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Christophersen IE, Ellinor PT. Genetics of atrial fibrillation: from families to genomes. J Hum Genet 2015; 61:61-70. [DOI: 10.1038/jhg.2015.44] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 03/27/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022]
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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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Haghvirdizadeh P, Mohamed Z, Abdullah NA, Haghvirdizadeh P, Haerian MS, Haerian BS. KCNJ11: Genetic Polymorphisms and Risk of Diabetes Mellitus. J Diabetes Res 2015; 2015:908152. [PMID: 26448950 PMCID: PMC4584059 DOI: 10.1155/2015/908152] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 11/18/2014] [Accepted: 11/27/2014] [Indexed: 01/12/2023] Open
Abstract
Diabetes mellitus (DM) is a major worldwide health problem and its prevalence has been rapidly increasing in the last century. It is caused by defects in insulin secretion or insulin action or both, leading to hyperglycemia. Of the various types of DM, type 2 occurs most frequently. Multiple genes and their interactions are involved in the insulin secretion pathway. Insulin secretion is mediated through the ATP-sensitive potassium (KATP) channel in pancreatic beta cells. This channel is a heteromeric protein, composed of four inward-rectifier potassium ion channel (Kir6.2) tetramers, which form the pore of the KATP channel, as well as sulfonylurea receptor 1 subunits surrounding the pore. Kir6.2 is encoded by the potassium inwardly rectifying channel, subfamily J, member 11 (KCNJ11) gene, a member of the potassium channel genes. Numerous studies have reported the involvement of single nucleotide polymorphisms of the KCNJ11 gene and their interactions in the susceptibility to DM. This review discusses the current evidence for the contribution of common KCNJ11 genetic variants to the development of DM. Future studies should concentrate on understanding the exact role played by these risk variants in the development of DM.
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Affiliation(s)
- Polin Haghvirdizadeh
- Pharmacogenomics Lab, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Zahurin Mohamed
- Pharmacogenomics Lab, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Nor Azizan Abdullah
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | | | - Monir Sadat Haerian
- Shahid Beheshti University of Medical Sciences, P.O. Box 19395-4763, Tehran, Iran
- Food and Drug Control Reference Labs Center (FDCRLC), Ministry of Health and Medical Education, Tehran 131456-8784, Iran
| | - Batoul Sadat Haerian
- Pharmacogenomics Lab, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
- *Batoul Sadat Haerian:
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Weeke P, Denny JC, Basterache L, Shaffer C, Bowton E, Ingram C, Darbar D, Roden DM. Examining rare and low-frequency genetic variants previously associated with lone or familial forms of atrial fibrillation in an electronic medical record system: a cautionary note. ACTA ACUST UNITED AC 2014; 8:58-63. [PMID: 25410959 DOI: 10.1161/circgenetics.114.000718] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Studies in individuals or small kindreds have implicated rare variants in 25 different genes in lone and familial atrial fibrillation (AF) using linkage and segregation analysis, functional characterization, and rarity in public databases. Here, we used a cohort of 20 204 patients of European or African ancestry with electronic medical records and exome chip data to compare the frequency of AF among carriers and noncarriers of these rare variants. METHODS AND RESULTS The exome chip included 19 of 115 rare variants, in 9 genes, previously associated with lone or familial AF. Using validated algorithms querying a combination of clinical notes, structured billing codes, ECG reports, and procedure codes, we identified 1056 AF cases (>18 years) and 19 148 non-AF controls (>50 years) with available genotype data on the Illumina HumanExome BeadChip v.1.0 in the Vanderbilt electronic medical record-linked DNA repository, BioVU. Known correlations between AF and common variants at 4q25 were replicated. None of the 19 variants previously associated with AF were over-represented among AF cases (P>0.1 for all), and the frequency of variant carriers among non-AF controls was >0.1% for 14 of 19. Repeat analyses using non-AF controls aged >60 (n=14 904), >70 (n=9670), and >80 (n=4729) years did not influence these findings. CONCLUSIONS Rare variants previously implicated in lone or familial forms of AF present on the exome chip are detected at low frequencies in a general population but are not associated with AF. These findings emphasize the need for caution when ascribing variants as pathogenic or causative.
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Affiliation(s)
- Peter Weeke
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Joshua C Denny
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Lisa Basterache
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Christian Shaffer
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Erica Bowton
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Christie Ingram
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Dawood Darbar
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.)
| | - Dan M Roden
- From the Department of Internal Medicine (P.W., J.C.D., C.S., C.I., D.D., D.M.R.) and Department of Biomedical Informatics (J.C.D., L.B.), Vanderbilt University Medical Center, Nashville, TN; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark (P.W.); and Institute for Clinical and Translational Research, Vanderbilt University School of Medicine, Nashville, TN (E.B.).
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Mahida S. Genetic Discoveries in Atrial Fibrillation and Implications for Clinical Practice. Arrhythm Electrophysiol Rev 2014; 3:69-75. [PMID: 26835069 DOI: 10.15420/aer.2014.3.2.69] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/04/2014] [Indexed: 11/04/2022] Open
Abstract
Atrial fibrillation (AF) is an arrhythmia with a genetic basis. Over the past decade, rapid advances in genotyping technology have revolutionised research regarding the genetic basis of AF. While AF genetics research was previously largely restricted to familial forms of AF, recent studies have begun to characterise the genetic architecture underlying the form of AF encountered in everyday clinical practice. These discoveries could have a significant impact on the management of AF. However, much work remains before genetic findings can be translated to clinical practice. This review summarises results of studies in AF genetics to date and discusses the potential implications of these findings in clinical practice.
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56
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de Araujo ED, Kanelis V. Successful development and use of a thermodynamic stability screen for optimizing the yield of nucleotide binding domains. Protein Expr Purif 2014; 103:38-47. [PMID: 25153533 DOI: 10.1016/j.pep.2014.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/08/2014] [Accepted: 08/09/2014] [Indexed: 01/09/2023]
Abstract
ATP sensitive potassium (KATP) channels consist of four copies of a pore-forming inward rectifying potassium channel (Kir6.1 or Kir6.2) and four copies of a sulfonylurea receptor (SUR1, SUR2A, or SUR2B). SUR proteins are members of the ATP-binding cassette superfamily of proteins. Binding of ATP to the Kir6.x subunit mediates channel inhibition, whereas MgATP binding and hydrolysis at the SUR NBDs results in channel opening. Mutations in SUR1 and SUR2A NBDs cause diseases of insulin secretion and cardiac disorders, respectively, underlying the importance of studying the NBDs. Although purification of SUR2A NBD1 in a soluble form is possible, the lack of long-term sample stability of the protein in a concentrated form has precluded detailed studies of the protein aimed at gaining a molecular-level understanding of how SUR mutations cause disease. Here we use a convenient and cost-effective thermodynamic screening method to probe stabilizing conditions for SUR2A NBD1. Results from the screen are used to alter the purification protocol to allow for significantly increased yields of the purified protein. In addition, the screen provides strategies for long-term storage of NBD1 and generating NBD1 samples at high concentrations suitable for NMR studies. NMR spectra of NBD1 with MgAMP-PNP are of higher quality compared to using MgATP, indicating that MgAMP-PNP be used as the ligand in future NMR studies. The screen presented here can be expanded to using different additives and can be employed to enhance purification yields, sample life times, and storage of other low stability nucleotide binding domains, such as GTPases.
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Affiliation(s)
- Elvin D de Araujo
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario L5L 1C6, Canada
| | - Voula Kanelis
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario L5L 1C6, Canada; Department of Cell and Systems Biology, University of Toronto, 25 Harbord St., Toronto, Ontario M5S 3G5, Canada.
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Savio-Galimberti E, Weeke P, Muhammad R, Blair M, Ansari S, Short L, Atack TC, Kor K, Vanoye CG, Olesen MS, LuCamp, Yang T, George AL, Roden DM, Darbar D. SCN10A/Nav1.8 modulation of peak and late sodium currents in patients with early onset atrial fibrillation. Cardiovasc Res 2014; 104:355-63. [PMID: 25053638 DOI: 10.1093/cvr/cvu170] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS To test the hypothesis that vulnerability to atrial fibrillation (AF) is associated with rare coding sequence variation in the SCN10A gene, which encodes the voltage-gated sodium channel isoform NaV1.8 found primarily in peripheral nerves and to identify potentially disease-related mechanisms in high-priority rare variants using in-vitro electrophysiology. METHODS AND RESULTS We re-sequenced SCN10A in 274 patients with early onset AF from the Vanderbilt AF Registry to identify rare coding variants. Engineered variants were transiently expressed in ND7/23 cells and whole-cell voltage clamp experiments were conducted to elucidate their functional properties. Resequencing SCN10A identified 18 heterozygous rare coding variants (minor allele frequency ≤1%) in 18 (6.6%) AF probands. Four probands were carriers of two rare variants each and 14 were carriers of one coding variant. Based on evidence of co-segregation, initial assessment of functional importance, and presence in ≥1 AF proband, three variants (417delK, A1886V, and the compound variant Y158D-R814H) were selected for functional studies. The 417delK variant displayed near absent current while A1886V and Y158D-R814H exhibited enhanced peak and late (INa-L) sodium currents; both Y158D and R818H individually contributed to this phenotype. CONCLUSION Rare SCN10A variants encoding Nav1.8 were identified in 6.6% of patients with early onset AF. In-vitro electrophysiological studies demonstrated profoundly altered function in 3/3 high-priority variants. Collectively, these data strongly support the hypothesis that rare SCN10A variants may contribute to AF susceptibility.
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Affiliation(s)
- Eleonora Savio-Galimberti
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Peter Weeke
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Raafia Muhammad
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Marcia Blair
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Sami Ansari
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Laura Short
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Thomas C Atack
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Kaylen Kor
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Carlos G Vanoye
- Division of Genetic Medicine, Vanderbilt University School of Medicine, Nashville, TN 37323-6602, USA
| | - Morten Salling Olesen
- Danish National Research Centre for Cardiac Arrhythmia, Rigshospitalet, University of Copenhagen, Denmark
| | - LuCamp
- LuCamp, The Lundbeck Foundation Centre for Applied Medical Genomics in Personalized Disease Prediction, Copenhagen, Denmark
| | - Tao Yang
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Alfred L George
- Division of Genetic Medicine, Vanderbilt University School of Medicine, Nashville, TN 37323-6602, USA
| | - Dan M Roden
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
| | - Dawood Darbar
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA Division of Clinical Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Room 1285A MRB IV, Nashville, TN 37323-6602, USA
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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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Abstract
Atrial fibrillation (AF) is the most common arrhythmia and is associated with increased morbidity. As the population ages and the prevalence of AF continues to rise, the socioeconomic consequences of AF will become increasingly burdensome. Although there are well-defined clinical risk factors for AF, a significant heritable component is also recognized. To identify the molecular basis for the heritability of AF, investigators have used a combination of classical Mendelian genetics, candidate gene screening, and genome-wide association studies. However, these avenues have, as yet, failed to define the majority of the heritability of AF. The goal of this review is to describe the results from both candidate gene and genome-wide studies, as well as to outline potential future avenues for creating a more complete understanding of AF genetics. Ultimately, a more comprehensive view of the genetic underpinnings for AF will lead to the identification of novel molecular pathways and improved risk prediction of this complex arrhythmia.
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Affiliation(s)
- Nathan R Tucker
- From the Cardiovascular Research Center, Massachusetts General Hospital, Boston
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60
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Andrade J, Khairy P, Dobrev D, Nattel S. The clinical profile and pathophysiology of atrial fibrillation: relationships among clinical features, epidemiology, and mechanisms. Circ Res 2014; 114:1453-68. [PMID: 24763464 DOI: 10.1161/circresaha.114.303211] [Citation(s) in RCA: 804] [Impact Index Per Article: 80.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia (estimated lifetime risk, 22%-26%). The aim of this article is to review the clinical epidemiological features of AF and to relate them to underlying mechanisms. Long-established risk factors for AF include aging, male sex, hypertension, valve disease, left ventricular dysfunction, obesity, and alcohol consumption. Emerging risk factors include prehypertension, increased pulse pressure, obstructive sleep apnea, high-level physical training, diastolic dysfunction, predisposing gene variants, hypertrophic cardiomyopathy, and congenital heart disease. Potential risk factors are coronary artery disease, kidney disease, systemic inflammation, pericardial fat, and tobacco use. AF has substantial population health consequences, including impaired quality of life, increased hospitalization rates, stroke occurrence, and increased medical costs. The pathophysiology of AF centers around 4 general types of disturbances that promote ectopic firing and reentrant mechanisms, and include the following: (1) ion channel dysfunction, (2) Ca(2+)-handling abnormalities, (3) structural remodeling, and (4) autonomic neural dysregulation. Aging, hypertension, valve disease, heart failure, myocardial infarction, obesity, smoking, diabetes mellitus, thyroid dysfunction, and endurance exercise training all cause structural remodeling. Heart failure and prior atrial infarction also cause Ca(2+)-handling abnormalities that lead to focal ectopic firing via delayed afterdepolarizations/triggered activity. Neural dysregulation is central to atrial arrhythmogenesis associated with endurance exercise training and occlusive coronary artery disease. Monogenic causes of AF typically promote the arrhythmia via ion channel dysfunction, but the mechanisms of the more common polygenic risk factors are still poorly understood and under intense investigation. Better recognition of the clinical epidemiology of AF, as well as an improved appreciation of the underlying mechanisms, is needed to develop improved methods for AF prevention and management.
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Affiliation(s)
- Jason Andrade
- From Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (J.A., P.K., S.N.); Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (J.A.); and Faculty of Medicine, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany (D.D.)
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61
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Theis JL, Zimmermann MT, Larsen BT, Rybakova IN, Long PA, Evans JM, Middha S, de Andrade M, Moss RL, Wieben ED, Michels VV, Olson TM. TNNI3K mutation in familial syndrome of conduction system disease, atrial tachyarrhythmia and dilated cardiomyopathy. Hum Mol Genet 2014; 23:5793-804. [PMID: 24925317 DOI: 10.1093/hmg/ddu297] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Locus mapping has uncovered diverse etiologies for familial atrial fibrillation (AF), dilated cardiomyopathy (DCM), and mixed cardiac phenotype syndromes, yet the molecular basis for these disorders remains idiopathic in most cases. Whole-exome sequencing (WES) provides a powerful new tool for familial disease gene discovery. Here, synergistic application of these genomic strategies identified the pathogenic mutation in a familial syndrome of atrial tachyarrhythmia, conduction system disease (CSD), and DCM vulnerability. Seven members of a three-generation family exhibited the variably expressed phenotype, three of whom manifested CSD and clinically significant arrhythmia in childhood. Genome-wide linkage analysis mapped two equally plausible loci to chromosomes 1p3 and 13q12. Variants from WES of two affected cousins were filtered for rare, predicted-deleterious, positional variants, revealing an unreported heterozygous missense mutation disrupting the highly conserved kinase domain in TNNI3K. The G526D substitution in troponin I interacting kinase, with the most deleterious SIFT and Polyphen2 scores possible, resulted in abnormal peptide aggregation in vitro and in silico docking models predicted altered yet energetically favorable wild-type mutant dimerization. Ventricular tissue from a mutation carrier displayed histopathological hallmarks of DCM and reduced TNNI3K protein staining with unique amorphous nuclear and sarcoplasmic inclusions. In conclusion, mutation of TNNI3K, encoding a heart-specific kinase previously shown to modulate cardiac conduction and myocardial function in mice, underlies a familial syndrome of electrical and myopathic heart disease. The identified substitution causes a TNNI3K aggregation defect and protein deficiency, implicating a dominant-negative loss of function disease mechanism.
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Affiliation(s)
| | - Michael T Zimmermann
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research
| | | | - Inna N Rybakova
- Department of Cell and Regenerative Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Jared M Evans
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research
| | - Sumit Middha
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research
| | - Mariza de Andrade
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research
| | - Richard L Moss
- Department of Cell and Regenerative Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | | | - Timothy M Olson
- Cardiovascular Genetics Research Laboratory, Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine,
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Kamide K, Asayama K, Katsuya T, Ohkubo T, Hirose T, Inoue R, Metoki H, Kikuya M, Obara T, Hanada H, Thijs L, Kuznetsova T, Noguchi Y, Sugimoto K, Ohishi M, Morimoto S, Nakahashi T, Takiuchi S, Ishimitsu T, Tsuchihashi T, Soma M, Higaki J, Matsuura H, Shinagawa T, Sasaguri T, Miki T, Takeda K, Shimamoto K, Ueno M, Hosomi N, Kato J, Komai N, Kojima S, Sase K, Miyata T, Tomoike H, Kawano Y, Ogihara T, Rakugi H, Staessen JA, Imai Y. Genome-wide response to antihypertensive medication using home blood pressure measurements: a pilot study nested within the HOMED-BP study. Pharmacogenomics 2014; 14:1709-21. [PMID: 24192120 DOI: 10.2217/pgs.13.161] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Patients with mild-to-moderate essential hypertension in the HOMED-BP trial were randomly allocated to first-line treatment with a calcium channel blocker (CCB), angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB). METHODS We recruited 265 (93 for CCB, 71 for ACEI and 101 for ARB) patients who completed the genomic study. Home blood pressure was measured for 5 days off-treatment before randomization and for 5 days after 2-4 weeks of randomized drug treatment. Genotyping was performed by 500K DNA microarray chips. The blood pressure responses to the three drugs were analyzed separately as a quantitative trait. For replication of SNPs with p < 10(-4), we used the multicenter GEANE study, in which patients were randomized to valsartan or amlodipine. RESULTS SNPs in PICALM, TANC2, NUMA1 and APCDD1 were found to be associated with CCB responses and those in ABCC9 and YIPF1 were found to be associated with ARB response with replication. CONCLUSION Our approach, the first based on high-fidelity phenotyping by home blood pressure measurement, might be a step in moving towards the personalized treatment of hypertension.
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Affiliation(s)
- Kei Kamide
- Department of Geriatric Medicine & Nephrology, Osaka University Graduate School of Medicine, Osaka, Japan and Department of Health Sciences, Osaka University Graduate School of Medicine, Osaka, Japan and Research Institute, National Cerebro & Cardiovascular Research Center, Osaka, Japan and Studies Coordinating Centre, Research Unit Hypertension & Cardiovascular Epidemiology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
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Olesen MS, Nielsen MW, Haunsø S, Svendsen JH. Atrial fibrillation: the role of common and rare genetic variants. Eur J Hum Genet 2014; 22:297-306. [PMID: 23838598 PMCID: PMC3925267 DOI: 10.1038/ejhg.2013.139] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 04/28/2013] [Accepted: 05/27/2013] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting 1-2% of the general population. A number of studies have demonstrated that AF, and in particular lone AF, has a substantial genetic component. Monogenic mutations in lone and familial AF, although rare, have been recognized for many years. Presently, mutations in 25 genes have been associated with AF. However, the complexity of monogenic AF is illustrated by the recent finding that both gain- and loss-of-function mutations in the same gene can cause AF. Genome-wide association studies (GWAS) have indicated that common single-nucleotide polymorphisms (SNPs) have a role in the development of AF. Following the first GWAS discovering the association between PITX2 and AF, several new GWAS reports have identified SNPs associated with susceptibility of AF. To date, nine SNPs have been associated with AF. The exact biological pathways involving these SNPs and the development of AF are now starting to be elucidated. Since the first GWAS, the number of papers concerning the genetic basis of AF has increased drastically and the majority of these papers are for the first time included in a review. In this review, we discuss the genetic basis of AF and the role of both common and rare genetic variants in the susceptibility of developing AF. Furthermore, all rare variants reported to be associated with AF were systematically searched for in the Exome Sequencing Project Exome Variant Server.
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Affiliation(s)
- Morten S Olesen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Morten W Nielsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper H Svendsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Hosy E, Vivaudou M. The unusual stoichiometry of ADP activation of the KATP channel. Front Physiol 2014; 5:11. [PMID: 24478723 PMCID: PMC3904077 DOI: 10.3389/fphys.2014.00011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 01/07/2014] [Indexed: 11/27/2022] Open
Abstract
KATP channels, oligomers of 4 pore-forming Kir6.2 proteins and 4 sulfonylurea receptors (SUR), sense metabolism by monitoring both cytosolic ATP, which closes the channel by interacting with Kir6.2, and ADP, which opens it via SUR. SUR mutations that alter activation by ADP are a major cause of KATP channelopathies. We examined the mechanism of ADP activation by analysis of single-channel and macropatch recordings from Xenopus oocytes expressing various mixtures of wild-type SUR2A and an ADP-activation-defective mutant. Evaluation of the data by a binomial distribution model suggests that wild-type and mutant SURs freely co-assemble and that channel activation results from interaction of ADP with only 2 of 4 SURs. This finding explains the heterozygous nature of most KATP channelopathies linked to mutations altering ADP activation. It also suggests that the channel deviates from circular symmetry and could function as a dimer-of-dimers.
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Affiliation(s)
- Eric Hosy
- Institut de Biologie Structurale, University Grenoble Alpes Grenoble, France ; Laboratory of Excellence, Ion Channel Science and Therapeutics, CNRS, Institut de Biologie Structurale Grenoble, France ; CEA, DSV, Institut de Biologie Structurale Grenoble, France
| | - Michel Vivaudou
- Institut de Biologie Structurale, University Grenoble Alpes Grenoble, France ; Laboratory of Excellence, Ion Channel Science and Therapeutics, CNRS, Institut de Biologie Structurale Grenoble, France ; CEA, DSV, Institut de Biologie Structurale Grenoble, France
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66
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Age-dependent myocardial transcriptomic changes in the rat. Novel insights into atrial and ventricular arrhythmias pathogenesis. REV ROMANA MED LAB 2014. [DOI: 10.2478/rrlm-2014-0001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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67
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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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68
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Corradi D. Atrial fibrillation from the pathologist's perspective. Cardiovasc Pathol 2013; 23:71-84. [PMID: 24462196 DOI: 10.1016/j.carpath.2013.12.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/03/2013] [Accepted: 12/07/2013] [Indexed: 12/18/2022] Open
Abstract
Atrial fibrillation (AF), the most common sustained cardiac arrhythmia encountered in clinical practice, is associated with increased morbidity and mortality. Electrophysiologically, it is characterized by a high rate of asynchronous atrial cell depolarization causing a loss of atrial contractile function and irregular ventricular rates. For a long time, AF was considered as a pure functional disorder without any structural background. Only in recent years, have new mapping and imaging techniques identified atrial locations, which are very often involved in the initiation and maintenance of this supraventricular arrhythmia (i.e. the distal portion of the pulmonary veins and the surrounding atrial myocardium). Morphological analysis of these myocardial sites has demonstrated significant structural remodeling as well as paved the way for further knowledge of AF natural history, pathogenesis, and treatment. This architectural myocardial disarrangement is induced by the arrhythmia itself and the very frequently associated cardiovascular disorders. At the same time, the structural remodeling is also capable of sustaining AF, thereby creating a sort of pathogenetic vicious circle. This review focuses on current understanding about the structural and genetic bases of AF with reference to their classification, pathogenesis, and clinical implications.
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Affiliation(s)
- Domenico Corradi
- Department of Biomedical, Biotechnological, and Translational Sciences (S.Bi.Bi.T.), Unit of Pathology, University of Parma, Parma, Italy.
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69
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Hiraki Y, Miyatake S, Hayashidani M, Nishimura Y, Matsuura H, Kamada M, Kawagoe T, Yunoki K, Okamoto N, Yofune H, Nakashima M, Tsurusaki Y, Satisu H, Murakami A, Miyake N, Nishimura G, Matsumoto N. Aortic aneurysm and craniosynostosis in a family with Cantu syndrome. Am J Med Genet A 2013; 164A:231-6. [PMID: 24352916 DOI: 10.1002/ajmg.a.36228] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/08/2013] [Indexed: 12/22/2022]
Abstract
Cantu syndrome is an autosomal dominant overgrowth syndrome associated with facial dysmorphism, congenital hypertrichosis, and cardiomegaly. Some affected individuals show bone undermodeling of variable severity. Recent investigations revealed that the disorder is caused by a mutation in ABCC9, encoding a regulatory SUR2 subunit of an ATP-sensitive potassium channel mainly expressed in cardiac and skeletal muscle as well as vascular smooth muscle. We report here on a Japanese family with this syndrome. An affected boy and his father had a novel missense mutation in ABCC9. Each patient had a coarse face and hypertrichosis. However, cardiomegaly was seen only in the boy, and macrosomia only in the father. Skeletal changes were not evident in either patient. Craniosynostosis in the boy and the development of aortic aneurysm in the father are previously undescribed associations with Cantu syndrome.
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Affiliation(s)
- Yoko Hiraki
- Hiroshima Municipal Center for Child Health and Development, Hiroshima, Japan
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Campbell CM, Campbell JD, Thompson CH, Vanoye CG, George AL. Selective targeting of gain-of-function KCNQ1 mutations predisposing to atrial fibrillation. Circ Arrhythm Electrophysiol 2013; 6:960-6. [PMID: 24006450 PMCID: PMC3892565 DOI: 10.1161/circep.113.000439] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Atrial fibrillation is the most common sustained cardiac arrhythmia in adults. We hypothesized that gain-of-function KCNQ1 mutations previously associated with familial atrial fibrillation have distinct pharmacological properties that may enable targeted inhibition. METHODS AND RESULTS Wild-type (WT) KCNQ1 or the familial atrial fibrillation mutation KCNQ1-S140G was heterologously coexpressed with KCNE1 to enable electrophysiological recording of the slow delayed rectifier current (IKs) and investigation of pharmacological effects of the IKs selective blocker HMR-1556. Coexpression of KCNQ1-S140G with KCNE1 generated potassium currents (S140G-IKs) that exhibited greater sensitivity to HMR-1556 than WT-IKs. Enhanced HMR-1556 sensitivity was also observed for another gain-of-function atrial fibrillation mutation, KCNQ1-V141M. Heteromeric expression of KCNE1 with both KCNQ1-WT and KCNQ1-S140G generated currents (HET-IKs) with gain-of-function features, including larger amplitude, a constitutively active component, hyperpolarized voltage dependence of activation, and extremely slow deactivation. A low concentration of HMR-1556, which had little effect on WT-IKs but was capable of inhibiting the mutant channel, reduced both instantaneous and steady state HET-IKs to levels that were not significantly different from WT-IKs and attenuated use-dependent accumulation of the current. In cultured adult rabbit left atrial myocytes, expression of S140G-IKs shortened action potential duration compared with WT-IKs. Application of HMR-1556 mitigated S140G-IKs-induced action potential duration shortening and did not alter action potential duration in cells expressing WT-IKs. CONCLUSIONS The enhanced sensitivity of KCNQ1 gain-of-function mutations for HMR-1556 suggests the possibility of selective therapeutic targeting, and, therefore, our data illustrate a potential proof of principle for genotype-specific treatment of this heritable arrhythmia.
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Affiliation(s)
| | - Jonathan D. Campbell
- Department of Engineering Management, Information, and Systems, Southern Methodist University, Dallas, TX
| | | | - Carlos G. Vanoye
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Alfred L. George
- Department of Pharmacology, Vanderbilt University, Nashville, TN
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
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71
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Abstract
ATP-sensitive potassium (KATP) channels were first discovered in the heart 30 years ago. Reconstitution of KATP channel activity by coexpression of members of the pore-forming inward rectifier gene family (Kir6.1, KCNJ8, and Kir6.2 KCNJ11) with sulfonylurea receptors (SUR1, ABCC8, and SUR2, ABCC9) of the ABCC protein subfamily has led to the elucidation of many details of channel gating and pore properties. In addition, the essential roles of Kir6.x and SURx subunits in generating cardiac and vascular KATP(2) and the detrimental consequences of genetic deletions or mutations in mice have been recognized. However, despite this extensive body of knowledge, there has been a paucity of defined roles of KATP subunits in human cardiovascular diseases, although there are reports of association of a single Kir6.1 variant with the J-wave syndrome in the ECG, and 2 isolated studies have reported association of loss of function mutations in SUR2 with atrial fibrillation and heart failure. Two new studies convincingly demonstrate that mutations in the SUR2 gene are associated with Cantu syndrome, a complex multi-organ disorder characterized by hypertrichosis, craniofacial dysmorphology, osteochondrodysplasia, patent ductus arteriosus, cardiomegaly, pericardial effusion, and lymphoedema. This realization of previously unconsidered consequences provides significant insight into the roles of the KATP channel in the cardiovascular system and suggests novel therapeutic possibilities.
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Affiliation(s)
- Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases and Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Nielsen MW, Olesen MS, Refsgaard L, Haunsø S, Svendsen JH. Screening of the ito regulatory subunit klf15 in patients with early-onset lone atrial fibrillation. Front Genet 2013; 4:88. [PMID: 23730307 PMCID: PMC3656344 DOI: 10.3389/fgene.2013.00088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 04/28/2013] [Indexed: 11/13/2022] Open
Abstract
Several studies have associated mutations in genes encoding potassium channels and accessory subunits involved in cardiac repolarization with increased susceptibility of atrial fibrillation (AF). Recently, the Krüppel-like factor 15 (Klf15) was found to transcriptionally control rhythmic expression of KChIP2, a critical subunit required for generating the transient outward potassium current (Ito), and that deficiency or excess of Klf15 increased the susceptibility of arrhythmias. On this basis we hypothesized that mutations in Klf15 could be associated with AF. A total of 209 unrelated Caucasian lone AF patients were screened for mutations in Klf15 by direct sequencing. No mutations in the lone AF cohort were found. In one patient we found a synonymous variant (c.36C > T). In NHLBI GO Exome Sequencing Project (ESP) the variant was present in 31 of 4269 Caucasian individuals and in 3 of 2200 African Americans. In our cohort Klf15 was not associated with lone AF.
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Affiliation(s)
- Morten Wagner Nielsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia Copenhagen, Denmark ; Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen Copenhagen, Denmark
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73
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Mirza M, Strunets A, Shen WK, Jahangir A. Mechanisms of arrhythmias and conduction disorders in older adults. Clin Geriatr Med 2013; 28:555-73. [PMID: 23101571 DOI: 10.1016/j.cger.2012.08.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Aging is associated with an increased prevalence of cardiac arrhythmias, which contribute to higher morbidity and mortality in the elderly. The frequency of cardiac arrhythmias, particularly atrial fibrillation and ventricular tachyarrhythmia, is projected to increase as the population ages, greatly impacting health care resource utilization. Several clinical factors associated with the risk of arrhythmias have been identified in the population, yet the molecular bases for the increased predisposition to arrhythmogenesis in the elderly are not fully understood. This review highlights the epidemiology of cardiac dysrhythmias, changes in cardiac structure and function associated with aging, and the basis for arrhythmogenesis in the elderly.
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Affiliation(s)
- Mahek Mirza
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora University of Wisconsin Medical Group, Aurora Health Care, 3033 South 27th Street, Milwaukee, WI 53215, USA
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74
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Sankaranarayanan R, Kirkwood G, Dibb K, Garratt CJ. Comparison of Atrial Fibrillation in the Young versus That in the Elderly: A Review. Cardiol Res Pract 2013; 2013:976976. [PMID: 23401843 PMCID: PMC3564268 DOI: 10.1155/2013/976976] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 08/09/2012] [Indexed: 02/07/2023] Open
Abstract
The incidence and prevalence of atrial fibrillation (AF) are projected to increase significantly worldwide, imposing a significant burden on healthcare resources. The disease itself is extremely heterogeneous in its epidemiology, pathophysiology, and treatment options based on individual patient characteristics. Whilst ageing is well recognised to be an independent risk factor for the development of AF, this condition also affects the young in whom the condition is frequently symptomatic and troublesome. Traditional thinking suggests that the causal factors and pathogenesis of the condition in the young with structurally normal atria but electrophysiological "triggers" in the form of pulmonary vein ectopics leading to lone AF are in stark contrast to that in the elderly who have AF primarily due to an abnormal substrate consisting of fibrosed and dilated atria acting in concert with the pulmonary vein triggers. However, there can be exceptions to this rule as there is increasing evidence of structural and electrophysiological abnormalities in the atrial substrate in young patients with "lone AF," as well as elderly patients who present with idiopathic AF. These reports seem to be blurring the distinction in the pathophysiology of so-called idiopathic lone AF in the young versus that in the elderly. Moreover with availability of improved and modern investigational and diagnostic techniques, novel causes of AF are being reported thereby seemingly consigning the diagnosis of "lone AF" to a rather mythical existence. We shall also elucidate in this paper the differences seen in the epidemiology, causes, pathogenesis, and clinical features of AF in the young versus that seen in the elderly, thereby requiring clearly defined management strategies to tackle this arrhythmia and its associated consequences.
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Affiliation(s)
- Rajiv Sankaranarayanan
- Unit of Cardiac Physiology, Cardiovascular Research Group, 3rd Floor, Core Technology Facility, The University of Manchester, M139PL, Grafton Street, Manchester M13 9NT, UK
- Manchester Heart Centre, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WPL, UK
| | - Graeme Kirkwood
- Unit of Cardiac Physiology, Cardiovascular Research Group, 3rd Floor, Core Technology Facility, The University of Manchester, M139PL, Grafton Street, Manchester M13 9NT, UK
- Manchester Heart Centre, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WPL, UK
| | - Katharine Dibb
- Manchester Heart Centre, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WPL, UK
| | - Clifford J. Garratt
- Unit of Cardiac Physiology, Cardiovascular Research Group, 3rd Floor, Core Technology Facility, The University of Manchester, M139PL, Grafton Street, Manchester M13 9NT, UK
- Manchester Heart Centre, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WPL, UK
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Czeschik JC, Voigt C, Goecke TO, Lüdecke HJ, Wagner N, Kuechler A, Wieczorek D. Wide clinical variability in conditions with coarse facial features and hypertrichosis caused by mutations in ABCC9. Am J Med Genet A 2013; 161A:295-300. [PMID: 23307537 DOI: 10.1002/ajmg.a.35735] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 10/01/2012] [Indexed: 11/09/2022]
Abstract
We present two previously unreported and unrelated female patients, one with the tentative diagnosis of acromegaloid facial appearance (AFA), the other with the tentative diagnosis of hypertrichosis with acromegaloid facial appearance (HAFF) with or without gingival hyperplasia. Main clinical features of HAFF were generalized hypertrichosis terminalis and coarse facial features. In both patients, pregnancy was complicated by polyhydramnios, and both had hyperbilirubinemia and persistent fetal circulation. Development was normal in one patient and slightly delayed in the other. At 13 years, both had round faces with full cheeks, thick scalp hair and eyebrows, a low frontal hairline, hirsutism, hyperextensible joints and deep palmar creases. One of them additionally showed gingival hypertrophy and epicanthus, the other one was macrocephalic at birth and at the age of 13 years and suffered from repeated swelling of the soft tissue. Array analysis excluded a 17q24.2-q24.3 microdeletion, which has been reported in patients with hypertrichosis terminalis with or without gingival hyperplasia. Sequencing of the mutational hotspots of the ABCC9 gene revealed two different de novo missense mutations in the two patients. Recently, identical mutations have been found recurrently in patients with Cantú syndrome. Therefore, we propose that ABCC9 mutations lead to a spectrum of phenotypes formerly known as Cantú syndrome, HAFF and AFA, which may not be clearly distinguishable by clinical criteria, and that all patients with clinical signs belonging to this spectrum should be revisited and offered ABCC9 mutation analysis.
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Kim SJ, Zhang H, Khaliulin I, Choisy SCM, Bond R, Lin H, El Haou S, Milnes JT, Hancox JC, Suleiman MS, James AF. Activation of glibenclamide-sensitive ATP-sensitive K+ channels during β-adrenergically induced metabolic stress produces a substrate for atrial tachyarrhythmia. Circ Arrhythm Electrophysiol 2012; 5:1184-92. [PMID: 23159416 DOI: 10.1161/circep.112.975425] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardiac ATP-sensitive K(+) channels have been suggested to contribute to the adaptive physiological response to metabolic challenge after β-adrenoceptor stimulation. However, an increased atrial K(+)-conductance might be expected to be proarrhythmic. We investigated the effect of ATP-sensitive K(+) channel blockade on the electrophysiological responses to β-adrenoceptor-induced metabolic challenge in intact atria. METHODS AND RESULTS Atrial electrograms were recorded from the left atrial epicardial surface of Langendorff-perfused rat hearts using a 5×5 electrode array. Atrial effective refractory period and conduction velocity were measured using an S(1)-S(2) protocol. The proportion of hearts in which atrial tachyarrhythmia was produced by burst-pacing was used as an index of atrial tachyarrhythmia-inducibility. Atrial nucleotide concentrations were measured by high performance liquid chromatography. Perfusion with ≥10(-9) mol/L of the β-adrenoceptor agonist, isoproterenol (ISO), resulted in a concentration-dependent reduction of atrial effective refractory period and conduction velocity. The ISO-induced changes produced a proarrhythmic substrate such that atrial tachyarrhythmia could be induced by burst-pacing. Atrial [ATP] was significantly reduced by ISO (10(-6) mol/L). Perfusion with either of the ATP-sensitive K(+) channel blockers, glibenclamide (10(-5) mol/L) or tolbutamide (10(-3) mol/L), in the absence of ISO had no effect on basal atrial electrophysiology. On the other hand, the proarrhythmic substrate induced by 10(-6) mol/L ISO was abolished by either of the sulfonylureas, which prevented induction of atrial tachyarrhythmia. CONCLUSIONS Atrial ATP-sensitive K(+) channels activate in response to β-adrenergic metabolic stress in Langendorff-perfused rat hearts, resulting in a proarrhythmic substrate.
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Affiliation(s)
- Shang-Jin Kim
- Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju-City, South Korea
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2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. J Interv Card Electrophysiol 2012; 33:171-257. [PMID: 22382715 DOI: 10.1007/s10840-012-9672-7] [Citation(s) in RCA: 256] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.
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78
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Judge DP. The complex genetics of atrial fibrillation. J Am Coll Cardiol 2012; 60:1182-4. [PMID: 22818066 DOI: 10.1016/j.jacc.2012.04.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 04/23/2012] [Indexed: 02/04/2023]
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79
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Dominant missense mutations in ABCC9 cause Cantú syndrome. Nat Genet 2012; 44:793-6. [DOI: 10.1038/ng.2324] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 05/14/2012] [Indexed: 11/09/2022]
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Delaney JT, Muhammad R, Blair MA, Kor K, Fish FA, Roden DM, Darbar D. A KCNJ8 mutation associated with early repolarization and atrial fibrillation. Europace 2012; 14:1428-32. [PMID: 22562657 DOI: 10.1093/europace/eus150] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIM The Kir 6.1 K(atp) channel is believed to play an important role in ventricular repolarization as determined from both functional and genetic studies of the potassium inwardly-rectifying channel, subfamily J, member 8 (KCNJ8)-S422L missense mutation in patients with J-wave syndromes. Although Kir6.1 is also present in atrial tissue, it is unknown whether this channel modulates atrial repolarization and hence whether the S422L mutation portends a greater risk of atrial arrhythmias. This study sought to examine whether there was an increased frequency of the KCNJ8-S422L mutation among patients with atrial fibrillation (AF) and early repolarization (ER) as a possible novel susceptibility gene for AF. METHODS AND RESULTS A total of 325 lone AF probands were identified from the Vanderbilt AF Registry, a collection of clinical data and DNA from consented, consecutively enrolled participants. The coding regions of KCNJ8 were sequenced, and the patient's presenting electrocardiogram (ECG) was reviewed by two independent physicians for ER abnormalities. The KCNJ8-S422L mutation was identified in two AF probands while no other candidate gene variants were identified in these cases. Twenty-two (7%) patients were found to have ER on the ECG, including the two probands carrying the S422L variant. In one small AF kindred, the S422L variant co-segregated with AF and ER. CONCLUSIONS The KCNJ8-S422L variant is associated with both increased AF susceptibility and ER indicating a role for Kir 6.1 K(atp) channel in both ventricular and atrial repolarization.
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Affiliation(s)
- Jessica T Delaney
- Departments of Medicine and Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
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81
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Mann SA, Otway R, Guo G, Soka M, Karlsdotter L, Trivedi G, Ohanian M, Zodgekar P, Smith RA, Wouters MA, Subbiah R, Walker B, Kuchar D, Sanders P, Griffiths L, Vandenberg JI, Fatkin D. Epistatic effects of potassium channel variation on cardiac repolarization and atrial fibrillation risk. J Am Coll Cardiol 2012; 59:1017-25. [PMID: 22402074 DOI: 10.1016/j.jacc.2011.11.039] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/13/2011] [Accepted: 11/01/2011] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate the role of cardiac K(+) channel gene variants in families with atrial fibrillation (AF). BACKGROUND The K(+) channels play a major role in atrial repolarization but single mutations in cardiac K(+) channel genes are infrequently present in AF families. The collective effect of background K(+) channel variants of varying prevalence and effect size on the atrial substrate for AF is largely unexplored. METHODS Genes encoding the major cardiac K(+) channels were resequenced in 80 AF probands. Nonsynonymous coding sequence variants identified in AF probands were evaluated in 240 control subjects. Novel variants were characterized using patch-clamp techniques and in silico modeling was performed using the Courtemanche atrial cell model. RESULTS Nineteen nonsynonymous variants in 9 genes were found, including 11 rare variants. Rare variants were more frequent in AF probands (18.8% vs. 4.2%, p < 0.001), and the mean number of variants was greater (0.21 vs. 0.04, p < 0.001). The majority of K(+) channel variants individually had modest functional effects. Modeling simulations to evaluate combinations of K(+) channel variants of varying population frequency indicated that simultaneous small perturbations of multiple current densities had nonlinear interactions and could result in substantial (>30 ms) shortening or lengthening of action potential duration as well as increased dispersion of repolarization. CONCLUSIONS Families with AF show an excess of rare functional K(+) channel gene variants of varying phenotypic effect size that may contribute to an atrial arrhythmogenic substrate. Atrial cell modeling is a useful tool to assess epistatic interactions between multiple variants.
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Affiliation(s)
- Stefan A Mann
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW 2010, Australia
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82
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Grandi E, Workman AJ, Pandit SV. Altered Excitation-Contraction Coupling in Human Chronic Atrial Fibrillation. J Atr Fibrillation 2012; 4:495. [PMID: 28496736 DOI: 10.4022/jafib.495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/10/2012] [Accepted: 03/19/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on the (mal)adaptive processes in atrial excitation-contraction coupling occurring in patients with chronic atrial fibrillation. Cellular remodeling includes shortening of the atrial action potential duration and effective refractory period, depressed intracellular Ca2+ transient, and reduced myocyte contractility. Here we summarize the current knowledge of the ionic bases underlying these changes. Understanding the molecular mechanisms of excitation-contraction-coupling remodeling in the fibrillating human atria is important to identify new potential targets for AF therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Antony J Workman
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Sandeep V Pandit
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, USA
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83
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Calkins H, Kuck KH, Cappato R, Brugada J, Camm AJ, Chen SA, Crijns HJG, Damiano RJ, Davies DW, DiMarco J, Edgerton J, Ellenbogen K, Ezekowitz MD, Haines DE, Haissaguerre M, Hindricks G, Iesaka Y, Jackman W, Jalife J, Jais P, Kalman J, Keane D, Kim YH, Kirchhof P, Klein G, Kottkamp H, Kumagai K, Lindsay BD, Mansour M, Marchlinski FE, McCarthy PM, Mont JL, Morady F, Nademanee K, Nakagawa H, Natale A, Nattel S, Packer DL, Pappone C, Prystowsky E, Raviele A, Reddy V, Ruskin JN, Shemin RJ, Tsao HM, Wilber D. 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Europace 2012; 14:528-606. [PMID: 22389422 DOI: 10.1093/europace/eus027] [Citation(s) in RCA: 1141] [Impact Index Per Article: 95.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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84
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Calkins H, Kuck KH, Cappato R, Brugada J, Camm AJ, Chen SA, Crijns HJG, Damiano RJ, Davies DW, DiMarco J, Edgerton J, Ellenbogen K, Ezekowitz MD, Haines DE, Haissaguerre M, Hindricks G, Iesaka Y, Jackman W, Jalife J, Jais P, Kalman J, Keane D, Kim YH, Kirchhof P, Klein G, Kottkamp H, Kumagai K, Lindsay BD, Mansour M, Marchlinski FE, McCarthy PM, Mont JL, Morady F, Nademanee K, Nakagawa H, Natale A, Nattel S, Packer DL, Pappone C, Prystowsky E, Raviele A, Reddy V, Ruskin JN, Shemin RJ, Tsao HM, Wilber D. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012; 9:632-696.e21. [PMID: 22386883 DOI: 10.1016/j.hrthm.2011.12.016] [Citation(s) in RCA: 1299] [Impact Index Per Article: 108.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Indexed: 12/20/2022]
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85
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Burashnikov A, Antzelevitch C. Novel pharmacological targets for the rhythm control management of atrial fibrillation. Pharmacol Ther 2011; 132:300-13. [PMID: 21867730 PMCID: PMC3205214 DOI: 10.1016/j.pharmthera.2011.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 08/05/2011] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is a growing clinical problem associated with increased morbidity and mortality. Development of safe and effective pharmacological treatments for AF is one of the greatest unmet medical needs facing our society. In spite of significant progress in non-pharmacological AF treatments (largely due to the use of catheter ablation techniques), anti-arrhythmic agents (AADs) remain first line therapy for rhythm control management of AF for most AF patients. When considering efficacy, safety and tolerability, currently available AADs for rhythm control of AF are less than optimal. Ion channel inhibition remains the principal strategy for termination of AF and prevention of its recurrence. Practical clinical experience indicates that multi-ion channel blockers are generally more optimal for rhythm control of AF compared to ion channel-selective blockers. Recent studies suggest that atrial-selective sodium channel block can lead to safe and effective suppression of AF and that concurrent inhibition of potassium ion channels may potentiate this effect. An important limitation of the ion channel block approach for AF treatment is that non-electrical factors (largely structural remodeling) may importantly determine the generation of AF, so that "upstream therapy", aimed at preventing or reversing structural remodeling, may be required for effective rhythm control management. This review focuses on novel pharmacological targets for the rhythm control management of AF.
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86
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Increased expression of adenosine triphosphate-sensitive K+ channels in mitral dysfunction: mechanically stimulated transcription and hypoxia-induced protein stability? J Am Coll Cardiol 2011; 59:390-6. [PMID: 22133355 DOI: 10.1016/j.jacc.2011.08.077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 07/26/2011] [Accepted: 08/17/2011] [Indexed: 01/08/2023]
Abstract
OBJECTIVES The aim of this study was to test whether adenosine triphosphate-sensitive K(+) (KATP) channel expression relates to mechanical and hypoxic stress within the left human heart. BACKGROUND The KATP channels play a vital role in preserving the metabolic integrity of the stressed heart. However, the mechanisms that govern the expression of their subunits (e.g., potassium inward rectifier [Kir] 6.2) in adult pathologies are mostly unknown. METHODS We collected biopsies from the 4 cardiac chambers and 50 clinical parameters from 30 surgical patients with severe mitral dysfunction. Proteins and messenger ribonucleic acids (mRNAs) of KATP pore subunits and mRNAs of their known transcriptional regulators (forkhead box [FOX] F2, FOXO1, FOXO3, and hypoxia inducible factor [HIF]-1α) were measured respectively by Western blotting, immunohistochemistry, and quantitative real-time polymerase chain reaction, and submitted to statistical analysis. RESULTS In all heart chambers, Kir6.2 mRNA correlated with HIF-1α mRNA. Neither Kir6.1 nor Kir6.2 proteins positively correlated with their respective mRNAs. The HIF-1α mRNA related in the left ventricle to aortic pressure, in the left atrium to left atrial pressure, and in all heart chambers to a decreased Kir6.2 protein/mRNA ratio. Interestingly, in the left heart, Kir6.2 protein and its immunohistochemical detection in myocytes were maximal at low venous PO(2). In the left ventricle, the Kir6.2 protein/mRNA ratio was also significantly higher at low venous PO(2), suggesting that tissue hypoxia might stabilize the Kir6.2 protein. CONCLUSIONS Results suggest that post-transcriptional events determine Kir6.2 protein expression in the left ventricle of patients with severe mitral dysfunction and low venous PO(2). Mechanical stress mainly affects transcription of HIF-1α and Kir6.2. This study implies that new therapies could aim at the proteasome for stabilizing the left ventricular Kir6.2 protein.
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87
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Xiao J, Liang D, Chen YH. The genetics of atrial fibrillation: from the bench to the bedside. Annu Rev Genomics Hum Genet 2011; 12:73-96. [PMID: 21682648 DOI: 10.1146/annurev-genom-082410-101515] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Atrial fibrillation (AF) has become a growing global epidemic and a financial burden for society. The past 10 years have seen significant advances in our understanding of the genetic aspects of AF: At least 2 chromosomal loci and 17 causal genes have been identified in familial AF, and an additional 7 common variants and single-nucleotide polymorphisms in 11 different genes have been indicated in nonfamilial AF. However, the current management strategies for AF are suboptimal. The integration of genetic information into clinical practice may aid the early identification of AF patients who are at risk as well as the characterization of molecular pathways that culminate in AF, with the eventual result of better treatment. Never before has such an opportunity arisen to advance our understanding of the biology of AF through the translation of genetics findings from the bench to the bedside.
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Affiliation(s)
- Junjie Xiao
- Key Laboratory of Arrhythmias, Ministry of Education, and Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
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88
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Terzic A, Alekseev AE, Yamada S, Reyes S, Olson TM. Advances in cardiac ATP-sensitive K+ channelopathies from molecules to populations. Circ Arrhythm Electrophysiol 2011; 4:577-85. [PMID: 21846889 DOI: 10.1161/circep.110.957662] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Andre Terzic
- Marriott Heart Disease Research Program, Division of Cardiovascular Diseases, Department of Internal Medicine, Department of Molecular Pharmacology and Experimental Therapeutics, Department of Medical Genetics, Mayo Clinic, Rochester, MN, USA.
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89
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de Araujo ED, Ikeda LK, Tzvetkova S, Kanelis V. The first nucleotide binding domain of the sulfonylurea receptor 2A contains regulatory elements and is folded and functions as an independent module. Biochemistry 2011; 50:6655-66. [PMID: 21714514 DOI: 10.1021/bi200434d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The sulfonylurea receptor 2A (SUR2A) is an ATP-binding cassette (ABC) protein that forms the regulatory subunit of ATP-sensitive potassium (K(ATP)) channels in the heart. ATP binding and hydrolysis at the SUR2A nucleotide binding domains (NBDs) control gating of K(ATP) channels, and mutations in the NBDs that affect ATP hydrolysis and cellular trafficking cause cardiovascular disorders. To date, there is limited information on the SUR2A NBDs and the effects of disease-causing mutations on their structure and interactions. Structural and biophysical studies of NBDs, especially from eukaryotic ABC proteins like SUR2A, have been hindered by low solubility of the isolated domains. We hypothesized that the solubility of heterologously expressed SUR2A NBDs depends on the precise definition of the domain boundaries. Putative boundaries of SUR2A NBD1 were identified by structure-based sequence alignments and subsequently tested by exploring the solubility of SUR2A NBD1 constructs with different N and C termini. We have determined boundaries of SUR2A NBD1 that allow for soluble heterologous expression of the protein, producing a folded domain with ATP binding activity. Surprisingly, our alignment and screening data indicate that SUR2A NBD1 contains two putative, previously unidentified, regulatory elements: a large insert within the β-sheet subdomain and a C-terminal extension. Our approach, which combines the use of structure-based sequence alignments and predictions of disordered regions combined with biochemical and biophysical studies, may be applied as a general method for developing suitable constructs of other NBDs of ABC proteins.
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Affiliation(s)
- Elvin D de Araujo
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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90
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Liu X, Wang F, Knight AC, Zhao J, Xiao J. Common variants for atrial fibrillation: results from genome-wide association studies. Hum Genet 2011; 131:33-9. [DOI: 10.1007/s00439-011-1052-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 06/20/2011] [Indexed: 12/19/2022]
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91
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Reyes S, Park S, Johnson BD, Terzic A, Olson TM. KATP channel Kir6.2 E23K variant overrepresented in human heart failure is associated with impaired exercise stress response. Hum Genet 2011; 126:779-89. [PMID: 19685080 DOI: 10.1007/s00439-009-0731-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 08/05/2009] [Indexed: 12/13/2022]
Abstract
ATP-sensitive K+ (K(ATP)) channels maintain cardiac homeostasis under stress, as revealed by murine gene knockout models of the KCNJ11-encoded Kir6.2 pore. However, the translational significance of K(ATP) channels in human cardiac physiology remains largely unknown. Here, the frequency of the minor K23 allele of the common functional Kir6.2 E23K polymorphism was found overrepresented in 115 subjects with congestive heart failure compared to 2,031 community-based controls (69 vs. 56%, P < 0.001). Moreover, the KK genotype, present in 18% of heart failure patients, was associated with abnormal cardiopulmonary exercise stress testing. In spite of similar baseline heart rates at rest among genotypic subgroups (EE: 72.2 ± 2.3, EK: 75.0 ± 1.8 and KK:77.1 ± 3.0 bpm), subjects with the KK genotype had a significantly reduced heart rate increase at matched workload (EE: 32.8 ± 2.7%, EK: 28.8 ± 2.1%, KK: 21.7 ± 2.6%, P < 0.05), at 75% of maximum oxygen consumption (EE: 53.9 ± 3.9%, EK: 49.9 ± 3.1%, KK: 36.8 ± 5.3%, P < 0.05), and at peak V(O2) (EE: 82.8 ± 6.0%, EK: 80.5 ± 4.7%, KK: 59.7 ± 8.1%, P < 0.05). Molecular modeling of the tetrameric Kir6.2 pore structure revealed the E23 residue within the functionally relevant intracellular slide helix region. Substitution of the wild-type E residue with an oppositely charged, bulkier K residue would potentially result in a significant structural rearrangement and disrupted interactions with neighboring Kir6.2 subunits, providing a basis for altered high-fidelity K(ATP) channel gating, particularly in the homozygous state. Blunted heart rate response during exercise is a risk factor for mortality in patients with heart failure, establishing the clinical relevance of Kir6.2 E23K as a biomarker for impaired stress performance and underscoring the essential role of K(ATP) channels in human cardiac physiology.
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Affiliation(s)
- Santiago Reyes
- Marriott Heart Disease Research Program, Mayo Clinic, Rochester, MN 55905, USA
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92
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Charalampopoulos AF, Nikolaou NI. Emerging pharmaceutical therapies in cardiopulmonary resuscitation and post-resuscitation syndrome. Resuscitation 2011; 82:371-7. [DOI: 10.1016/j.resuscitation.2010.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/05/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
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93
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Arrell DK, Zlatkovic Lindor J, Yamada S, Terzic A. K(ATP) channel-dependent metaboproteome decoded: systems approaches to heart failure prediction, diagnosis, and therapy. Cardiovasc Res 2011; 90:258-66. [PMID: 21321057 DOI: 10.1093/cvr/cvr046] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Systems biology provides an integrative platform by which to account for the biological complexity related to cardiac health and disease. In this way, consequences of ATP-sensitive K(+) (K(ATP)) channel deficiency for heart failure prediction, diagnosis, and therapy were resolved recently at a proteomic level. Under stress-free conditions, knockout of the Kir6.2 K(ATP) channel pore induced metabolic proteome remodelling, revealing overrepresentation of markers of cardiovascular disease. Imposed stress precipitated structural and functional defects in Kir6.2-knockout hearts, decreasing survival and validating prediction of disease susceptibility. In the setting of hypertension, a leading risk for heart failure development, proteomic analysis diagnosed the metabolism-centric impact of K(ATP) channel deficiency in disease. Bioinformatic interrogation of K(ATP) channel-dependent proteome prioritized heart-specific adverse effects, exposing cardiomyopathic traits of aggravated contractility, fibrosis, and ventricular hypertrophy. In dilated cardiomyopathy induced by Kir6.2-knockout pressure overload, proteomic remodelling was exacerbated, underlying a multifaceted molecular pathology that indicates the necessity for a broad-based strategy to achieve repair. Embryonic stem cell intervention in cardiomyopathic K(ATP) channel knockout hearts elicited a distinct proteome signature that forecast amelioration of adverse cardiac outcomes. Functional/structural measurements validated improved contractile performance, reduced ventricular size, and decreased cardiac damage in the treated cohort, while systems assessment unmasked cardiovascular development as a prioritized biological function in stem cell-reconstructed hearts. Thus, proteomic deconvolution of K(ATP) channel-deficient hearts provides definitive evidence for the channel's homeostatic contribution to the cardiac metaboproteome and establishes the utility of systems-oriented approaches to predict disease susceptibility, diagnose consequences of heart failure progression, and monitor therapy outcome.
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Affiliation(s)
- D Kent Arrell
- Marriott Heart Disease Research Program, Mayo Clinic, Stabile 5, 200 First Street SW, Rochester, MN, USA
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Reyes S, Kane GC, Zingman LV, Yamada S, Terzic A. Targeted disruption of K(ATP) channels aggravates cardiac toxicity in cocaine abuse. Clin Transl Sci 2010; 2:361-5. [PMID: 20443920 DOI: 10.1111/j.1752-8062.2009.00145.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cocaine is the most frequently used illicit drug among individuals seeking emergency-room care, with fatal outcome most often attributable to the cardiovascular manifestations of drug abuse. While the symptomatic presentations of cocaine toxicity are increasingly understood, the molecular determinants that define outcome remain largely unknown. Here, we report that the susceptibility to cocaine-induced cardiotoxicity is genetically regulated. Targeted deletion of the KCNJ11-encoded Kir6.2 pore-forming subunit of sarcolemmal K(ATP) channels resulted in amplified vulnerability to the toxic effects of chronic cocaine abuse. Under the hyperadrenergic stress, imposed by daily 3-week-long intraperitoneal administration of 30 mg/kg cocaine in Kir6.2-knockout mice, failure to maintain cardiac homeostasis translated into decreased exercise tolerance revealed by poor treadmill stress performance, and dilated hypokinetic left hearts with aggravated cellular hypertrophy and pathognomonic characteristics of chronic cocaine-induced cardiac toxicity. This study therefore reveals a previously unrecognized role of Kir6.2-encoded K(ATP) channels in determining cardiovascular outcome in chronic cocaine abuse, identifying a novel molecular determinant of cocaine cardiotoxicity.
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Affiliation(s)
- Santiago Reyes
- Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
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95
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Reyes S, Park S, Terzic A, Alekseev AE. K(ATP) channels process nucleotide signals in muscle thermogenic response. Crit Rev Biochem Mol Biol 2010; 45:506-19. [PMID: 20925594 DOI: 10.3109/10409238.2010.513374] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Uniquely gated by intracellular adenine nucleotides, sarcolemmal ATP-sensitive K(+) (K(ATP)) channels have been typically assigned to protective cellular responses under severe energy insults. More recently, K(ATP) channels have been instituted in the continuous control of muscle energy expenditure under non-stressed, physiological states. These advances raised the question of how K(ATP) channels can process trends in cellular energetics within a milieu where each metabolic system is set to buffer nucleotide pools. Unveiling the mechanistic basis of the K(ATP) channel-driven thermogenic response in muscles thus invites the concepts of intracellular compartmentalization of energy and proteins, along with nucleotide signaling over diffusion barriers. Furthermore, it requires gaining insight into the properties of reversibility of intrinsic ATPase activity associated with K(ATP) channel complexes. Notwithstanding the operational paradigm, the homeostatic role of sarcolemmal K(ATP) channels can be now broadened to a wider range of environmental cues affecting metabolic well-being. In this way, under conditions of energy deficit such as ischemic insult or adrenergic stress, the operation of K(ATP) channel complexes would result in protective energy saving, safeguarding muscle performance and integrity. Under energy surplus, downregulation of K(ATP) channel function may find potential implications in conditions of energy imbalance linked to obesity, cold intolerance and associated metabolic disorders.
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Affiliation(s)
- Santiago Reyes
- Marriott Heart Diseases Research Program, Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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97
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Syed F, Lachman N, Christensen K, Mears JA, Buescher T, Cha YM, Friedman PA, Munger TM, Asirvatham SJ. The Pericardial Space: Obtaining Access and an Approach to Fluoroscopic Anatomy. Card Electrophysiol Clin 2010; 2:9-23. [PMID: 28770739 DOI: 10.1016/j.ccep.2009.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The pericardial space is now increasingly used as a means and vantage point for mapping and ablating various arrhythmias. In this review, present techniques to access the pericardial space are examined and potential improvements over this technique discussed. The authors then examine in detail the regional anatomy of the pericardial space relevant to the major arrhythmias treated in contemporary electrophysiology. In each of these sections, emphasis is placed on anatomic fluoroscopic correlation and avoiding complications that may result.
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Affiliation(s)
- Faisal Syed
- Department of Internal Medicine, Mayo Clinic, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Nirusha Lachman
- Department of Anatomy, Mayo Clinic, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Kevin Christensen
- Mayo Medical School, Mayo Clinic, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Jennifer A Mears
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Traci Buescher
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Yong-Mei Cha
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Paul A Friedman
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Thomas M Munger
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
| | - Samuel J Asirvatham
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA; Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, Mayo Clinic College of Medicine, 200 1st Street, SW, Rochester, MN 55905, USA
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Arrell DK, Zlatkovic J, Kane GC, Yamada S, Terzic A. ATP-sensitive K+ channel knockout induces cardiac proteome remodeling predictive of heart disease susceptibility. J Proteome Res 2010; 8:4823-34. [PMID: 19673485 DOI: 10.1021/pr900561g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Forecasting disease susceptibility requires detection of maladaptive signatures prior to onset of overt symptoms. A case-in-point are cardiac ATP-sensitive K+ (K(ATP)) channelopathies, for which the substrate underlying disease vulnerability remains to be identified. Resolving molecular pathobiology, even for single genetic defects, mandates a systems platform to reliably diagnose disease predisposition. High-throughput proteomic analysis was here integrated with network biology to decode consequences of Kir6.2 K(ATP) channel pore deletion. Differential two-dimensional gel electrophoresis reproducibly resolved >800 protein species from hearts of asymptomatic wild-type and Kir6.2-knockout counterparts. K(ATP) channel ablation remodeled the cardiac proteome, significantly altering 71 protein spots, from which 102 unique identities were assigned following hybrid linear ion trap quadrupole-Orbitrap tandem mass spectrometry. Ontological annotation stratified the K(ATP) channel-dependent protein cohort into a predominant bioenergetic module (63 resolved identities), with additional focused sets representing signaling molecules (6), oxidoreductases (8), chaperones (6), and proteins involved in catabolism (6), cytostructure (8), and transcription and translation (5). Protein interaction mapping, in conjunction with expression level changes, localized a K(ATP) channel-associated subproteome within a nonstochastic scale-free network. Global assessment of the K(ATP) channel deficient environment verified the primary impact on metabolic pathways and revealed overrepresentation of markers associated with cardiovascular disease. Experimental imposition of graded stress precipitated exaggerated structural and functional myocardial defects in the Kir6.2-knockout, decreasing survivorship and validating the forecast of disease susceptibility. Proteomic cartography thus provides an integral view of molecular remodeling in the heart induced by K(ATP) channel deletion, establishing a systems approach that predicts outcome at a presymptomatic stage.
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Affiliation(s)
- D Kent Arrell
- Marriott Heart Disease Research Program, Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Park S, Terzic A. Quaternary structure of KATP channel SUR2A nucleotide binding domains resolved by synchrotron radiation X-ray scattering. J Struct Biol 2010; 169:243-51. [PMID: 19919849 PMCID: PMC2818519 DOI: 10.1016/j.jsb.2009.11.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/11/2009] [Accepted: 11/10/2009] [Indexed: 01/03/2023]
Abstract
Heterodimeric nucleotide binding domains NBD1/NBD2 distinguish the ATP-binding cassette protein SUR2A, a recognized regulatory subunit of cardiac ATP-sensitive K(+) (K(ATP)) channels. The tandem function of these core domains ensures metabolism-dependent gating of the Kir6.2 channel pore, yet their structural arrangement has not been resolved. Here, purified monodisperse and interference-free recombinant particles were subjected to synchrotron radiation small-angle X-ray scattering (SAXS) in solution. Intensity function analysis of SAXS profiles resolved NBD1 and NBD2 as octamers. Implemented by ab initio simulated annealing, shape determination prioritized an oblong envelope wrapping NBD1 and NBD2 with respective dimensions of 168x80x37A(3) and 175x81x37A(3) based on symmetry constraints, validated by atomic force microscopy. Docking crystal structure homology models against SAXS data reconstructed the NBD ensemble surrounding an inner cleft suitable for Kir6.2 insertion. Human heart disease-associated mutations introduced in silico verified the criticality of the mapped protein-protein interface. The resolved quaternary structure delineates thereby a macromolecular arrangement of K(ATP) channel SUR2A regulatory domains.
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Affiliation(s)
- Sungjo Park
- Marriott Heart Disease Research Program, Division of Cardiovascular Diseases, Departments of Medicine, Molecular Pharmacology and Experimental Therapeutics, and Medical Genetics, Mayo Clinic, Rochester, MN 55905, USA
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Human K(ATP) channelopathies: diseases of metabolic homeostasis. Pflugers Arch 2009; 460:295-306. [PMID: 20033705 PMCID: PMC2883927 DOI: 10.1007/s00424-009-0771-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 11/30/2009] [Indexed: 10/27/2022]
Abstract
Assembly of an inward rectifier K+ channel pore (Kir6.1/Kir6.2) and an adenosine triphosphate (ATP)-binding regulatory subunit (SUR1/SUR2A/SUR2B) forms ATP-sensitive K+ (KATP) channel heteromultimers, widely distributed in metabolically active tissues throughout the body. KATP channels are metabolism-gated biosensors functioning as molecular rheostats that adjust membrane potential-dependent functions to match cellular energetic demands. Vital in the adaptive response to (patho)physiological stress, KATP channels serve a homeostatic role ranging from glucose regulation to cardioprotection. Accordingly, genetic variation in KATP channel subunits has been linked to the etiology of life-threatening human diseases. In particular, pathogenic mutations in KATP channels have been identified in insulin secretion disorders, namely, congenital hyperinsulinism and neonatal diabetes. Moreover, KATP channel defects underlie the triad of developmental delay, epilepsy, and neonatal diabetes (DEND syndrome). KATP channelopathies implicated in patients with mechanical and/or electrical heart disease include dilated cardiomyopathy (with ventricular arrhythmia; CMD1O) and adrenergic atrial fibrillation. A common Kir6.2 E23K polymorphism has been associated with late-onset diabetes and as a risk factor for maladaptive cardiac remodeling in the community-at-large and abnormal cardiopulmonary exercise stress performance in patients with heart failure. The overall mutation frequency within KATP channel genes and the spectrum of genotype-phenotype relationships remain to be established, while predicting consequences of a deficit in channel function is becoming increasingly feasible through systems biology approaches. Thus, advances in molecular medicine in the emerging field of human KATP channelopathies offer new opportunities for targeted individualized screening, early diagnosis, and tailored therapy.
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