201
|
Anderson JH, Tester DJ, Will ML, Ackerman MJ. Whole-Exome Molecular Autopsy After Exertion-Related Sudden Unexplained Death in the Young. ACTA ACUST UNITED AC 2016; 9:259-65. [DOI: 10.1161/circgenetics.115.001370] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/21/2016] [Indexed: 11/16/2022]
Affiliation(s)
- Jason H. Anderson
- From the Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine (J.H.A., M.J.A.), Department of Molecular Pharmacology and Experimental Therapeutics/Windland Smith Rice Sudden Death Genomics Laboratory (D.J.T., M.L.W., M.J.A.), and Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (M.J.A.)
| | - David J. Tester
- From the Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine (J.H.A., M.J.A.), Department of Molecular Pharmacology and Experimental Therapeutics/Windland Smith Rice Sudden Death Genomics Laboratory (D.J.T., M.L.W., M.J.A.), and Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (M.J.A.)
| | - Melissa L. Will
- From the Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine (J.H.A., M.J.A.), Department of Molecular Pharmacology and Experimental Therapeutics/Windland Smith Rice Sudden Death Genomics Laboratory (D.J.T., M.L.W., M.J.A.), and Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (M.J.A.)
| | - Michael J. Ackerman
- From the Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine (J.H.A., M.J.A.), Department of Molecular Pharmacology and Experimental Therapeutics/Windland Smith Rice Sudden Death Genomics Laboratory (D.J.T., M.L.W., M.J.A.), and Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (M.J.A.)
| |
Collapse
|
202
|
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac arrhythmia disorder that is characterized by emotion- and exercise-induced polymorphic ventricular arrhythmias and may lead to sudden cardiac death (SCD). CPVT plays an important role in SCD in the young and therefore recognition and adequate treatment of the disease are of vital importance. In the past years tremendous improvements have been made in the diagnostic methods and treatment of the disease. In this review, we summarize the clinical characteristics, genetics, and diagnostic and therapeutic strategies of CPVT and describe the most recent advances and some of the current challenges. (Circ J 2016; 80: 1285-1291).
Collapse
Affiliation(s)
- Krystien V Lieve
- Heart Centre, Department of Clinical and Experimental Cardiology, Academic Medical Centre
| | | | | |
Collapse
|
203
|
Yu CC, Ko JS, Ai T, Tsai WC, Chen Z, Rubart M, Vatta M, Everett TH, George AL, Chen PS. Arrhythmogenic calmodulin mutations impede activation of small-conductance calcium-activated potassium current. Heart Rhythm 2016; 13:1716-23. [PMID: 27165696 DOI: 10.1016/j.hrthm.2016.05.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Indexed: 01/27/2023]
Abstract
BACKGROUND Apamin-sensitive small-conductance calcium-activated potassium (SK) channels are gated by intracellular Ca(2+) through a constitutive interaction with calmodulin. OBJECTIVE We hypothesize that arrhythmogenic human calmodulin mutations impede activation of SK channels. METHODS We studied 5 previously published calmodulin mutations (N54I, N98S, D96V, D130G, and F90L). Plasmids encoding either wild-type or mutant calmodulin were transiently transfected into human embryonic kidney 293 cells that stably express subtype 2 of SK protein channels (SK2 cells). Whole-cell voltage-clamp recording was used to determine apamin-sensitive current densities. We also performed optical mapping studies in normal murine hearts to determine the effects of apamin in hearts with (n=7) or without (n=3) pretreatment with sea anemone toxin. RESULTS SK2 cells transfected with wild-type calmodulin exhibited an apamin-sensitive current density of 33.6 pA/pF (31.4-36.5 pA/pF) (median and confidence interval 25th-75th percentile), which was significantly higher than that observed for cells transfected with N54I (17.0 pA/pF [14.0-27.7 pA/pF]; P = .016), F90L (22.6 pA/pF [20.3-24.3 pA/pF]; P = .011), D96V (13.0 pA/pF [10.9-15.8 pA/pF]; P = .003), N98S (13.7 pA/pF [8.8-20.4 pA/pF]; P = .005), and D130G (17.6 pA/pF [13.8-24.6 pA/pF]; P = .003). The decrease in SK2 current densities was not associated with a decrease in membrane protein expression or intracellular distribution of the channel protein. Apamin increased the ventricular action potential duration at 80% repolarization (from 79.6 ms [63.4-93.3 ms] to 121.8 ms [97.9-127.2 ms]; P = .010) in hearts pretreated with anemone toxin but not in control hearts. CONCLUSION Human arrhythmogenic calmodulin mutations impede the activation of SK2 channels in human embryonic kidney 293 cells.
Collapse
Affiliation(s)
- Chih-Chieh Yu
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jum-Suk Ko
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Wonkwang University School of Medicine and Hospital, Iksan, Korea
| | - Tomohiko Ai
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Department of Molecular Pathogenesis, Medical Research Institute; Department of Emergency Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Wen-Chin Tsai
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Hualien Tzu-Chi General Hospital, Hualien City, Taiwan
| | - Zhenhui Chen
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana
| | - Michael Rubart
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Department of Pediatrics, Riley Heart Research Center
| | - Matteo Vatta
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Thomas H Everett
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Peng-Sheng Chen
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University, Indianapolis, Indiana.
| |
Collapse
|
204
|
Jiménez-Jáimez J, Palomino Doza J, Ortega Á, Macías-Ruiz R, Perin F, Rodríguez-Vázquez del Rey MM, Ortiz-Genga M, Monserrat L, Barriales-Villa R, Blanca E, Álvarez M, Tercedor L. Calmodulin 2 Mutation N98S Is Associated with Unexplained Cardiac Arrest in Infants Due to Low Clinical Penetrance Electrical Disorders. PLoS One 2016; 11:e0153851. [PMID: 27100291 PMCID: PMC4839566 DOI: 10.1371/journal.pone.0153851] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/05/2016] [Indexed: 01/08/2023] Open
Abstract
Background Calmodulin 1, 2 and 3 (CALM) mutations have been found to cause cardiac arrest in children at a very early age. The underlying aetiology described is long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT) and idiopathic ventricular fibrillation (IVF). Little phenotypical data about CALM2 mutations is available. Objectives The aim of this paper is to describe the clinical manifestations of the Asn98Ser mutation in CALM2 in two unrelated children in southern Spain with apparently unexplained cardiac arrest/death. Methods Two unrelated children aged 4 and 7, who were born to healthy parents, were studied. Both presented with sudden cardiac arrest. The first was resuscitated after a VF episode, and the second died suddenly. In both cases the baseline QTc interval was within normal limits. Peripheral blood DNA was available to perform targeted gene sequencing. Results The surviving 4-year-old girl had a positive epinephrine test for LQTS, and polymorphic ventricular ectopic beats were seen on a previous 24-hour Holter recording from the deceased 7-year-old boy, suggestive of a possible underlying CPVT phenotype. A p.Asn98Ser mutation in CALM2 was detected in both cases. This affected a highly conserved across species residue, and the location in the protein was adjacent to critical calcium binding loops in the calmodulin carboxyl-terminal domain, predicting a high pathogenic effect. Conclusions Human calmodulin 2 mutation p.Asn98Ser is associated with sudden cardiac death in childhood with a variable clinical penetrance. Our results provide new phenotypical information about clinical behaviour of this mutation.
Collapse
Affiliation(s)
- Juan Jiménez-Jáimez
- Cardiology Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
- Instituto de Investigación Biosanitario de Granada, Granada, Spain
- * E-mail:
| | | | - Ángeles Ortega
- Paediatrics Department, Hospital de Torrecárdenas, Almería, Spain
| | - Rosa Macías-Ruiz
- Cardiology Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
- Instituto de Investigación Biosanitario de Granada, Granada, Spain
| | - Francesca Perin
- Paediatrics Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
| | | | | | | | | | - Enrique Blanca
- Paediatrics Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
| | - Miguel Álvarez
- Cardiology Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
- Instituto de Investigación Biosanitario de Granada, Granada, Spain
| | - Luis Tercedor
- Cardiology Department, Complejo Hospitalario Universitario de Granada, Granada, Spain
- Instituto de Investigación Biosanitario de Granada, Granada, Spain
| |
Collapse
|
205
|
Chaix MA, Koopmann TT, Goyette P, Alikashani A, Latour F, Fatah M, Hamilton RM, Rioux JD. Novel CALM3 mutations in pediatric long QT syndrome patients support a CALM3-specific calmodulinopathy. HeartRhythm Case Rep 2016; 2:250-254. [PMID: 28491681 PMCID: PMC5419757 DOI: 10.1016/j.hrcr.2016.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Marie-A Chaix
- Montreal Heart Institute, Montreal, Quebec, Canada.,Université de Montréal, Montreal, Quebec, Canada
| | - Tamara T Koopmann
- Physiology and Experimental Medicine, The Hospital for Sick Children & Research Institute, Toronto, Ontario, Canada
| | | | | | | | - Meena Fatah
- Physiology and Experimental Medicine, The Hospital for Sick Children & Research Institute, Toronto, Ontario, Canada
| | - Robert M Hamilton
- Physiology and Experimental Medicine, The Hospital for Sick Children & Research Institute, Toronto, Ontario, Canada
| | - John D Rioux
- Montreal Heart Institute, Montreal, Quebec, Canada.,Université de Montréal, Montreal, Quebec, Canada
| |
Collapse
|
206
|
Boczek NJ, Gomez-Hurtado N, Ye D, Calvert ML, Tester DJ, Kryshtal D, Hwang HS, Johnson CN, Chazin WJ, Loporcaro CG, Shah M, Papez AL, Lau YR, Kanter R, Knollmann BC, Ackerman MJ. Spectrum and Prevalence of CALM1-, CALM2-, and CALM3-Encoded Calmodulin Variants in Long QT Syndrome and Functional Characterization of a Novel Long QT Syndrome-Associated Calmodulin Missense Variant, E141G. ACTA ACUST UNITED AC 2016; 9:136-146. [PMID: 26969752 DOI: 10.1161/circgenetics.115.001323] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/04/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Calmodulin (CaM) is encoded by 3 genes, CALM1, CALM2, and CALM3, all of which harbor pathogenic variants linked to long QT syndrome (LQTS) with early and severe expressivity. These LQTS-causative variants reduce CaM affinity to Ca(2+) and alter the properties of the cardiac L-type calcium channel (CaV1.2). CaM also modulates NaV1.5 and the ryanodine receptor, RyR2. All these interactions may play a role in disease pathogenesis. Here, we determine the spectrum and prevalence of pathogenic CaM variants in a cohort of genetically elusive LQTS, and functionally characterize the novel variants. METHODS AND RESULTS Thirty-eight genetically elusive LQTS cases underwent whole-exome sequencing to identify CaM variants. Nonsynonymous CaM variants were over-represented significantly in this heretofore LQTS cohort (13.2%) compared with exome aggregation consortium (0.04%; P<0.0001). When the clinical sequelae of these 5 CaM-positive cases were compared with the 33 CaM-negative cases, CaM-positive cases had a more severe phenotype with an average age of onset of 10 months, an average corrected QT interval of 676 ms, and a high prevalence of cardiac arrest. Functional characterization of 1 novel variant, E141G-CaM, revealed an 11-fold reduction in Ca(2+)-binding affinity and a functionally dominant loss of inactivation in CaV1.2, mild accentuation in NaV1.5 late current, but no effect on intracellular RyR2-mediated calcium release. CONCLUSIONS Overall, 13% of our genetically elusive LQTS cohort harbored nonsynonymous variants in CaM. Genetic testing of CALM1-3 should be pursued for individuals with LQTS, especially those with early childhood cardiac arrest, extreme QT prolongation, and a negative family history.
Collapse
Affiliation(s)
- Nicole J Boczek
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | | | - Dan Ye
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Melissa L Calvert
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - David J Tester
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Dmytro Kryshtal
- Department of Medicine, Vanderbilt University, Nashville, TN
| | - Hyun Seok Hwang
- Department of Medicine, Vanderbilt University, Nashville, TN
| | - Christopher N Johnson
- Departments of Biochemistry & Chemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN
| | - Walter J Chazin
- Departments of Biochemistry & Chemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN
| | - Christina G Loporcaro
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.,Mayo Medical School, Mayo Clinic, Rochester, MN
| | - Maully Shah
- Children's Hospital of Philadelphia, Philadelphia, PA
| | - Andrew L Papez
- Department of Pediatric Cardiology, Phoenix Children's Hospital, Phoenix, AZ
| | - Yung R Lau
- Department of Pediatrics, Division of Pediatric Cardiology, University of Alabama at Birmingham, Birmingham, AL
| | - Ronald Kanter
- Division of Cardiology, Nicklaus Children's Hospital, Miami, FL
| | | | - Michael J Ackerman
- Department Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.,Department of Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.,Department of Pediatrics, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| |
Collapse
|
207
|
Waddell-Smith KE, Skinner JR. Update on the Diagnosis and Management of Familial Long QT Syndrome. Heart Lung Circ 2016; 25:769-76. [PMID: 27262388 DOI: 10.1016/j.hlc.2016.01.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/20/2016] [Indexed: 01/16/2023]
Abstract
This update was reviewed by the CSANZ Continuing Education and Recertification Committee and ratified by the CSANZ board in August 2015. Since the CSANZ 2011 guidelines, adjunctive clinical tests have proven useful in the diagnosis of LQTS and are discussed in this update. Understanding of the diagnostic and risk stratifying role of LQTS genetics is also discussed. At least 14 LQTS genes are now thought to be responsible for the disease. High-risk individuals may have multiple mutations, large gene rearrangements, C-loop mutations in KCNQ1, transmembrane mutations in KCNH2, or have certain gene modifiers present, particularly NOS1AP polymorphisms. In regards to treatment, nadolol is preferred, particularly for long QT type 2, and short acting metoprolol should not be used. Thoracoscopic left cardiac sympathectomy is valuable in those who cannot adhere to beta blocker therapy, particularly in long QT type 1. Indications for ICD therapies have been refined; and a primary indication for ICD in post-pubertal females with long QT type 2 and a very long QT interval is emerging.
Collapse
Affiliation(s)
- Kathryn E Waddell-Smith
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand
| | - Jonathan R Skinner
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand.
| |
Collapse
|
208
|
Halling DB, Liebeskind BJ, Hall AW, Aldrich RW. Conserved properties of individual Ca2+-binding sites in calmodulin. Proc Natl Acad Sci U S A 2016; 113:E1216-25. [PMID: 26884197 PMCID: PMC4780646 DOI: 10.1073/pnas.1600385113] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Calmodulin (CaM) is a Ca(2+)-sensing protein that is highly conserved and ubiquitous in eukaryotes. In humans it is a locus of life-threatening cardiomyopathies. The primary function of CaM is to transduce Ca(2+) concentration into cellular signals by binding to a wide range of target proteins in a Ca(2+)-dependent manner. We do not fully understand how CaM performs its role as a high-fidelity signal transducer for more than 300 target proteins, but diversity among its four Ca(2+)-binding sites, called EF-hands, may contribute to CaM's functional versatility. We therefore looked at the conservation of CaM sequences over deep evolutionary time, focusing primarily on the four EF-hand motifs. Expanding on previous work, we found that CaM evolves slowly but that its evolutionary rate is substantially faster in fungi. We also found that the four EF-hands have distinguishing biophysical and structural properties that span eukaryotes. These results suggest that all eukaryotes require CaM to decode Ca(2+) signals using four specialized EF-hands, each with specific, conserved traits. In addition, we provide an extensive map of sites associated with target proteins and with human disease and correlate these with evolutionary sequence diversity. Our comprehensive evolutionary analysis provides a basis for understanding the sequence space associated with CaM function and should help guide future work on the relationship between structure, function, and disease.
Collapse
Affiliation(s)
- D Brent Halling
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712
| | - Benjamin J Liebeskind
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712
| | - Amelia W Hall
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Richard W Aldrich
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712;
| |
Collapse
|
209
|
Abstract
OPINION STATEMENT Ion channelopathies are a frequent cause of sudden cardiac death (SCD) in patients with structurally normal hearts. These are generally Mendelian inherited electrical disorders with variable penetrance and expressivity. The ability to predict the development of life threatening arrhythmias in these patients is challenging. This chapter will present an update on the genetics, the role of genetic testing, and management of the inherited cardiac channelopathies with a focus on the relatively more common syndromes associated with an increased risk of SCD.
Collapse
Affiliation(s)
- Gordon F Tomaselli
- Division of Cardiology, Johns Hopkins University, 720 N. Rutland Ave. Ross 844, Baltimore, MD, 21205, USA.
- Department of Medicine, Johns Hopkins University, 720 N. Rutland Ave. Ross 844, Baltimore, MD, 21205, USA.
| | - Andreas S Barth
- Division of Cardiology, Johns Hopkins University, 720 N. Rutland Ave. Ross 844, Baltimore, MD, 21205, USA
- Department of Medicine, Johns Hopkins University, 720 N. Rutland Ave. Ross 844, Baltimore, MD, 21205, USA
| |
Collapse
|
210
|
Mizusawa Y. Recent advances in genetic testing and counseling for inherited arrhythmias. J Arrhythm 2016; 32:389-397. [PMID: 27761163 PMCID: PMC5063262 DOI: 10.1016/j.joa.2015.12.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 12/01/2015] [Accepted: 12/17/2015] [Indexed: 12/19/2022] Open
Abstract
Inherited arrhythmias, such as cardiomyopathies and cardiac ion channelopathies, along with coronary heart disease (CHD) are three most common disorders that predispose adults to sudden cardiac death. In the last three decades, causal genes in inherited arrhythmias have been successfully identified. At the same time, it has become evident that the genetic architectures are more complex than previously known. Recent advancements in DNA sequencing technology (next generation sequencing) have enabled us to study such complex genetic traits. This article discusses indications for genetic testing of patients with inherited arrhythmias. Further, it describes the benefits and challenges that we face in the era of next generation sequencing. Finally, it briefly discusses genetic counseling, in which a multidisciplinary approach is required due to the increased complexity of the genetic information related to inherited arrhythmias.
Collapse
Key Words
- ARVD/C, arrhythmogenic right ventricular dysplasia/cardiomyopathy
- BrS, Brugada syndrome
- CHD, coronary heart disease
- CPVT, catecholaminergic polymorphic ventricular tachycardia
- Cardiac ion channelopathies
- Cardiomyopathies
- DCM, dilated cardiomyopathy
- GWAS, genome wide association study
- Genetic counseling
- Genetic testing
- HCM, hypertrophic cardiomyopathy
- HF, heart failure
- ICD, implantable cardioverter defibrillator
- Inherited arrhythmias
- LQTS, long QT syndrome
- NGS, next generation sequencing
- SCD, sudden cardiac death
- VA, ventricular arrhythmia
- VF, ventricular fibrillation
- WES, whole exome sequencing
Collapse
Affiliation(s)
- Yuka Mizusawa
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Room K2-115, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| |
Collapse
|
211
|
The role of genetic testing in unexplained sudden death. Transl Res 2016; 168:59-73. [PMID: 26143861 DOI: 10.1016/j.trsl.2015.06.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Revised: 06/08/2015] [Accepted: 06/11/2015] [Indexed: 12/19/2022]
Abstract
Most sudden deaths are because of a cardiac etiology and are termed sudden cardiac death (SCD). In younger individuals coronary artery disease is less prevalent and cardiac genetic disorders are more common. If sudden death is unexplained despite an appropriate autopsy and toxicologic assessment the term sudden arrhythmic death syndrome (SADS) may be used. This is an umbrella term and common underlying etiologies are primary arrhythmia syndromes with a familial basis such as Brugada syndrome, long QT syndrome, and subtle forms of cardiomyopathy. The first clinical presentation of these conditions is often SCD, which makes identification, screening, and risk stratification crucial to avert further deaths. This review will focus on genetic testing in the context of family screening. It will address the role of the "molecular autopsy" alongside current postmortem practices in the evaluation of SADS deaths. We describe the current data underlying genetic testing in these conditions, explore the potential for next-generation sequencing, and discuss the inherent diagnostic problems in determination of pathogenicity.
Collapse
|
212
|
Nebel RA, Zhao D, Pedrosa E, Kirschen J, Lachman HM, Zheng D, Abrahams BS. Reduced CYFIP1 in Human Neural Progenitors Results in Dysregulation of Schizophrenia and Epilepsy Gene Networks. PLoS One 2016; 11:e0148039. [PMID: 26824476 PMCID: PMC4732616 DOI: 10.1371/journal.pone.0148039] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/12/2016] [Indexed: 11/19/2022] Open
Abstract
Deletions encompassing the BP1-2 region at 15q11.2 increase schizophrenia and epilepsy risk, but only some carriers have either disorder. To investigate the role of CYFIP1, a gene within the region, we performed knockdown experiments in human neural progenitors derived from donors with 2 copies of each gene at the BP1-2 locus. RNA-seq and cellular assays determined that knockdown of CYFIP1 compromised cytoskeletal remodeling. FMRP targets and postsynaptic density genes, each implicated in schizophrenia, were significantly overrepresented among differentially expressed genes (DEGs). Schizophrenia and/or epilepsy genes, but not those associated with randomly selected disorders, were likewise significantly overrepresented. Mirroring the variable expressivity seen in deletion carriers, marked between-line differences were observed for dysregulation of disease genes. Finally, a subset of DEGs showed a striking similarity to known epilepsy genes and represents novel disease candidates. Results support a role for CYFIP1 in disease and demonstrate that disease-related biological signatures are apparent prior to neuronal differentiation.
Collapse
Affiliation(s)
- Rebecca A. Nebel
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Dejian Zhao
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Erika Pedrosa
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Jill Kirschen
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Herbert M. Lachman
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Brett S. Abrahams
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
| |
Collapse
|
213
|
Pouché L, Stojanova J, Marquet P, Picard N. New challenges and promises in solid organ transplantation pharmacogenetics: the genetic variability of proteins involved in the pharmacodynamics of immunosuppressive drugs. Pharmacogenomics 2016; 17:277-96. [PMID: 26799749 DOI: 10.2217/pgs.15.169] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Interindividual variability in immunosuppressive drug responses might be partly explained by genetic variants in proteins involved in the immune response or associated with IS pharmacodynamics. On a general basis, the pharmacogenetics of drug target proteins is less known and understood than that of proteins involved in drug disposition pathways. The aim of this review is to facilitate research related to the pharmacodynamics of the main immunosuppressive drugs used in solid organ transplantation. We elaborated a quality of evidence grading system based on a literature review and identified 'highly recommended', 'recommended' or 'potential' candidates for further research. It is likely that a number of additional rare variants might further explain drug response phenotypes in transplantation, and particularly the most severe ones. The advent of next-generation sequencing will help to identify those variants.
Collapse
Affiliation(s)
- Lucie Pouché
- Inserm, UMR 850, 2 Avenue Martin-Luther King, F-87042 Limoges, France.,CHU Limoges, Department of Pharmacology, Toxicology & Pharmacovigilance, 2 Avenue Martin-Luther King, F-87042 Limoges, France
| | - Jana Stojanova
- Laboratory of Chemical Carcinogenesis & Pharmacogenetics, University of Chile, Santiago, Chile
| | - Pierre Marquet
- Inserm, UMR 850, 2 Avenue Martin-Luther King, F-87042 Limoges, France.,CHU Limoges, Department of Pharmacology, Toxicology & Pharmacovigilance, 2 Avenue Martin-Luther King, F-87042 Limoges, France.,Univ. Limoges, Faculty of Medicine & Pharmacy, 2 rue du Dr Marcland, F-87025 Limoges, France.,FHU SUPORT, 87000 Limoges, France
| | - Nicolas Picard
- Inserm, UMR 850, 2 Avenue Martin-Luther King, F-87042 Limoges, France.,CHU Limoges, Department of Pharmacology, Toxicology & Pharmacovigilance, 2 Avenue Martin-Luther King, F-87042 Limoges, France.,Univ. Limoges, Faculty of Medicine & Pharmacy, 2 rue du Dr Marcland, F-87025 Limoges, France.,FHU SUPORT, 87000 Limoges, France
| |
Collapse
|
214
|
Gao Y, Liu W, Li C, Qiu X, Qin X, Guo B, Liu X, Li J, Yuan Y, Li X, Liang L, Li L, Hong K, Pu J, Liu J, Wang Q, Zhang L, Hu DY. Common Genotypes of Long QT Syndrome in China and the Role of ECG Prediction. Cardiology 2015; 133:73-8. [PMID: 26496715 DOI: 10.1159/000440608] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/24/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Genetic testing, a gold standard for long QT syndrome (LQTS) diagnosis, is time-consuming and costly when all the 15 candidate genes are screened. Since genotype-specific ECG patterns are present in most LQT1-3 mutation carriers, we tested the utility of ECG-guided genotyping in a large cohort of Chinese LQTS patients. METHODS AND RESULTS We enrolled 230 patients (26 ± 17 years, 66% female) with a clinical diagnosis of LQTS. Genotypes were predicted as LQT1-3 based on the presence of ECG patterns typical for each genotype in 200 patients (85 LQT1, 110 LQT2 and 5 LQT3). Family-based genotype prediction was also conducted if gene-specific ECG patterns were found in other affected family members. Mutational screening identified 104 mutations (44% novel), i.e. 46 KCNQ1, 54 KCNH2 and 4 SCN5A mutations. The overall predictive accuracy of ECG-guided genotyping was 79% (157/200) and 79% (67/85), 78% (86/110) and 80% (4/5) for LQT1, LQT2 and LQT3, respectively. The predictive accuracy was 98% (42/43) when family-based ECG assessment was performed. CONCLUSIONS From this large-scale genotyping study, we found that LQT2 is the most common genotype among the Chinese. Family-based ECG-guided genotyping is highly accurate. ECG-guided genotyping is time- and cost-effective. We therefore recommend it as an optimal approach for the genetic diagnosis of LQTS.
Collapse
Affiliation(s)
- Yuanfeng Gao
- Heart Center, Peking University People's Hospital, Beijing, PR China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
215
|
Spears DA, Gollob MH. Genetics of inherited primary arrhythmia disorders. APPLICATION OF CLINICAL GENETICS 2015; 8:215-33. [PMID: 26425105 PMCID: PMC4583121 DOI: 10.2147/tacg.s55762] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A sudden unexplained death is felt to be due to a primary arrhythmic disorder when no structural heart disease is found on autopsy, and there is no preceding documentation of heart disease. In these cases, death is presumed to be secondary to a lethal and potentially heritable abnormality of cardiac ion channel function. These channelopathies include congenital long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome, and short QT syndrome. In certain cases, genetic testing may have an important role in supporting a diagnosis of a primary arrhythmia disorder, and can also provide prognostic information, but by far the greatest strength of genetic testing lies in the screening of family members, who may be at risk. The purpose of this review is to describe the basic genetic and molecular pathophysiology of the primary inherited arrhythmia disorders, and to outline a rational approach to genetic testing, management, and family screening.
Collapse
Affiliation(s)
- Danna A Spears
- Division of Cardiology - Electrophysiology, University Health Network, Toronto General Hospital, Toronto, ON, Canada
| | - Michael H Gollob
- Division of Cardiology - Electrophysiology, University Health Network, Toronto General Hospital, Toronto, ON, Canada
| |
Collapse
|
216
|
Hertz CL, Christiansen SL, Larsen MK, Dahl M, Ferrero-Miliani L, Weeke PE, Pedersen O, Hansen T, Grarup N, Ottesen GL, Frank-Hansen R, Banner J, Morling N. Genetic investigations of sudden unexpected deaths in infancy using next-generation sequencing of 100 genes associated with cardiac diseases. Eur J Hum Genet 2015; 24:817-22. [PMID: 26350513 DOI: 10.1038/ejhg.2015.198] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/08/2015] [Accepted: 08/24/2015] [Indexed: 02/07/2023] Open
Abstract
Sudden infant death syndrome (SIDS) is the most frequent manner of post-perinatal death among infants. One of the suggested causes of the syndrome is inherited cardiac diseases, mainly channelopathies, that can trigger arrhythmias and sudden death. The purpose of this study was to investigate cases of sudden unexpected death in infancy (SUDI) for potential causative variants in 100 cardiac-associated genes. We investigated 47 SUDI cases of which 38 had previously been screened for variants in RYR2, KCNQ1, KCNH2 and SCN5A. Using the Haloplex Target Enrichment System (Agilent) and next-generation sequencing (NGS), the coding regions of 100 genes associated with inherited channelopathies and cardiomyopathies were captured and sequenced on the Illumina MiSeq platform. Sixteen (34%) of the SUDI cases had variants with likely functional effects, based on conservation, computational prediction and allele frequency, in one or more of the genes screened. The possible effects of the variants were not verified with family or functional studies. Eight (17%) of the SUDI cases had variants in genes affecting ion channel functions. The remaining eight cases had variants in genes associated with cardiomyopathies. In total, one third of the SUDI victims in a forensic setting had variants with likely functional effect that presumably contributed to the cause of death. The results support the assumption that channelopathies are important causes of SUDI. Thus, analysis of genes associated with cardiac diseases in SUDI victims is important in the forensic setting and a valuable supplement to the clinical investigation in all cases of sudden death.
Collapse
Affiliation(s)
- Christin Loeth Hertz
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Lindgren Christiansen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maiken Kudahl Larsen
- Department of Forensic Medicine, Faculty of Health Sciences, University of Aarhus, Aarhus, Denmark
| | - Morten Dahl
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Clinical Biochemistry, Køge, Copenhagen University Hospital, Copenhagen, Denmark
| | - Laura Ferrero-Miliani
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Ejvin Weeke
- Department of Cardiology, Laboratory of Molecular Cardiology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Oluf Pedersen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Torben Hansen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Niels Grarup
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gyda Lolk Ottesen
- Section of Forensic Pathology, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rune Frank-Hansen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jytte Banner
- Section of Forensic Pathology, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Morling
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
217
|
Bazzazi H, Sang L, Dick IE, Joshi-Mukherjee R, Yang W, Yue DT. Novel fluorescence resonance energy transfer-based reporter reveals differential calcineurin activation in neonatal and adult cardiomyocytes. J Physiol 2015; 593:3865-84. [PMID: 26096996 PMCID: PMC4575574 DOI: 10.1113/jp270510] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/16/2015] [Indexed: 12/26/2022] Open
Abstract
Novel fluorescence resonance energy transfer-based genetically encoded reporters of calcineurin are constructed by fusing the two subunits of calcineurin with P2A-based linkers retaining the expected native conformation of calcineurin. Calcineurin reporters display robust responses to calcium transients in HEK293 cells. The sensor responses are correlated with NFATc1 translocation dynamics in HEK293 cells. The sensors are uniformly distributed in neonatal myocytes and respond efficiently to single electrically evoked calcium transients and show cumulative activation at frequencies of 0.5 and 1 Hz. In adult myocytes, the calcineurin sensors appear to be localized to the cardiac z-lines, and respond to cumulative calcium transients at frequencies of 0.5 and 1 Hz. The phosphatase calcineurin is a central component of many calcium signalling pathways, relaying calcium signals from the plasma membrane to the nucleus. It has critical functions in a multitude of systems, including immune, cardiac and neuronal. Given the widespread importance of calcineurin in both normal and pathological conditions, new tools that elucidate the spatiotemporal dynamics of calcineurin activity would be invaluable. Here we develop two separate genetically encoded fluorescence resonance energy transfer (FRET)-based sensors of calcineurin activation, DuoCaN and UniCaN. Both sensors showcase a large dynamic range and rapid response kinetics, differing primarily in the linker structure between the FRET pairs. Both sensors were calibrated in HEK293 cells and their responses correlated well with NFAT translocation to the nucleus, validating the biological relevance of the sensor readout. The sensors were subsequently expressed in neonatal rat ventricular myocytes and acutely isolated adult guinea pig ventricular myocytes. Both sensors demonstrated robust responses in myocytes and revealed kinetic differences in calcineurin activation during changes in pacing rate for neonatal versus adult myocytes. Finally, mathematical modelling combined with quantitative FRET measurements provided novel insights into the kinetics and integration of calcineurin activation in response to myocyte Ca transients. In all, DuoCaN and UniCaN stand as valuable new tools for understanding the role of calcineurin in normal and pathological signalling.
Collapse
Affiliation(s)
- Hojjat Bazzazi
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | - Lingjie Sang
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | - Ivy E Dick
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | - Rosy Joshi-Mukherjee
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | - Wanjun Yang
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | | |
Collapse
|
218
|
Søndergaard MT, Tian X, Liu Y, Wang R, Chazin WJ, Chen SRW, Overgaard MT. Arrhythmogenic Calmodulin Mutations Affect the Activation and Termination of Cardiac Ryanodine Receptor-mediated Ca2+ Release. J Biol Chem 2015; 290:26151-62. [PMID: 26309258 DOI: 10.1074/jbc.m115.676627] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Indexed: 11/06/2022] Open
Abstract
The intracellular Ca(2+) sensor calmodulin (CaM) regulates the cardiac Ca(2+) release channel/ryanodine receptor 2 (RyR2), and mutations in CaM cause arrhythmias such as catecholaminergic polymorphic ventricular tachycardia (CPVT) and long QT syndrome. Here, we investigated the effect of CaM mutations causing CPVT (N53I), long QT syndrome (D95V and D129G), or both (CaM N97S) on RyR2-mediated Ca(2+) release. All mutations increased Ca(2+) release and rendered RyR2 more susceptible to store overload-induced Ca(2+) release (SOICR) by lowering the threshold of store Ca(2+) content at which SOICR occurred and the threshold at which SOICR terminated. To obtain mechanistic insights, we investigated the Ca(2+) binding of the N- and C-terminal domains (N- and C-domain) of CaM in the presence of a peptide corresponding to the CaM-binding domain of RyR2. The N53I mutation decreased the affinity of Ca(2+) binding to the N-domain of CaM, relative to CaM WT, but did not affect the C-domain. Conversely, mutations N97S, D95V, and D129G had little or no effect on Ca(2+) binding to the N-domain but markedly decreased the affinity of the C-domain for Ca(2+). These results suggest that mutations D95V, N97S, and D129G alter the interaction between CaM and the CaMBD and thus RyR2 regulation. Because the N53I mutation minimally affected Ca(2+) binding to the C-domain, it must cause aberrant regulation via a different mechanism. These results support aberrant RyR2 regulation as the disease mechanism for CPVT associated with CaM mutations and shows that CaM mutations not associated with CPVT can also affect RyR2. A model for the CaM-RyR2 interaction, where the Ca(2+)-saturated C-domain is constitutively bound to RyR2 and the N-domain senses increases in Ca(2+) concentration, is proposed.
Collapse
Affiliation(s)
- Mads T Søndergaard
- From the Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark, the Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - Xixi Tian
- the Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - Yingjie Liu
- the Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - Ruiwu Wang
- the Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - Walter J Chazin
- the Departments of Biochemistry and Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235
| | - S R Wayne Chen
- the Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - Michael T Overgaard
- From the Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark,
| |
Collapse
|
219
|
Abstract
PURPOSE OF REVIEW The purpose of this study is to update the perinatal cardiologist and obstetrical care provider on the presentation and management of the fetus with long QT syndrome (LQTS). RECENT FINDINGS LQTS is a known cause of sudden death in childhood, adolescence and young adulthood that presents during fetal life, but is often not recognized. Torsades de pointes (TdP) ±2° atrioventricular block (AVB) are not always attributed to LQTS, although the most common LQTS rhythm, a fetal heart rate of less than third percentile for gestational age (GA), is not recognized as abnormal because it does not meet the standard obstetrical criteria for bradycardia. Early recognition and appropriate treatment can be life saving for the fetus and unsuspecting LQTS family members. Fetal rhythm phenotype and postnatal QTc can predict postnatal rhythm and suggest genotype: bradycardic fetuses usually have KCNQ1 mutation, while those with TdP and/or a postnatal QTc more than 500 ms have SCN5A, KCNH2 or uncharacterized mutations. SUMMARY The fetus with repeated heart rates of less than third percentile of GA and those with TdP ±2° AVB are likely to manifest the same rhythm after birth and have an LQTS mutation.
Collapse
|
220
|
Marshall CB, Nishikawa T, Osawa M, Stathopulos PB, Ikura M. Calmodulin and STIM proteins: Two major calcium sensors in the cytoplasm and endoplasmic reticulum. Biochem Biophys Res Commun 2015; 460:5-21. [PMID: 25998729 DOI: 10.1016/j.bbrc.2015.01.106] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 01/22/2015] [Indexed: 01/22/2023]
Abstract
The calcium (Ca(2+)) ion is a universal signalling messenger which plays vital physiological roles in all eukaryotes. To decode highly regulated intracellular Ca(2+) signals, cells have evolved a number of sensor proteins that are ideally adapted to respond to a specific range of Ca(2+) levels. Among many such proteins, calmodulin (CaM) is a multi-functional cytoplasmic Ca(2+) sensor with a remarkable ability to interact with and regulate a plethora of structurally diverse target proteins. CaM achieves this 'multi-talented' functionality through two EF-hand domains, each with an independent capacity to bind targets, and an adaptable flexible linker. By contrast, stromal interaction molecule-1 and -2 (STIMs) have evolved for a specific role in endoplasmic reticulum (ER) Ca(2+) sensing using EF-hand machinery analogous to CaM; however, whereas CaM structurally adjusts to dissimilar binding partners, STIMs use the EF-hand machinery to self-regulate the stability of the Ca(2+) sensing domain. The molecular mechanisms underlying the Ca(2+)-dependent signal transduction by CaM and STIMs have revealed a remarkable repertoire of actions and underscore the flexibility of nature in molecular evolution and adaption to discrete Ca(2+) levels. Recent genomic sequencing efforts have uncovered a number of disease-associated mutations in both CaM and STIM1. This article aims to highlight the most recent key structural and functional findings in the CaM and STIM fields, and discusses how these two Ca(2+) sensor proteins execute their biological functions.
Collapse
Affiliation(s)
- Christopher B Marshall
- Princess Margaret Cancer Centre, University Health Network and University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | - Tadateru Nishikawa
- Princess Margaret Cancer Centre, University Health Network and University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Tokyo, 113-0033, Japan
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada.
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Centre, University Health Network and University of Toronto, Toronto, Ontario, M5G 1L7, Canada.
| |
Collapse
|
221
|
Dick IE, Limpitikul WB, Niu J, Banerjee R, Issa JB, Ben-Johny M, Adams PJ, Kang PW, Lee SR, Sang L, Yang W, Babich J, Zhang M, Bazazzi H, Yue NC, Tomaselli GF. A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory. Channels (Austin) 2015; 10:20-32. [PMID: 26176690 DOI: 10.1080/19336950.2015.1051272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca(2+) signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.
Collapse
Affiliation(s)
- Ivy E Dick
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Worawan B Limpitikul
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jacqueline Niu
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Rahul Banerjee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - John B Issa
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manu Ben-Johny
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Paul J Adams
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,b Kwantlen Polytechnic University ; Surrey , BC Canada
| | - Po Wei Kang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Shin Rong Lee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Lingjie Sang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Wanjun Yang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jennifer Babich
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manning Zhang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Hojjat Bazazzi
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Nancy C Yue
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Gordon F Tomaselli
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,c Division of Cardiology; Department of Medicine ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| |
Collapse
|
222
|
Distinctive malfunctions of calmodulin mutations associated with heart RyR2-mediated arrhythmic disease. Biochim Biophys Acta Gen Subj 2015; 1850:2168-76. [PMID: 26164367 DOI: 10.1016/j.bbagen.2015.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/22/2015] [Accepted: 07/02/2015] [Indexed: 01/11/2023]
Abstract
Calmodulin (CaM) is a cytoplasmic calcium sensor that interacts with the cardiac ryanodine receptor (RyR2), a large Ca(2+) channel complex that mediates Ca(2+) efflux from the sarcoplasmic reticulum (SR) to activate cardiac muscle contraction. Direct CaM association with RyR2 is an important physiological regulator of cardiac muscle excitation-contraction coupling and defective CaM-RyR2 protein interaction has been reported in cases of heart failure. Recent genetic studies have identified CaM missense mutations in patients with a history of severe cardiac arrhythmogenic disorders that present divergent clinical features, including catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS) and idiopathic ventricular fibrillation (IVF). Herein, we describe how two CPVT- (N54I & N98S) and three LQTS-associated (D96V, D130G & F142L) CaM mutations result in alteration of their biochemical and biophysical properties. Ca(2+)-binding studies indicate that the CPVT-associated CaM mutations, N54I & N98S, exhibit the same or a 3-fold reduced Ca(2+)-binding affinity, respectively, versus wild-type CaM, whereas the LQTS-associated CaM mutants, D96V, D130G & F142L, display more profoundly reduced Ca(2+)-binding affinity. In contrast, all five CaM mutations confer a disparate RyR2 interaction and modulation of [(3)H]ryanodine binding to RyR2, regardless of CPVT or LQTS association. Our findings suggest that the clinical presentation of CPVT or LQTS associated with these five CaM mutations may involve both altered intrinsic Ca(2+)-binding as well as defective interaction with RyR2.
Collapse
|
223
|
Abstract
Ca2+-dependent inactivation (CDI) is a negative feedback regulation of voltage-gated Cav1 and Cav2 channels that is mediated by the Ca2+ sensing protein, calmodulin (CaM), binding to the pore-forming Cav α1 subunit. David Yue and his colleagues made seminal contributions to our understanding of this process, as well as factors that regulate CDI. Important in this regard are members of a family of Ca2+ binding proteins (CaBPs) that are related to calmodulin. CaBPs are expressed mainly in neural tissues and can antagonize CaM-dependent CDI for Cav1 L-type channels. This review will focus on the roles of CaBPs as Cav1-interacting proteins, and the significance of these interactions for vision, hearing, and neuronal Ca2+ signaling events.
Collapse
Affiliation(s)
- Jason Hardie
- a Departments of Molecular Physiology and Biophysics ; Otolaryngology-Head and Neck Surgery and Neurology; University of Iowa ; Iowa City , IA USA
| | - Amy Lee
- a Departments of Molecular Physiology and Biophysics ; Otolaryngology-Head and Neck Surgery and Neurology; University of Iowa ; Iowa City , IA USA
| |
Collapse
|
224
|
Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
Collapse
Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
| |
Collapse
|
225
|
Nakano Y, Shimizu W. Genetics of long-QT syndrome. J Hum Genet 2015; 61:51-5. [PMID: 26108145 DOI: 10.1038/jhg.2015.74] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/31/2015] [Accepted: 05/31/2015] [Indexed: 11/09/2022]
Abstract
Congenital long QT syndrome (LQTS) is an inherited arrhythmia syndrome characterized by a prolonged QT interval in the 12-lead ECG, torsades de pointes and not negligible prevalence of sudden cardiac death. The genetic testing plays an important role in the diagnosis of LQTS. A total of 15 genes have been reported for autosomal-dominant forms of Romano-Ward-type congenital LQTS and 2 genes for autosomal-recessive forms of the Jervell and Lange-Nielsen syndrome. In this review, we summarize the recent advances in genetics of LQTS and briefly describe forward perspectives of LQTS investigation.
Collapse
Affiliation(s)
- Yukiko Nakano
- Programs for Biomedical Research Graduate School of Biomedical Science, Division of Frontier Medical Science, Department of Cardiovascular Medicine, Hiroshima University, Hiroshima, Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| |
Collapse
|
226
|
FENG RUI, LIU YAN, SUN XUEFEI, WANG YAN, HU HUIYUAN, GUO FENG, ZHAO JINSHENG, HAO LIYING. Molecular cloning and expression of the calmodulin gene from guinea pig hearts. Exp Ther Med 2015; 9:2311-2318. [DOI: 10.3892/etm.2015.2411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 03/19/2015] [Indexed: 11/06/2022] Open
|
227
|
Huang TQ, Zou MX, Pasek DA, Meissner G. mTOR signaling in mice with dysfunctional cardiac ryanodine receptor ion channel. ACTA ACUST UNITED AC 2015; 8:43-51. [PMID: 26312014 PMCID: PMC4547478 DOI: 10.2147/jrlcr.s78410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Simultaneous substitution of three amino acid residues in the calmodulin binding domain (W3587A/L3591D/F3603A, ADA) of the cardiac ryanodine receptor ion channel (RyR2) impairs calmodulin inhibition of RyR2 and causes cardiac hypertrophy and early death of Ryr2ADA/ADA mice. To determine the physiological significance of growth promoting signaling molecules, the protein and phosphorylation levels of Ser/Thr kinase mTOR and upstream and downstream signaling molecules were determined in hearts of wild-type and Ryr2ADA/ADA mice. Phosphorylation of mTOR at Ser-2448, and mTOR downstream targets p70S6 kinase at Thr-389, S6 ribosomal protein at Ser-240/244, and 4E-BP1 at Ser-65 were increased. However, there was no increased phosphorylation of mTOR upstream kinases PDK1 at Ser-241, AKT at Thr-308, AMPK at Thr-172, and ERK1/2 at Thr-202/Tyr204. To confirm a role for mTOR signaling in the development of cardiac hypertrophy, rapamycin, an inhibitor of mTOR, was injected into wild-type and mutant mice. Rapamycin decreased mouse heart-to-body weight ratio, improved cardiac performance, and decreased phosphorylation of mTOR and downstream targets p70S6K and S6 in 10-day-old Ryr2ADA/ADA mice but did not extend longevity. Taken together, the results link a dysfunctional RyR2 to an altered activity of signaling molecules that regulate cardiac growth and function.
Collapse
Affiliation(s)
- Tai-Qin Huang
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Min-Xu Zou
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Daniel A Pasek
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| |
Collapse
|
228
|
Nakajima T, Kaneko Y, Kurabayashi M. Unveiling specific triggers and precipitating factors for fatal cardiac events in inherited arrhythmia syndromes. Circ J 2015; 79:1185-92. [PMID: 25925977 DOI: 10.1253/circj.cj-15-0322] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Patients with inherited arrhythmia syndromes, such as long QT syndrome, Brugada syndrome, early repolarization syndrome, catecholaminergic polymorphic ventricular tachycardia, and their latent forms, are at risk for fatal arrhythmias. These diseases are typically associated with genetic mutations that perturb cardiac ionic currents. The analysis of cardiac events by genotype-phenotype correlation studies has revealed that fatal arrhythmias in some genotypes are triggered by physical or emotional stress, and those in the others are more likely to occur during sleep or at rest. Thus, the risk stratification and management of affected patients differ strikingly according to the genetic variant of the inherited arrhythmia syndrome. Risk stratification may be further refined by considering the precipitating factors, such as drugs, bradycardia, electrolyte disturbances, fever, and cardiac memory. Moreover, an increasing number of studies imply that the susceptibility of fatal arrhythmias in patients with acute coronary syndrome or takotsubo cardiomyopathy is at least partly ascribed to the genetic variants causing inherited arrhythmia syndromes. In this article, we review the recent advances in the understanding of the molecular genetics and genotype-phenotype correlations in inherited arrhythmia syndromes and consider the triggers and precipitating factors for fatal arrhythmias in these disorders. Further studies to explore the triggers and precipitating factors specific to the genotypes and diseases are needed for better clinical management.
Collapse
Affiliation(s)
- Tadashi Nakajima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | | | | |
Collapse
|
229
|
Altmann HM, Tester DJ, Will ML, Middha S, Evans JM, Eckloff BW, Ackerman MJ. Homozygous/Compound Heterozygous Triadin Mutations Associated With Autosomal-Recessive Long-QT Syndrome and Pediatric Sudden Cardiac Arrest: Elucidation of the Triadin Knockout Syndrome. Circulation 2015; 131:2051-60. [PMID: 25922419 DOI: 10.1161/circulationaha.115.015397] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/17/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Long-QT syndrome (LQTS) may result in syncope, seizures, or sudden cardiac arrest. Although 16 LQTS-susceptibility genes have been discovered, 20% to 25% of LQTS remains genetically elusive. METHODS AND RESULTS We performed whole-exome sequencing child-parent trio analysis followed by recessive and sporadic inheritance modeling and disease-network candidate analysis gene ranking to identify a novel underlying genetic mechanism for LQTS. Subsequent mutational analysis of the candidate gene was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing on a cohort of 33 additional unrelated patients with genetically elusive LQTS. After whole-exome sequencing and variant filtration, a homozygous p.D18fs*13 TRDN-encoded triadin frameshift mutation was discovered in a 10-year-old female patient with LQTS with a QTc of 500 milliseconds who experienced recurrent exertion-induced syncope/cardiac arrest beginning at 1 year of age. Subsequent mutational analysis of TRDN revealed either homozygous or compound heterozygous frameshift mutations in 4 of 33 unrelated cases of LQTS (12%). All 5 TRDN-null patients displayed extensive T-wave inversions in precordial leads V1 through V4, with either persistent or transient QT prolongation and severe disease expression of exercise-induced cardiac arrest in early childhood (≤3 years of age) and required aggressive therapy. The overall yield of TRDN mutations was significantly greater in patients ≤10 years of age (5 of 10, 50%) compared with older patients (0 of 24, 0%; P=0.0009). CONCLUSIONS We identified TRDN as a novel underlying genetic basis for recessively inherited LQTS. All TRDN-null patients had strikingly similar phenotypes. Given the recurrent nature of potential lethal arrhythmias, patients fitting this phenotypic profile should undergo cardiac TRDN genetic testing.
Collapse
Affiliation(s)
- Helene M Altmann
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - David J Tester
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - Melissa L Will
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - Sumit Middha
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - Jared M Evans
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - Bruce W Eckloff
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.)
| | - Michael J Ackerman
- From Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (H.M.A., D.J.T., M.L.W., M.J.A.), Department of Medicine/Division of Cardiovascular Diseases (D.J.T., M.L.W., M.J.A.), Medical Genome Facility (B.W.E.), and Department of Pediatrics/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN; and Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo College of Medicine, Rochester, MN (S.M., J.M.E.).
| |
Collapse
|
230
|
Stateva SR, Salas V, Benaim G, Menéndez M, Solís D, Villalobo A. Characterization of phospho-(tyrosine)-mimetic calmodulin mutants. PLoS One 2015; 10:e0120798. [PMID: 25830911 PMCID: PMC4382182 DOI: 10.1371/journal.pone.0120798] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/06/2015] [Indexed: 11/18/2022] Open
Abstract
Calmodulin (CaM) phosphorylated at different serine/threonine and tyrosine residues is known to exert differential regulatory effects on a variety of CaM-binding enzymes as compared to non-phosphorylated CaM. In this report we describe the preparation and characterization of a series of phospho-(Y)-mimetic CaM mutants in which either one or the two tyrosine residues present in CaM (Y99 and Y138) were substituted to aspartic acid or glutamic acid. It was expected that the negative charge of the respective carboxyl group of these amino acids mimics the negative charge of phosphate and reproduce the effects that distinct phospho-(Y)-CaM species may have on target proteins. We describe some physicochemical properties of these CaM mutants as compared to wild type CaM, after their expression in Escherichia coli and purification to homogeneity, including: i) changes in their electrophoretic mobility in the absence and presence of Ca2+; ii) ultraviolet (UV) light absorption spectra, far- and near-UV circular dichroism data; iii) thermal stability in the absence and presence of Ca2+; and iv) Tb3+-emitted fluorescence upon tyrosine excitation. We also describe some biochemical properties of these CaM mutants, such as their differential phosphorylation by the tyrosine kinase c-Src, and their action as compared to wild type CaM, on the activity of two CaM-dependent enzymes: cyclic nucleotide phosphodiesterase 1 (PDE1) and endothelial nitric oxide synthase (eNOS) assayed in vitro.
Collapse
Affiliation(s)
- Silviya R. Stateva
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Valentina Salas
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
- Universidad Central de Venezuela, Facultad de Ciencias, Instituto de Biología Experimental, Caracas, Venezuela
| | - Gustavo Benaim
- Universidad Central de Venezuela, Facultad de Ciencias, Instituto de Biología Experimental, Caracas, Venezuela
- Instituto de Estudios Avanzados (IDEA), Caracas, Venezuela
| | - Margarita Menéndez
- Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Dolores Solís
- Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Antonio Villalobo
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
- * E-mail:
| |
Collapse
|
231
|
Narula N, Tester DJ, Paulmichl A, Maleszewski JJ, Ackerman MJ. Post-mortem Whole exome sequencing with gene-specific analysis for autopsy-negative sudden unexplained death in the young: a case series. Pediatr Cardiol 2015; 36:768-78. [PMID: 25500949 PMCID: PMC4907366 DOI: 10.1007/s00246-014-1082-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/05/2014] [Indexed: 02/02/2023]
Abstract
Annually, thousands of sudden deaths in individuals under 35 years remain unexplained following comprehensive medico-legal autopsy. Previously, post-mortem genetic analysis by Sanger sequencing of four major cardiac channelopathy genes revealed that approximately one-fourth of these autopsy-negative sudden unexplained death in the young (SUDY) cases harbored an underlying mutation. However, there are now over 100 sudden death-predisposing cardiac channelopathy-, cardiomyopathy-, and metabolic disorder-susceptibility genes. Here, we set out to determine whether post-mortem whole exome sequencing (WES) is an efficient strategy to detect ultra-rare, potentially pathogenic variants. We performed post-mortem WES and gene-specific analysis of 117 sudden death-susceptibility genes for 14 consecutively referred Caucasian SUDY victims (average age at death 17.4 ± 8.6 years) to identify putative SUDY-associated mutations. On average, each SUDY case had 12,758 ± 2,016 non-synonymous variants, of which 79 ± 15 localized to these 117 genes. Overall, eight ultra-rare variants (seven missense, one in-frame insertion) absent in three publically available exome databases were identified in six genes (three in TTN, and one each in CACNA1C, JPH2, MYH7, VCL, RYR2) in seven of 14 cases (50 %). Of the seven missense alterations, two (T171M-CACNA1C, I22160T-TTN) were predicted damaging by three independent in silico tools. Although WES and gene-specific surveillance is an efficient means to detect rare genetic variants that might underlie the pathogenic cause of death, accurate interpretation of each variant is challenging. Great restraint and caution must be exercised otherwise families may be informed prematurely and incorrectly that the root cause has been found.
Collapse
Affiliation(s)
- Nupoor Narula
- Department of Internal Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - David J. Tester
- Department of Internal Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN,Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Anna Paulmichl
- Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Joseph J. Maleszewski
- Department of Internal Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN,Department of Laboratory Medicine and Pathology, Divisions of Anatomic Pathology and Molecular Genetics
| | - Michael J. Ackerman
- Department of Internal Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN,Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.,Department of Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, MN,Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| |
Collapse
|
232
|
McNally EM, George AL. New approaches to establish genetic causality. Trends Cardiovasc Med 2015; 25:646-52. [PMID: 25864169 DOI: 10.1016/j.tcm.2015.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 01/06/2023]
Abstract
Cardiovascular medicine has evolved rapidly in the era of genomics with many diseases having primary genetic origins becoming the subject of intense investigation. The resulting avalanche of information on the molecular causes of these disorders has prompted a revolution in our understanding of disease mechanisms and provided new avenues for diagnoses. At the heart of this revolution is the need to correctly classify genetic variants discovered during the course of research or reported from clinical genetic testing. This review will address current concepts related to establishing the cause and effect relationship between genomic variants and heart diseases. A survey of general approaches used for functional annotation of variants will also be presented.
Collapse
Affiliation(s)
- Elizabeth M McNally
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL; Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL.
| |
Collapse
|
233
|
Abstract
Long QT syndrome (LQTS) is a potentially life-threatening cardiac arrhythmia characterized by delayed myocardial repolarization that produces QT prolongation and increased risk for torsades des pointes (TdP)-triggered syncope, seizures, and sudden cardiac death (SCD) in an otherwise healthy young individual with a structurally normal heart. Currently, there are three major LQTS genes (KCNQ1, KCNH2, and SCN5A) that account for approximately 75% of the disorder. For the major LQTS genotypes, genotype-phenotype correlations have yielded gene-specific arrhythmogenic triggers, electrocardiogram (ECG) patterns, response to therapies, and intragenic and increasingly mutation-specific risk stratification. The 10 minor LQTS-susceptibility genes collectively account for less than 5% of LQTS cases. In addition, three atypical LQTS or multisystem syndromic disorders that have been associated with QT prolongation have been described, including ankyrin-B syndrome, Anderson-Tawil syndrome (ATS), and Timothy syndrome (TS). Genetic testing for LQTS is recommended in patients with either a strong clinical index of suspicion or persistent QT prolongation despite their asymptomatic state. However, genetic test results must be interpreted carefully.
Collapse
|
234
|
Friedrich C, Rinné S, Zumhagen S, Kiper AK, Silbernagel N, Netter MF, Stallmeyer B, Schulze-Bahr E, Decher N. Gain-of-function mutation in TASK-4 channels and severe cardiac conduction disorder. EMBO Mol Med 2015; 6:937-51. [PMID: 24972929 PMCID: PMC4119356 DOI: 10.15252/emmm.201303783] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Analyzing a patient with progressive and severe cardiac conduction disorder combined with idiopathic ventricular fibrillation (IVF), we identified a splice site mutation in the sodium channel gene SCN5A. Due to the severe phenotype, we performed whole-exome sequencing (WES) and identified an additional mutation in the KCNK17 gene encoding the K2P potassium channel TASK-4. The heterozygous change (c.262G>A) resulted in the p.Gly88Arg mutation in the first extracellular pore loop. Mutant TASK-4 channels generated threefold increased currents, while surface expression was unchanged, indicating enhanced conductivity. When co-expressed with wild-type channels, the gain-of-function by G88R was conferred in a dominant-active manner. We demonstrate that KCNK17 is strongly expressed in human Purkinje cells and that overexpression of G88R leads to a hyperpolarization and strong slowing of the upstroke velocity of spontaneously beating HL-1 cells. Thus, we propose that a gain-of-function by TASK-4 in the conduction system might aggravate slowed conductivity by the loss of sodium channel function. Moreover, WES supports a second hit-hypothesis in severe arrhythmia cases and identified KCNK17 as a novel arrhythmia gene.
Collapse
Affiliation(s)
- Corinna Friedrich
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Nicole Silbernagel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Michael F Netter
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| |
Collapse
|
235
|
Mesirca P, Torrente AG, Mangoni ME. Functional role of voltage gated Ca(2+) channels in heart automaticity. Front Physiol 2015; 6:19. [PMID: 25698974 PMCID: PMC4313592 DOI: 10.3389/fphys.2015.00019] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/12/2015] [Indexed: 01/08/2023] Open
Abstract
Pacemaker activity of automatic cardiac myocytes controls the heartbeat in everyday life. Cardiac automaticity is under the control of several neurotransmitters and hormones and is constantly regulated by the autonomic nervous system to match the physiological needs of the organism. Several classes of ion channels and proteins involved in intracellular Ca(2+) dynamics contribute to pacemaker activity. The functional role of voltage-gated calcium channels (VGCCs) in heart automaticity and impulse conduction has been matter of debate for 30 years. However, growing evidence shows that VGCCs are important regulators of the pacemaker mechanisms and play also a major role in atrio-ventricular impulse conduction. Incidentally, studies performed in genetically modified mice lacking L-type Cav1.3 (Cav1.3(-/-)) or T-type Cav3.1 (Cav3.1(-/-)) channels show that genetic inactivation of these channels strongly impacts pacemaking. In cardiac pacemaker cells, VGCCs activate at negative voltages at the beginning of the diastolic depolarization and importantly contribute to this phase by supplying inward current. Loss-of-function of these channels also impairs atrio-ventricular conduction. Furthermore, inactivation of Cav1.3 channels promotes also atrial fibrillation and flutter in knockout mice suggesting that these channels can play a role in stabilizing atrial rhythm. Genomic analysis demonstrated that Cav1.3 and Cav3.1 channels are widely expressed in pacemaker tissue of mice, rabbits and humans. Importantly, human diseases of pacemaker activity such as congenital bradycardia and heart block have been attributed to loss-of-function of Cav1.3 and Cav3.1 channels. In this article, we will review the current knowledge on the role of VGCCs in the generation and regulation of heart rate and rhythm. We will discuss also how loss of Ca(2+) entry through VGCCs could influence intracellular Ca(2+) handling and promote atrial arrhythmias.
Collapse
Affiliation(s)
- Pietro Mesirca
- Laboratory of Excellence in Ion Channel Science and Therapeutics, Département de Physiologie, Institut de Génomique Fonctionnelle Montpellier, France ; UMR-5203, Centre National de la Recherche Scientifique, Universités de Montpellier 1 and 2 Montpellier, France ; INSERM U 1191, Département de Physiologie, Universités de Montpellier 1 and 2 Montpellier, France
| | - Angelo G Torrente
- Laboratory of Excellence in Ion Channel Science and Therapeutics, Département de Physiologie, Institut de Génomique Fonctionnelle Montpellier, France ; UMR-5203, Centre National de la Recherche Scientifique, Universités de Montpellier 1 and 2 Montpellier, France ; INSERM U 1191, Département de Physiologie, Universités de Montpellier 1 and 2 Montpellier, France
| | - Matteo E Mangoni
- Laboratory of Excellence in Ion Channel Science and Therapeutics, Département de Physiologie, Institut de Génomique Fonctionnelle Montpellier, France ; UMR-5203, Centre National de la Recherche Scientifique, Universités de Montpellier 1 and 2 Montpellier, France ; INSERM U 1191, Département de Physiologie, Universités de Montpellier 1 and 2 Montpellier, France
| |
Collapse
|
236
|
Søndergaard MT, Sorensen AB, Skov LL, Kjaer-Sorensen K, Bauer MC, Nyegaard M, Linse S, Oxvig C, Overgaard MT. Calmodulin mutations causing catecholaminergic polymorphic ventricular tachycardia confer opposing functional and biophysical molecular changes. FEBS J 2015; 282:803-16. [PMID: 25557436 DOI: 10.1111/febs.13184] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/11/2014] [Accepted: 12/19/2014] [Indexed: 01/27/2023]
Abstract
Calmodulin (CaM) is the central mediator of intracellular Ca(2+) signalling in cardiomyocytes, where it conveys the intricate Ca(2+) transients to the proteins controlling cardiac contraction. We recently linked two separate mutations in CaM (N53I and N97S) to dominantly inherited catecholaminergic polymorphic ventricular tachycardia (CPVT), an arrhythmic disorder in which exercise or acute emotion can lead to syncope and sudden cardiac death. Given the ubiquitous presence of CaM in all eukaryote cells, it is particular intriguing that carriers of either mutation show no additional symptoms. Here, we investigated the effects of the CaM CPVT mutations in a zebrafish animal model. Three-day-old embryos injected with either CaM mRNA showed no detectable pathologies or developmental abnormalities. However, embryos injected with CPVT CaM mRNA displayed increased heart rate compared to wild-type CaM mRNA under β-adrenergic stimulation, demonstrating a conserved dominant cardiac specific effect between zebrafish and human carriers of these mutations. Motivated by the highly similar physiological phenotypes, we compared the effects of the N53I and N97S mutations on the biophysical and functional properties of CaM. Surprisingly, the mutations have opposing effects on CaM C-lobe Ca(2+) binding affinity and kinetics, and changes to the CaM N-lobe Ca(2+) binding are minor and specific to the N53I mutation. Furthermore, both mutations induce differential perturbations to structure and stability towards unfolding. Our results suggest different molecular disease mechanisms for the CPVT (N53I and N97S mutations) and strongly support that cardiac contraction is the physiological process most sensitive to CaM integrity.
Collapse
|
237
|
Astegno A, Maresi E, Marino V, Dominici P, Pedroni M, Piccinelli F, Dell'Orco D. Structural plasticity of calmodulin on the surface of CaF2 nanoparticles preserves its biological function. NANOSCALE 2014; 6:15037-47. [PMID: 25367003 DOI: 10.1039/c4nr04368e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanoparticles are increasingly used in biomedical applications and are especially attractive as biocompatible and biodegradable protein delivery systems. Herein, the interaction between biocompatible 25 nm CaF2 nanoparticles and the ubiquitous calcium sensor calmodulin has been investigated in order to assess the potential of these particles to serve as suitable surface protein carriers. Calmodulin is a multifunctional messenger protein that activates a wide variety of signaling pathways in eukaryotic cells by changing its conformation in a calcium-dependent manner. Isothermal titration calorimetry and circular dichroism studies have shown that the interaction between calmodulin and CaF2 nanoparticles occurs with physiologically relevant affinity and that the binding process is fully reversible, occurring without significant alterations in protein secondary and tertiary structures. Experiments performed with a mutant form of calmodulin having an impaired Ca(2+)-binding ability in the C-terminal lobe suggest that the EF-hand Ca(2+)-binding motifs are directly involved in the binding of calmodulin to the CaF2 matrix. The residual capability of nanoparticle-bound calmodulin to function as a calcium sensor protein, binding to and altering the activity of a target protein, was successfully probed by biochemical assays. Even if efficiently carried by CaF2 nanoparticles, calmodulin may dissociate, thus retaining the ability to bind the peptide encompassing the putative C-terminal calmodulin-binding domain of glutamate decarboxylase and activate the enzyme. We conclude that the high flexibility and structural plasticity of calmodulin are responsible for the preservation of its function when bound in high amounts to a nanoparticle surface.
Collapse
|
238
|
Abstract
PURPOSE OF REVIEW The review is designed to outline the major developments in genetic testing in the cardiovascular arena in the past year or so. This is an exciting time in genetic testing as whole exome and whole genome approaches finally reach the clinic. These new approaches offer insight into disease causation in families in which this might previously have been inaccessible, and also bring a wide range of interpretative challenges. RECENT FINDINGS Among the most significant recent findings has been the extent of physiologic rare coding variation in the human genome. New disease genes have been identified through whole exome studies in neonatal arrhythmia, congenital heart disease and coronary artery disease that were simply inaccessible with other techniques. This has not only shed light on the challenges of genetic testing at this scale, but has also sharply defined the limits of prior gene-panel focused testing. As novel therapies targeting specific genetic subsets of disease become available, genetic testing will become a part of routine clinical care. SUMMARY The pace of change in sequencing technologies has begun to transform clinical medicine, and cardiovascular disease is no exception. The complexity of such studies emphasizes the importance of real-time communication between the genetics laboratory and genetically informed clinicians. New efforts in data and knowledge management will be central to the continued advancement of genetic testing.
Collapse
|
239
|
Abstract
Sodium current in the heart flows principally through the pore protein NaV1.5, which is part of a complex of interacting proteins that serve both to target and localize the complex in the membrane, and to modulate function by such post-translational modifications as phosphorylation and nitrosylation. Multiple mutations in seven different NaV1.5 interacting proteins have been associated with dysfunctional sodium current and inherited cardiac diseases, including long QT syndrome, Brugada syndrome, atrial fibrillation, and cardiomyopathy, as well as sudden infant death syndrome (SIDS). Mutations in as yet unidentified interacting proteins may account for cardiac disease for which a genetic basis has not yet been established. Characterizing the mechanisms by which these mutations cause disease may give insight into etiologies and treatments of more common acquired cardiac disease, such as ischemia and heart failure.
Collapse
Affiliation(s)
- John W Kyle
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Jonathan C Makielski
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| |
Collapse
|
240
|
Recessive cardiac phenotypes in induced pluripotent stem cell models of Jervell and Lange-Nielsen syndrome: disease mechanisms and pharmacological rescue. Proc Natl Acad Sci U S A 2014; 111:E5383-92. [PMID: 25453094 DOI: 10.1073/pnas.1419553111] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Jervell and Lange-Nielsen syndrome (JLNS) is one of the most severe life-threatening cardiac arrhythmias. Patients display delayed cardiac repolarization, associated high risk of sudden death due to ventricular tachycardia, and congenital bilateral deafness. In contrast to the autosomal dominant forms of long QT syndrome, JLNS is a recessive trait, resulting from homozygous (or compound heterozygous) mutations in KCNQ1 or KCNE1. These genes encode the α and β subunits, respectively, of the ion channel conducting the slow component of the delayed rectifier K(+) current, IKs. We used complementary approaches, reprogramming patient cells and genetic engineering, to generate human induced pluripotent stem cell (hiPSC) models of JLNS, covering splice site (c.478-2A>T) and missense (c.1781G>A) mutations, the two major classes of JLNS-causing defects in KCNQ1. Electrophysiological comparison of hiPSC-derived cardiomyocytes (CMs) from homozygous JLNS, heterozygous, and wild-type lines recapitulated the typical and severe features of JLNS, including pronounced action and field potential prolongation and severe reduction or absence of IKs. We show that this phenotype had distinct underlying molecular mechanisms in the two sets of cell lines: the previously unidentified c.478-2A>T mutation was amorphic and gave rise to a strictly recessive phenotype in JLNS-CMs, whereas the missense c.1781G>A lesion caused a gene dosage-dependent channel reduction at the cell membrane. Moreover, adrenergic stimulation caused action potential prolongation specifically in JLNS-CMs. Furthermore, sensitivity to proarrhythmic drugs was strongly enhanced in JLNS-CMs but could be pharmacologically corrected. Our data provide mechanistic insight into distinct classes of JLNS-causing mutations and demonstrate the potential of hiPSC-CMs in drug evaluation.
Collapse
|
241
|
Ben-Johny M, Yue DT. Calmodulin regulation (calmodulation) of voltage-gated calcium channels. ACTA ACUST UNITED AC 2014; 143:679-92. [PMID: 24863929 PMCID: PMC4035741 DOI: 10.1085/jgp.201311153] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calmodulin regulation (calmodulation) of the family of voltage-gated CaV1-2 channels comprises a prominent prototype for ion channel regulation, remarkable for its powerful Ca(2+) sensing capabilities, deep in elegant mechanistic lessons, and rich in biological and therapeutic implications. This field thereby resides squarely at the epicenter of Ca(2+) signaling biology, ion channel biophysics, and therapeutic advance. This review summarizes the historical development of ideas in this field, the scope and richly patterned organization of Ca(2+) feedback behaviors encompassed by this system, and the long-standing challenges and recent developments in discerning a molecular basis for calmodulation. We conclude by highlighting the considerable synergy between mechanism, biological insight, and promising therapeutics.
Collapse
Affiliation(s)
- Manu Ben-Johny
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| |
Collapse
|
242
|
Affiliation(s)
- Alfred L George
- Department of Pharmacology and Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
| |
Collapse
|
243
|
Reed GJ, Boczek NJ, Etheridge SP, Ackerman MJ. CALM3 mutation associated with long QT syndrome. Heart Rhythm 2014; 12:419-22. [PMID: 25460178 DOI: 10.1016/j.hrthm.2014.10.035] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 11/25/2022]
Affiliation(s)
- Griffin J Reed
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory
| | - Nicole J Boczek
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory; Center for Clinical and Translational Science; Mayo Graduate School, Mayo Clinic, Rochester, Minnesota
| | | | - Michael J Ackerman
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory; Division of Cardiovascular Diseases, Department of Medicine; Division of Pediatric Cardiology, Department of Pediatrics, Mayo Clinic, Rochester, Minnesota.
| |
Collapse
|
244
|
Valdés-Mas R, Gutiérrez-Fernández A, Gómez J, Coto E, Astudillo A, Puente DA, Reguero JR, Álvarez V, Morís C, León D, Martín M, Puente XS, López-Otín C. Mutations in filamin C cause a new form of familial hypertrophic cardiomyopathy. Nat Commun 2014; 5:5326. [PMID: 25351925 DOI: 10.1038/ncomms6326] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 09/19/2014] [Indexed: 01/21/2023] Open
Abstract
Mutations in different genes encoding sarcomeric proteins are responsible for 50-60% of familial cases of hypertrophic cardiomyopathy (HCM); however, the genetic alterations causing the disease in one-third of patients are currently unknown. Here we describe a case with familial HCM of unknown cause. Whole-exome sequencing reveals a variant in the gene encoding the sarcomeric protein filamin C (p.A1539T) that segregates with the disease in this family. Sequencing of 92 HCM cases identifies seven additional variants segregating with the disease in eight families. Patients with FLNC mutations show marked sarcomeric abnormalities in cardiac muscle, and functional analysis reveals that expression of these FLNC variants resulted in the formation of large filamin C aggregates. Clinical studies indicate that FLNC-mutated patients have higher incidence of sudden cardiac death. On the basis of these findings, we conclude that mutations in the gene encoding the sarcomeric protein filamin C cause a new form of familial HMC.
Collapse
Affiliation(s)
- Rafael Valdés-Mas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Ana Gutiérrez-Fernández
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Juan Gómez
- Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain
| | - Eliecer Coto
- 1] Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain [2] Departamento de Medicina, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Aurora Astudillo
- Servicio de Anatomía Patológica, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Diana A Puente
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Julián R Reguero
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Victoria Álvarez
- Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain
| | - César Morís
- 1] Departamento de Medicina, Universidad de Oviedo, 33006 Oviedo, Spain [2] Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Diego León
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - María Martín
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Xose S Puente
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Carlos López-Otín
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| |
Collapse
|
245
|
Kim EE, Shekhar A, Lu J, Lin X, Liu FY, Zhang J, Delmar M, Fishman GI. PCP4 regulates Purkinje cell excitability and cardiac rhythmicity. J Clin Invest 2014; 124:5027-36. [PMID: 25295538 DOI: 10.1172/jci77495] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/04/2014] [Indexed: 11/17/2022] Open
Abstract
Cardiac Purkinje cells are important triggers of ventricular arrhythmias associated with heritable and acquired syndromes; however, the mechanisms responsible for this proarrhythmic behavior are incompletely understood. Here, through transcriptional profiling of genetically labeled cardiomyocytes, we identified expression of Purkinje cell protein-4 (Pcp4), a putative regulator of calmodulin and Ca2+/calmodulin-dependent kinase II (CaMKII) signaling, exclusively within the His-Purkinje network. Using Pcp4-null mice and acquired cardiomyopathy models, we determined that reduced expression of PCP4 is associated with CaMKII activation, abnormal electrophysiology, dysregulated intracellular calcium handling, and proarrhythmic behavior in isolated Purkinje cells. Pcp4-null mice also displayed profound autonomic dysregulation and arrhythmic behavior in vivo. Together, these results demonstrate that PCP4 regulates cardiac excitability through both Purkinje cell-autonomous and central mechanisms and identify this modulator of CaMKII signaling as a potential arrhythmia-susceptibility candidate.
Collapse
|
246
|
Structural analyses of Ca²⁺/CaM interaction with NaV channel C-termini reveal mechanisms of calcium-dependent regulation. Nat Commun 2014; 5:4896. [PMID: 25232683 PMCID: PMC4170523 DOI: 10.1038/ncomms5896] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 08/01/2014] [Indexed: 12/15/2022] Open
Abstract
Ca2+ regulates voltage-gated Na+ (NaV) channels and perturbed Ca2+ regulation of NaV function is associated with epilepsy syndromes, autism, and cardiac arrhythmias. Understanding the disease mechanisms, however, has been hindered by a lack of structural information and competing models for how Ca2+ affects NaV channel function. Here, we report the crystal structures of two ternary complexes of a human NaV cytosolic C-terminal domain (CTD), a fibroblast growth factor homologous factor, and Ca2+/calmodulin (Ca2+/CaM). These structures rule out direct binding of Ca2+ to the NaV CTD, and uncover new contacts between CaM and the NaV CTD. Probing these new contacts with biochemical and functional experiments allows us to propose a mechanism by which Ca2+ could regulate NaV channels. Further, our model provides hints towards understanding the molecular basis of the neurologic disorders and cardiac arrhythmias caused by NaV channel mutations.
Collapse
|
247
|
Bagnall RD, Molloy LK, Kalman JM, Semsarian C. Exome sequencing identifies a mutation in the ACTN2 gene in a family with idiopathic ventricular fibrillation, left ventricular noncompaction, and sudden death. BMC MEDICAL GENETICS 2014; 15:99. [PMID: 25224718 PMCID: PMC4355500 DOI: 10.1186/s12881-014-0099-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 08/12/2014] [Indexed: 02/04/2023]
Abstract
Background Potentially lethal and heritable cardiomyopathies and cardiac channelopathies are caused by heterogeneous autosomal dominant mutations in over 50 distinct genes, and multiple genes are responsible for a given disease. Clinical genetic tests are available for several of the inherited cardiac diseases and clinical investigations guide which test to order. This study describes a family with cardiac disease in which marked clinical diversity exists. In the absence of a unified clinical diagnosis, we used exome sequencing to identify a causal mutation. Methods Clinical evaluation of family members was performed, including physical examination, electrocardiography, 2D transthoracic echocardiography and review of autopsy records. Exome sequencing was performed on a clinically affected individual and co-segregation studies and haplotype analysis were performed to further confirm pathogenicity. Results Clinically affected members showed marked cardiac phenotype heterogeneity. While some individuals were asymptomatic, other presentations included left ventricular non-compaction, a resuscitated cardiac arrest due to idiopathic ventricular fibrillation, dilated cardiomyopathy, and sudden unexplained death. Whole exome sequencing identified an Ala119Thr mutation in the alpha-actinin-2 (ACTN2) gene that segregated with disease. Haplotype analysis showed that this mutation segregated with an identical haplotype in a second, previously described family with clinically diverse cardiac disease, and is likely inherited from a common ancestor. Conclusions Mutations in the ACTN2 gene can be responsible for marked cardiac phenotype heterogeneity in families. The diverse mechanistic roles of ACTN2 in the cardiac Z-disc may explain this heterogeneous clinical presentation. Exome sequencing is a useful adjunct to cardiac genetic testing in families with mixed clinical presentations. Electronic supplementary material The online version of this article (doi:10.1186/s12881-014-0099-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Richard D Bagnall
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Locked Bag 6, Newtown, Sydney, NSW, 2042, Australia. .,Faculty of Medicine, University of Sydney, Sydney, NSW, Australia.
| | - Laura K Molloy
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Locked Bag 6, Newtown, Sydney, NSW, 2042, Australia. .,Department of Medical Genomics, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
| | - Jonathan M Kalman
- Department of Cardiology, The Royal Melbourne Hospital, Parkville, Melbourne, Victoria, Australia.
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Locked Bag 6, Newtown, Sydney, NSW, 2042, Australia. .,Faculty of Medicine, University of Sydney, Sydney, NSW, Australia. .,Department of Cardiology, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
| |
Collapse
|
248
|
Conservation of Ca2+/calmodulin regulation across Na and Ca2+ channels. Cell 2014; 157:1657-70. [PMID: 24949975 DOI: 10.1016/j.cell.2014.04.035] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/25/2014] [Accepted: 04/15/2014] [Indexed: 11/20/2022]
Abstract
Voltage-gated Na and Ca2+ channels comprise distinct ion channel superfamilies, yet the carboxy tails of these channels exhibit high homology, hinting at a long-shared and purposeful module. For different Ca2+ channels, carboxyl-tail interactions with calmodulin do elaborate robust and similar forms of Ca2+ regulation. However, Na channels have only shown subtler Ca2+ modulation that differs among reports, challenging attempts at unified understanding. Here, by rapid Ca2+ photorelease onto Na channels, we reset this view of Na channel regulation. For cardiac-muscle channels (NaV1.5), reported effects from which most mechanistic proposals derive, we observe no Ca2+ modulation. Conversely, for skeletal-muscle channels (NaV1.4), we uncover fast Ca2+ regulation eerily similar to that of Ca2+ channels. Channelopathic myotonia mutations halve NaV1.4 Ca2+ regulation, and transplanting the NaV1.4 carboxy tail onto Ca2+ channels recapitulates Ca2+ regulation. Thus, we argue for the persistence and physiological relevance of an ancient Ca2+ regulatory module across Na and Ca2+ channels.
Collapse
|
249
|
Semsarian C, Ingles J. Expanding the genetic spectrum of hypertrophic cardiomyopathy: X marks the spot. ACTA ACUST UNITED AC 2014; 6:528-30. [PMID: 24347617 DOI: 10.1161/circgenetics.113.000377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Newtown, Australia
| | | |
Collapse
|
250
|
Altered RyR2 regulation by the calmodulin F90L mutation associated with idiopathic ventricular fibrillation and early sudden cardiac death. FEBS Lett 2014; 588:2898-902. [PMID: 25036739 DOI: 10.1016/j.febslet.2014.07.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/28/2014] [Accepted: 07/01/2014] [Indexed: 11/23/2022]
Abstract
Calmodulin (CaM) association with the cardiac muscle ryanodine receptor (RyR2) regulates excitation-contraction coupling. Defective CaM-RyR2 interaction is associated with heart failure. A novel CaM mutation (CaM(F90L)) was recently identified in a family with idiopathic ventricular fibrillation (IVF) and early onset sudden cardiac death. We report the first biochemical characterization of CaM(F90L). F90L confers a deleterious effect on protein stability. Ca(2+)-binding studies reveal reduced Ca(2+)-binding affinity and a loss of co-operativity. Moreover, CaM(F90L) displays reduced RyR2 interaction and defective modulation of [(3)H]ryanodine binding. Hence, dysregulation of RyR2-mediated Ca(2+) release via aberrant CaM(F90L)-RyR2 interaction is a potential mechanism that underlies familial IVF.
Collapse
|