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- Volume 20, Issue 4, 2014
Current Pharmaceutical Design - Volume 20, Issue 4, 2014
Volume 20, Issue 4, 2014
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What Fans the Fire: Insights into Mechanisms of Leptin in Metabolic Syndrome- Associated Heart Diseases
Authors: Maolong Dong and Jun RenObesity and metabolic syndrome are one of the most devastating risk factors for cardiovascular diseases. The obesity gene product leptin plays a central role in the regulation of food intake and energy expenditure. The physiological and pathophysiological roles of leptin in cardiovascular system have been investigated extensively since its discovery in 1994. In addition to its well-established metabolic effects, more recent evidence have depicted a rather pivotal role of leptin in inflammation, oxidative stress, endoplasmic reticulum stress, apoptosis and tissue remodeling en route to the pathogenesis of type 2 diabetes mellitus, hypertension, atherosclerosis, and insulin resistance. Under physiological condition, leptin is known to reduce appetite, promote energy expenditure, increase sympathetic activity, facilitate glucose utilization and improve insulin sensitivity. In addition, leptin may regulate cardiac and vascular function through a nitric oxide-dependent mechanism. However, hyperleptinemia usually occurs with progressively increased body weight and metabolic syndrome development, leading to a state of global or selective leptin resistance. Both central and peripheral leptin resistance may be present under pathophysiological conditions such as inflammation, insulin resistance, hyperlipidemia and a cadre of other cardiovascular diseases including hypertension, atherosclerosis, obesity, ischemic heart disease and heart failure. In this review, we will discuss cardiovascular actions of leptin related to various components of metabolic syndrome. Particular emphasis will be given to insights derived from therapeutic interventions with lifestyle modification, cardiovascular drugs, anti-diabetic and anti-obesity drugs.
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Novel Superactive Leptin Antagonists and their Potential Therapeutic Applications
Authors: Arieh Gertler and Eran ElinavRandom mutagenesis of mouse leptin antagonist (L39A/D40A/F41) followed by selection of high-affinity mutants by yeastsurface display indicated that replacing residue D23 with a non-negatively charged amino acid (most specifically with Leu) leads to dramatically enhanced affinity of leptin toward LEPR leading to development of superactive mouse, human, ovine and rat leptin antagonists (D23L/L39A/D40A/F41A). Superactive leptin antagonist mutants of mouse, human, rat or ovine leptins were developed in our laboratory, expressed in E. coli, refolded and purified to homogeneity as monomeric proteins. Pegylation of leptin antagonists resulted in potent and effective long-acting reagents suitable for in vivo studies or therapies. In the present review we explain the mechanism of leptin inhibition and summarize the possible use of leptin antagonists as possible leptin blockers in various human pathologies such as antiinflammatory and anti-autoimmune diseases, uremic cachexia, and cancer. We also suggest the use of leptin antagonists as research reagents for creation of a novel, fast and reversible model of T2DM in mice.
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Increased Risk of Cardiovascular Complications in Chronic Kidney Disease: A Possible Role of Leptin
Authors: Agnieszka Korolczuk and Jaroslaw DudkaLeptin is a small peptide hormone (16 kDa), a product of the obesity gene (Ob), and is mainly synthesized and secreted by adipocytes. It is removed from the blood by the kidneys. The kidney is not only a site of leptin clearance, but also a target organ for its action in different pathophysiological states. Several studies have documented a strong relationship between chronic kidney disease (CKD) and accelerated cardiovascular disease (CVD) defined as a cardiorenal syndrome. Patients with stage 3 and 4 CKD develop cardiovascular complications and are at increased risk of death from CVD. Renal dysfunction promotes several mechanisms responsible for exacerbation of cardiovascular disease. These include activation of the renin-angiotensin system, oxidative stress, elevated asymmetric dimethylarginine (ADMA), low-grade inflammation with increased circulating cytokines, and dyslipidemia. Recently, it has been observed that plasma leptin level is elevated in patients with cardiorenal syndrome. In obesity, hyperleptinemia combined with selective leptin resistance appear to have a critical role in the development and progression of kidney disease, CVD and metabolic syndrome. This has clinical implications for the treatment of obesity–related hypertension and kidney disease. In this paper the role of leptin in chronic kidney disease and accelerated cardiovascular disease is out lined. The link between hyperleptinemia and development and progression of morphologic changes that effect kidney in obese patients is also discussed.
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Autophagy Inhibition Rescues Against Leptin-Induced Cardiac Contractile Dysfunction
Authors: Machender R. Kandadi, Nathan D. Roe and Jun RenLeptin hormone plays a vital role in the pathophysiological changes in heart geometry and function. Nonetheless, the precise mechanism(s) triggering leptin-induced cardiomyocyte contractile dysfunction is not well understood. The present study was designed to examine if autophagy plays a role in leptin-induced cardiac contractile anomalies. Cardiomyocyte contractile function was evaluated using an IonOptix edge detection system in cardiomyocytes following treatment with leptin in the presence or absence of the autophagy inhibiting chemical 3-methyladenine (3-MA). Immunoblotting was employed to evaluate expression of AMPK, Beclin1, Atg 5, p62 and LC3-II. GFP-LC3 puncta was used to assess autophagosome formation. Leptin suppressed cardiac contractile function as evidenced by decreased peak shortening, maximal velocity of shortening and relengthening, increased time-to-90% relengthening, all the observed effects were reduced or obliterated by autophagy inhibition. Leptin promoted superoxide generation, AMPK activation and overt autophagy induction. Leptin promoted autophagy as evidenced by enhanced LC3-II, Beclin, Atg 5 and decreased p62 levels. Pharmacological inhibition of reactive oxygen species (ROS) using tempol significantly attenuated leptin-induced autophagosome formation and cardiac contractile anomalies. In addition, genetic deletion of AMPKα2 or pharmacological inhibition of AMPK using compound C abrogated leptin or superoxide induced cardiac contractile dysfunction and autophagosome formation. In summary, our data revealed that leptin impairs cardiac contractile function through a superoxide generation-AMPK activation-and autophagy dependent mechanism.
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Volumes & issues
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Volume 30 (2024)
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Volume 29 (2023)
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Volume 28 (2022)
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Volume 27 (2021)
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Volume 26 (2020)
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Volume 25 (2019)
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Volume 24 (2018)
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Volume 23 (2017)
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Volume 22 (2016)
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Volume 21 (2015)
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Volume 20 (2014)
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Volume 19 (2013)
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Volume 18 (2012)
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Volume 17 (2011)
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Volume 16 (2010)
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Volume 15 (2009)
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Volume 14 (2008)
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Volume 13 (2007)
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Volume 12 (2006)
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Volume 11 (2005)
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Volume 10 (2004)
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Volume 9 (2003)
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Volume 8 (2002)
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Volume 7 (2001)
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Volume 6 (2000)