1
|
Thomson KL, Jiang C, Richardson E, Westphal DS, Burkard T, Wolf CM, Vatta M, Harrison SM, Ingles J, Bezzina CR, Kroncke BM, Vandenberg JI, Ng CA. Clinical interpretation of KCNH2 variants using a robust PS3/BS3 functional patch-clamp assay. HGG Adv 2024; 5:100270. [PMID: 38219013 PMCID: PMC10840334 DOI: 10.1016/j.xhgg.2024.100270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 01/15/2024] Open
Abstract
Long QT syndrome (LQTS), caused by the dysfunction of cardiac ion channels, increases the risk of sudden death in otherwise healthy young people. For many variants in LQTS genes, there is insufficient evidence to make a definitive genetic diagnosis. We have established a robust functional patch-clamp assay to facilitate classification of missense variants in KCNH2, one of the key LQTS genes. A curated set of 30 benign and 30 pathogenic missense variants were used to establish the range of normal and abnormal function. The extent to which variants reduced protein function was quantified using Z scores, the number of standard deviations from the mean of the normalized current density of the set of benign variant controls. A Z score of -2 defined the threshold for abnormal loss of function, which corresponds to 55% wild-type function. More extreme Z scores were observed for variants with a greater loss-of-function effect. We propose that the Z score for each variant can be used to inform the application and weighting of abnormal and normal functional evidence criteria (PS3 and BS3) within the American College of Medical Genetics and Genomics variant classification framework. The validity of this approach was demonstrated using a series of 18 KCNH2 missense variants detected in a childhood onset LQTS cohort, where the level of function assessed using our assay correlated to the Schwartz score (a scoring system used to quantify the probability of a clinical diagnosis of LQTS) and the length of the corrected QT (QTc) interval.
Collapse
Affiliation(s)
- Kate L Thomson
- Oxford Genetics Laboratories, Churchill Hospital, Oxford, UK
| | - Connie Jiang
- Faculty of Medicine and Health, UNSW Sydney, Kensington, NSW, Australia; Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Ebony Richardson
- Centre for Population Genomics, Garvan Institute of Medical Research and UNSW Sydney, Sydney, NSW, Australia; Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Dominik S Westphal
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany; Department of Internal Medicine I, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart: ERN GUARD-Heart
| | - Tobias Burkard
- Department of Congenital Heart Disease and Pediatric Cardiology, German Heart Center Munich, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Cordula M Wolf
- European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart: ERN GUARD-Heart; Department of Congenital Heart Disease and Pediatric Cardiology, German Heart Center Munich, Technical University of Munich, School of Medicine and Health, Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany
| | | | | | - Jodie Ingles
- Centre for Population Genomics, Garvan Institute of Medical Research and UNSW Sydney, Sydney, NSW, Australia; Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Connie R Bezzina
- European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart: ERN GUARD-Heart; Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jamie I Vandenberg
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia.
| | - Chai-Ann Ng
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia.
| |
Collapse
|
2
|
O’Neill MJ, Ng CA, Aizawa T, Sala L, Bains S, Denjoy I, Winbo A, Ullah R, Shen Q, Tan CY, Kozek K, Vanags LR, Mitchell DW, Shen A, Wada Y, Kashiwa A, Crotti L, Dagradi F, Musu G, Spazzolini C, Neves R, Bos JM, Giudicessi JR, Bledsoe X, Lancaster M, Glazer AM, Roden DM, Leenhardt A, Salem JE, Earle N, Stiles R, Agee T, Johnson CN, Horie M, Skinner J, Extramiana F, Ackerman MJ, Schwartz PJ, Ohno S, Vandenberg JI, Kroncke BM. Prognostic Value of Multiplexed Assays of Variant Effect and Automated Patch-clamping for KCNH2-LQTS Risk Stratification. medRxiv 2024:2024.02.01.24301443. [PMID: 38370760 PMCID: PMC10871451 DOI: 10.1101/2024.02.01.24301443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Background Long QT syndrome (LQTS) is a lethal arrhythmia condition, frequently caused by rare loss-of-function variants in the cardiac potassium channel encoded by KCNH2. Variant-based risk stratification is complicated by heterogenous clinical data, incomplete penetrance, and low-throughput functional data. Objective To test the utility of variant-specific features, including high-throughput functional data, to predict cardiac events among KCNH2 variant heterozygotes. Methods We quantified cell-surface trafficking of 18,323 variants in KCNH2 and recorded potassium current densities for 506 KCNH2 variants. Next, we deeply phenotyped 1150 KCNH2 missense variant patients, including ECG features, cardiac event history (528 total cardiac events), and mortality. We then assessed variant functional, in silico, structural, and LQTS penetrance data to stratify event-free survival for cardiac events in the study cohort. Results Variant-specific current density (HR 0.28 [0.13-0.60]) and estimates of LQTS penetrance incorporating MAVE data (HR 3.16 [1.59-6.27]) were independently predictive of severe cardiac events when controlling for patient-specific features. Risk prediction models incorporating these data significantly improved prediction of 20 year cardiac events (AUC 0.79 [0.75-0.82]) over patient-only covariates (QTc and sex) (AUC 0.73 [0.70-0.77]). Conclusion We show that high-throughput functional data, and other variant-specific features, meaningfully contribute to both diagnosis and prognosis of a clinically actionable monogenic disease.
Collapse
Affiliation(s)
- Matthew J. O’Neill
- Vanderbilt University School of Medicine, Medical Scientist Training Program, Nashville, TN, USA
- These authors contributed equally
| | - Chai-Ann Ng
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia
- These authors contributed equally
| | - Takanori Aizawa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine Kyoto, Japan
| | - Luca Sala
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Sahej Bains
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Isabelle Denjoy
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Annika Winbo
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Rizwan Ullah
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Qianyi Shen
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Chek-Ying Tan
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Krystian Kozek
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Loren R. Vanags
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Devyn W. Mitchell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alex Shen
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine Kyoto, Japan
| | - Lia Crotti
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
- Department of Medicine and Surgery, University Milano Bicocca, Milan, Italy
| | - Federica Dagradi
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Giulia Musu
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Carla Spazzolini
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Raquel Neves
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - J. Martijn Bos
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - John R. Giudicessi
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Xavier Bledsoe
- Vanderbilt University School of Medicine, Medical Scientist Training Program, Nashville, TN, USA
| | - Megan Lancaster
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andrew M. Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dan M. Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Antoine Leenhardt
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Joe-Elie Salem
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Nikki Earle
- Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Rachael Stiles
- Department of Cardiology, Waikato Hospital, Hamilton, New Zealand
| | - Taylor Agee
- Department of Chemistry, Mississippi State University, Starkville, MS 39759, USA
| | | | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Jonathan Skinner
- Sydney Children’s Hospital Network, University of Sydney, Sydney, Australia
| | - Fabrice Extramiana
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Michael J. Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Peter J. Schwartz
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Jamie I. Vandenberg
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia
| | - Brett M. Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| |
Collapse
|
3
|
O'Neill MJ, Chen SN, Rumping L, Johnson R, van Slegtenhorst M, Glazer AM, Yang T, Solus JF, Laudeman J, Mitchell DW, Vanags LR, Kroncke BM, Anderson K, Gao S, Verdonschot JAJ, Brunner H, Hellebrekers D, Taylor MRG, Roden DM, Wessels MW, Lekanne Dit Deprez RH, Fatkin D, Mestroni L, Shoemaker MB. Multicenter clinical and functional evidence reclassifies a recurrent noncanonical filamin C splice-altering variant. Heart Rhythm 2023; 20:1158-1166. [PMID: 37164047 PMCID: PMC10530503 DOI: 10.1016/j.hrthm.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 04/25/2023] [Accepted: 05/03/2023] [Indexed: 05/12/2023]
Abstract
BACKGROUND Truncating variants in filamin C (FLNC) can cause arrhythmogenic cardiomyopathy (ACM) through haploinsufficiency. Noncanonical splice-altering variants may contribute to this phenotype. OBJECTIVE The purpose of this study was to investigate the clinical and functional consequences of a recurrent FLNC intronic variant of uncertain significance (VUS), c.970-4A>G. METHODS Clinical data in 9 variant heterozygotes from 4 kindreds were obtained from 5 tertiary health care centers. We used in silico predictors and functional studies with peripheral blood and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Isolated RNA was studied by reverse transcription polymerase chain reaction. iPSC-CMs were further characterized at baseline and after nonsense-mediated decay (NMD) inhibition, using quantitative polymerase chain reaction (qPCR), RNA-sequencing, and cellular electrophysiology. American College of Medical Genetics and Genomics (ACMG) criteria were used to adjudicate variant pathogenicity. RESULTS Variant heterozygotes displayed a spectrum of disease phenotypes, spanning from mild ventricular dysfunction with palpitations to severe ventricular arrhythmias requiring device shocks or progressive cardiomyopathy requiring heart transplantation. Consistent with in silico predictors, the c.970-4A>G FLNC variant activated a cryptic splice acceptor site, introducing a 3-bp insertion containing a premature termination codon. NMD inhibition upregulated aberrantly spliced transcripts by qPCR and RNA-sequencing. Patch clamp studies revealed irregular spontaneous action potentials, increased action potential duration, and increased sodium late current in proband-derived iPSC-CMs. These findings fulfilled multiple ACMG criteria for pathogenicity. CONCLUSION Clinical, in silico, and functional evidence support the prediction that the intronic c.970-4A>G VUS disrupts splicing and drives ACM, enabling reclassification from VUS to pathogenic.
Collapse
Affiliation(s)
- Matthew J O'Neill
- Vanderbilt University School of Medicine, Medical Scientist Training Program, Vanderbilt University, Nashville, Tennessee
| | - Suet Nee Chen
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Lynne Rumping
- Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands
| | - Renee Johnson
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | | | - Andrew M Glazer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Tao Yang
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Joseph F Solus
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Julie Laudeman
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Devyn W Mitchell
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Loren R Vanags
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Brett M Kroncke
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Katherine Anderson
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Shanshan Gao
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Job A J Verdonschot
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Han Brunner
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Debby Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Dan M Roden
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marja W Wessels
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Diane Fatkin
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia; Cardiology Department, St. Vincent's Hospital, Sydney, NSW, Australia
| | - Luisa Mestroni
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - M Benjamin Shoemaker
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
| |
Collapse
|
4
|
O'Neill MJ, Sala L, Denjoy I, Wada Y, Kozek K, Crotti L, Dagradi F, Kotta MC, Spazzolini C, Leenhardt A, Salem JE, Kashiwa A, Ohno S, Tao R, Roden DM, Horie M, Extramiana F, Schwartz PJ, Kroncke BM. Continuous Bayesian variant interpretation accounts for incomplete penetrance among Mendelian cardiac channelopathies. Genet Med 2023; 25:100355. [PMID: 36496179 PMCID: PMC9992222 DOI: 10.1016/j.gim.2022.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 12/05/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
PURPOSE The congenital Long QT Syndrome (LQTS) and Brugada Syndrome (BrS) are Mendelian autosomal dominant diseases that frequently precipitate fatal cardiac arrhythmias. Incomplete penetrance is a barrier to clinical management of heterozygotes harboring variants in the major implicated disease genes KCNQ1, KCNH2, and SCN5A. We apply and evaluate a Bayesian penetrance estimation strategy that accounts for this phenomenon. METHODS We generated Bayesian penetrance models for KCNQ1-LQT1 and SCN5A-LQT3 using variant-specific features and clinical data from the literature, international arrhythmia genetic centers, and population controls. We analyzed the distribution of posterior penetrance estimates across 4 genotype-phenotype relationships and compared continuous estimates with ClinVar annotations. Posterior estimates were mapped onto protein structure. RESULTS Bayesian penetrance estimates of KCNQ1-LQT1 and SCN5A-LQT3 are empirically equivalent to 10 and 5 clinically phenotype heterozygotes, respectively. Posterior penetrance estimates were bimodal for KCNQ1-LQT1 and KCNH2-LQT2, with a higher fraction of missense variants with high penetrance among KCNQ1 variants. There was a wide distribution of variant penetrance estimates among identical ClinVar categories. Structural mapping revealed heterogeneity among "hot spot" regions and featured high penetrance estimates for KCNQ1 variants in contact with calmodulin and the S6 domain. CONCLUSIONS Bayesian penetrance estimates provide a continuous framework for variant interpretation.
Collapse
Affiliation(s)
- Matthew J O'Neill
- Vanderbilt University School of Medicine, Medical Scientist Training Program, Vanderbilt University, Nashville, TN
| | - Luca Sala
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Isabelle Denjoy
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Krystian Kozek
- Vanderbilt University School of Medicine, Medical Scientist Training Program, Vanderbilt University, Nashville, TN
| | - Lia Crotti
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Federica Dagradi
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Maria-Christina Kotta
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Carla Spazzolini
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Antoine Leenhardt
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Joe-Elie Salem
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine Kyoto, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Ran Tao
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Fabrice Extramiana
- Department of Cardiovascular Medicine, Hôpital Bichat, APHP, Université de Paris Cité, Paris, France
| | - Peter J Schwartz
- IRCCS, Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milano, Italy
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN.
| |
Collapse
|
5
|
Jiang C, Richardson E, Farr J, Hill AP, Ullah R, Kroncke BM, Harrison SM, Thomson KL, Ingles J, Vandenberg JI, Ng CA. A calibrated functional patch-clamp assay to enhance clinical variant interpretation in KCNH2-related long QT syndrome. Am J Hum Genet 2022; 109:1199-1207. [PMID: 35688147 PMCID: PMC9300752 DOI: 10.1016/j.ajhg.2022.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/03/2022] [Indexed: 01/09/2023] Open
Abstract
Modern sequencing technologies have revolutionized our detection of gene variants. However, in most genes, including KCNH2, the majority of missense variants are currently classified as variants of uncertain significance (VUSs). The aim of this study was to investigate the utility of an automated patch-clamp assay for aiding clinical variant classification in KCNH2. The assay was designed according to recommendations proposed by the Clinical Genome Sequence Variant Interpretation Working Group. Thirty-one variants (17 pathogenic/likely pathogenic, 14 benign/likely benign) were classified internally as variant controls. They were heterozygously expressed in Flp-In HEK293 cells for assessing the effects of variants on current density and channel gating in order to determine the sensitivity and specificity of the assay. All 17 pathogenic variant controls had reduced current density, and 13 of 14 benign variant controls had normal current density, which enabled determination of normal and abnormal ranges for applying evidence of moderate or supporting strength for VUS reclassification. Inclusion of functional assay evidence enabled us to reclassify 6 out of 44 KCNH2 VUSs as likely pathogenic. The high-throughput patch-clamp assay can provide moderate-strength evidence for clinical interpretation of clinical KCNH2 variants and demonstrates the value of developing automated patch-clamp assays for functional characterization of ion channel gene variants.
Collapse
Affiliation(s)
- Connie Jiang
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Ebony Richardson
- Centre for Population Genomics, Garvan Institute of Medical Research and UNSW Sydney, Sydney, Australia; Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Australia
| | - Jessica Farr
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Computer Science and Engineering, UNSW Sydney, Kensington, NSW, Australia
| | - Adam P Hill
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia
| | - Rizwan Ullah
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Kate L Thomson
- Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford, UK
| | - Jodie Ingles
- Centre for Population Genomics, Garvan Institute of Medical Research and UNSW Sydney, Sydney, Australia; Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Australia
| | - Jamie I Vandenberg
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia.
| | - Chai-Ann Ng
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia.
| |
Collapse
|
6
|
Ng CA, Ullah R, Farr J, Hill AP, Kozek KA, Vanags LR, Mitchell DW, Kroncke BM, Vandenberg JI. A massively parallel assay accurately discriminates between functionally normal and abnormal variants in a hotspot domain of KCNH2. Am J Hum Genet 2022; 109:1208-1216. [PMID: 35688148 PMCID: PMC9300756 DOI: 10.1016/j.ajhg.2022.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/03/2022] [Indexed: 01/09/2023] Open
Abstract
Many genes, including KCNH2, contain "hotspot" domains associated with a high density of variants associated with disease. This has led to the suggestion that variant location can be used as evidence supporting classification of clinical variants. However, it is not known what proportion of all potential variants in hotspot domains cause loss of function. Here, we have used a massively parallel trafficking assay to characterize all single-nucleotide variants in exon 2 of KCNH2, a known hotspot for variants that cause long QT syndrome type 2 and an increased risk of sudden cardiac death. Forty-two percent of KCNH2 exon 2 variants caused at least 50% reduction in protein trafficking, and 65% of these trafficking-defective variants exerted a dominant-negative effect when co-expressed with a WT KCNH2 allele as assessed using a calibrated patch-clamp electrophysiology assay. The massively parallel trafficking assay was more accurate (AUC of 0.94) than bioinformatic prediction tools (REVEL and CardioBoost, AUC of 0.81) in discriminating between functionally normal and abnormal variants. Interestingly, over half of variants in exon 2 were found to be functionally normal, suggesting a nuanced interpretation of variants in this "hotspot" domain is necessary. Our massively parallel trafficking assay can provide this information prospectively.
Collapse
Affiliation(s)
- Chai-Ann Ng
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia
| | - Rizwan Ullah
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jessica Farr
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Computer Science and Engineering, UNSW Sydney, Kensington, NSW, Australia
| | - Adam P Hill
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia
| | - Krystian A Kozek
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Loren R Vanags
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Devyn W Mitchell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Jamie I Vandenberg
- Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; School of Clinical Medicine, UNSW Sydney, Darlinghurst, NSW, Australia.
| |
Collapse
|
7
|
Glazer AM, Davogustto G, Shaffer CM, Vanoye CG, Desai RR, Farber-Eger EH, Dikilitas O, Shang N, Pacheco JA, Yang T, Muhammad A, Mosley JD, Van Driest SL, Wells QS, Shaffer LL, Kalash OR, Wada Y, Bland S, Yoneda ZT, Mitchell DW, Kroncke BM, Kullo IJ, Jarvik GP, Gordon AS, Larson EB, Manolio TA, Mirshahi T, Luo JZ, Schaid D, Namjou B, Alsaied T, Singh R, Singhal A, Liu C, Weng C, Hripcsak G, Ralston JD, McNally EM, Chung WK, Carrell DS, Leppig KA, Hakonarson H, Sleiman P, Sohn S, Glessner J, Denny J, Wei WQ, George AL, Shoemaker MB, Roden DM. Arrhythmia Variant Associations and Reclassifications in the eMERGE-III Sequencing Study. Circulation 2022; 145:877-891. [PMID: 34930020 PMCID: PMC8940719 DOI: 10.1161/circulationaha.121.055562] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Sequencing Mendelian arrhythmia genes in individuals without an indication for arrhythmia genetic testing can identify carriers of pathogenic or likely pathogenic (P/LP) variants. However, the extent to which these variants are associated with clinically meaningful phenotypes before or after return of variant results is unclear. In addition, the majority of discovered variants are currently classified as variants of uncertain significance, limiting clinical actionability. METHODS The eMERGE-III study (Electronic Medical Records and Genomics Phase III) is a multicenter prospective cohort that included 21 846 participants without previous indication for cardiac genetic testing. Participants were sequenced for 109 Mendelian disease genes, including 10 linked to arrhythmia syndromes. Variant carriers were assessed with electronic health record-derived phenotypes and follow-up clinical examination. Selected variants of uncertain significance (n=50) were characterized in vitro with automated electrophysiology experiments in HEK293 cells. RESULTS As previously reported, 3.0% of participants had P/LP variants in the 109 genes. Herein, we report 120 participants (0.6%) with P/LP arrhythmia variants. Compared with noncarriers, arrhythmia P/LP carriers had a significantly higher burden of arrhythmia phenotypes in their electronic health records. Fifty-four participants had variant results returned. Nineteen of these 54 participants had inherited arrhythmia syndrome diagnoses (primarily long-QT syndrome), and 12 of these 19 diagnoses were made only after variant results were returned (0.05%). After in vitro functional evaluation of 50 variants of uncertain significance, we reclassified 11 variants: 3 to likely benign and 8 to P/LP. CONCLUSIONS Genome sequencing in a large population without indication for arrhythmia genetic testing identified phenotype-positive carriers of variants in congenital arrhythmia syndrome disease genes. As the genomes of large numbers of people are sequenced, the disease risk from rare variants in arrhythmia genes can be assessed by integrating genomic screening, electronic health record phenotypes, and in vitro functional studies. REGISTRATION URL: https://www. CLINICALTRIALS gov; Unique identifier; NCT03394859.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Ning Shang
- Columbia University Irving Medical Center, New York NY
| | | | - Tao Yang
- Vanderbilt University Medical Center, Nashville TN
| | | | | | | | | | | | | | - Yuko Wada
- Vanderbilt University Medical Center, Nashville TN
| | - Sarah Bland
- Vanderbilt University Medical Center, Nashville TN
| | | | | | | | | | - Gail P. Jarvik
- Departments of Medicine (Medical Genetics) and Genome Sciences, University of Washington School of Medicine, Seattle, WA
| | | | | | | | | | | | | | - Bahram Namjou
- Cincinnati Children’s Hospital Medical Center, Cincinnati OH
| | - Tarek Alsaied
- Cincinnati Children’s Hospital Medical Center, Cincinnati OH
| | | | | | - Cong Liu
- Columbia University Irving Medical Center, New York NY
| | - Chunhua Weng
- Columbia University Irving Medical Center, New York NY
| | | | - James D. Ralston
- Departments of Medicine (Medical Genetics) and Genome Sciences, University of Washington School of Medicine, Seattle, WA
| | | | | | | | | | | | | | | | | | | | | | - Wei-Qi Wei
- Vanderbilt University Medical Center, Nashville TN
| | | | | | - Dan M. Roden
- Vanderbilt University Medical Center, Nashville TN
- Correspondence should be addressed to Dan M. Roden, MD, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232,
| |
Collapse
|
8
|
Gulsevin A, Glazer AM, Shields T, Kroncke BM, Roden DM, Meiler J. Veratridine Can Bind to a Site at the Mouth of the Channel Pore at Human Cardiac Sodium Channel NaV1.5. Int J Mol Sci 2022; 23:ijms23042225. [PMID: 35216338 PMCID: PMC8878851 DOI: 10.3390/ijms23042225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/07/2022] [Accepted: 02/15/2022] [Indexed: 02/05/2023] Open
Abstract
The cardiac sodium ion channel (NaV1.5) is a protein with four domains (DI-DIV), each with six transmembrane segments. Its opening and subsequent inactivation results in the brief rapid influx of Na+ ions resulting in the depolarization of cardiomyocytes. The neurotoxin veratridine (VTD) inhibits NaV1.5 inactivation resulting in longer channel opening times, and potentially fatal action potential prolongation. VTD is predicted to bind at the channel pore, but alternative binding sites have not been ruled out. To determine the binding site of VTD on NaV1.5, we perform docking calculations and high-throughput electrophysiology experiments in the present study. The docking calculations identified two distinct binding regions. The first site was in the pore, close to the binding site of NaV1.4 and NaV1.5 blocking drugs in experimental structures. The second site was at the “mouth” of the pore at the cytosolic side, partly solvent-exposed. Mutations at this site (L409, E417, and I1466) had large effects on VTD binding, while residues deeper in the pore had no effect, consistent with VTD binding at the mouth site. Overall, our results suggest a VTD binding site close to the cytoplasmic mouth of the channel pore. Binding at this alternative site might indicate an allosteric inactivation mechanism for VTD at NaV1.5.
Collapse
Affiliation(s)
- Alican Gulsevin
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA; (T.S.); (J.M.)
- Correspondence:
| | - Andrew M. Glazer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (A.M.G.); (B.M.K.); (D.M.R.)
| | - Tiffany Shields
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA; (T.S.); (J.M.)
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (A.M.G.); (B.M.K.); (D.M.R.)
| | - Brett M. Kroncke
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (A.M.G.); (B.M.K.); (D.M.R.)
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Dan M. Roden
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (A.M.G.); (B.M.K.); (D.M.R.)
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jens Meiler
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA; (T.S.); (J.M.)
- Institute for Drug Discovery, Leipzig University Medical School, 04103 Leipzig, Germany
| |
Collapse
|
9
|
Kozek K, Wada Y, Sala L, Denjoy I, Egly C, O'Neill MJ, Aiba T, Shimizu W, Makita N, Ishikawa T, Crotti L, Spazzolini C, Kotta MC, Dagradi F, Castelletti S, Pedrazzini M, Gnecchi M, Leenhardt A, Salem JE, Ohno S, Zuo Y, Glazer AM, Mosley JD, Roden DM, Knollmann BC, Blume JD, Extramiana F, Schwartz PJ, Horie M, Kroncke BM. Estimating the Posttest Probability of Long QT Syndrome Diagnosis for Rare KCNH2 Variants. Circ Genom Precis Med 2021; 14:e003289. [PMID: 34309407 DOI: 10.1161/circgen.120.003289] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The proliferation of genetic profiling has revealed many associations between genetic variations and disease. However, large-scale phenotyping efforts in largely healthy populations, coupled with DNA sequencing, suggest variants currently annotated as pathogenic are more common in healthy populations than previously thought. In addition, novel and rare variants are frequently observed in genes associated with disease both in healthy individuals and those under suspicion of disease. This raises the question of whether these variants can be useful predictors of disease. To answer this question, we assessed the degree to which the presence of a variant in the cardiac potassium channel gene KCNH2 was diagnostically predictive for the autosomal dominant long QT syndrome. METHODS We estimated the probability of a long QT diagnosis given the presence of each KCNH2 variant using Bayesian methods that incorporated variant features such as changes in variant function, protein structure, and in silico predictions. We call this estimate the posttest probability of disease. Our method was applied to over 4000 individuals heterozygous for 871 missense or in-frame insertion/deletion variants in KCNH2 and validated against a separate international cohort of 933 individuals heterozygous for 266 missense or in-frame insertion/deletion variants. RESULTS Our method was well-calibrated for the observed fraction of heterozygotes diagnosed with long QT syndrome. Heuristically, we found that the innate diagnostic information one learns about a variant from 3-dimensional variant location, in vitro functional data, and in silico predictors is equivalent to the diagnostic information one learns about that same variant by clinically phenotyping 10 heterozygotes. Most importantly, these data can be obtained in the absence of any clinical observations. CONCLUSIONS We show how variant-specific features can inform a prior probability of disease for rare variants even in the absence of clinically phenotyped heterozygotes.
Collapse
Affiliation(s)
- Krystian Kozek
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.)
| | - Luca Sala
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.)
| | - Isabelle Denjoy
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.)
| | - Christian Egly
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Matthew J O'Neill
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Takeshi Aiba
- Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan (W.S.)
| | - Naomasa Makita
- Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita.,7Omics Research Center (N.M., T.I.), National Cerebral and Cardiovascular Center, Suita
| | - Taisuke Ishikawa
- 7Omics Research Center (N.M., T.I.), National Cerebral and Cardiovascular Center, Suita
| | - Lia Crotti
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.).,Department of Cardiovascular, Neural & Metabolic Sciences, San Luca Hospital (L.C.), Istituto Auxologico Italiano IRCCS.,Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS.,Department of Medicine and Surgery, University Milano Bicocca, Milan (L.C.)
| | - Carla Spazzolini
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | | | - Federica Dagradi
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Silvia Castelletti
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Matteo Pedrazzini
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.)
| | - Massimiliano Gnecchi
- Department of Molecular Medicine, Unit of Cardiology, University of Pavia (M.G.).,Intensive Cardiac Care Unit and Lab of Experimental Cardiology for Cell and Molecular Therapy, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy (M.G.)
| | - Antoine Leenhardt
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.).,University de Paris (A.L., F.E.)
| | - Joe-Elie Salem
- Division of Cardiovascular Medicine, Cardio-oncology Program (J.-E.S.), Vanderbilt University Medical Center, Nashville, TN.,Sorbonne Université, INSERM CIC-1901, AP-HP, Department of Pharmacology, Regional Pharmacovigilance Center, Pitié-Salpêtrière Hospital, Paris, France (J.-E.S.)
| | - Seiko Ohno
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.).,Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita
| | - Yi Zuo
- Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Jonathan D Mosley
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN.,Biomedical Informatics (J.D.M.), Vanderbilt University, Nashville, TN
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | | | - Fabrice Extramiana
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.).,University de Paris (A.L., F.E.)
| | - Peter J Schwartz
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.).,Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.)
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| |
Collapse
|
10
|
Glazer AM, Wada Y, Li B, Muhammad A, Kalash OR, O'Neill MJ, Shields T, Hall L, Short L, Blair MA, Kroncke BM, Capra JA, Roden DM. High-Throughput Reclassification of SCN5A Variants. Am J Hum Genet 2020; 107:111-123. [PMID: 32533946 PMCID: PMC7332654 DOI: 10.1016/j.ajhg.2020.05.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/19/2020] [Indexed: 12/19/2022] Open
Abstract
Partial or complete loss-of-function variants in SCN5A are the most common genetic cause of the arrhythmia disorder Brugada syndrome (BrS1). However, the pathogenicity of SCN5A variants is often unknown or disputed; 80% of the 1,390 SCN5A missense variants observed in at least one individual to date are variants of uncertain significance (VUSs). The designation of VUS is a barrier to the use of sequence data in clinical care. We selected 83 variants: 10 previously studied control variants, 10 suspected benign variants, and 63 suspected Brugada syndrome-associated variants, selected on the basis of their frequency in the general population and in individuals with Brugada syndrome. We used high-throughput automated patch clamping to study the function of the 83 variants, with the goal of reclassifying variants with functional data. The ten previously studied controls had functional properties concordant with published manual patch clamp data. All 10 suspected benign variants had wild-type-like function. 22 suspected BrS variants had loss of channel function (<10% normalized peak current) and 22 variants had partial loss of function (10%-50% normalized peak current). The previously unstudied variants were initially classified as likely benign (n = 2), likely pathogenic (n = 10), or VUSs (n = 61). After the patch clamp studies, 16 variants were benign/likely benign, 45 were pathogenic/likely pathogenic, and only 12 were still VUSs. Structural modeling identified likely mechanisms for loss of function including altered thermostability and disruptions to alpha helices, disulfide bonds, or the permeation pore. High-throughput patch clamping enabled reclassification of the majority of tested VUSs in SCN5A.
Collapse
Affiliation(s)
- Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Bian Li
- Department of Biological Sciences, Center for Structural Biology, and Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN 37235, USA
| | - Ayesha Muhammad
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Olivia R Kalash
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Matthew J O'Neill
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Tiffany Shields
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lynn Hall
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Laura Short
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Marcia A Blair
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John A Capra
- Department of Biological Sciences, Center for Structural Biology, and Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN 37235, USA
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| |
Collapse
|
11
|
Kozek KA, Glazer AM, Ng CA, Blackwell D, Egly CL, Vanags LR, Blair M, Mitchell D, Matreyek KA, Fowler DM, Knollmann BC, Vandenberg JI, Roden DM, Kroncke BM. High-throughput discovery of trafficking-deficient variants in the cardiac potassium channel K V11.1. Heart Rhythm 2020; 17:2180-2189. [PMID: 32522694 DOI: 10.1016/j.hrthm.2020.05.041] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/27/2020] [Accepted: 05/31/2020] [Indexed: 01/09/2023]
Abstract
BACKGROUND KCHN2 encodes the KV11.1 potassium channel responsible for IKr, a major repolarization current during the cardiomyocyte action potential. Variants in KCNH2 that lead to decreased IKr have been associated with long QT syndrome type 2 (LQT2). The mechanism of LQT2 is most often induced loss of KV11.1 trafficking to the cell surface. Accurately discriminating between variants with normal and abnormal trafficking would aid in understanding the deleterious nature of these variants; however, the volume of reported nonsynonymous KCNH2 variants precludes the use of conventional methods for functional study. OBJECTIVE The purpose of this study was to report a high-throughput, multiplexed screening method for KCNH2 genetic variants capable of measuring the cell surface abundance of hundreds of missense variants in the resulting KV11.1 channel. METHODS We developed a method to quantitate KV11.1 variant trafficking on a pilot region of 11 residues in the S5 helix. RESULTS We generated trafficking scores for 220 of 231 missense variants in the pilot region. For 5 of 5 variants, high-throughput trafficking scores validated when tested in single variant flow cytometry and confocal microscopy experiments. We further explored these results with planar patch electrophysiology and found that loss-of-trafficking variants do not produce IKr. Conversely, but expectedly, some variants that traffic normally were still functionally compromised. CONCLUSION We describe a new method for detecting KV11.1 trafficking-deficient variants in a multiplexed assay. This new method accurately generated trafficking data for variants in KV11.1 and is extendable both to all residues in KV11.1 and to other cell surface proteins.
Collapse
Affiliation(s)
- Krystian A Kozek
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Chai-Ann Ng
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St Vincent's Clinical School, UNSW Sydney, Darlinghurst, New South Wales, Australia
| | - Daniel Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Christian L Egly
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Loren R Vanags
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marcia Blair
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Devyn Mitchell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Kenneth A Matreyek
- Department of Genome Sciences, University of Washington, Seattle, Washington
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, Washington; Department of Bioengineering, University of Washington, Seattle, Washington
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jamie I Vandenberg
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St Vincent's Clinical School, UNSW Sydney, Darlinghurst, New South Wales, Australia
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
| |
Collapse
|
12
|
Kroncke BM, Smith DK, Zuo Y, Glazer AM, Roden DM, Blume JD. A Bayesian method to estimate variant-induced disease penetrance. PLoS Genet 2020; 16:e1008862. [PMID: 32569262 PMCID: PMC7347235 DOI: 10.1371/journal.pgen.1008862] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 07/09/2020] [Accepted: 05/14/2020] [Indexed: 01/09/2023] Open
Abstract
A major challenge emerging in genomic medicine is how to assess best disease risk from rare or novel variants found in disease-related genes. The expanding volume of data generated by very large phenotyping efforts coupled to DNA sequence data presents an opportunity to reinterpret genetic liability of disease risk. Here we propose a framework to estimate the probability of disease given the presence of a genetic variant conditioned on features of that variant. We refer to this as the penetrance, the fraction of all variant heterozygotes that will present with disease. We demonstrate this methodology using a well-established disease-gene pair, the cardiac sodium channel gene SCN5A and the heart arrhythmia Brugada syndrome. From a review of 756 publications, we developed a pattern mixture algorithm, based on a Bayesian Beta-Binomial model, to generate SCN5A penetrance probabilities for the Brugada syndrome conditioned on variant-specific attributes. These probabilities are determined from variant-specific features (e.g. function, structural context, and sequence conservation) and from observations of affected and unaffected heterozygotes. Variant functional perturbation and structural context prove most predictive of Brugada syndrome penetrance.
Collapse
Affiliation(s)
- Brett M. Kroncke
- Department of Medicine Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pharmacology Vanderbilt University, Nashville, Tennessee, United States of America
| | - Derek K. Smith
- Department of Biostatistics Vanderbilt University, Nashville, Tennessee, United States of America
| | - Yi Zuo
- Department of Biostatistics Vanderbilt University, Nashville, Tennessee, United States of America
| | - Andrew M. Glazer
- Department of Medicine Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Dan M. Roden
- Department of Medicine Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pharmacology Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biomedical Informatics Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jeffrey D. Blume
- Department of Biostatistics Vanderbilt University, Nashville, Tennessee, United States of America
| |
Collapse
|
13
|
Glazer AM, Kroncke BM, Matreyek KA, Yang T, Wada Y, Shields T, Salem JE, Fowler DM, Roden DM. Deep Mutational Scan of an SCN5A Voltage Sensor. Circ Genom Precis Med 2020; 13:e002786. [PMID: 31928070 DOI: 10.1161/circgen.119.002786] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Variants in ion channel genes have classically been studied in low throughput by patch clamping. Deep mutational scanning is a complementary approach that can simultaneously assess function of thousands of variants. METHODS We have developed and validated a method to perform a deep mutational scan of variants in SCN5A, which encodes the major voltage-gated sodium channel in the heart. We created a library of nearly all possible variants in a 36 base region of SCN5A in the S4 voltage sensor of domain IV and stably integrated the library into HEK293T cells. RESULTS In preliminary experiments, challenge with 3 drugs (veratridine, brevetoxin, and ouabain) could discriminate wild-type channels from gain- and loss-of-function pathogenic variants. High-throughput sequencing of the pre- and postdrug challenge pools was used to count the prevalence of each variant and identify variants with abnormal function. The deep mutational scan scores identified 40 putative gain-of-function and 33 putative loss-of-function variants. For 8 of 9 variants, patch clamping data were consistent with the scores. CONCLUSIONS These experiments demonstrate the accuracy of a high-throughput in vitro scan of SCN5A variant function, which can be used to identify deleterious variants in SCN5A and other ion channel genes.
Collapse
Affiliation(s)
- Andrew M Glazer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Brett M Kroncke
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Kenneth A Matreyek
- Department of Genome Sciences, University of Washington, Seattle (K.A.M., D.M.F.)
| | - Tao Yang
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Yuko Wada
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Tiffany Shields
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Joe-Elie Salem
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Clinical Pharmacology, APHP, Sorbonne Université, INSERM, CIC-1421, Hôpital Pitié-Salpêtrière, Paris, France (J.-E.S.)
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle (K.A.M., D.M.F.)
| | - Dan M Roden
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biomedical Informatics (D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Pharmacology (D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| |
Collapse
|
14
|
Kroncke BM, Glazer AM, Smith DK, Blume JD, Roden DM. SCN5A (Na V1.5) Variant Functional Perturbation and Clinical Presentation: Variants of a Certain Significance. Circ Genom Precis Med 2019; 11:e002095. [PMID: 29728395 DOI: 10.1161/circgen.118.002095] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 03/05/2018] [Indexed: 01/20/2023]
Abstract
BACKGROUND Accurately predicting the impact of rare nonsynonymous variants on disease risk is an important goal in precision medicine. Variants in the cardiac sodium channel SCN5A (protein NaV1.5; voltage-dependent cardiac Na+ channel) are associated with multiple arrhythmia disorders, including Brugada syndrome and long QT syndrome. Rare SCN5A variants also occur in ≈1% of unaffected individuals. We hypothesized that in vitro electrophysiological functional parameters explain a statistically significant portion of the variability in disease penetrance. METHODS From a comprehensive literature review, we quantified the number of carriers presenting with and without disease for 1712 reported SCN5A variants. For 356 variants, data were also available for 5 NaV1.5 electrophysiological parameters: peak current, late/persistent current, steady-state V1/2 of activation and inactivation, and recovery from inactivation. RESULTS We found that peak and late current significantly associate with Brugada syndrome (P<0.001; ρ=-0.44; Spearman rank test) and long QT syndrome disease penetrance (P<0.001; ρ=0.37). Steady-state V1/2 activation and recovery from inactivation associate significantly with Brugada syndrome and long QT syndrome penetrance, respectively. Continuous estimates of disease penetrance align with the current American College of Medical Genetics classification paradigm. CONCLUSIONS NaV1.5 in vitro electrophysiological parameters are correlated with Brugada syndrome and long QT syndrome disease risk. Our data emphasize the value of in vitro electrophysiological characterization and incorporating counts of affected and unaffected carriers to aid variant classification. This quantitative analysis of the electrophysiological literature should aid the interpretation of NaV1.5 variant electrophysiological abnormalities and help improve NaV1.5 variant classification.
Collapse
Affiliation(s)
| | | | - Derek K Smith
- Vanderbilt University Medical Center, Nashville, TN. Department of Biostatistics, Vanderbilt University, Nashville, TN (D.K.S., J.D.B.)
| | - Jeffrey D Blume
- Vanderbilt University Medical Center, Nashville, TN. Department of Biostatistics, Vanderbilt University, Nashville, TN (D.K.S., J.D.B.)
| | - Dan M Roden
- Department of Medicine (B.M.K., A.M.G., D.M.R.) .,Department of Biomedical Informatics (D.M.R.).,and Department of Pharmacology (D.M.R.)
| |
Collapse
|
15
|
Chavali NV, Kryshtal DO, Parikh SS, Wang L, Glazer AM, Blackwell DJ, Kroncke BM, Shoemaker MB, Knollmann BC. Patient-independent human induced pluripotent stem cell model: A new tool for rapid determination of genetic variant pathogenicity in long QT syndrome. Heart Rhythm 2019; 16:1686-1695. [PMID: 31004778 DOI: 10.1016/j.hrthm.2019.04.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Commercial genetic testing for long QT syndrome (LQTS) has rapidly expanded, but the inability to accurately predict whether a rare variant is pathogenic has limited its clinical benefit. Novel missense variants are routinely reported as variant of unknown significance (VUS) and cannot be used to screen family members at risk for sudden cardiac death. Better approaches to determine the pathogenicity of VUS are needed. OBJECTIVE The purpose of this study was to rapidly determine the pathogenicity of a CACNA1C variant reported by commercial genetic testing as a VUS using a patient-independent human induced pluripotent stem cell (hiPSC) model. METHODS Using CRISPR/Cas9 genome editing, CACNA1C-p.N639T was introduced into a previously established hiPSC from an unrelated healthy volunteer, thereby generating a patient-independent hiPSC model. Three independent heterozygous N639T hiPSC lines were generated and differentiated into cardiomyocytes (CM). Electrophysiological properties of N639T hiPSC-CM were compared to those of isogenic and population control hiPSC-CM by measuring the extracellular field potential (EFP) of 96-well hiPSC-CM monolayers and by patch clamp. RESULTS Significant EFP prolongation was observed only in optically stimulated but not in spontaneously beating N639T hiPSC-CM. Patch-clamp studies revealed that N639T prolonged the ventricular action potential by slowing voltage-dependent inactivation of CaV1.2 currents. Heterologous expression studies confirmed the effect of N639T on CaV1.2 inactivation. CONCLUSION The patient-independent hiPSC model enabled rapid generation of functional data to support reclassification of a CACNA1C VUS to likely pathogenic, thereby establishing a novel LQTS type 8 mutation. Furthermore, our results indicate the importance of controlling beating rates to evaluate the functional significance of LQTS VUS in high-throughput hiPSC-CM assays.
Collapse
Affiliation(s)
- Nikhil V Chavali
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Dmytro O Kryshtal
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Shan S Parikh
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Lili Wang
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Moore Benjamin Shoemaker
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Bjorn C Knollmann
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee.
| |
Collapse
|
16
|
Kroncke BM, Mendenhall J, Smith DK, Sanders CR, Capra JA, George AL, Blume JD, Meiler J, Roden DM. Protein structure aids predicting functional perturbation of missense variants in SCN5A and KCNQ1. Comput Struct Biotechnol J 2019; 17:206-214. [PMID: 30828412 PMCID: PMC6383132 DOI: 10.1016/j.csbj.2019.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 11/28/2022] Open
Abstract
Rare variants in the cardiac potassium channel KV7.1 (KCNQ1) and sodium channel NaV1.5 (SCN5A) are implicated in genetic disorders of heart rhythm, including congenital long QT and Brugada syndromes (LQTS, BrS), but also occur in reference populations. We previously reported two sets of NaV1.5 (n = 356) and KV7.1 (n = 144) variants with in vitro characterized channel currents gathered from the literature. Here we investigated the ability to predict commonly reported NaV1.5 and KV7.1 variant functional perturbations by leveraging diverse features including variant classifiers PROVEAN, PolyPhen-2, and SIFT; evolutionary rate and BLAST position specific scoring matrices (PSSM); and structure-based features including “functional densities” which is a measure of the density of pathogenic variants near the residue of interest. Structure-based functional densities were the most significant features for predicting NaV1.5 peak current (adj. R2 = 0.27) and KV7.1 + KCNE1 half-maximal voltage of activation (adj. R2 = 0.29). Additionally, use of structure-based functional density values improves loss-of-function classification of SCN5A variants with an ROC-AUC of 0.78 compared with other predictive classifiers (AUC = 0.69; two-sided DeLong test p = .01). These results suggest structural data can inform predictions of the effect of uncharacterized SCN5A and KCNQ1 variants to provide a deeper understanding of their burden on carriers.
Collapse
Affiliation(s)
- Brett M Kroncke
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jeffrey Mendenhall
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.,Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Derek K Smith
- Department of Biostatistics, Vanderbilt University, Nashville, TN 37240, USA
| | - Charles R Sanders
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.,Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - John A Capra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.,Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37235, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jeffrey D Blume
- Department of Biostatistics, Vanderbilt University, Nashville, TN 37240, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.,Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37235, USA.,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| |
Collapse
|
17
|
Abstract
BACKGROUND We recently reported a quantitative relationship between the degree of functional perturbation reported in the literature for 356 variants in the cardiac sodium channel gene SCN5A and the penetrance of resulting arrhythmia phenotypes. In the course of that work, we identified multiple SCN5A variants, including R1193Q, that are common in populations but are reported in human embryonic kidney (HEK) cells to generate large late sodium current (INa-L). OBJECTIVE The purpose of this study was to compare the functional properties of R1193Q with those of the well-studied type 3 long QT syndrome mutation ΔKPQ. METHODS We compared functional properties of SCN5A R1193Q with those of ΔKPQ in Chinese hamster ovary (CHO) cells at baseline and after exposure to intracellular phosphatidylinositol (3,4,5)-trisphosphate (PIP3), which inhibits INa-L generated by decreased Phosphoinositide 3-kinase (PI3K) activity. We also used CRISPR/Cas9 editing to generate R1193Q in human-induced pluripotent stem cells differentiated to cardiomyocytes (hiPSC-CMs). RESULTS Both R1193Q and ΔKPQ generated robust INa-L in CHO cells. PIP3 abrogated the late current phenotype in R1193Q cells but had no effect on ΔKPQ. Homozygous R1193Q hiPSC-CMs displayed increased INa-L and long action potentials with frequent triggered beats, which were reversed with the addition of PIP3. CONCLUSION The consistency between the late current produced in HEK cells, CHO cells, and hiPSC-CMs suggests that the late current is a feature of the SCN5A R1193Q variant in human cardiomyocytes but that the mechanism by which the late current is produced is distinct and indirect, as compared with the more highly penetrant ΔKPQ. These data suggest that observing a late current in an in vitro setting does not necessarily translate to highly pathogenic type 3 long QT syndrome phenotype but depends on the underlying mechanism.
Collapse
Affiliation(s)
- Brett M Kroncke
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| |
Collapse
|
18
|
Li B, Mendenhall JL, Kroncke BM, Taylor KC, Huang H, Smith DK, Vanoye CG, Blume JD, George AL, Sanders CR, Meiler J. Predicting the Functional Impact of KCNQ1 Variants of Unknown Significance. ACTA ACUST UNITED AC 2018; 10:CIRCGENETICS.117.001754. [PMID: 29021305 DOI: 10.1161/circgenetics.117.001754] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 08/24/2017] [Indexed: 12/22/2022]
Abstract
BACKGROUND An emerging standard-of-care for long-QT syndrome uses clinical genetic testing to identify genetic variants of the KCNQ1 potassium channel. However, interpreting results from genetic testing is confounded by the presence of variants of unknown significance for which there is inadequate evidence of pathogenicity. METHODS AND RESULTS In this study, we curated from the literature a high-quality set of 107 functionally characterized KCNQ1 variants. Based on this data set, we completed a detailed quantitative analysis on the sequence conservation patterns of subdomains of KCNQ1 and the distribution of pathogenic variants therein. We found that conserved subdomains generally are critical for channel function and are enriched with dysfunctional variants. Using this experimentally validated data set, we trained a neural network, designated Q1VarPred, specifically for predicting the functional impact of KCNQ1 variants of unknown significance. The estimated predictive performance of Q1VarPred in terms of Matthew's correlation coefficient and area under the receiver operating characteristic curve were 0.581 and 0.884, respectively, superior to the performance of 8 previous methods tested in parallel. Q1VarPred is publicly available as a web server at http://meilerlab.org/q1varpred. CONCLUSIONS Although a plethora of tools are available for making pathogenicity predictions over a genome-wide scale, previous tools fail to perform in a robust manner when applied to KCNQ1. The contrasting and favorable results for Q1VarPred suggest a promising approach, where a machine-learning algorithm is tailored to a specific protein target and trained with a functionally validated data set to calibrate informatics tools.
Collapse
Affiliation(s)
- Bian Li
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Jeffrey L Mendenhall
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Brett M Kroncke
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Keenan C Taylor
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Hui Huang
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Derek K Smith
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Carlos G Vanoye
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Jeffrey D Blume
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Alfred L George
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Charles R Sanders
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.)
| | - Jens Meiler
- From the Department of Chemistry (B.L., J.L.M., J.M.), Center for Structural Biology (B.L., J.L.M., B.M.K., K.C.T., H.H., C.R.S., J.M.), Department of Biochemistry (B.M.K., H.H., C.R.S.), and Department of Biostatistics (D.K.S., J.D.B.), Vanderbilt University, Nashville, TN; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (B.M.K., C.R.S.); and Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (C.G.V., A.L.G.).
| |
Collapse
|
19
|
Johnson CN, Potet F, Thompson MK, Kroncke BM, Glazer AM, Voehler MW, Knollmann BC, George AL, Chazin WJ. A Mechanism of Calmodulin Modulation of the Human Cardiac Sodium Channel. Structure 2018; 26:683-694.e3. [PMID: 29606593 DOI: 10.1016/j.str.2018.03.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/26/2018] [Accepted: 03/08/2018] [Indexed: 12/26/2022]
Abstract
The function of the human cardiac sodium channel (NaV1.5) is modulated by the Ca2+ sensor calmodulin (CaM), but the underlying mechanism(s) are controversial and poorly defined. CaM has been reported to bind in a Ca2+-dependent manner to two sites in the intracellular loop that is critical for inactivation of NaV1.5 (inactivation gate [IG]). The affinity of CaM for the complete IG was significantly stronger than that of fragments that lacked both complete binding sites. Structural analysis by nuclear magnetic resonance, crystallographic, and scattering approaches revealed that CaM simultaneously engages both IG sites using an extended configuration. Patch-clamp recordings for wild-type and mutant channels with an impaired CaM-IG interaction revealed CaM binding to the IG promotes recovery from inactivation while impeding the kinetics of inactivation. Models of full-length NaV1.5 suggest that CaM binding to the IG directly modulates channel function by destabilizing the inactivated state, which would promote resetting of the IG after channels close.
Collapse
Affiliation(s)
- Christopher N Johnson
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37240, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN 37205, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Center for Arrhythmia Research and Therapeutics, Vanderbilt University, Nashville, TN 37240, USA.
| | - Franck Potet
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Matthew K Thompson
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37205, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Brett M Kroncke
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37240, USA; Center for Arrhythmia Research and Therapeutics, Vanderbilt University, Nashville, TN 37240, USA
| | - Andrew M Glazer
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37240, USA; Center for Arrhythmia Research and Therapeutics, Vanderbilt University, Nashville, TN 37240, USA
| | - Markus W Voehler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Bjorn C Knollmann
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37240, USA; Center for Arrhythmia Research and Therapeutics, Vanderbilt University, Nashville, TN 37240, USA
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Walter J Chazin
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37205, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
| |
Collapse
|
20
|
Deatherage CL, Lu Z, Kroncke BM, Ma S, Smith JA, Voehler MW, McFeeters RL, Sanders CR. Structural and biochemical differences between the Notch and the amyloid precursor protein transmembrane domains. Sci Adv 2017; 3:e1602794. [PMID: 28439555 PMCID: PMC5389784 DOI: 10.1126/sciadv.1602794] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/13/2017] [Indexed: 05/11/2023]
Abstract
γ-Secretase cleavage of the Notch receptor transmembrane domain is a critical signaling event for various cellular processes. Efforts to develop inhibitors of γ-secretase cleavage of the amyloid-β precursor C99 protein as potential Alzheimer's disease therapeutics have been confounded by toxicity resulting from the inhibition of normal cleavage of Notch. We present biochemical and structural data for the combined transmembrane and juxtamembrane Notch domains (Notch-TMD) that illuminate Notch signaling and that can be compared and contrasted with the corresponding traits of C99. The Notch-TMD and C99 have very different conformations, adapt differently to changes in model membrane hydrophobic span, and exhibit different cholesterol-binding properties. These differences may be exploited in the design of agents that inhibit cleavage of C99 while allowing Notch cleavage.
Collapse
Affiliation(s)
- Catherine L. Deatherage
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Zhenwei Lu
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Brett M. Kroncke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Sirui Ma
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Jarrod A. Smith
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Markus W. Voehler
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Robert L. McFeeters
- Department of Chemistry, University of Alabama in Huntsville, Huntsville, AL 35899, USA
| | - Charles R. Sanders
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
- Center for Structural Biology and Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Corresponding author.
| |
Collapse
|
21
|
Kroncke BM, Van Horn WD, Smith J, Kang C, Welch RC, Song Y, Nannemann DP, Taylor KC, Sisco NJ, George AL, Meiler J, Vanoye CG, Sanders CR. Structural basis for KCNE3 modulation of potassium recycling in epithelia. Sci Adv 2016; 2:e1501228. [PMID: 27626070 PMCID: PMC5017827 DOI: 10.1126/sciadv.1501228] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 08/10/2016] [Indexed: 05/25/2023]
Abstract
The single-span membrane protein KCNE3 modulates a variety of voltage-gated ion channels in diverse biological contexts. In epithelial cells, KCNE3 regulates the function of the KCNQ1 potassium ion (K(+)) channel to enable K(+) recycling coupled to transepithelial chloride ion (Cl(-)) secretion, a physiologically critical cellular transport process in various organs and whose malfunction causes diseases, such as cystic fibrosis (CF), cholera, and pulmonary edema. Structural, computational, biochemical, and electrophysiological studies lead to an atomically explicit integrative structural model of the KCNE3-KCNQ1 complex that explains how KCNE3 induces the constitutive activation of KCNQ1 channel activity, a crucial component in K(+) recycling. Central to this mechanism are direct interactions of KCNE3 residues at both ends of its transmembrane domain with residues on the intra- and extracellular ends of the KCNQ1 voltage-sensing domain S4 helix. These interactions appear to stabilize the activated "up" state configuration of S4, a prerequisite for full opening of the KCNQ1 channel gate. In addition, the integrative structural model was used to guide electrophysiological studies that illuminate the molecular basis for how estrogen exacerbates CF lung disease in female patients, a phenomenon known as the "CF gender gap."
Collapse
Affiliation(s)
- Brett M. Kroncke
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Wade D. Van Horn
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
- Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
- Center for Personalized Diagnostics, Arizona State University, Tempe, AZ 85287, USA
| | - Jarrod Smith
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - CongBao Kang
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Experimental Therapeutics Centre, Agency for Science Technology and Research, Singapore, Singapore
| | - Richard C. Welch
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - Yuanli Song
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - David P. Nannemann
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Keenan C. Taylor
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Nicholas J. Sisco
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
- Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
- Center for Personalized Diagnostics, Arizona State University, Tempe, AZ 85287, USA
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Carlos G. Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Charles R. Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| |
Collapse
|
22
|
Kroncke BM, Duran AM, Mendenhall JL, Meiler J, Blume JD, Sanders CR. Documentation of an Imperative To Improve Methods for Predicting Membrane Protein Stability. Biochemistry 2016; 55:5002-9. [PMID: 27564391 PMCID: PMC5024705 DOI: 10.1021/acs.biochem.6b00537] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
There
is a compelling and growing need to accurately predict the
impact of amino acid mutations on protein stability for problems in
personalized medicine and other applications. Here the ability of
10 computational tools to accurately predict mutation-induced perturbation
of folding stability (ΔΔG) for membrane
proteins of known structure was assessed. All methods for predicting
ΔΔG values performed significantly worse
when applied to membrane proteins than when applied to soluble proteins,
yielding estimated concordance, Pearson, and Spearman correlation
coefficients of <0.4 for membrane proteins. Rosetta and PROVEAN
showed a modest ability to classify mutations as destabilizing (ΔΔG < −0.5 kcal/mol), with a 7 in 10 chance of correctly
discriminating a randomly chosen destabilizing variant from a randomly
chosen stabilizing variant. However, even this performance is significantly
worse than for soluble proteins. This study highlights the need for
further development of reliable and reproducible methods for predicting
thermodynamic folding stability in membrane proteins.
Collapse
Affiliation(s)
- Brett M Kroncke
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Amanda M Duran
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jeffrey L Mendenhall
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jens Meiler
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jeffrey D Blume
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Charles R Sanders
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| |
Collapse
|
23
|
Huang H, Taylor KC, Kroncke BM, George AL, Sanders CR. Impact of Mutations on the Structure of the Human Potassium Channel KCNQ1. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
24
|
Sahu ID, Craig AF, Dunagan MM, Troxel KR, Zhang R, Meiberg AG, Harmon CN, McCarrick RM, Kroncke BM, Sanders CR, Lorigan GA. Probing Structural Dynamics and Topology of the KCNE1 Membrane Protein in Lipid Bilayers via Site-Directed Spin Labeling and Electron Paramagnetic Resonance Spectroscopy. Biochemistry 2015; 54:6402-12. [PMID: 26418890 DOI: 10.1021/acs.biochem.5b00505] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
KCNE1 is a single transmembrane protein that modulates the function of voltage-gated potassium channels, including KCNQ1. Hereditary mutations in the genes encoding either protein can result in diseases such as congenital deafness, long QT syndrome, ventricular tachyarrhythmia, syncope, and sudden cardiac death. Despite the biological significance of KCNE1, the structure and dynamic properties of its physiologically relevant native membrane-bound state are not fully understood. In this study, the structural dynamics and topology of KCNE1 in bilayered lipid vesicles was investigated using site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) spectroscopy. A 53-residue nitroxide EPR scan of the KCNE1 protein sequence including all 27 residues of the transmembrane domain (45-71) and 26 residues of the N- and C-termini of KCNE1 in lipid bilayered vesicles was analyzed in terms of nitroxide side-chain motion. Continuous wave-EPR spectral line shape analysis indicated the nitroxide spin label side-chains located in the KCNE1 TMD are less mobile when compared to the extracellular region of KCNE1. The EPR data also revealed that the C-terminus of KCNE1 is more mobile when compared to the N-terminus. EPR power saturation experiments were performed on 41 sites including 18 residues previously proposed to reside in the transmembrane domain (TMD) and 23 residues of the N- and C-termini to determine the topology of KCNE1 with respect to the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) lipid bilayers. The results indicated that the transmembrane domain is indeed buried within the membrane, spanning the width of the lipid bilayer. Power saturation data also revealed that the extracellular region of KCNE1 is solvent-exposed with some of the portions partially or weakly interacting with the membrane surface. These results are consistent with the previously published solution NMR structure of KCNE1 in micelles.
Collapse
Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Andrew F Craig
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Megan M Dunagan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Kaylee R Troxel
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Rongfu Zhang
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Andrew G Meiberg
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Corrinne N Harmon
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Brett M Kroncke
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37232, United States
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37232, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| |
Collapse
|
25
|
Lo RH, Kroncke BM, Solomon TL, Columbus L. Mapping membrane protein backbone dynamics: a comparison of site-directed spin labeling with NMR 15N-relaxation measurements. Biophys J 2015; 107:1697-702. [PMID: 25296323 DOI: 10.1016/j.bpj.2014.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 08/15/2014] [Accepted: 08/19/2014] [Indexed: 11/26/2022] Open
Abstract
The ability to detect nanosecond backbone dynamics with site-directed spin labeling (SDSL) in soluble proteins has been well established. However, for membrane proteins, the nitroxide appears to have more interactions with the protein surface, potentially hindering the sensitivity to backbone motions. To determine whether membrane protein backbone dynamics could be mapped with SDSL, a nitroxide was introduced at 55 independent sites in a model polytopic membrane protein, TM0026. Electron paramagnetic resonance spectral parameters were compared with NMR (15)N-relaxation data. Sequential scans revealed backbone dynamics with the same trends observed for the R1 relaxation rate, suggesting that nitroxide dynamics remain coupled to the backbone on membrane proteins.
Collapse
Affiliation(s)
- Ryan H Lo
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Brett M Kroncke
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Tsega L Solomon
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, Virginia.
| |
Collapse
|
26
|
Abstract
![]()
Whole human genome sequencing of
individuals is becoming rapid
and inexpensive, enabling new strategies for using personal genome
information to help diagnose, treat, and even prevent human disorders
for which genetic variations are causative or are known to be risk
factors. Many of the exploding number of newly discovered genetic
variations alter the structure, function, dynamics, stability, and/or
interactions of specific proteins and RNA molecules. Accordingly,
there are a host of opportunities for biochemists and biophysicists
to participate in (1) developing tools to allow accurate and sometimes
medically actionable assessment of the potential pathogenicity of
individual variations and (2) establishing the mechanistic linkage
between pathogenic variations and their physiological consequences,
providing a rational basis for treatment or preventive care. In this
review, we provide an overview of these opportunities and their associated
challenges in light of the current status of genomic science and personalized
medicine, the latter often termed precision medicine.
Collapse
Affiliation(s)
- Brett M Kroncke
- †Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States.,‡Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Carlos G Vanoye
- §Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
| | - Jens Meiler
- ‡Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States.,∥Departments of Chemistry, Pharmacology, and Bioinformatics, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Alfred L George
- §Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
| | - Charles R Sanders
- †Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States.,‡Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| |
Collapse
|
27
|
Sahu ID, Kroncke BM, Dunagan MM, Zhang R, Craig A, Wang K, Bali A, McCarrick RM, Sanders CR, Lorigan GA. EPR Spectroscopic Study of the Voltage-Sensor Domain (VSD) of the Human KCNQ1 Potassium Ion Channel. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.3351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
28
|
Sahu ID, Kroncke BM, Zhang R, Dunagan MM, Smith HJ, Craig A, McCarrick RM, Sanders CR, Lorigan GA. Structural investigation of the transmembrane domain of KCNE1 in proteoliposomes. Biochemistry 2014; 53:6392-401. [PMID: 25234231 PMCID: PMC4196734 DOI: 10.1021/bi500943p] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
KCNE1 is a single-transmembrane protein
of the KCNE family that modulates the function of voltage-gated potassium
channels, including KCNQ1. Hereditary mutations in KCNE1 have been
linked to diseases such as long QT syndrome (LQTS), atrial fibrillation,
sudden infant death syndrome, and deafness. The transmembrane domain
(TMD) of KCNE1 plays a key role in mediating the physical association
with KCNQ1 and in subsequent modulation of channel gating kinetics
and conductance. However, the mechanisms associated with these roles
for the TMD remain poorly understood, highlighting a need for experimental
structural studies. A previous solution NMR study of KCNE1 in LMPG
micelles revealed a curved transmembrane domain, a structural feature
proposed to be critical to KCNE1 function. However, this curvature
potentially reflects an artifact of working in detergent micelles.
Double electron electron resonance (DEER) measurements were conducted
on KCNE1 in LMPG micelles, POPC/POPG proteoliposomes, and POPC/POPG
lipodisq nanoparticles to directly compare the structure of the TMD
in a variety of different membrane environments. Experimentally derived
DEER distances coupled with simulated annealing molecular dynamic
simulations were used to probe the bilayer structure of the TMD of
KCNE1. The results indicate that the structure is helical in proteoliposomes
and is slightly curved, which is consistent with the previously determined
solution NMR structure in micelles. The evident resilience of the
curvature in the KCNE1 TMD leads us to hypothesize that the curvature
is likely to be maintained upon binding of the protein to the KCNQ1
channel.
Collapse
Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Mittendorf KF, Kroncke BM, Meiler J, Sanders CR. The homology model of PMP22 suggests mutations resulting in peripheral neuropathy disrupt transmembrane helix packing. Biochemistry 2014; 53:6139-41. [PMID: 25243937 PMCID: PMC4188248 DOI: 10.1021/bi500809t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
Peripheral myelin protein 22 (PMP22)
is a tetraspan membrane protein
strongly expressed in myelinating Schwann cells of the peripheral
nervous system. Myriad missense mutations in PMP22 result in varying
degrees of peripheral neuropathy. We used Rosetta 3.5 to generate
a homology model of PMP22 based on the recently published crystal
structure of claudin-15. The model suggests that several mutations
known to result in neuropathy act by disrupting transmembrane helix
packing interactions. Our model also supports suggestions from previous
studies that the first transmembrane helix is not tightly associated
with the rest of the helical bundle.
Collapse
Affiliation(s)
- Kathleen F Mittendorf
- Department of Biochemistry, ‡Center for Structural Biology, and §Departments of Pharmacology and Bioinformatics, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
| | | | | | | |
Collapse
|
30
|
Fox D, Larsson P, Lo RH, Kroncke BM, Kasson PM, Columbus L. Structure of the Neisserial outer membrane protein Opa₆₀: loop flexibility essential to receptor recognition and bacterial engulfment. J Am Chem Soc 2014; 136:9938-46. [PMID: 24813921 PMCID: PMC4105060 DOI: 10.1021/ja503093y] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 03/27/2014] [Indexed: 12/27/2022]
Abstract
The structure and dynamics of Opa proteins, which we report herein, are responsible for the receptor-mediated engulfment of Neisseria gonorrheae or Neisseria meningitidis by human cells and can offer deep understanding into the molecular recognition of pathogen-host receptor interactions. Such interactions are vital to understanding bacterial pathogenesis as well as the mechanism of foreign body entry to a human cell, which may provide insights for the development of targeted pharmaceutical delivery systems. The size and dynamics of the extracellular loops of Opa60 required a hybrid refinement approach wherein membrane and distance restraints were used to generate an initial NMR structural ensemble, which was then further refined using molecular dynamics in a DMPC bilayer. The resulting ensemble revealed that the extracellular loops, which bind host receptors, occupy compact conformations, interact with each other weakly, and are dynamic on the nanosecond time scale. We predict that this conformational sampling is critical for enabling diverse Opa loop sequences to engage a common set of receptors.
Collapse
Affiliation(s)
- Daniel
A. Fox
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Per Larsson
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
| | - Ryan H. Lo
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Brett M. Kroncke
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Peter M. Kasson
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
| | - Linda Columbus
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
| |
Collapse
|
31
|
Peng D, Kim JH, Kroncke BM, Law CL, Xia Y, Droege KD, Van Horn WD, Vanoye CG, Sanders CR. Purification and structural study of the voltage-sensor domain of the human KCNQ1 potassium ion channel. Biochemistry 2014; 53:2032-42. [PMID: 24606221 PMCID: PMC3977583 DOI: 10.1021/bi500102w] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
KCNQ1 (also known as KV7.1 or KVLQT1) is a voltage-gated potassium channel modulated by members of the KCNE protein family. Among multiple functions, KCNQ1 plays a critical role in the cardiac action potential. This channel is also subject to inherited mutations that cause certain cardiac arrhythmias and deafness. In this study, we report the overexpression, purification, and preliminary structural characterization of the voltage-sensor domain (VSD) of human KCNQ1 (Q1-VSD). Q1-VSD was expressed in Escherichia coli and purified into lyso-palmitoylphosphatidylglycerol micelles, conditions under which this tetraspan membrane protein yields excellent nuclear magnetic resonance (NMR) spectra. NMR studies reveal that Q1-VSD shares a common overall topology with other channel VSDs, with an S0 helix followed by transmembrane helices S1-S4. The exact sequential locations of the helical spans do, however, show significant variations from those of the homologous segments of previously characterized VSDs. The S4 segment of Q1-VSD was seen to be α-helical (with no 310 component) and underwent rapid backbone amide H-D exchange over most of its length. These results lay the foundation for more advanced structural studies and can be used to generate testable hypotheses for future structure-function experiments.
Collapse
Affiliation(s)
- Dungeng Peng
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Sahu ID, Kroncke BM, McCarrick RM, Dunagan MM, Zhang R, Craig A, Smith HJ, Sanders CR, Lorigan GA. Structure Refinement of the Transmembrane Domain (TMD) of KCNE1 Protein using Deer Spectroscopy. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
33
|
Kroncke BM, Van Horn W, Vanoye C, Nannemann D, Meiler J, Sanders C. A Model of Human Potassium Channel KCNQ1 Modulation by Accessory Protein KCNE3. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
34
|
Kroncke BM, Columbus L. Backbone ¹H, ¹³C and ¹⁵N resonance assignments of the α-helical membrane protein TM0026 from Thermotoga maritima. Biomol NMR Assign 2013; 7:203-206. [PMID: 23011877 PMCID: PMC3543498 DOI: 10.1007/s12104-012-9410-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 07/16/2012] [Indexed: 06/01/2023]
Abstract
Critical to the use of solution NMR to describe the structure and flexibility of membrane proteins is the thorough understanding of the degree of perturbation induced by the detergent or other membrane mimetic. To develop a deeper understanding of the interaction between membrane proteins and micelles or bicelles, we will investigate the differences in structure and flexibility of a model membrane protein TM0026 from Thermotoga maritima using solution NMR. A comparison of the structural differences between TM0026 solubilized in different detergent combinations will provide important insight into the degree of modulation of membrane proteins by detergent physical properties. Here we report the nearly complete backbone and Cβ resonance assignments of the two transmembrane helical model protein TM0026. These assignments are the first step to using TM0026 to elucidate the interaction between membrane proteins and membrane mimetics.
Collapse
Affiliation(s)
| | - Linda Columbus
- To whom correspondence should be addressed. Linda Columbus: University of Virginia, Department of Chemistry, McCormick Rd, Charlottesville, VA, 22904, phone: (434) 243-2123, fax: (434) 924-3710,
| |
Collapse
|
35
|
Sahu ID, McCarrick RM, Troxel KR, Zhang R, Smith HJ, Dunagan MM, Swartz MS, Rajan PV, Kroncke BM, Sanders CR, Lorigan GA. DEER EPR measurements for membrane protein structures via bifunctional spin labels and lipodisq nanoparticles. Biochemistry 2013; 52:6627-32. [PMID: 23984855 DOI: 10.1021/bi4009984] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Pulsed EPR DEER structural studies of membrane proteins in a lipid bilayer have often been hindered by difficulties in extracting accurate distances when compared to those of globular proteins. In this study, we employed a combination of three recently developed methodologies, (1) bifunctional spin labels (BSL), (2) SMA-Lipodisq nanoparticles, and (3) Q band pulsed EPR measurements, to obtain improved signal sensitivity, increased transverse relaxation time, and more accurate and precise distances in DEER measurements on the integral membrane protein KCNE1. The KCNE1 EPR data indicated an ∼2-fold increase in the transverse relaxation time for the SMA-Lipodisq nanoparticles when compared to those of proteoliposomes and narrower distance distributions for the BSL when compared to those of the standard MTSL. The certainty of information content in DEER data obtained for KCNE1 in SMA-Lipodisq nanoparticles is comparable to that in micelles. The combination of techniques will enable researchers to potentially obtain more precise distances in cases where the traditional spin labels and membrane systems yield imprecise distance distributions.
Collapse
Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Schlebach JP, Peng D, Kroncke BM, Mittendorf KF, Narayan M, Carter BD, Sanders CR. Reversible folding of human peripheral myelin protein 22, a tetraspan membrane protein. Biochemistry 2013; 52:3229-41. [PMID: 23639031 DOI: 10.1021/bi301635f] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Misfolding of the α-helical membrane protein peripheral myelin protein 22 (PMP22) has been implicated in the pathogenesis of the common neurodegenerative disease known as Charcot-Marie-Tooth disease (CMTD) and also several other related peripheral neuropathies. Emerging evidence suggests that the propensity of PMP22 to misfold in the cell may be due to an intrinsic lack of conformational stability. Therefore, quantitative studies of the conformational equilibrium of PMP22 are needed to gain insight into the molecular basis of CMTD. In this work, we have investigated the folding and unfolding of wild type (WT) human PMP22 in mixed micelles. Both kinetic and thermodynamic measurements demonstrate that the denaturation of PMP22 by n-lauroyl sarcosine (LS) in dodecylphosphocholine (DPC) micelles is reversible. Assessment of the conformational equilibrium indicates that a significant fraction of unfolded PMP22 persists even in the absence of the denaturing detergent. However, we find the stability of PMP22 is increased by glycerol, which facilitates quantitation of thermodynamic parameters. To our knowledge, this work represents the first report of reversible unfolding of a eukaryotic multispan membrane protein. The results indicate that WT PMP22 possesses minimal conformational stability in micelles, which parallels its poor folding efficiency in the endoplasmic reticulum. Folding equilibrium measurements for PMP22 in micelles may provide an approach to assess the effects of cellular metabolites or potential therapeutic agents on its stability. Furthermore, these results pave the way for future investigation of the effects of pathogenic mutations on the conformational equilibrium of PMP22.
Collapse
Affiliation(s)
- Jonathan P Schlebach
- Department of Biochemistry and ‡Center for Structural Biology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
| | | | | | | | | | | | | |
Collapse
|
37
|
Johnstone SR, Kroncke BM, Straub AC, Best AK, Dunn CA, Mitchell LA, Peskova Y, Nakamoto RK, Koval M, Lo CW, Lampe PD, Columbus L, Isakson BE. MAPK phosphorylation of connexin 43 promotes binding of cyclin E and smooth muscle cell proliferation. Circ Res 2012; 111:201-11. [PMID: 22652908 DOI: 10.1161/circresaha.112.272302] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
RATIONALE Dedifferentiation of vascular smooth muscle cells (VSMC) leading to a proliferative cell phenotype significantly contributes to the development of atherosclerosis. Mitogen-activated protein kinase (MAPK) phosphorylation of proteins including connexin 43 (Cx43) has been associated with VSMC proliferation in atherosclerosis. OBJECTIVE To investigate whether MAPK phosphorylation of Cx43 is directly involved in VSMC proliferation. METHODS AND RESULTS We show in vivo that MAPK-phosphorylated Cx43 forms complexes with the cell cycle control proteins cyclin E and cyclin-dependent kinase 2 (CDK2) in carotids of apolipoprotein-E receptor null (ApoE(-/-)) mice and in C57Bl/6 mice treated with platelet-derived growth factor-BB (PDGF). We tested the involvement of Cx43 MAPK phosphorylation in vitro using constructs for full-length Cx43 (Cx43) or the Cx43 C-terminus (Cx43(CT)) and produced null phosphorylation Ser>Ala (Cx43(MK4A)/Cx43(CTMK4A)) and phospho-mimetic Ser>Asp (Cx43(MK4D)/Cx43(CTMK4D)) mutations. Coimmunoprecipitation studies in primary VSMC isolated from Cx43 wild-type (Cx43(+/+)) and Cx43 null (Cx43(-/-)) mice and analytic size exclusion studies of purified proteins identify that interactions between cyclin E and Cx43 requires Cx43 MAPK phosphorylation. We further demonstrate that Cx43 MAPK phosphorylation is required for PDGF-mediated VSMC proliferation. Finally, using a novel knock-in mouse containing Cx43-MK4A mutation, we show in vivo that interactions between Cx43 and cyclin E are lost and VSMC proliferation does not occur after treatment of carotids with PDGF and that neointima formation is significantly reduced in carotids after injury. CONCLUSIONS We identify MAPK-phosphorylated Cx43 as a novel interacting partner of cyclin E in VSMC and show that this interaction is critical for VSMC proliferation. This novel interaction may be important in the development of atherosclerotic lesions.
Collapse
Affiliation(s)
- Scott R Johnstone
- Robert M. Berne Cardiovascular Research Center, Charlottesville, VA 22908, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Johnstone SR, Kroncke BM, Straub AC, Best AK, Dunn CA, Koval M, Lampe PD, Columbus L, Isakson BE. MAPK phosphorylation of connexin 43 promotes binding of cyclin E and smooth muscle cell proliferation. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.870.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Brett M Kroncke
- Department of ChemistryUniversity of VirginiaCharlottesvilleVA
| | - Adam C Straub
- Cardiovascular Research CentreUniversity of VirginiaCharlottesvilleVA
| | - Angela K Best
- Cardiovascular Research CentreUniversity of VirginiaCharlottesvilleVA
| | | | - Michael Koval
- Dept of Pulmonary, Allergy and Critical Care MedicineUniversity of EmoryAtlantaGA
| | | | - Linda Columbus
- Department of ChemistryUniversity of VirginiaCharlottesvilleVA
| | - Brant E Isakson
- Cardiovascular Research CentreUniversity of VirginiaCharlottesvilleVA
- Department of Molecular Physiology and Biological PhysicsUniversity of VirginiaCharlottesvilleVA
| |
Collapse
|
39
|
Kroncke BM, Columbus L. Identification and removal of nitroxide spin label contaminant: impact on PRE studies of α-helical membrane proteins in detergent. Protein Sci 2012; 21:589-95. [PMID: 22389096 DOI: 10.1002/pro.2038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 01/23/2012] [Accepted: 01/24/2012] [Indexed: 11/06/2022]
Abstract
NMR paramagnetic relaxation enhancement (PRE) provides long-range distance constraints (~15-25 Å) that can be critical to determining overall protein topology, especially where long-range NOE information is unavailable such as in the case of larger proteins that require deuteration. However, several challenges currently limit the use of NMR PRE for α-helical membrane proteins. One challenge is the nonspecific association of the nitroxide spin label to the protein-detergent complex that can result in spurious PRE derived distance restraints. The effect of the nitroxide spin label contaminant is evaluated and quantified and a robust method for the removal of the contaminant is provided to advance the application of PRE restraints to membrane protein NMR structure determination.
Collapse
Affiliation(s)
- Brett M Kroncke
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA
| | | |
Collapse
|
40
|
Kroncke BM, Kim J, Columbus LM. Nitroxide Spin Label Side Chain Dynamics of Solvent Exposed Sites on Membrane Proteins. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
|
41
|
Abstract
Understanding the structure and dynamics of membrane proteins in their native, hydrophobic environment is important to understanding how these proteins function. EPR spectroscopy in combination with site-directed spin labeling (SDSL) can measure dynamics and structure of membrane proteins in their native lipid environment; however, until now the dynamics measured have been qualitative due to limited knowledge of the nitroxide spin label's intramolecular motion in the hydrophobic environment. Although several studies have elucidated the structural origins of EPR line shapes of water-soluble proteins, EPR spectra of nitroxide spin-labeled proteins in detergents or lipids have characteristic differences from their water-soluble counterparts, suggesting significant differences in the underlying molecular motion of the spin label between the two environments. To elucidate these differences, membrane-exposed α-helical sites of the leucine transporter, LeuT, from Aquifex aeolicus, were investigated using X-ray crystallography, mutational analysis, nitroxide side chain derivatives, and spectral simulations in order to obtain a motional model of the nitroxide. For each crystal structure, the nitroxide ring of a disulfide-linked spin label side chain (R1) is resolved and makes contacts with hydrophobic residues on the protein surface. The spin label at site I204 on LeuT makes a nontraditional hydrogen bond with the ortho-hydrogen on its nearest neighbor F208, whereas the spin label at site F177 makes multiple van der Waals contacts with a hydrophobic pocket formed with an adjacent helix. These results coupled with the spectral effect of mutating the i ± 3, 4 residues suggest that the spin label has a greater affinity for its local protein environment in the low dielectric than on a water-soluble protein surface. The simulations of the EPR spectra presented here suggest the spin label oscillates about the terminal bond nearest the ring while maintaining weak contact with the protein surface. Combined, the results provide a starting point for determining a motional model for R1 on membrane proteins, allowing quantification of nitroxide dynamics in the aliphatic environment of detergent and lipids. In addition, initial contributions to a rotamer library of R1 on membrane proteins are provided, which will assist in reliably modeling the R1 conformational space for pulsed dipolar EPR and NMR paramagnetic relaxation enhancement distance determination.
Collapse
Affiliation(s)
- Brett M Kroncke
- Department of Chemistry, University of Virginia,Charlottesville, Virginia 22904, United States
| | | | | |
Collapse
|