animals, indicating no change in arterial stiffness. The rupture pressure was lower in alpha(1)(-/-) mice, demonstrating decreased mechanical strength. Lack of alpha(1)-integrin was accompanied by an increase in beta(1)-, alpha(v)-, and alpha(5)-integrins but no change in alpha(2)-integrin. ANG II increased medial cross-sectional area of the CA in alpha(1)(+/+), but not alpha(1)(-/-), mice, whereas equivalent pressor doses of NE did not produce a significant increase in either group. In alpha(1)(+/+) mice, ANG II induced alpha(1)-integrin expression and smooth muscle cell (SMC) hypertrophy in the CA in association with increased aortic expression of alpha-smooth muscle actin and smooth muscle myosin heavy chain and phosphorylation of ERK1/2, p38 MAPK, and FAK. ANG II did not induce SMC hypertrophy or phosphorylation of p38 MAPK and FAK in alpha(1)(-/-) mice. A functional anti-alpha(1)-integrin antibody inhibited in vitro the ANG II-induced phosphorylation of FAK and p38 MAPK. In conclusion, alpha(1)(-/-) mice exhibit a reduced mechanical strength at baseline and a lack of ANG II-induced SMC hypertrophy. These results emphasize the importance of alpha(1)beta(1)-integrin in p38 MAPK and FAK phosphorylation during vascular hypertrophy in response to ANG II.
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MESH Headings
- Angiotensin II/metabolism
- Angiotensin II/pharmacology
- Animals
- Aorta/enzymology
- Aorta/metabolism
- Blood Pressure
- Carotid Artery, Common/drug effects
- Carotid Artery, Common/metabolism
- Carotid Artery, Common/pathology
- Carotid Artery, Common/physiopathology
- Elasticity
- Focal Adhesion Kinase 1/metabolism
- Genotype
- Heart Rate
- Hypertrophy
- Integrin alpha1/genetics
- Integrin alpha1/metabolism
- Integrin alpha1beta1/deficiency
- Integrin alpha1beta1/genetics
- Integrin alpha1beta1/metabolism
- Mice
- Mice, Knockout
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/metabolism
- Norepinephrine/metabolism
- Norepinephrine/pharmacology
- Phenotype
- Phosphorylation
- Rupture
- Tensile Strength
- Vasoconstrictor Agents/metabolism
- Vasoconstrictor Agents/pharmacology
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- Huguette Louis
- Institut National de la Santé et de la Recherche Médicale, U684, Nancy, France
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30
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Chao HH, Hong HJ, Liu JC, Lin JW, Chen YL, Chiu WT, Wu CH, Shyu KG, Cheng TH. Leptin stimulates endothelin-1 expression via extracellular signal-regulated kinase by epidermal growth factor receptor transactivation in rat aortic smooth muscle cells. Eur J Pharmacol 2007; 573:49-54. [PMID: 17678888 DOI: 10.1016/j.ejphar.2007.06.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 04/16/2007] [Accepted: 06/20/2007] [Indexed: 11/30/2022]
Abstract
Obesity is a major risk factor for the development of hypertension. Recent studies have suggested that leptin, a 167-amino acid peptide hormone produced by white adipose tissue, is related to the pathogenesis of obesity-related hypertension. However, the signaling mechanisms underlying the effects of leptin remain to be extensively examined. In this study, we found that leptin induced extracellular signal-regulated kinase phosphorylation and endothelin-1 expression in rat aortic smooth muscle cells. Both PD98059 and U0126, inhibitors of the upstream activator of mitogen-activated protein kinase kinase, inhibited augmentation of endothelin-1 expression stimulated with leptin. Leptin induced significant tyrosine phosphorylation of epidermal growth factor receptor, which was significantly attenuated by two inhibitors, an epidermal growth factor receptor tyrosine kinase inhibitor, AG1478, and a broad-spectrum matrix metalloproteinase inhibitor, GM6001. This indicates that the pathway of epidermal growth factor receptor transactivation induced by leptin is dependent on proteolytically released epidermal growth factor receptor ligands. Pretreatment of cells with AG1478 significantly reduced the degree of phosphorylation of extracellular signal-regulated kinase and endothelin-1 expression. Our results reveal that epidermal growth factor receptor transactivation is involved in the leptin signaling pathway in vascular smooth muscle cells, which may be related to the increased risk of hypertension and other cardiovascular diseases in obese subjects.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Blotting, Northern
- Blotting, Western
- Butadienes/pharmacology
- Cells, Cultured
- Dipeptides/pharmacology
- Dose-Response Relationship, Drug
- Endothelin-1/genetics
- Endothelin-1/metabolism
- ErbB Receptors/antagonists & inhibitors
- ErbB Receptors/genetics
- ErbB Receptors/metabolism
- Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors
- Extracellular Signal-Regulated MAP Kinases/genetics
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Flavonoids/pharmacology
- Leptin/pharmacology
- Male
- Metalloendopeptidases/antagonists & inhibitors
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitriles/pharmacology
- Phosphorylation/drug effects
- Quinazolines
- RNA/genetics
- RNA/isolation & purification
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Signal Transduction/drug effects
- Transcriptional Activation/drug effects
- Tyrosine/metabolism
- Tyrphostins/pharmacology
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Affiliation(s)
- Hung-Hsing Chao
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
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31
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Napoleone E, DI Santo A, Amore C, Baccante G, di Febbo C, Porreca E, de Gaetano G, Donati MB, Lorenzet R. Leptin induces tissue factor expression in human peripheral blood mononuclear cells: a possible link between obesity and cardiovascular risk? J Thromb Haemost 2007; 5:1462-8. [PMID: 17425664 DOI: 10.1111/j.1538-7836.2007.02578.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Obesity is a major modifiable risk factor for cardiovascular disease. Leptin, the hormone synthesized and released primarily by adipose tissue and found increased in obese individuals, has been implicated in the regulation of inflammation and arterial and venous thrombosis. OBJECTIVE To investigate the role of tissue factor (TF), the pivotal agonist of the clotting cascade, as a link between obesity and cardiovascular disease. METHODS AND RESULTS In 15 obese patients, plasma levels of leptin and TF as well as TF expression in resting and endotoxin-stimulated mononuclear leukocytes (MN) were increased when compared with healthy donors. In a selected sample of obese patients, loss of body weight led to decreased circulating leptin levels, accompanied by a reduction in plasma TF as well as in TF expression, both in resting and endotoxin-stimulated MN. In subsequent in vitro experiments, leptin was incubated with MN from healthy subjects. Leptin induced TF activity and antigen in a dose-dependent fashion, as assessed by clotting assay and ELISA, respectively. Increased migration of c-Rel/p65 into the nucleus, as determined by EMSA, and development of TF mRNA in monocytes, as assessed by RT-PCR, were observed. Experiments with mitogen-activated protein kinase (MAPK) inhibitors, indicated the involvement of p38 and ERK1/2 pathways. CONCLUSIONS The presence of TF-expressing MN in blood from obese subjects and the in vitro induction of TF by pharmacologic concentrations of leptin in MN from healthy subjects suggest that TF expression by leptin-stimulated monocytes may contribute to the cardiovascular risk associated with obesity.
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Affiliation(s)
- E Napoleone
- Centro Giovanni Paolo II di Ricerche e Formazione ad Alta Tecnologia nelle Scienze Biomediche, Università Cattolica, Campobasso, Italy
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32
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Zeidan A, Paylor B, Steinhoff KJ, Javadov S, Rajapurohitam V, Chakrabarti S, Karmazyn M. Actin cytoskeleton dynamics promotes leptin-induced vascular smooth muscle hypertrophy via RhoA/ROCK- and phosphatidylinositol 3-kinase/protein kinase B-dependent pathways. J Pharmacol Exp Ther 2007; 322:1110-6. [PMID: 17562852 DOI: 10.1124/jpet.107.122440] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Obesity is associated with increased leptin production that may contribute to cardiovascular pathology through a multiplicity of effects. Leptin has been shown to contribute to vascular remodeling through various mechanisms, including production of vascular smooth muscle (VSMC) hypertrophy; however, the mechanisms underlying the vascular hypertrophic effect of leptin remain unknown. In the present study, we investigated the contributions of the RhoA/Rho kinase (ROCK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathways, actin dynamics, and the expression of serum-response factor (SRF) in the hypertrophic effects of leptin on vascular tissue. Strips of rat portal vein (RPV) were cultured with or without leptin at 3.1 nM for 1 to 3 days. Leptin significantly increased RhoA activity by 163 +/- 20%, whereas phosphorylation of downstream factors, including LIM kinase 1 and cofilin-2, was increased by 160 +/- 25 and 290 +/- 25%, respectively. Leptin also significantly phosphorylated Akt by 130 +/- 30%, which was inhibited by the PI3K inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002). RhoA/ROCK and PI3K/Akt activation was associated with a significant increase in RPV wet weight (11 +/- 1%), protein synthesis (45 +/- 7%), SRF expression (136 +/- 11%), and polymerization of actin, as reflected by an increase in the F-/G-actin ratio, effects that were significantly attenuated by a leptin receptor (leptin obese receptor) antibody, the ROCK inhibitor (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) (Y-27632) as well as the PI3K inhibitor LY294002. Our results indicate that the activation of RhoA/ROCK and PI3K/Akt plays a pivotal role in leptin signaling, leading to the development of VSMC hypertrophy through a mechanism involving altered actin dynamics.
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Affiliation(s)
- Asad Zeidan
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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33
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Abstract
Obesity is a major risk factor for cardiovascular diseases, but the mechanisms for increased cardiovascular risk in obesity are still unclear. Inflammation and increased oxidative stress are two potential mechanisms proposed to play a major role in the morbidity associated with obesity. Studies that investigate these mechanisms rely on biomarkers, but validated biomarkers for obesity-related cardiovascular outcomes are lacking. By finding optimal biomarkers, diagnostic criteria for cardiovascular diseases can be refined in the obese beyond "traditional" risk factors to identify early pathologic processes. The objective of this review is to identify potential early biomarkers resulting from obesity and associated with cardiovascular disease. Studies were initially identified through the search engine PubMed by using the keywords "obesity" and "biomarker." Subsequently, combinations of the keywords "obesity," "biomarker," "cardiovascular risk," "adipose tissue," "adipokine," "adipocytokine," and "oxidative stress" were used. The SOURCE database and Online Mendelian Inheritance in Man (OMIM) were used to obtain more information on the biomarkers. Results of the searches yielded a large number of potential biomarkers that occur in obesity and which either correlate with traditional cardiovascular risk factors or predict subsequent cardiovascular events. Several biomarkers are promising regarding their biologic properties, but they require further validation in humans.
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Affiliation(s)
- Salma Musaad
- Division of Epidemiology and Biostatistics, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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34
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Matesanz N, Lafuente N, Azcutia V, Martín D, Cuadrado A, Nevado J, Rodríguez-Mañas L, Sánchez-Ferrer CF, Peiró C. Xanthine oxidase-derived extracellular superoxide anions stimulate activator protein 1 activity and hypertrophy in human vascular smooth muscle via c-Jun N-terminal kinase and p38 mitogen-activated protein kinases. J Hypertens 2007; 25:609-18. [PMID: 17278978 DOI: 10.1097/hjh.0b013e328013e7c4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Vascular xanthine oxidase (XO) activity has been found to be elevated in chronic vascular disease. Although a role for XO in endothelial dysfunction has been proposed, little is known about its influence on vascular smooth muscle maladaptive growth. METHODS The proliferative and hypertrophic response of human aortic smooth muscle cells (HASMC) stimulated with xanthine/xanthine oxidase (X/XO) was quantified by determining cell number, cell size and protein synthesis. The levels and activity of the growth-related transcription factor activator protein 1 (AP-1) and the activation of mitogen-activated protein kinase (MAPK) by X/XO were determined by either Western blot or transient transfection experiments. RESULTS X/XO did not affect HASMC proliferation, but led to enhanced planar cell surface area and protein synthesis. In addition, X/XO enhanced c-jun levels and AP-1 transcriptional activity. Although X/XO did not modify extracellular signal-regulated protein kinases 1/2 MAPK or Akt/PKB activity, it promoted the activation of c-Jun N-terminal kinase and p38 MAPK, which were both necessary for X/XO to increase AP-1 activity and cell size in HASMC cultures. Finally, the effects of X/XO on MAPK activation, AP-1 activity and cell size were dependent on the extracellular release of superoxide anions through the enzymatic activity of XO, as they were prevented by both superoxide dismutase and allopurinol. CONCLUSION X/XO exhibits hypertrophic properties for human vascular smooth muscle, which are mediated by redox-sensitive pathways involving MAPK activation. XO can therefore participate in the maladaptive vascular remodeling observed in chronic cardiovascular diseases exhibiting elevated vascular XO activity.
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MESH Headings
- Allopurinol/pharmacology
- Aorta/cytology
- Aorta/drug effects
- Cell Enlargement/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Humans
- Hypertrophy
- JNK Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Replication Protein C/metabolism
- Superoxides/pharmacology
- Xanthine Oxidase/antagonists & inhibitors
- Xanthine Oxidase/metabolism
- Xanthine Oxidase/pharmacology
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- Nuria Matesanz
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
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35
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Fantuzzi G, Mazzone T. Adipose tissue and atherosclerosis: exploring the connection. Arterioscler Thromb Vasc Biol 2007; 27:996-1003. [PMID: 17303782 DOI: 10.1161/atvbaha.106.131755] [Citation(s) in RCA: 282] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The prevalence of obesity, especially among the young, is dramatically increasing in the United States. Obesity is associated with accelerated atherosclerosis and increased rates of cardiovascular death. There are many plausible mechanisms by which an increase in adipose tissue could adversely affect the vessel wall. These include the changes in blood pressure, glucose level, lipid/lipoprotein metabolism, and systemic inflammation. In addition, factors secreted by adipose tissue may directly influence vessel wall homeostasis by influencing the function of endothelial cells, arterial smooth muscle cells, and macrophages in the vessel wall. There is general agreement that central, as opposed to peripheral, adipose tissue confers the most cardio-metabolic risk. Although the basis of this differential risk has not been not established, the pattern of gene expression and secretory products in visceral fat would be predicted to be more atherogenic compared with that in subcutaneous peripheral fat. Numerous studies have shown the beneficial effects of weight loss on markers of cardiovascular risk but fewer have demonstrated improvement in direct measures of large vessel disease. The unfolding role of adipose tissue as an important metabolic and secretory organ provides new opportunities for developing more effective approaches for preventing obesity and its atherosclerotic complications.
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Affiliation(s)
- Giamila Fantuzzi
- Department of Human Nutrition, University of Illinois at Chicago, USA
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36
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Koklu E, Kurtoglu S, Akcakus M, Yikilmaz A, Gunes T. Serum insulin-like growth factor-I (IGF-I) IGF binding protein-3 (IGFBP-3) and leptin levels are related to abdominal aortic intima-media thickness in macrosomic newborns. Growth Horm IGF Res 2007; 17:26-32. [PMID: 17113804 DOI: 10.1016/j.ghir.2006.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Revised: 10/07/2006] [Accepted: 10/10/2006] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Exposure to diabetes in utero has been established as a significant risk factor for some of the components of metabolic syndrome, and was associated with increased levels of maternal, placental, and fetal insulin-like growth factors and leptin. The atherogenic effects of leptin and insulin-like growth factor-I (IGF-I) have been extensively described. The present study was therefore designed to investigate relationships between abdominal aortic intima-media thickness (aIMT), serum IGF-I, IGF binding protein-3 (IGFBP-3) and leptin levels in macrosomic newborns. DESIGN Neonates whose birth weights exceed 90th percentile for gestational age and gender are termed macrosomic. Abdominal aortic intima-media thickness was measured in 30 macrosomic neonates of diabetic mothers (group A), 30 macrosomic neonates of healthy mothers (group B) and 30 healthy neonates (group C). Serum IGF-I, IGFBP-3 and leptin levels were determined in all infants and their mothers. Stepwise logistic regression analysis was used to determine independent risk factors for aortic intima-media thickness. RESULTS Mean aortic intima-media thickness was significantly higher in groups A and B (0.489+/-0.015,0.466+/-0.019 mm, respectively) than in controls (0.375+/-0.024 mm, p<0.0001). Weight-adjusted aortic intima-media thickness was significantly higher in-group A than in groups B (p=0.004) and C (p=0.048). Serum leptin concentration in-group B (37.4+/-10.7 ng/ml) was significantly greater than in-group C (23.5+/-7.1 ng/ml, p<0.0001), but significantly lower than in-group A (46.6+/-14.1 ng/ml, p<0.0001). Serum IGF-I levels of the infants were significantly lower in-group C (113.2+/-33.1 ng/ml) than in groups A and B (205.2+/-60.1 and 179.3+/-55.1 ng/ml respectively, p<0.0001). Serum IGF-I, IGFBP-3 and leptin levels of the infants were positively correlated with mean (p<0.0001) and weight-adjusted aortic intima-media thickness measurements (p=0.003, p=0.006 and p=0.001, respectively). CONCLUSIONS Macrosomic neonates of diabetic mothers have significantly increased aortic intima-media thickness with higher serum IGF-I, IGFBP-3 and leptin concentrations than those of controls. It might be speculated that these changes may exaggerate the atherosclerotic process later in life.
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Affiliation(s)
- Esad Koklu
- Erciyes University, School of Medicine, Department of Pediatrics, Division of Neonatology, 38039 Kayseri, Turkey.
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37
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Shin MJ, Park E. Plasma Levels of Leptin Are Associated with the Plasma Levels of LDL Conjugated Dienes in Children. ANNALS OF NUTRITION AND METABOLISM 2007; 51:1-6. [PMID: 17259698 DOI: 10.1159/000099010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Accepted: 08/23/2006] [Indexed: 01/25/2023]
Abstract
BACKGROUND Plasma leptin has been suggested to be involved in the proatherogenic process by increasing oxidative stress. We investigated the relationship between leptin and plasma conjugated diene formation, a measure of LDL oxidation in vivo in schoolchildren. METHODS We measured blood lipid profiles, plasma antioxidant vitamins, leptin and diene conjugation in LDL of 118 Korean children (35 overweight-obese vs. 83 normal weight children). RESULTS The overweight-obese children showed significantly higher levels of leptin (p < 0.0001), conjugated dienes (p = 0.02), total cholesterol (p < 0.05), triglyceride (p < 0.005) and LDL cholesterol (p < 0.01) and a significantly lower level of plasma lycopene (p < 0.0001) compared with the normal weight children. When all the subjects were classified into the three groups by tertiles of leptin levels, significant differences in circulating conjugated dienes (p < 0.05), lipid-corrected lycopene (p < 0.05), total cholesterol (p < 0.05), triglyceride (p < 0.05) and LDL cholesterol (p < 0.05) were found among the three groups. CONCLUSION Our results showed that leptin was positively associated with the LDL conjugated diene formation, which might be related to the proatherogenic process in schoolchildren.
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Affiliation(s)
- Min-Jeong Shin
- Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
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38
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Rodríguez A, Fortuño A, Gómez-Ambrosi J, Zalba G, Díez J, Frühbeck G. The inhibitory effect of leptin on angiotensin II-induced vasoconstriction in vascular smooth muscle cells is mediated via a nitric oxide-dependent mechanism. Endocrinology 2007; 148:324-31. [PMID: 17038553 DOI: 10.1210/en.2006-0940] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin inhibits the contractile response induced by angiotensin (Ang) II in vascular smooth muscle cells (VSMCs) of the aorta. We studied in vitro and ex vivo the role of nitric oxide (NO) in the effect of leptin on the Ang II-induced vasoconstriction of the aorta of 10-wk-old Wistar rats. NO and nitric oxide synthase (NOS) activity were assessed by the Griess and (3)H-arginine/citrulline conversion assays, respectively. Stimulation of inducible NOS (iNOS) as well as Janus kinases/signal transducers and activators of transcription (JAK/STAT) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways were determined by Western blot. The contractile responses to Ang II were evaluated in endothelium-denuded aortic rings using the organ bath system. Changes in intracellular Ca(2+) were measured in VSMCs using fura-2 fluorescence. Leptin significantly (P < or = 0.01) stimulated NO release and NOS activity in VSMCs. Leptin's effect on NO was abolished by the NOS inhibitor, N(G)-monomethyl l-arginine, or the iNOS selective inhibitor L-N(6)-(1-iminoethyl)-lysine. Accordingly, leptin increased iNOS protein expression, with a comparable time course with that of NO production and NOS activity. Leptin also significantly increased STAT3 (P < or = 0.01) and Akt (P < or = 0.001) phosphorylation. Moreover, either the JAK2 inhibitor, AG490, or the PI3K inhibitor, wortmannin, significantly (P < or = 0.05) abrogated the leptin-induced increase in iNOS protein. Finally, both N(G)-monomethyl L-arginine and L-N(6)-(1-iminoethyl)-lysine inhibitors completely blunted (P < or = 0.001) the leptin-mediated inhibition of the Ang II-induced VSMC activation and vasoconstriction. These findings suggest that the endothelium-independent depressor action of leptin is mediated by an increase of NO bioavailability in VSMCs. This process requires the up-regulation of iNOS through mechanisms involving JAK2/STAT3 and PI3K/Akt pathways.
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Affiliation(s)
- Amaia Rodríguez
- Department of Endocrinology, Clínica Universitaria de Navarra, Avda. Pío XII, 36, 31008 Pamplona, Spain
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39
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Cui H, Cai F, Belsham DD. Leptin signaling in neurotensin neurons involves STAT, MAP kinases ERK1/2, and p38 through c‐Fos and ATF1. FASEB J 2006; 20:2654-6. [PMID: 17077290 DOI: 10.1096/fj.06-5989fje] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The adipokine leptin signals energy status to the hypothalamus, which triggers a network of neuropeptide responses. Each hypothalamic cell type expresses a unique complement of neuropeptides, receptors, and second messengers; thus each likely responds specifically to peripheral hormones. We describe here the analysis of leptin signaling in a clonal population of mouse neurotensin (NT) -expressing hypothalamic neurons, N-39. Leptin induced phosphorylation of STAT3 and MAPK ERK1/2, but not the downstream effector of PI3K, Akt, and also induced c-Fos protein. We found activation of p38 MAPK by leptin, accompanied by phosphorylation of its downstream effector ATF-1. Phosphorylation of ATF-1 is blocked by the p38 MAPK inhibitor SB 203580. We linked this signaling directly to NT transcription. Protein binding analysis indicates that both ATF-1 and c-Fos are capable of binding to the mouse NT/N gene predominantly at physiological or high concentrations of leptin. The evidence indicates activation of distinct leptin signal transduction pathways that directly result in changes in NT gene expression and links these specific neurons to the control of energy homeostasis.
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Affiliation(s)
- Hong Cui
- Department of Physiology, University of Toronto, Toronto, ON, Canada M5S 1A8
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40
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Rajapurohitam V, Javadov S, Purdham DM, Kirshenbaum LA, Karmazyn M. An autocrine role for leptin in mediating the cardiomyocyte hypertrophic effects of angiotensin II and endothelin-1. J Mol Cell Cardiol 2006; 41:265-74. [PMID: 16806260 DOI: 10.1016/j.yjmcc.2006.05.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 04/14/2006] [Accepted: 05/01/2006] [Indexed: 11/24/2022]
Abstract
Leptin is a 16 kDa product of the obesity gene secreted primarily by adipocytes. We recently identified cardiomyocytes as a target for the direct hypertrophic effects of leptin and suggested that leptin may be a biological link between obesity and cardiovascular pathologies. Activation of the renin-angiotensin and endothelin systems is associated with development of cardiovascular diseases and plasma renin levels are elevated in obese individuals. We therefore determined possible interaction between these factors in mediating hypertrophy in cultured neonatal rat ventricular myocytes. Treatment for 24 h with leptin (3.1 nM), angiotensin II (100 nM) or endothelin-1 (ET-1, 10 nM) significantly increased cell area by 37%, 36% and 35%, respectively and significantly increased gene expression of myosin light chain-2 and alpha-skeletal actin as well as leucine incorporation. The hypertrophic effects of all three agents were prevented by leptin and a leptin triple mutant receptor antagonist whereas the AT(1) receptor blocker (Sar1-lle(8))-Ang II or the ET(A) receptor blocker BQ123 was ineffective against leptin-induced hypertrophy. Both angiotensin II and ET-1 significantly increased leptin levels in the culture medium by fivefold. Moreover, both angiotensin II and ET-1 increased the gene expression of the short form (OBRa) by 180% and long form (OBRb) of leptin receptors by 200%, and this increase was abolished by both leptin receptor and leptin antibodies and leptin triple mutant. Although both angiotensin II and ET-1 increased phosphorylation of MAPK (p38, ERK1/2 and JNK) and NF-kappaB, the ability of leptin blockade to attenuate the hypertrophic responses was generally dissociated from these effects suggesting an alternate, yet to be identified cellular pathway mediating this role of leptin. Our studies therefore suggest a novel autocrine function for leptin in mediating the hypertrophic effects of both angiotensin II and ET-1 in cardiac myocytes.
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Smith CCT, Mocanu MM, Davidson SM, Wynne AM, Simpkin JC, Yellon DM. Leptin, the obesity-associated hormone, exhibits direct cardioprotective effects. Br J Pharmacol 2006; 149:5-13. [PMID: 16847434 PMCID: PMC1629412 DOI: 10.1038/sj.bjp.0706834] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Protection against ischaemia-reperfusion (I/R) injury involves PI3K-Akt and p44/42 MAPK activation. Leptin which regulates appetite and energy balance also promotes myocyte proliferation via PI3K-Akt and p44/42 MAPK activation. We, therefore, hypothesized that leptin may also exhibit cardioprotective activity. EXPERIMENTAL APPROACH The influence of leptin on I/R injury was examined in perfused hearts from C57Bl/6 J mice that underwent 35 min global ischaemia and 35 min reperfusion, infarct size being assessed by triphenyltetrazolium chloride staining. The concomitant activation of cell-signalling pathways was investigated by Western blotting. The effect of leptin on mitochondrial permeability transition pore (MPTP) opening was studied in rat cardiomyocytes. KEY RESULTS Leptin (10 nM) administered during reperfusion reduced infarct size significantly. Protection was blocked by either LY294002 or UO126, inhibitors of Akt and p44/42 MAPK, respectively. Western blotting confirmed that leptin stimulated p44/42 MAPK phosphorylation significantly. Akt phosphorylation was also enhanced but did not achieve statistical significance. Additionally, leptin treatment was associated with a significant increase in p38 phosphorylation. By contrast, leptin caused downregulation of phosphorylated and non-phosphorylated STAT3, and of total AMP-activated kinase. Cardiomyocytes responded to leptin with delayed opening of the MPTP and delayed time until contracture. CONCLUSIONS AND IMPLICATIONS Our data indicate for the first time that the adipocytokine, leptin, has direct cardioprotective properties which may involve the PI3-Akt and p44/42 MAPK pathways.
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Affiliation(s)
- C C T Smith
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
| | - M M Mocanu
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
| | - S M Davidson
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
| | - A M Wynne
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
| | - J C Simpkin
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
| | - D M Yellon
- The Hatter Cardiovascular Institute, University College London Hospital and Medical School, London, UK
- Author for correspondence:
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Abstract
Leptin, a 167-amino acid peptide hormone produced by white adipose tissue, is primarily involved in the regulation of food intake and energy expenditure. Leptin receptors are expressed in many tissues including the cardiovascular system. Plasma leptin concentration is proportional to body adiposity and is markedly increased in obese individuals. Recent studies suggest that hyperleptinemia may play an important role in obesity-associated cardiovascular diseases including atherosclerosis. Leptin exerts many potentially atherogenic effects such as induction of endothelial dysfunction, stimulation of inflammatory reaction, oxidative stress, decrease in paraoxonase activity, platelet aggregation, migration, hypertrophy and proliferation of vascular smooth muscle cells. Leptin-deficient and leptin receptor-deficient mice are protected from arterial thrombosis and neointimal hyperplasia in response to arterial wall injury. Several clinical studies have demonstrated that high leptin level predicts acute cardiovascular events, restenosis after coronary angioplasty, and cerebral stroke independently of traditional risk factors. In addition, plasma leptin correlates with markers of subclinical atherosclerosis such as carotid artery intima-media thickness and coronary artery calcifications. Inhibition of leptin signaling may be a promising strategy to slow the progression of atherosclerosis in hyperleptinemic obese subjects.
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Affiliation(s)
- Jerzy Beltowski
- Department of Pathophysiology, Medical University, ul. Jaczewskiego 8, 20-090 Lublin, Poland.
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Abstract
The metabolic syndrome, which is very common in the general population, is defined by the clustering of several classic cardiovascular risk factors, such as type 2 diabetes, hypertension, high triglycerides and low high-density lipoprotein cholesterol (HDL). Central obesity and insulin resistance, which are the two underlying disorders of the syndrome, are further risk factors for cardiovascular disease. Moreover, a panel of novel (non-traditional) risk factors are ancillary features of the metabolic syndrome. They include biomarkers of chronic mild inflammation (e.g. C-reactive protein, CRP), increased oxidant stress (e.g. oxidized low density lipoprotein, LDL), thrombophilia (e.g. plasminogen activator inhibitor-1, PAI-1) and endothelial dysfunction (e.g. E-selectin). Therefore, subjects with the metabolic syndrome are potentially at high risk of developing atherosclerosis and clinical cardiovascular events.In recent years several longitudinal studies have confirmed that subjects with the metabolic syndrome present with atherosclerosis and suffer from myocardial infarction and stroke at rates higher than subjects without the syndrome. The risk of cardiovascular disease (CVD) is particularly high in women with the syndrome and in subjects with pre-existing diabetes, CVD and/or high CRP. However, an increased risk is already present in subjects with a cluster of multiple mild abnormalities. The risk related to the metabolic syndrome is definitely higher when subjects affected are compared to subjects free of any metabolic abnormality.
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Affiliation(s)
- Enzo Bonora
- Department of Endocrinology and Metabolic Diseases, University of Verona Medical School, Verona, Italy.
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Frühbeck G. Intracellular signalling pathways activated by leptin. Biochem J 2006; 393:7-20. [PMID: 16336196 PMCID: PMC1383660 DOI: 10.1042/bj20051578] [Citation(s) in RCA: 578] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 10/07/2005] [Accepted: 10/07/2005] [Indexed: 12/15/2022]
Abstract
Leptin is a versatile 16 kDa peptide hormone, with a tertiary structure resembling that of members of the long-chain helical cytokine family. It is mainly produced by adipocytes in proportion to fat size stores, and was originally thought to act only as a satiety factor. However, the ubiquitous distribution of OB-R leptin receptors in almost all tissues underlies the pleiotropism of leptin. OB-Rs belong to the class I cytokine receptor family, which is known to act through JAKs (Janus kinases) and STATs (signal transducers and activators of transcription). The OB-R gene is alternatively spliced to produce at least five isoforms. The full-length isoform, OB-Rb, contains intracellular motifs required for activation of the JAK/STAT signal transduction pathway, and is considered to be the functional receptor. Considerable evidence for systemic effects of leptin on body mass control, reproduction, angiogenesis, immunity, wound healing, bone remodelling and cardiovascular function, as well as on specific metabolic pathways, indicates that leptin operates both directly and indirectly to orchestrate complex pathophysiological processes. Consistent with leptin's pleiotropic role, its participation in and crosstalk with some of the main signalling pathways, including those involving insulin receptor substrates, phosphoinositide 3-kinase, protein kinase B, protein kinase C, extracellular-signal-regulated kinase, mitogen-activated protein kinases, phosphodiesterase, phospholipase C and nitric oxide, has been observed. The impact of leptin on several equally relevant signalling pathways extends also to Rho family GTPases in relation to the actin cytoskeleton, production of reactive oxygen species, stimulation of prostaglandins, binding to diacylglycerol kinase and catecholamine secretion, among others.
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Key Words
- adipocyte
- cytokine
- janus kinase/signal transducer and activator of transcription pathway (jak/stat pathway)
- leptin receptor
- obesity
- signalling cascade
- acc, acetyl-coa carboxylase
- ampk, 5′-amp-activated protein kinase
- cntf, ciliary neurotrophic factor
- ct-1, cardiotrophin-1
- erk, extracellular-signal-regulated kinase
- hif-1α, hypoxia-inducible factor 1α
- il, interleukin
- irs, insulin receptor substrate
- jak, janus kinase
- jnk, c-jun n-terminal kinase
- lif, leukaemia inhibitory factor
- mapk, mitogen-activated protein kinase
- nf-κb, nuclear factor κb
- npy, neuropeptide y
- osm, oncostatin-m
- pde, phosphodiesterase
- pi3k, phosphoinositide 3-kinase
- pka, protein kinase a
- pkc, protein kinase c
- ptp1b, protein tyrosine phosphatase 1b
- sh2, src-like homology 2
- shp-2, sh2 domain-containing protein tyrosine phosphatase
- socs, suppressor of cytokine signalling
- stat, signal transducer and activator of transcription
- tnfα, tumour necrosis factor α
- tyk2, tyrosine kinase 2
- vegf, vascular endothelial growth factor
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Affiliation(s)
- Gema Frühbeck
- Department of Endocrinology, Clínica Universitaria de Navarra and Metabolic Research Laboratory, University of Navarra, 36 Avda. Pío XII, 31008 Pamplona, Spain.
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Zeidan A, Purdham DM, Rajapurohitam V, Javadov S, Chakrabarti S, Karmazyn M. Leptin induces vascular smooth muscle cell hypertrophy through angiotensin II- and endothelin-1-dependent mechanisms and mediates stretch-induced hypertrophy. J Pharmacol Exp Ther 2005; 315:1075-84. [PMID: 16144973 DOI: 10.1124/jpet.105.091561] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Various cardiovascular pathologies are associated with vascular smooth muscle cell (VSMC) hypertrophy and elevated plasma leptin levels. We used the rat portal vein (RPV) cultured for three days to investigate the effect of mechanical stretch on autocrine secretion of leptin and the effect of exogenous leptin (3.1 nM) on VSMC. Stretching the RPV significantly up-regulated leptin production by greater than 100-fold and leptin receptor expression by up to 10-fold. In addition, stretch increased tissue weight by 23 +/- 1.3 and 30 +/- 1% (P < 0.05), respectively, in the absence or presence of leptin, although this was significantly attenuated by an antileptin antibody (166 ng/ml). Unstretched RPV weight decreased by 7.5 +/- 1.8% in the absence of leptin, whereas in the presence of leptin, weight increased by 6.5 +/- 1.8% (P < 0.05). VSMC size and [3H]leucine incorporation rates were significantly increased by leptin in stretched and unstretched tissues. Leptin-induced hypertrophy was associated with significant extracellular signal-regulated kinase (ERK1/2) activation as well as increased expression of angiotensinogen, the angiotensin type 1 receptor as well as preproendothelin-1, and the endothelin type A receptor, whereas ERK inhibition or inhibition of either the angiotensin II or endothelin-1 systems at both the synthesis and receptor levels blocked the hypertrophic response. The effects of leptin were also completely blocked by the cholesterol-chelating agent methyl-beta-cyclodextrin. Therefore, our study demonstrates stretch-dependent leptin release and a direct hypertrophic effect of leptin on RPV, the latter likely dependent on intact cholesterol-rich membrane microdomains and locally produced paracrine factors.
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MESH Headings
- Angiotensin II/antagonists & inhibitors
- Angiotensin II/pharmacology
- Animals
- Cell Culture Techniques
- Cells, Cultured
- Culture Media/analysis
- Endothelin-1/metabolism
- Endothelin-1/pharmacology
- Hypertrophy/chemically induced
- Leptin/metabolism
- Leptin/pharmacology
- Male
- Models, Biological
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/metabolism
- Organ Size
- Portal Vein/cytology
- Rats
- Rats, Sprague-Dawley
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/metabolism
- Receptors, Leptin
- Stress, Mechanical
- Up-Regulation
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Affiliation(s)
- Asad Zeidan
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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