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Inoue T, Maeda Y, Sonoda N, Sasaki S, Kabemura T, Kobayashi K, Inoguchi T. Hyperinsulinemia and sulfonylurea use are independently associated with left ventricular diastolic dysfunction in patients with type 2 diabetes mellitus with suboptimal blood glucose control. BMJ Open Diabetes Res Care 2016; 4:e000223. [PMID: 27648285 PMCID: PMC5013397 DOI: 10.1136/bmjdrc-2016-000223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 07/26/2016] [Accepted: 07/29/2016] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE Although diabetes mellitus is associated with an increased risk of heart failure with preserved ejection fraction, the underlying mechanisms leading to left ventricular diastolic dysfunction (LVDD) remain poorly understood. The study was designed to assess the risk factors for LVDD in patients with type 2 diabetes mellitus. RESEARCH DESIGN AND METHODS The study cohort included 101 asymptomatic patients with type 2 diabetes mellitus without overt heart disease. Left ventricular diastolic function was estimated as the ratio of early diastolic velocity (E) from transmitral inflow to early diastolic velocity (e') of tissue Doppler at mitral annulus (E/e'). Parameters of glycemic control, plasma insulin concentration, treatment with antidiabetic drugs, lipid profile, and other clinical characteristics were evaluated, and their association with E/e' determined. Patients with New York Heart Association class >1, ejection fraction <50%, history of coronary artery disease, severe valvulopathy, chronic atrial fibrillation, or creatinine clearance <30 mL/min, as well as those receiving insulin treatment, were excluded. RESULTS Univariate analysis showed that E/e' was significantly correlated with age (p<0.001), sex (p<0.001), duration of diabetes (p=0.002), systolic blood pressure (p=0.017), pulse pressure (p=0.010), fasting insulin concentration (p=0.025), and sulfonylurea use (p<0.001). Multivariate linear regression analysis showed that log E/e' was significantly and positively correlated with log age (p=0.034), female sex (p=0.019), log fasting insulin concentration (p=0.010), and sulfonylurea use (p=0.027). CONCLUSIONS Hyperinsulinemia and sulfonylurea use may be important in the development of LVDD in patients with type 2 diabetes mellitus.
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Affiliation(s)
- Tomoaki Inoue
- Endocrinology and Metabolism Division, Fukuoka City Medical Association Hospital, Fukuoka, Japan
| | - Yasutaka Maeda
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan
| | - Noriyuki Sonoda
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shuji Sasaki
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Teppei Kabemura
- Gastroenterology Division, Fukuoka City Medical Association Hospital, Fukuoka, Japan
| | - Kunihisa Kobayashi
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Fukuoka, Japan
| | - Toyoshi Inoguchi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan
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Miura M, Nagano T, Murai N, Taguchi Y, Handoh T, Satoh M, Miyata S, Miller L, Shindoh C, Stuyvers BD. Effect of Carbenoxolone on Arrhythmogenesis in Rat Ventricular Muscle. Circ J 2016; 80:76-84. [DOI: 10.1253/circj.cj-15-0401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tsuyoshi Nagano
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Naomi Murai
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yuhto Taguchi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tetsuya Handoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Minami Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Satoshi Miyata
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
| | - Lawson Miller
- Faculty of Medicine, Biomedical Sciences, Memorial University
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
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Liu Z, Cai H, Dang Y, Qiu C, Wang J. Adenosine triphosphate-sensitive potassium channels and cardiomyopathies (Review). Mol Med Rep 2015; 13:1447-54. [PMID: 26707080 DOI: 10.3892/mmr.2015.4714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 06/05/2015] [Indexed: 11/06/2022] Open
Abstract
Cardiomyopathies have been indicated to be one of the leading causes of heart failure. Though it was indicated that genetic defects, viral infection and trace element deficiency were among the causes of cardiomyopathy, the etiology has remained to be fully elucidated. Cardiomyocytes require large amounts of energy to maintain their normal biological functions. Adenosine triphosphate-sensitive potassium channels (KATP), composed of inward-rectifier potassium ion channel and sulfonylurea receptor subunits, are present on the cell surface and mitochondrial membrane of cardiac muscle cells. As metabolic sensors sensitive to changes in intracellular energy levels, KATP adapt electrical activities to metabolic challenges, maintaining normal biological functions of myocytes. It is implied that malfunctions, mutations and altered expression of KATP are associated with the pathogenesis of conditions including c hypertrophy, diabetes as well as dilated, ischemic and endemic cardiomyopathy. However, the current knowledge is only the tip of the iceberg and the roles of KATP in cardiomyopathies largely remain to be elucidated in future studies.
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Affiliation(s)
- Zhongwei Liu
- Department of Cardiology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China
| | - Hui Cai
- Department of Anesthesiology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yonghui Dang
- College of Medicine and Forensics, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, P.R. China
| | - Chuan Qiu
- Department of Biostatistics and Bioinformatics, School of Public Health and Tropical Medicine, Tulane University, New Orleans 70112‑2705, LA, USA
| | - Junkui Wang
- Department of Cardiology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China
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Levin MD, Zhang H, Uchida K, Grange DK, Singh GK, Nichols CG. Electrophysiologic consequences of KATP gain of function in the heart: Conduction abnormalities in Cantu syndrome. Heart Rhythm 2015; 12:2316-24. [PMID: 26142302 PMCID: PMC4624040 DOI: 10.1016/j.hrthm.2015.06.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND Gain-of-function (GOF) mutations in the KATP channel subunits Kir6.1 and SUR2 cause Cantu syndrome (CS), a disease characterized by multiple cardiovascular abnormalities. OBJECTIVE The purpose of this study was to better determine the electrophysiologic consequences of such GOF mutations in the heart. METHODS We generated transgenic mice (Kir6.1-GOF) expressing ATP-insensitive Kir6.1[G343D] subunits under α-myosin heavy chain (α-MHC) promoter control, to target gene expression specifically in cardiomyocytes, and performed patch-clamp experiments on isolated ventricular myocytes and invasive electrophysiology on anesthetized mice. RESULTS In Kir6.1-GOF ventricular myocytes, KATP channels showed decreased ATP sensitivity but no significant change in current density. Ambulatory ECG recordings on Kir6.1-GOF mice revealed AV nodal conduction abnormalities and junctional rhythm. Invasive electrophysiologic analyses revealed slowing of conduction and conduction failure through the AV node but no increase in susceptibility to atrial or ventricular ectopic activity. Surface ECGs recorded from CS patients also demonstrated first-degree AV block and fascicular block. CONCLUSION The primary electrophysiologic consequence of cardiac KATP GOF is on the conduction system, particularly the AV node, resulting in conduction abnormalities in CS patients who carry KATP GOF mutations.
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Affiliation(s)
- Mark D Levin
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Haixia Zhang
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - Keita Uchida
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - Dorothy K Grange
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Gautam K Singh
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri.
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Nelson PT, Jicha GA, Wang WX, Ighodaro E, Artiushin S, Nichols CG, Fardo DW. ABCC9/SUR2 in the brain: Implications for hippocampal sclerosis of aging and a potential therapeutic target. Ageing Res Rev 2015; 24:111-25. [PMID: 26226329 PMCID: PMC4661124 DOI: 10.1016/j.arr.2015.07.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/24/2015] [Indexed: 01/06/2023]
Abstract
The ABCC9 gene and its polypeptide product, SUR2, are increasingly implicated in human neurologic disease, including prevalent diseases of the aged brain. SUR2 proteins are a component of the ATP-sensitive potassium ("KATP") channel, a metabolic sensor for stress and/or hypoxia that has been shown to change in aging. The KATP channel also helps regulate the neurovascular unit. Most brain cell types express SUR2, including neurons, astrocytes, oligodendrocytes, microglia, vascular smooth muscle, pericytes, and endothelial cells. Thus it is not surprising that ABCC9 gene variants are associated with risk for human brain diseases. For example, Cantu syndrome is a result of ABCC9 mutations; we discuss neurologic manifestations of this genetic syndrome. More common brain disorders linked to ABCC9 gene variants include hippocampal sclerosis of aging (HS-Aging), sleep disorders, and depression. HS-Aging is a prevalent neurological disease with pathologic features of both neurodegenerative (aberrant TDP-43) and cerebrovascular (arteriolosclerosis) disease. As to potential therapeutic intervention, the human pharmacopeia features both SUR2 agonists and antagonists, so ABCC9/SUR2 may provide a "druggable target", relevant perhaps to both HS-Aging and Alzheimer's disease. We conclude that more work is required to better understand the roles of ABCC9/SUR2 in the human brain during health and disease conditions.
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Affiliation(s)
- Peter T Nelson
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; University of Kentucky, Department of Pathology, Lexington, KY 40536, USA.
| | - Gregory A Jicha
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; University of Kentucky, Department of Neurology, Lexington, KY, 40536, USA
| | - Wang-Xia Wang
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Eseosa Ighodaro
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Sergey Artiushin
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - David W Fardo
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; Department of Biostatistics, Lexington, KY, 40536, USA
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Sulfonylurea use is associated with larger infarct size in patients with diabetes and ST-elevation myocardial infarction. Int J Cardiol 2015; 202:126-30. [PMID: 26386939 DOI: 10.1016/j.ijcard.2015.08.213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 08/27/2015] [Indexed: 12/25/2022]
Abstract
BACKGROUND Animal models have demonstrated that sulfonylureas increase the size of myocardial infarction; however, data in humans is scarce. This study evaluated the association between sulfonylurea use and infarct size in diabetes patients with ST-elevation myocardial infarction (STEMI). METHODS Consecutive STEMI patients admitted in Edmonton, Canada between 2006 and 2011 were enrolled in a regional prospective registry program. Patients with type 2 diabetes were identified from this group and the maximum recorded troponin I (max cTnI) within the first 48 h of chest pain onset was used as the primary outcome to quantify infarct size. The relationship between preadmission sulfonylurea use and max cTnI was assessed using multivariable linear regression to adjust for patient demographics, cardiovascular risk factors, clinical data on admission, ischemia time, reperfusion therapy and preadmission drugs. RESULTS There were 560 STEMI patients with type 2 diabetes; mean (standard deviation; SD) age was 63.3 (12.8) years, 395 (70.5%) were male, 216 (38.6%) received primary percutaneous intervention, and 211 (37.7%) received thrombolysis. The max cTnI was higher in 146 sulfonylurea users compared to 414 non-sulfonylurea users (mean (SD): 49.8 (74.3) ng/mL versus 39.9 (50.4) ng/mL, respectively; adjusted between-group difference: 12.9 ng/mL; 95% CI 0.3-25.5; p=0.044). CONCLUSION This study adds further evidence to the proposed causal relationship between sulfonylureas and adverse cardiovascular events by observing a significant difference in infarct size among type 2 diabetes patients presenting with STEMI. Clinicians should consider this association when prescribing sulfonylureas to manage patients with type 2 diabetes.
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Cole CM, Brea RJ, Kim YH, Hardy MD, Yang J, Devaraj NK. Spontaneous Reconstitution of Functional Transmembrane Proteins During Bioorthogonal Phospholipid Membrane Synthesis. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201504339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Cole CM, Brea RJ, Kim YH, Hardy MD, Yang J, Devaraj NK. Spontaneous Reconstitution of Functional Transmembrane Proteins During Bioorthogonal Phospholipid Membrane Synthesis. Angew Chem Int Ed Engl 2015; 54:12738-42. [PMID: 26316292 DOI: 10.1002/anie.201504339] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/02/2015] [Indexed: 11/11/2022]
Abstract
Transmembrane proteins are critical for signaling, transport, and metabolism, yet their reconstitution in synthetic membranes is often challenging. Non-enzymatic and chemoselective methods to generate phospholipid membranes in situ would be powerful tools for the incorporation of membrane proteins. Herein, the spontaneous reconstitution of functional integral membrane proteins during the de novo synthesis of biomimetic phospholipid bilayers is described. The approach takes advantage of bioorthogonal coupling reactions to generate proteoliposomes from micelle-solubilized proteins. This method was successfully used to reconstitute three different transmembrane proteins into synthetic membranes. This is the first example of the use of non-enzymatic chemical synthesis of phospholipids to prepare proteoliposomes.
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Affiliation(s)
- Christian M Cole
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Urey Hall 4120, La Jolla, CA 92093 (USA) http://devarajgroup.ucsd.edu
| | - Roberto J Brea
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Urey Hall 4120, La Jolla, CA 92093 (USA) http://devarajgroup.ucsd.edu
| | - Young Hun Kim
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Pacific Hall 6160, La Jolla, CA 92093 (USA)
| | - Michael D Hardy
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Urey Hall 4120, La Jolla, CA 92093 (USA) http://devarajgroup.ucsd.edu
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Pacific Hall 6160, La Jolla, CA 92093 (USA)
| | - Neal K Devaraj
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Building: Urey Hall 4120, La Jolla, CA 92093 (USA) http://devarajgroup.ucsd.edu.
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Henn MC, Janjua MB, Kanter EM, Makepeace CM, Schuessler RB, Nichols CG, Lawton JS. Adenosine Triphosphate-Sensitive Potassium Channel Kir Subunits Implicated in Cardioprotection by Diazoxide. J Am Heart Assoc 2015; 4:e002016. [PMID: 26304939 PMCID: PMC4599460 DOI: 10.1161/jaha.115.002016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background ATP-sensitive potassium (KATP) channel openers provide cardioprotection in multiple models. Ion flux at an unidentified mitochondrial KATP channel has been proposed as the mechanism. The renal outer medullary kidney potassium channel subunit, potassium inward rectifying (Kir)1.1, has been implicated as a mitochondrial channel pore-forming subunit. We hypothesized that subunit Kir1.1 is involved in cardioprotection (maintenance of volume homeostasis and contractility) of the KATP channel opener diazoxide (DZX) during stress (exposure to hyperkalemic cardioplegia [CPG]) at the myocyte and mitochondrial levels. Methods and Results Kir subunit inhibitor Tertiapin Q (TPN-Q) was utilized to evaluate response to stress. Mouse ventricular mitochondrial volume was measured in the following groups: isolation buffer; 200 μmol/L of ATP; 100 μmol/L of DZX+200 μmol/L of ATP; or 100 μmol/L of DZX+200 μmol/L of ATP+TPN-Q (500 or 100 nmol/L). Myocytes were exposed to Tyrode’s solution (5 minutes), test solution (Tyrode’s, cardioplegia [CPG], CPG+DZX, CPG+DZX+TPN-Q, Tyrode’s+TPN-Q, or CPG+TPN-Q), N=12 for all (10 minutes); followed by Tyrode’s (5 minutes). Volumes were compared. TPN-Q, with or without DZX, did not alter mitochondrial or myocyte volume. Stress (CPG) resulted in myocyte swelling and reduced contractility that was prevented by DZX. TPN-Q prevented the cardioprotection afforded by DZX (volume homeostasis and maintenance of contractility). Conclusions TPN-Q inhibited myocyte cardioprotection provided by DZX during stress; however, it did not alter mitochondrial volume. Because TPN-Q inhibits Kir1.1, Kir3.1, and Kir3.4, these data support that any of these Kir subunits could be involved in the cardioprotection afforded by diazoxide. However, these data suggest that mitochondrial swelling by diazoxide does not involve Kir1.1, 3.1, or 3.4.
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Affiliation(s)
- Matthew C Henn
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
| | - M Burhan Janjua
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
| | - Evelyn M Kanter
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
| | - Carol M Makepeace
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
| | - Richard B Schuessler
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO (C.G.N.)
| | - Jennifer S Lawton
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO (M.C.H., B.J., E.M.K., C.M.M., R.B.S., J.S.L.)
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Hippocampal Sclerosis of Aging Can Be Segmental: Two Cases and Review of the Literature. J Neuropathol Exp Neurol 2015; 74:642-52. [PMID: 26083567 DOI: 10.1097/nen.0000000000000204] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hippocampal sclerosis of aging (HS-Aging) is a neurodegenerative disease that mimics Alzheimer disease (AD) clinically and has a prevalence rivaling AD in advanced age. Whereas clinical biomarkers are not yet optimized, HS-Aging has distinctive pathological features that distinguish it from other diseases with "hippocampal sclerosis" pathology, such as epilepsy, cerebrovascular perturbations, and frontotemporal lobar degeneration. By definition, HS-Aging brains show neuronal cell loss and gliosis in the hippocampal formation out of proportion to AD-type pathology; it is strongly associated with aberrant TDP-43 pathology and arteriolosclerosis. Here, we describe 2 cases of "segmental" HS-Aging in which "sclerosis" in the hippocampus was evident only in a subset of brain sections by hematoxylin and eosin (H&E) stain. In these cases, TDP-43 pathology was more widespread on immunostained sections than the neuronal cell loss and gliosis seen in H&E stains. The 2 patients were cognitively intact at baseline and were tracked longitudinally over a decade using cognitive studies with at least 1 neuroimaging scan. We discuss the relevant HS-Aging literature, which indicates the need for a clearer consensus-based delineation of "hippocampal sclerosis" and TDP-43 pathologies in aged subjects.
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Abstract
Ion channels are critical for all aspects of cardiac function, including rhythmicity and contractility. Consequently, ion channels are key targets for therapeutics aimed at cardiac pathophysiologies such as atrial fibrillation or angina. At the same time, off-target interactions of drugs with cardiac ion channels can be the cause of unwanted side effects. This manuscript aims to review the physiology and pharmacology of key cardiac ion channels. The intent is to highlight recent developments for therapeutic development, as well as elucidate potential mechanisms for drug-induced cardiac side effects, rather than present an in-depth review of each channel subtype.
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Guinamard R, Bouvagnet P, Hof T, Liu H, Simard C, Sallé L. TRPM4 in cardiac electrical activity. Cardiovasc Res 2015; 108:21-30. [PMID: 26272755 DOI: 10.1093/cvr/cvv213] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 07/31/2015] [Indexed: 11/12/2022] Open
Abstract
TRPM4 forms a non-selective cation channel activated by internal Ca(2+). Its functional expression was demonstrated in cardiomyocytes of several mammalian species including humans, but the channel is also present in many other tissues. The recent characterization of the TRPM4 inhibitor 9-phenanthrol, and the availability of transgenic mice have helped to clarify the role of TRPM4 in cardiac electrical activity, including diastolic depolarization from the sino-atrial node cells in mouse, rat, and rabbit, as well as action potential duration in mouse cardiomyocytes. In rat and mouse, pharmacological inhibition of TRPM4 prevents cardiac ischaemia-reperfusion injuries and decreases the occurrence of arrhythmias. Several studies have identified TRPM4 mutations in patients with inherited cardiac diseases including conduction blocks and Brugada syndrome. This review identifies TRPM4 as a significant actor in cardiac electrophysiology.
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Affiliation(s)
- Romain Guinamard
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | | | - Thomas Hof
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Hui Liu
- Department of Anatomy, Hainan Medical College, Haikou, Hainan 571101, China
| | - Christophe Simard
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Laurent Sallé
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
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Abriel H, Rougier JS, Jalife J. Ion channel macromolecular complexes in cardiomyocytes: roles in sudden cardiac death. Circ Res 2015; 116:1971-88. [PMID: 26044251 DOI: 10.1161/circresaha.116.305017] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The movement of ions across specific channels embedded on the membrane of individual cardiomyocytes is crucial for the generation and propagation of the cardiac electric impulse. Emerging evidence over the past 20 years strongly suggests that the normal electric function of the heart is the result of dynamic interactions of membrane ion channels working in an orchestrated fashion as part of complex molecular networks. Such networks work together with exquisite temporal precision to generate each action potential and contraction. Macromolecular complexes play crucial roles in transcription, translation, oligomerization, trafficking, membrane retention, glycosylation, post-translational modification, turnover, function, and degradation of all cardiac ion channels known to date. In addition, the accurate timing of each cardiac beat and contraction demands, a comparable precision on the assembly and organizations of sodium, calcium, and potassium channel complexes within specific subcellular microdomains, where physical proximity allows for prompt and efficient interaction. This review article, part of the Compendium on Sudden Cardiac Death, discusses the major issues related to the role of ion channel macromolecular assemblies in normal cardiac electric function and the mechanisms of arrhythmias leading to sudden cardiac death. It provides an idea of how these issues are being addressed in the laboratory and in the clinic, which important questions remain unanswered, and what future research will be needed to improve knowledge and advance therapy.
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Affiliation(s)
- Hugues Abriel
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.)
| | - Jean-Sébastien Rougier
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.)
| | - José Jalife
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.).
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Nelson PT, Wang WX, Wilfred BR, Wei A, Dimayuga J, Huang Q, Ighodaro E, Artiushin S, Fardo DW. Novel human ABCC9/SUR2 brain-expressed transcripts and an eQTL relevant to hippocampal sclerosis of aging. J Neurochem 2015; 134:1026-39. [PMID: 26115089 DOI: 10.1111/jnc.13202] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 05/19/2015] [Accepted: 06/09/2015] [Indexed: 01/08/2023]
Abstract
ABCC9 genetic polymorphisms are associated with increased risk for various human diseases including hippocampal sclerosis of aging. The main goals of this study were 1 > to detect the ABCC9 variants and define the specific 3' untranslated region (3'UTR) for each variant in human brain, and 2 > to determine whether a polymorphism (rs704180) associated with risk for hippocampal sclerosis of aging pathology is also associated with variation in ABCC9 transcript expression and/or splicing. Rapid amplification of ABCC9 cDNA ends (3'RACE) provided evidence of novel 3' UTR portions of ABCC9 in human brain. In silico and experimental studies were performed focusing on the single nucleotide polymorphism, rs704180. Analyses from multiple databases, focusing on rs704180 only, indicated that this risk allele is a local expression quantitative trait locus (eQTL). Analyses of RNA from human brains showed increased ABCC9 transcript levels in individuals with the risk genotype, corresponding with enrichment for a shorter 3' UTR which may be more stable than variants with the longer 3' UTR. MicroRNA transfection experiments yielded results compatible with the hypothesis that miR-30c causes down-regulation of SUR2 transcripts with the longer 3' UTR. Thus we report evidence of complex ABCC9 genetic regulation in brain, which may be of direct relevance to human disease. ABCC9 gene variants are associated with increased risk for hippocampal sclerosis of aging (HS-Aging--a prevalent brain disease with symptoms that mimic Alzheimer's disease). We describe novel ABCC9 variants in human brain, corresponding to altered 3'UTR length, which could lead to targeting by miR-30c. We also determined that the HS-Aging risk mutation is associated with variation in ABCC9 transcript expression.
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Affiliation(s)
- Peter T Nelson
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA.,Department of Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Wang-Xia Wang
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Bernard R Wilfred
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Angela Wei
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - James Dimayuga
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Qingwei Huang
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Eseosa Ighodaro
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - Sergey Artiushin
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA
| | - David W Fardo
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA.,Department of Biostatistics, University of Kentucky, Lexington, Kentucky, USA
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115
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Abdelmoneim AS, Eurich DT, Light PE, Senior PA, Seubert JM, Makowsky MJ, Simpson SH. Cardiovascular safety of sulphonylureas: over 40 years of continuous controversy without an answer. Diabetes Obes Metab 2015; 17:523-532. [PMID: 25711240 DOI: 10.1111/dom.12456] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 10/10/2015] [Accepted: 02/20/2015] [Indexed: 12/12/2022]
Abstract
More than 40 years after publication of the University Group Diabetes Program trial, the cardiovascular safety of sulphonylureas is still contentious. Although several hypotheses linking sulphonylureas to adverse cardiovascular effects exist, none provide conclusive evidence. Adding to the controversy, current clinical trials and observational studies provide inconsistent, and sometimes conflicting, evidence for the cardiovascular effects of sulphonylureas. Overall, observational evidence suggests that an increased risk of adverse cardiovascular outcomes is associated with sulphonylureas; however, these data may be subject to residual confounding and bias. Although evidence from randomized controlled trials has suggested a neutral effect, the majority of these studies were not specifically designed to assess the effect of sulphonylureas on adverse cardiovascular event risk. Current ongoing large clinical trials may provide some clarity on the cardiovascular safety of sulphonylureas, but the results are not expected for several years. With the continued uncertainties concerning the cardiovascular safety of all antidiabetic drugs, a clear answer with regard to sulphonylureas is warranted. The objectives of the present article were to provide an overview of the controversy surrounding sulphonylurea-related cardiovascular effects, to discuss the limitations of the current literature, and to provide recommendations for future studies aiming to elucidate the true relationship between sulphonylureas and adverse cardiovascular effects in people with type 2 diabetes.
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Affiliation(s)
- A S Abdelmoneim
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - D T Eurich
- School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - P E Light
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - P A Senior
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - J M Seubert
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - M J Makowsky
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - S H Simpson
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
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116
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Zhou Q, Chen PC, Devaraneni PK, Martin GM, Olson EM, Shyng SL. Carbamazepine inhibits ATP-sensitive potassium channel activity by disrupting channel response to MgADP. Channels (Austin) 2015; 8:376-82. [PMID: 24849284 DOI: 10.4161/chan.29117] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In pancreatic β-cells, K(ATP) channels consisting of Kir6.2 and SUR1 couple cell metabolism to membrane excitability and regulate insulin secretion. Sulfonylureas, insulin secretagogues used to treat type II diabetes, inhibit K(ATP) channel activity primarily by abolishing the stimulatory effect of MgADP endowed by SUR1. In addition, sulfonylureas have been shown to function as pharmacological chaperones to correct channel biogenesis and trafficking defects. Recently, we reported that carbamazepine, an anticonvulsant known to inhibit voltage-gated sodium channels, has profound effects on K(ATP) channels. Like sulfonylureas, carbamazepine corrects trafficking defects in channels bearing mutations in the first transmembrane domain of SUR1. Moreover, carbamazepine inhibits the activity of K(ATP) channels such that rescued mutant channels are unable to open when the intracellular ATP/ADP ratio is lowered by metabolic inhibition. Here, we investigated the mechanism by which carbamazepine inhibits K(ATP) channel activity. We show that carbamazepine specifically blocks channel response to MgADP. This gating effect resembles that of sulfonylureas. Our results reveal striking similarities between carbamazepine and sulfonylureas in their effects on K(ATP) channel biogenesis and gating and suggest that the 2 classes of drugs may act via a converging mechanism.
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117
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Smith LE, White MY. The role of post-translational modifications in acute and chronic cardiovascular disease. Proteomics Clin Appl 2015; 8:506-21. [PMID: 24961403 DOI: 10.1002/prca.201400052] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 05/27/2014] [Accepted: 06/17/2014] [Indexed: 12/22/2022]
Abstract
Cardiovascular disease (CVD) in one of the leading causes of mortality and morbidity worldwide, accounting for both primary diseases of the heart and vasculature and arising as a co-morbidity with numerous pathologies, including type 2 diabetes mellitus (T2DM). There has been significant emphasis on the role of the genome in CVD, aiding in the definition of 'at-risk' patients. The extent of disease penetrance however, can be influenced by environmental factors that are not detectable by investigating the genome alone. By targeting the transcriptome in response to CVD, the interplay between genome and environment is more apparent, however this implies the level of protein expression without reference to proteolytic turnover, or potentially more importantly, without defining the role of PTMs in the development of disease. Here, we discuss the role of both brief and irreversible PTMs in the setting of myocardial ischemia/reperfusion injury. Key proteins involved in calcium regulation have been observed as differentially modified by phosphorylation/O-GlcNAcylation or phosphorylation/redox modifications, with the level of interplay dependent on the physiological or pathophysiological state. The ability to modify crucial sites to produce the desired functional output is modulated by the presence of other PTMs as exemplified in the T2DM heart, where hyperglycemia results in aberrant O-GlcNAcylation and advanced glycation end products. By using the signalling events predicted to be critical to post-conditioning, an intervention with great promise for the cardioprotection of the ischemia/reperfusion injured heart, as an example, we discuss the level of PTMs and their interplay. The inability of post-conditioning to protect the diabetic heart may be regulated by aberrant PTMs influencing those sites necessary for protection.
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Affiliation(s)
- Lauren E Smith
- Discipline of Pathology, Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
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118
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Henn MC, Janjua MB, Zhang H, Kanter EM, Makepeace CM, Schuessler RB, Nichols CG, Lawton JS. Diazoxide Cardioprotection Is Independent of Adenosine Triphosphate-Sensitive Potassium Channel Kir6.1 Subunit in Response to Stress. J Am Coll Surg 2015; 221:319-25. [PMID: 25872691 DOI: 10.1016/j.jamcollsurg.2015.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/10/2015] [Accepted: 02/10/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND The sarcolemmal adenosine triphosphate-sensitive potassium channel (sK(ATP)), composed primarily of potassium inward rectifier (Kir) 6.2 and sulfonylurea receptor 2A subunits, has been implicated in cardiac myocyte volume regulation during stress; however, it is not involved in cardioprotection by the adenosine triphosphate-sensitive potassium channel (K(ATP)) channel opener diazoxide (7-chloro-3-methyl-1,2,4-benzothiadiazine-1,1-dioxide [DZX]). Paradoxically, the sK(ATP) channel subunit Kir6.2 is necessary for detrimental myocyte swelling secondary to stress. The Kir6.1 subunit can also contribute to K(ATP) channels in the heart, and we hypothesized that this subunit might play a role in myocyte volume regulation in response to stress. STUDY DESIGN Isolated cardiac myocytes from either wild-type mice or mice lacking the Kir6.1 subunit (Kir6.1[-/-]) were exposed to control Tyrode's solution (TYR) for 20 minutes, test solution (TYR, hypothermic hyperkalemic cardioplegia [CPG], or CPG + K(ATP) channel opener DZX [CPG + DZX]) for 20 minutes, followed by TYR for 20 minutes. Myocyte volume and contractility were measured and analyzed. RESULTS Both wild-type and Kir6.1(-/-) myocytes demonstrated substantial swelling during exposure to stress (CPG), which was prevented by DZX. Wild-type myocytes also demonstrated reduced contractility during stress of CPG that was prevented by DZX. However, Kir6.1(-/-) myocytes did not show reduced contractility during stress. CONCLUSIONS These data indicate that K(ATP) channel subunit Kir6.1 is not necessary for DZX's maintenance of cell volume during the stress of CPG. The absence of Kir6.1 does not affect the contractile properties of myocytes during stress, suggesting the absence of Kir6.1 improves myocyte tolerance to stress via an unknown mechanism.
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Affiliation(s)
- Matthew C Henn
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO
| | | | - Haixia Zhang
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO
| | - Evelyn M Kanter
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO
| | - Carol M Makepeace
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO
| | - Richard B Schuessler
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO
| | - Jennifer S Lawton
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO.
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119
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Devaraneni PK, Martin GM, Olson EM, Zhou Q, Shyng SL. Structurally distinct ligands rescue biogenesis defects of the KATP channel complex via a converging mechanism. J Biol Chem 2015; 290:7980-91. [PMID: 25637631 DOI: 10.1074/jbc.m114.634576] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small molecules that correct protein misfolding and misprocessing defects offer a potential therapy for numerous human diseases. However, mechanisms underlying pharmacological correction of such defects, especially in heteromeric complexes with structurally diverse constituent proteins, are not well understood. Here we investigate how two chemically distinct compounds, glibenclamide and carbamazepine, correct biogenesis defects in ATP-sensitive potassium (KATP) channels composed of sulfonylurea receptor 1 (SUR1) and Kir6.2. We present evidence that despite structural differences, carbamazepine and glibenclamide compete for binding to KATP channels, and both drugs share a binding pocket in SUR1 to exert their effects. Moreover, both compounds engage Kir6.2, in particular the distal N terminus of Kir6.2, which is involved in normal channel biogenesis, for their chaperoning effects on SUR1 mutants. Conversely, both drugs can correct channel biogenesis defects caused by Kir6.2 mutations in a SUR1-dependent manner. Using an unnatural, photocross-linkable amino acid, azidophenylalanine, genetically encoded in Kir6.2, we demonstrate in living cells that both drugs promote interactions between the distal N terminus of Kir6.2 and SUR1. These findings reveal a converging pharmacological chaperoning mechanism wherein glibenclamide and carbamazepine stabilize the heteromeric subunit interface critical for channel biogenesis to overcome defective biogenesis caused by mutations in individual subunits.
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Affiliation(s)
- Prasanna K Devaraneni
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Gregory M Martin
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Erik M Olson
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Qing Zhou
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
| | - Show-Ling Shyng
- From the Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239
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120
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Nelson PT, Wang WX, Partch AB, Monsell SE, Valladares O, Ellingson SR, Wilfred BR, Naj AC, Wang LS, Kukull WA, Fardo DW. Reassessment of risk genotypes (GRN, TMEM106B, and ABCC9 variants) associated with hippocampal sclerosis of aging pathology. J Neuropathol Exp Neurol 2015; 74:75-84. [PMID: 25470345 PMCID: PMC4270894 DOI: 10.1097/nen.0000000000000151] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hippocampal sclerosis of aging (HS-Aging) is a common high-morbidity neurodegenerative condition in elderly persons. To understand the risk factors for HS-Aging, we analyzed data from the Alzheimer's Disease Genetics Consortium and correlated the data with clinical and pathologic information from the National Alzheimer's Coordinating Center database. Overall, 268 research volunteers with HS-Aging and 2,957 controls were included; detailed neuropathologic data were available for all. The study focused on single-nucleotide polymorphisms previously associated with HS-Aging risk: rs5848 (GRN), rs1990622 (TMEM106B), and rs704180 (ABCC9). Analyses of a subsample that was not previously evaluated (51 HS-Aging cases and 561 controls) replicated the associations of previously identified HS-Aging risk alleles. To test for evidence of gene-gene interactions and genotype-phenotype relationships, pooled data were analyzed. The risk for HS-Aging diagnosis associated with these genetic polymorphisms was not secondary to an association with either Alzheimer disease or dementia with Lewy body neuropathologic changes. The presence of multiple risk genotypes was associated with a trend for additive risk for HS-Aging pathology. We conclude that multiple genes play important roles in HS-Aging, which is a distinctive neurodegenerative disease of aging.
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Affiliation(s)
- Peter T. Nelson
- University of Kentucky, Department of Pathology and Sanders-Brown Center on Aging, Lexington, Kentucky (PTN)
| | - Wang-Xia Wang
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, Kentucky (W-XW, BRW)
| | - Amanda B. Partch
- University of Pennsylvania, Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania (ABP, OV, L-SW)
| | - Sarah E. Monsell
- University of Washington, National Alzheimer's Coordinating Center, Seattle, Washington (SEM)
| | - Otto Valladares
- University of Pennsylvania, Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania (ABP, OV, L-SW)
| | - Sally R. Ellingson
- University of Kentucky, Division of Biomedical Informatics, College of Public Health, Lexington, Kentucky (SRE)
| | - Bernard R. Wilfred
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, Kentucky (W-XW, BRW)
| | - Adam C. Naj
- University of Pennsylvania, Department of Biostatistics and Epidemiology, Perelman School of Medicine, Philadelphia, Pennsylvania (ACN)
| | - Li-San Wang
- University of Pennsylvania, Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania (ABP, OV, L-SW)
| | - Walter A. Kukull
- University of Washington, Department of Epidemiology, Seattle, Washington (WAK)
| | - David W. Fardo
- University of Kentucky, Department of Biostatistics and Sanders-Brown Center on Aging, Lexington, Kentucky (DWF)
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121
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Zhou HM, Zhong ML, Zhang YF, Cui WY, Long CL, Wang H. Natakalim improves post-infarction left ventricular remodeling by restoring the coordinated balance between endothelial function and cardiac hypertrophy. Int J Mol Med 2014; 34:1209-18. [PMID: 25215478 PMCID: PMC4199399 DOI: 10.3892/ijmm.2014.1931] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/28/2014] [Indexed: 12/15/2022] Open
Abstract
Endothelial dysfunction can lead to congestive heart failure and the activation of endothelial ATP-sensitive potassium (KATP) channels may contribute to endothelial protection. Therefore, the present study was carried out to investigate the hypothesis that natakalim, a novel KATP channel opener, ameliorates post-infarction left ventricular remodeling and failure by correcting endothelial dysfunction. The effects of myocardial infarction were assessed 8 weeks following left anterior descending coronary artery occlusion in male Wistar rats. Depressed blood pressure, cardiac dysfunction, evidence of left ventricular remodeling and congestive heart failure were observed in the rats with myocardial infarction. Treatment with natakalim at daily oral doses of 1, 3 or 9 mg/kg/day for 8 weeks prevented these changes. Natakalim also prevented the progression to cardiac failure, which was demonstrated by the increase in right ventricular weight/body weight (RVW/BW) and relative lung weight, signs of cardiac dysfunction, as well as the overexpression of atrial and brain natriuretic peptide mRNAs. Our results also demonstrated that natakalim enhanced the downregulation of endothelium-derived nitric oxide, attenuated the upregulation of inducible nitric oxide synthase-derived nitric oxide (NO), inhibited the upregulated endothelin system and corrected the imbalance between prostacyclin and thromboxane A2. Overall, our findings suggest that natakalim prevents post-infarction hypertrophy and cardiac failure by restoring the coordinated balance between endothelial function and cardiac hypertrophy.
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Affiliation(s)
- Hong-Min Zhou
- Cardiovascular Drug Research Center, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Beijing 100850, P.R. China
| | - Ming-Li Zhong
- Cardiovascular Drug Research Center, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Beijing 100850, P.R. China
| | - Yan-Fang Zhang
- Cardiovascular Drug Research Center, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Beijing 100850, P.R. China
| | - Wen-Yu Cui
- Cardiovascular Drug Research Center, Thadweik Academy of Medicine, Beijing 100039, P.R. China
| | - Chao-Liang Long
- Cardiovascular Drug Research Center, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Beijing 100850, P.R. China
| | - Hai Wang
- Cardiovascular Drug Research Center, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Beijing 100850, P.R. China
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Liu Z, Li W, Ma X, Ding N, Spallotta F, Southon E, Tessarollo L, Gaetano C, Mukouyama YS, Thiele CJ. Essential role of the zinc finger transcription factor Casz1 for mammalian cardiac morphogenesis and development. J Biol Chem 2014; 289:29801-16. [PMID: 25190801 DOI: 10.1074/jbc.m114.570416] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Chromosome 1p36 deletion syndrome is one of the most common terminal deletions observed in humans and is related to congenital heart disease (CHD). However, the 1p36 genes that contribute to heart disease have not been clearly delineated. Human CASZ1 gene localizes to 1p36 and encodes a zinc finger transcription factor. Casz1 is required for Xenopus heart ventral midline progenitor cell differentiation. Whether Casz1 plays a role during mammalian heart development is unknown. Our aim is to determine 1p36 gene CASZ1 function at regulating heart development in mammals. We generated a Casz1 knock-out mouse using Casz1-trapped embryonic stem cells. Casz1 deletion in mice resulted in abnormal heart development including hypoplasia of myocardium, ventricular septal defect, and disorganized morphology. Hypoplasia of myocardium was caused by decreased cardiomyocyte proliferation. Comparative genome-wide RNA transcriptome analysis of Casz1 depleted embryonic hearts identifies abnormal expression of genes that are critical for muscular system development and function, such as muscle contraction genes TNNI2, TNNT1, and CKM; contractile fiber gene ACTA1; and cardiac arrhythmia associated ion channel coding genes ABCC9 and CACNA1D. The transcriptional regulation of some of these genes by Casz1 was also found in cellular models. Our results showed that loss of Casz1 during mouse development led to heart defect including cardiac noncompaction and ventricular septal defect, which phenocopies 1p36 deletion syndrome related CHD. This suggests that CASZ1 is a novel 1p36 CHD gene and that the abnormal expression of cardiac morphogenesis and contraction genes induced by loss of Casz1 contributes to the heart defect.
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Affiliation(s)
| | - Wenling Li
- the Laboratories of Stem Cell and Neuro-vascular Biology and
| | - Xuefei Ma
- the Molecular Cardiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | | | - Francesco Spallotta
- the Division of Cardiovascular Epigenetics, Department of Cardiology, Goethe University, Frankfurt am Main 60596, Germany
| | - Eileen Southon
- the Mouse Cancer Genetics Program, Neural Development Section, National Cancer Institute, Bethesda, Maryland 20892
| | - Lino Tessarollo
- the Mouse Cancer Genetics Program, Neural Development Section, National Cancer Institute, Bethesda, Maryland 20892
| | - Carlo Gaetano
- the Division of Cardiovascular Epigenetics, Department of Cardiology, Goethe University, Frankfurt am Main 60596, Germany
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Dual response of the KATP channels to staurosporine: a novel role of SUR2B, SUR1 and Kir6.2 subunits in the regulation of the atrophy in different skeletal muscle phenotypes. Biochem Pharmacol 2014; 91:266-75. [PMID: 24998494 DOI: 10.1016/j.bcp.2014.06.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 06/26/2014] [Accepted: 06/26/2014] [Indexed: 11/23/2022]
Abstract
We investigated on the role of the genes encoding for the ATP-sensitive K(+)-channel (KATP) subunits (SUR1-2A/B, Kir6.2) in the atrophy induced "in vitro" by staurosporine (STS) in different skeletal muscle phenotypes of mouse. Patch-clamp and gene expression experiments showed that the expression/activity of the sarcolemma KATP channel subunits was higher in the fast-twitch than in the slow-twitch fibers. After 1 to 3h of incubation time, the STS (2.14×10(-6)M) treatment enhanced the expression/activity of the SUR2B, SUR1 and Kir6.2 subunit genes, but not SUR2A, in the slow-twitch muscle fibers, induced the caspase-3-9, Atrogin-1 and Murf-1 gene expression without affecting protein content. After 3 to 6h, the STS-related atrophy markedly down-regulated the SUR2B, SUR1 and Kir6.2 genes reducing the KATP currents and reduced the protein content/muscle weight ratio of the slow-twitch muscle by -36.4±6% (p<0.05). After 6 to 24h, no additional changes of the SUR1-2B and Kir6.2 gene expression and muscle protein were observed. In the fast-twitch muscles, STS mildly affected the atrophic genes and protein content, but potentiated the KATP currents down-regulating the Bnip-3 gene. Diazoxide (250-500×10(-6)M), a SUR1-2B/Kir6.2 channel opener, prevented the protein loss induced by STS in the slow-twitch muscle after 6h showing an EC50 of 1.35×10(-7)M and Emax of 75%, down-regulated the caspase-9 gene and enhanced the KATP currents. The enhanced expression/activity of the SUR2B, SUR1 and Kir6.2 genes are cytoprotective against STS-induced atrophy in the slow-twitch muscle; their reduced expression/activity is associated with proteolysis and atrophy in skeletal muscle.
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125
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Affiliation(s)
- Geoffrey W Abbott
- 1360 Medical Surge II, Dept. of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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126
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Nelson PT, Estus S, Abner EL, Parikh I, Malik M, Neltner JH, Ighodaro E, Wang WX, Wilfred BR, Wang LS, Kukull WA, Nandakumar K, Farman ML, Poon WW, Corrada MM, Kawas CH, Cribbs DH, Bennett DA, Schneider JA, Larson EB, Crane PK, Valladares O, Schmitt FA, Kryscio RJ, Jicha GA, Smith CD, Scheff SW, Sonnen JA, Haines JL, Pericak-Vance MA, Mayeux R, Farrer LA, Van Eldik LJ, Horbinski C, Green RC, Gearing M, Poon LW, Kramer PL, Woltjer RL, Montine TJ, Partch AB, Rajic AJ, Richmire K, Monsell SE, Schellenberg GD, Fardo DW. ABCC9 gene polymorphism is associated with hippocampal sclerosis of aging pathology. Acta Neuropathol 2014; 127:825-43. [PMID: 24770881 PMCID: PMC4113197 DOI: 10.1007/s00401-014-1282-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 04/10/2014] [Accepted: 04/10/2014] [Indexed: 12/13/2022]
Abstract
Hippocampal sclerosis of aging (HS-Aging) is a high-morbidity brain disease in the elderly but risk factors are largely unknown. We report the first genome-wide association study (GWAS) with HS-Aging pathology as an endophenotype. In collaboration with the Alzheimer's Disease Genetics Consortium, data were analyzed from large autopsy cohorts: (#1) National Alzheimer's Coordinating Center (NACC); (#2) Rush University Religious Orders Study and Memory and Aging Project; (#3) Group Health Research Institute Adult Changes in Thought study; (#4) University of California at Irvine 90+ Study; and (#5) University of Kentucky Alzheimer's Disease Center. Altogether, 363 HS-Aging cases and 2,303 controls, all pathologically confirmed, provided statistical power to test for risk alleles with large effect size. A two-tier study design included GWAS from cohorts #1-3 (Stage I) to identify promising SNP candidates, followed by focused evaluation of particular SNPs in cohorts #4-5 (Stage II). Polymorphism in the ATP-binding cassette, sub-family C member 9 (ABCC9) gene, also known as sulfonylurea receptor 2, was associated with HS-Aging pathology. In the meta-analyzed Stage I GWAS, ABCC9 polymorphisms yielded the lowest p values, and factoring in the Stage II results, the meta-analyzed risk SNP (rs704178:G) attained genome-wide statistical significance (p = 1.4 × 10(-9)), with odds ratio (OR) of 2.13 (recessive mode of inheritance). For SNPs previously linked to hippocampal sclerosis, meta-analyses of Stage I results show OR = 1.16 for rs5848 (GRN) and OR = 1.22 rs1990622 (TMEM106B), with the risk alleles as previously described. Sulfonylureas, a widely prescribed drug class used to treat diabetes, also modify human ABCC9 protein function. A subsample of patients from the NACC database (n = 624) were identified who were older than age 85 at death with known drug history. Controlling for important confounders such as diabetes itself, exposure to a sulfonylurea drug was associated with risk for HS-Aging pathology (p = 0.03). Thus, we describe a novel and targetable dementia risk factor.
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Affiliation(s)
- Peter T. Nelson
- Department of Pathology, Division of Neuropathology, Rm 311, Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone Avenue, Lexington, KY 40536-0230, USA
| | | | | | | | | | | | | | | | | | - Li-San Wang
- University of Pennsylvania, Philadelphia, PA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Leonard W. Poon
- Institute of Gerontology, University of Georgia, Athens, GA, USA
| | | | | | | | | | | | | | | | | | | | - David W. Fardo
- Department of Biostatistics, University of Kentucky, 205E Multidisciplinary Science Building, 725 Rose Street, Lexington, KY 40536-0082, USA
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127
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Raphemot R, Swale DR, Dadi PK, Jacobson DA, Cooper P, Wojtovich AP, Banerjee S, Nichols CG, Denton JS. Direct activation of β-cell KATP channels with a novel xanthine derivative. Mol Pharmacol 2014; 85:858-65. [PMID: 24646456 DOI: 10.1124/mol.114.091884] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ATP-regulated potassium (KATP) channel complexes of inward rectifier potassium channel (Kir) 6.2 and sulfonylurea receptor (SUR) 1 critically regulate pancreatic islet β-cell membrane potential, calcium influx, and insulin secretion, and consequently, represent important drug targets for metabolic disorders of glucose homeostasis. The KATP channel opener diazoxide is used clinically to treat intractable hypoglycemia caused by excessive insulin secretion, but its use is limited by off-target effects due to lack of potency and selectivity. Some progress has been made in developing improved Kir6.2/SUR1 agonists from existing chemical scaffolds and compound screening, but there are surprisingly few distinct chemotypes that are specific for SUR1-containing KATP channels. Here we report the serendipitous discovery in a high-throughput screen of a novel activator of Kir6.2/SUR1: VU0071063 [7-(4-(tert-butyl)benzyl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione]. The xanthine derivative rapidly and dose-dependently activates Kir6.2/SUR1 with a half-effective concentration (EC50) of approximately 7 μM, is more efficacious than diazoxide at low micromolar concentrations, directly activates the channel in excised membrane patches, and is selective for SUR1- over SUR2A-containing Kir6.1 or Kir6.2 channels, as well as Kir2.1, Kir2.2, Kir2.3, Kir3.1/3.2, and voltage-gated potassium channel 2.1. Finally, we show that VU0071063 activates native Kir6.2/SUR1 channels, thereby inhibiting glucose-stimulated calcium entry in isolated mouse pancreatic β cells. VU0071063 represents a novel tool/compound for investigating β-cell physiology, KATP channel gating, and a new chemical scaffold for developing improved activators with medicinal chemistry.
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Affiliation(s)
- Rene Raphemot
- Departments of Anesthesiology (R.R., D.R.S., S.B., J.S.D.), Pharmacology (R.R., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.) and Institutes of Chemical Biology (J.S.D.) and Global Health (J.S.D.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, University of Rochester Medical Center, Rochester, New York (A.P.W.); and Department of Cell Biology and Physiology (P.C., C.G.N.) and Center for the Investigation of Membrane Excitability Disorders (P.C., C.G.N.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
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128
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Mele A, Calzolaro S, Cannone G, Cetrone M, Conte D, Tricarico D. Database search of spontaneous reports and pharmacological investigations on the sulfonylureas and glinides-induced atrophy in skeletal muscle. Pharmacol Res Perspect 2014; 2:e00028. [PMID: 25505577 PMCID: PMC4186404 DOI: 10.1002/prp2.28] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 01/09/2014] [Accepted: 01/11/2014] [Indexed: 12/14/2022] Open
Abstract
The ATP-sensitive K(+) (KATP) channel is an emerging pathway in the skeletal muscle atrophy which is a comorbidity condition in diabetes. The "in vitro" effects of the sulfonylureas and glinides were evaluated on the protein content/muscle weight, fibers viability, mitochondrial succinic dehydrogenases (SDH) activity, and channel currents in oxidative soleus (SOL), glycolitic/oxidative flexor digitorum brevis (FDB), and glycolitic extensor digitorum longus (EDL) muscle fibers of mice using biochemical and cell-counting Kit-8 assay, image analysis, and patch-clamp techniques. The sulfonylureas were: tolbutamide, glibenclamide, and glimepiride; the glinides were: repaglinide and nateglinide. Food and Drug Administration-Adverse Effects Reporting System (FDA-AERS) database searching of atrophy-related signals associated with the use of these drugs in humans has been performed. The drugs after 24 h of incubation time reduced the protein content/muscle weight and fibers viability more effectively in FDB and SOL than in the EDL. The order of efficacy of the drugs in reducing the protein content in FDB was: repaglinide (EC50 = 5.21 × 10(-6)) ≥ glibenclamide(EC50 = 8.84 × 10(-6)) > glimepiride(EC50 = 2.93 × 10(-5)) > tolbutamide(EC50 = 1.07 × 10(-4)) > nateglinide(EC50 = 1.61 × 10(-4)) and it was: repaglinide(7.15 × 10(-5)) ≥ glibenclamide(EC50 = 9.10 × 10(-5)) > nateglinide(EC50 = 1.80 × 10(-4)) ≥ tolbutamide(EC50 = 2.19 × 10(-4)) > glimepiride(EC50=-) in SOL. The drug-induced atrophy can be explained by the KATP channel block and by the enhancement of the mitochondrial SDH activity. In an 8-month period, muscle atrophy was found in 0.27% of the glibenclamide reports in humans and in 0.022% of the other not sulfonylureas and glinides drugs. No reports of atrophy were found for the other sulfonylureas and glinides in the FDA-AERS. Glibenclamide induces atrophy in animal experiments and in human patients. Glimepiride shows less potential for inducing atrophy.
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Affiliation(s)
- Antonietta Mele
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Sara Calzolaro
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Gianluigi Cannone
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Michela Cetrone
- Departments of Pharmacovigilance, University-Hospital Policlinico, Ministry of Health Bari, Italy
| | - Diana Conte
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
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129
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Arakel EC, Brandenburg S, Uchida K, Zhang H, Lin YW, Kohl T, Schrul B, Sulkin MS, Efimov IR, Nichols CG, Lehnart SE, Schwappach B. Tuning the electrical properties of the heart by differential trafficking of KATP ion channel complexes. J Cell Sci 2014; 127:2106-19. [PMID: 24569881 PMCID: PMC4004980 DOI: 10.1242/jcs.141440] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The copy number of membrane proteins at the cell surface is tightly regulated. Many ion channels and receptors present retrieval motifs to COPI vesicle coats and are retained in the early secretory pathway. In some cases, the interaction with COPI is prevented by binding to 14-3-3 proteins. However, the functional significance of this antagonism between COPI and 14-3-3 in terminally differentiated cells is unknown. Here, we show that ATP-sensitive K+ (KATP) channels, which are composed of Kir6.2 and SUR1 subunits, are stalled in the Golgi complex of ventricular, but not atrial, cardiomyocytes. Upon sustained β-adrenergic stimulation, which leads to activation of protein kinase A (PKA), SUR1-containing channels reach the plasma membrane of ventricular cells. We show that PKA-dependent phosphorylation of the C-terminus of Kir6.2 decreases binding to COPI and, thereby, silences the arginine-based retrieval signal. Thus, activation of the sympathetic nervous system releases this population of KATP channels from storage in the Golgi and, hence, might facilitate the adaptive response to metabolic challenges.
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Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
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130
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Du RH, Dai T, Cao WJ, Lu M, Ding JH, Hu G. Kir6.2-containing ATP-sensitive K(+) channel is required for cardioprotection of resveratrol in mice. Cardiovasc Diabetol 2014; 13:35. [PMID: 24498880 PMCID: PMC3916794 DOI: 10.1186/1475-2840-13-35] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/21/2014] [Indexed: 01/05/2023] Open
Abstract
Background Resveratrol is a natural compound that affects energy metabolism and is also known to possess an array of cardioprotective effects. However, its overall effects on energy metabolism and the underlying mechanism involved in cardioprotection require further investigation. Herein we hypothesize that ATP-sensitive potassium (K-ATP) channels as molecular sensors of cellular metabolism may mediate the cardioprotective effects of resveratrol. Methods Kir6.2 knockout, Kir6.1 heterozygous and wild-type (WT) mice were subjected to ischemia/reperfusion injury and were injected with resveratrol (10 mg/kg, i.p). Myocardial infarct size, serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities were determined. Neonatal cardiomyocytes were used in in vitro assays to investigate the underlying mechanism of resveratrol in cardioprotection. Results Resveratrol treatment significantly reduced myocardial infarct size and serum LDH and CK activity and inhibited oxygen-glucose deprivation/reoxygenation – induced cardiomyocyte apoptosis in WT and Kir6.1 heterozygous mice, but Kir6.2 deficiency can abolish the cardioprotective effects of resveratrol in vivo and in vitro. We further found that resveratrol enhanced 5′-AMP-activated protein kinase (AMPK) phosphorylation and promoted the association of AMPK with Kir6.2. Suppression of AMPK attenuated and activation of AMPK mimicked the cardioprotective effects of resveratrol in cardiomyocytes. Notably, Kir6.2 knockout also reversed the cardioprotection of AMPK activator. Conclusions Our study demonstrates that resveratrol exerts cardioprotective effects through AMPK -Kir6.2/K-ATP signal pathway and Kir6.2-containing K-ATP channel is required for cardioprotection of resveratrol.
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Affiliation(s)
| | | | | | | | | | - Gang Hu
- Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, P,R, China.
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131
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Albaqumi M, Alhabib FA, Shamseldin HE, Mohammed F, Alkuraya FS. A syndrome of congenital hyperinsulinism and rhabdomyolysis is caused by KCNJ11 mutation. J Med Genet 2014; 51:271-4. [PMID: 24421282 DOI: 10.1136/jmedgenet-2013-102085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Congenital hyperinsulinism is a genetically heterogeneous disorder, but mutations in the components of the ATP-sensitive potassium channel K(ATP) account for more than a third of all isolated congenital hyperinsulinism cases. The association between congenital hyperinsulinism and rhabdomyolysis has not been reported. OBJECTIVE To describe significant skeletal muscle manifestations in a family with a novel mutation in KCNJ11 (encoding the Kir6.2 component of K(ATP)). METHODS Cross-sectional analysis of members of a large multiplex consanguineous family with congenital hyperinsulinism and rhabdomyolysis using autozygosity mapping and exome sequencing. RESULTS Five affected members of an extended consanguineous Saudi family were recruited along with relevant unaffected relatives. We were able to map an apparently novel syndrome of congenital hyperinsulinism and severe rhabdomyolysis leading to acute renal failure to a single locus that harbours KCNJ11 in which we identified a novel homozygous mutation. CONCLUSIONS This study expands the phenotype associated with KCNJ11 loss of function in humans and calls for increased awareness of rhabdomyolysis as a potential late-onset life-threatening complication of KCNJ11-related congenital hyperinsulinism.
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Affiliation(s)
- Mamdouh Albaqumi
- Division of Nephrology, Department of Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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132
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Kruse M, Pongs O. TRPM4 channels in the cardiovascular system. Curr Opin Pharmacol 2013; 15:68-73. [PMID: 24721656 DOI: 10.1016/j.coph.2013.12.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 02/08/2023]
Abstract
The non-selective Transient Receptor Potential Melastatin 4 (TRPM4) cation channel is abundantly expressed in cardiac cells, being involved in several aspects of cardiac rhythmicity, including cardiac conduction, pace making and action-potential repolarization. Dominantly inherited mutations in the TRPM4 gene are associated with the cardiac bundle-branch disorder progressive familial heart block type I (PFHBI) and isolated cardiac conduction disease (ICCD) giving rise to atrio-ventricular conduction block (AVB), right bundle branch block, bradycardia, and the Brugada syndrome. The mutant phenotypes closely resemble those associated with mutations in the SCN5A gene, encoding the voltage-gated Na(+) channel NaV1.5. These observations and the unexpected partnership with sulfonylurea-receptors (SURs) makes the TRPM4 channel a promising novel target for treatment of cardiac disorders.
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Affiliation(s)
- Martin Kruse
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Olaf Pongs
- Institute of Physiology, Universitätsklinikum des Saarlandes, Homburg, Germany.
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133
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Abstract
The sarcolemmal adenosine triphosphate (ATP)-sensitive K(+) (sarcKATP) channel in the heart is a hetero-octamer comprising the pore-forming subunit Kir6.2 and the regulatory subunit sulfonylurea receptor SUR2A. By functional analysis of genetically engineered mice lacking sarcKATP channels, the pathophysiological roles of the K(+) channel in the heart have been extensively evaluated. Although mitochondrial KATP (mitoKATP) channel is proposed to be an important effector for the protection of ischemic myocardium and the inhibition of ischemia/reperfusion-induced ventricular arrhythmias, the molecular identity of mitoKATP channel has not been established. Although selective sarcKATP-channel blockers can prevent ischemia/reperfusion-induced ventricular arrhythmias by inhibiting the action potential shortening in the acute phase, the drugs may aggravate the ischemic damages due to intracellular Ca(2+) overload. The sarcKATP channel is also mandatory for optimal adaptation to hemodynamic stress such as sympathetic activation. Dysfunction of mutated sarcKATP channels in atrial cells may lead to electrical instability and atrial fibrillation. Recently, it has been proposed that the gain-of-function mutation of cardiac Kir6.1 channel can be a pathogenic substrate for J wave syndromes, a cause of idiopathic ventricular fibrillation as early repolarization syndrome or Brugada syndrome, whereas loss of function of the channel mutations can underlie sudden infant death syndrome. However, precise role of Kir6.1 channels in cardiac cells remains to be defined and further study may be needed to clarify the role of Kir6.1 channel in the heart.
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Affiliation(s)
- Haruaki Nakaya
- 1Department of Pharmacology, Chiba University Graduate School of Medicine, Chiba, Japan
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134
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Zhu Z, Sierra A, Burnett CML, Chen B, Subbotina E, Koganti SRK, Gao Z, Wu Y, Anderson ME, Song LS, Goldhamer DJ, Coetzee WA, Hodgson-Zingman DM, Zingman LV. Sarcolemmal ATP-sensitive potassium channels modulate skeletal muscle function under low-intensity workloads. ACTA ACUST UNITED AC 2013; 143:119-34. [PMID: 24344248 PMCID: PMC3874572 DOI: 10.1085/jgp.201311063] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ATP-sensitive potassium (KATP) channels have the unique ability to adjust membrane excitability and functions in accordance with the metabolic status of the cell. Skeletal muscles are primary sites of activity-related energy consumption and have KATP channels expressed in very high density. Previously, we demonstrated that transgenic mice with skeletal muscle–specific disruption of KATP channel function consume more energy than wild-type littermates. However, how KATP channel activation modulates skeletal muscle resting and action potentials under physiological conditions, particularly low-intensity workloads, and how this can be translated to muscle energy expenditure are yet to be determined. Here, we developed a technique that allows evaluation of skeletal muscle excitability in situ, with minimal disruption of the physiological environment. Isometric twitching of the tibialis anterior muscle at 1 Hz was used as a model of low-intensity physical activity in mice with normal and genetically disrupted KATP channel function. This workload was sufficient to induce KATP channel opening, resulting in membrane hyperpolarization as well as reduction in action potential overshoot and duration. Loss of KATP channel function resulted in increased calcium release and aggravated activity-induced heat production. Thus, this study identifies low-intensity workload as a trigger for opening skeletal muscle KATP channels and establishes that this coupling is important for regulation of myocyte function and thermogenesis. These mechanisms may provide a foundation for novel strategies to combat metabolic derangements when energy conservation or dissipation is required.
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Affiliation(s)
- Zhiyong Zhu
- Department of Internal Medicine and 2 Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242
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Brownstein CA, Towne MC, Luquette LJ, Harris DJ, Marinakis NS, Meinecke P, Kutsche K, Campeau PM, Yu TW, Margulies DM, Agrawal PB, Beggs AH. Mutation of KCNJ8 in a patient with Cantú syndrome with unique vascular abnormalities - support for the role of K(ATP) channels in this condition. Eur J Med Genet 2013; 56:678-82. [PMID: 24176758 DOI: 10.1016/j.ejmg.2013.09.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 09/19/2013] [Indexed: 11/19/2022]
Abstract
KCNJ8 (NM_004982) encodes the pore forming subunit of one of the ATP-sensitive inwardly rectifying potassium (KATP) channels. KCNJ8 sequence variations are traditionally associated with J-wave syndromes, involving ventricular fibrillation and sudden cardiac death. Recently, the KATP gene ABCC9 (SUR2, NM_020297) has been associated with the multi-organ disorder Cantú syndrome or hypertrichotic osteochondrodysplasia (MIM 239850) (hypertrichosis, macrosomia, osteochondrodysplasia, and cardiomegaly). Here, we report on a patient with a de novo nonsynonymous KCNJ8 SNV (p.V65M) and Cantú syndrome, who tested negative for mutations in ABCC9. The genotype and multi-organ abnormalities of this patient are reviewed. A careful screening of the KATP genes should be performed in all individuals diagnosed with Cantú syndrome and no mutation in ABCC9.
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Affiliation(s)
- Catherine A Brownstein
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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KATP vs Purkinje fibers: which should we shoot first, or should we? Heart Rhythm 2013; 10:1718-9. [PMID: 23994077 DOI: 10.1016/j.hrthm.2013.08.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Indexed: 11/20/2022]
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