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Markandeya YS, Gregorich ZR, Feng L, Ramchandran V, O' Hara T, Vaidyanathan R, Mansfield C, Keefe AM, Beglinger CJ, Best JM, Kalscheur MM, Lea MR, Hacker TA, Gorelik J, Trayanova NA, Eckhardt LL, Makielski JC, Balijepalli RC, Kamp TJ. Caveolin-3 and Caveolae regulate ventricular repolarization. J Mol Cell Cardiol 2023; 177:38-49. [PMID: 36842733 PMCID: PMC10065933 DOI: 10.1016/j.yjmcc.2023.02.005] [Citation(s) in RCA: 3] [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] [Received: 07/02/2021] [Revised: 02/03/2023] [Accepted: 02/21/2023] [Indexed: 02/28/2023]
Abstract
RATIONALE Flask-shaped invaginations of the cardiomyocyte sarcolemma called caveolae require the structural protein caveolin-3 (Cav-3) and host a variety of ion channels, transporters, and signaling molecules. Reduced Cav-3 expression has been reported in models of heart failure, and variants in CAV3 have been associated with the inherited long-QT arrhythmia syndrome. Yet, it remains unclear whether alterations in Cav-3 levels alone are sufficient to drive aberrant repolarization and increased arrhythmia risk. OBJECTIVE To determine the impact of cardiac-specific Cav-3 ablation on the electrophysiological properties of the adult mouse heart. METHODS AND RESULTS Cardiac-specific, inducible Cav3 homozygous knockout (Cav-3KO) mice demonstrated a marked reduction in Cav-3 expression by Western blot and loss of caveolae by electron microscopy. However, there was no change in macroscopic cardiac structure or contractile function. The QTc interval was increased in Cav-3KO mice, and there was an increased propensity for ventricular arrhythmias. Ventricular myocytes isolated from Cav-3KO mice exhibited a prolonged action potential duration (APD) that was due to reductions in outward potassium currents (Ito, Iss) and changes in inward currents including slowed inactivation of ICa,L and increased INa,L. Mathematical modeling demonstrated that the changes in the studied ionic currents were adequate to explain the prolongation of the mouse ventricular action potential. Results from human iPSC-derived cardiomyocytes showed that shRNA knockdown of Cav-3 similarly prolonged APD. CONCLUSION We demonstrate that Cav-3 and caveolae regulate cardiac repolarization and arrhythmia risk via the integrated modulation of multiple ionic currents.
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Affiliation(s)
- Yogananda S Markandeya
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA; National Institute of Mental Health and Neuroscience, Bengaluru, India
| | - Zachery R Gregorich
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Li Feng
- Department of Cardiology, Beijing Anzhen Hospital, Captial Medical University, National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Vignesh Ramchandran
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Thomas O' Hara
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Ravi Vaidyanathan
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Catherine Mansfield
- National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Alexis M Keefe
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Carl J Beglinger
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Jabe M Best
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Matthew M Kalscheur
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Martin R Lea
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Timothy A Hacker
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Julia Gorelik
- National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Jonathan C Makielski
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Ravi C Balijepalli
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA
| | - Timothy J Kamp
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin Madison, WI, USA.
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2
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Gumz ML, Shimbo D, Abdalla M, Balijepalli RC, Benedict C, Chen Y, Earnest DJ, Gamble KL, Garrison SR, Gong MC, Hogenesch JB, Hong Y, Ivy JR, Joe B, Laposky AD, Liang M, MacLaughlin EJ, Martino TA, Pollock DM, Redline S, Rogers A, Dan Rudic R, Schernhammer ES, Stergiou GS, St-Onge MP, Wang X, Wright J, Oh YS. Toward Precision Medicine: Circadian Rhythm of Blood Pressure and Chronotherapy for Hypertension - 2021 NHLBI Workshop Report. Hypertension 2023; 80:503-522. [PMID: 36448463 PMCID: PMC9931676 DOI: 10.1161/hypertensionaha.122.19372] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [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] [Indexed: 12/02/2022]
Abstract
Healthy individuals exhibit blood pressure variation over a 24-hour period with higher blood pressure during wakefulness and lower blood pressure during sleep. Loss or disruption of the blood pressure circadian rhythm has been linked to adverse health outcomes, for example, cardiovascular disease, dementia, and chronic kidney disease. However, the current diagnostic and therapeutic approaches lack sufficient attention to the circadian rhythmicity of blood pressure. Sleep patterns, hormone release, eating habits, digestion, body temperature, renal and cardiovascular function, and other important host functions as well as gut microbiota exhibit circadian rhythms, and influence circadian rhythms of blood pressure. Potential benefits of nonpharmacologic interventions such as meal timing, and pharmacologic chronotherapeutic interventions, such as the bedtime administration of antihypertensive medications, have recently been suggested in some studies. However, the mechanisms underlying circadian rhythm-mediated blood pressure regulation and the efficacy of chronotherapy in hypertension remain unclear. This review summarizes the results of the National Heart, Lung, and Blood Institute workshop convened on October 27 to 29, 2021 to assess knowledge gaps and research opportunities in the study of circadian rhythm of blood pressure and chronotherapy for hypertension.
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Affiliation(s)
- Michelle L Gumz
- Department of Physiology and Aging; Center for Integrative Cardiovascular and Metabolic Disease, Department of Medicine, Division of Nephrology, Hypertension and Renal Transplantation, University of Florida, Gainesville, FL (M.L.G.)
| | - Daichi Shimbo
- Department of Medicine, The Columbia Hypertension Center, Columbia University Irving Medical Center, New York, NY (D.S.)
| | - Marwah Abdalla
- Department of Medicine, Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York, NY (M.A.)
| | - Ravi C Balijepalli
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Christian Benedict
- Department of Pharmaceutical Biosciences, Molecular Neuropharmacology, Uppsala University, Sweden (C.B.)
| | - Yabing Chen
- Department of Pathology, University of Alabama at Birmingham, and Research Department, Birmingham VA Medical Center, AL (Y.C.)
| | - David J Earnest
- Department of Neuroscience & Experimental Therapeutics, Texas A&M University, Bryan, TX (D.J.E.)
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, AL (K.L.G.)
| | - Scott R Garrison
- Department of Family Medicine, University of Alberta, Canada (S.R.G.)
| | - Ming C Gong
- Department of Physiology, University of Kentucky, Lexington, KY (M.C.G.)
| | | | - Yuling Hong
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Jessica R Ivy
- University/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh, United Kingdom (J.R.I.)
| | - Bina Joe
- Department of Physiology and Pharmacology and Center for Hypertension and Precision Medicine, University of Toledo College of Medicine and Life Sciences, OH (B.J.)
| | - Aaron D Laposky
- National Center on Sleep Disorders Research, Division of Lung Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (A.D.L.)
| | - Mingyu Liang
- Center of Systems Molecular Medicine, Department of Physiology, Medical College of Wisconsin, Milwaukee, WI (M.L.)
| | - Eric J MacLaughlin
- Department of Pharmacy Practice, Texas Tech University Health Sciences Center, Amarillo, TX (E.J.M.)
| | - Tami A Martino
- Center for Cardiovascular Investigations, Department of Biomedical Sciences, University of Guelph, Ontario, Canada (T.A.M.)
| | - David M Pollock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, AL (D.M.P.)
| | - Susan Redline
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (S.R.)
| | - Amy Rogers
- Division of Molecular and Clinical Medicine, University of Dundee, United Kingdom (A.R.)
| | - R Dan Rudic
- Department of Pharmacology and Toxicology, Augusta University, GA (R.D.R.)
| | - Eva S Schernhammer
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (E.S.S.)
| | - George S Stergiou
- Hypertension Center, STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece (G.S.S.)
| | - Marie-Pierre St-Onge
- Division of General Medicine, Department of Medicine, Columbia University Irving Medical Center' New York, NY (M.-P.S.-O.)
| | - Xiaoling Wang
- Georgia Prevention Institute, Department of Medicine, Augusta University, GA (X.W.)
| | - Jacqueline Wright
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Young S Oh
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
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Nguyen DT, Bilchick KC, Narayan SM, Chung MK, Thomas KL, Laurita KR, Vaseghi M, Sandhu R, Chelu MG, Kannankeril PJ, Packer DL, McManus DD, Verma A, Singleton M, Tarakji K, Al-Khatib SM, Kaltman JR, Balijepalli RC, Van Hare GF, Hurwitz JL, Russo AM, Kusumoto FM, Albert CM. Opportunities and challenges in heart rhythm research: Rationale and development of an electrophysiology collaboratory. Heart Rhythm 2022; 19:1927-1945. [PMID: 37850602 PMCID: PMC10824490 DOI: 10.1016/j.hrthm.2022.08.004] [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: 08/02/2022] [Accepted: 08/02/2022] [Indexed: 11/04/2022]
Abstract
There are many challenges in the current landscape of electrophysiology (EP) clinical and translational research, including increasing costs and complexity, competing demands, regulatory requirements, and challenges with study implementation. This review seeks to broadly discuss the state of EP research, including challenges and opportunities. Included here are results from a Heart Rhythm Society (HRS) Research Committee member survey detailing HRS members' perspectives regarding both barriers to clinical and translational research and opportunities to address these challenges. We also provide stakeholder perspectives on barriers and opportunities for future EP research, including input from representatives of the U.S. Food and Drug Administration, industry, and research funding institutions that participated in a Research Collaboratory Summit convened by HRS. This review further summarizes the experiences of the heart failure and heart valve communities and how they have approached similar challenges in their own fields. We then explore potential solutions, including various models of research ecosystems designed to identify research challenges and to coordinate ways to address them in a collaborative fashion in order to optimize innovation, increase efficiency of evidence generation, and advance the development of new therapeutic products. The objectives of the proposed collaborative cardiac EP research community are to encourage and support scientific discourse, research efficiency, and evidence generation by exploring collaborative and equitable solutions in which stakeholders within the EP community can interact to address knowledge gaps, innovate, and advance new therapies.
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Affiliation(s)
| | | | | | - Mina K Chung
- Department of Cardiology, Cleveland Clinic, Cleveland, Ohio
| | | | | | - Marmar Vaseghi
- University of California, Los Angeles Cardiac Arrhythmia Center, Los Angeles, California
| | - Roopinder Sandhu
- Department of Cardiology and Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | | | | | | | - David D McManus
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Atul Verma
- Southlake Regional Health Center, Toronto, Ontario, Canada
| | | | | | | | | | - Ravi C Balijepalli
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - George F Van Hare
- Office of Cardiovascular Devices, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland
| | | | | | | | - Christine M Albert
- Department of Cardiology and Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
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4
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Delisle BP, George AL, Nerbonne JM, Bass JT, Ripplinger CM, Jain MK, Hermanstyne TO, Young ME, Kannankeril PJ, Duffy JF, Goldhaber JI, Hall MH, Somers VK, Smolensky MH, Garnett CE, Anafi RC, Scheer FAJL, Shivkumar K, Shea SA, Balijepalli RC. Understanding Circadian Mechanisms of Sudden Cardiac Death: A Report From the National Heart, Lung, and Blood Institute Workshop, Part 2: Population and Clinical Considerations. Circ Arrhythm Electrophysiol 2021; 14:e010190. [PMID: 34719257 DOI: 10.1161/circep.121.010190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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] [Indexed: 01/10/2023]
Abstract
Sudden cardiac death (SCD) is the sudden, unexpected death due to abrupt loss of heart function secondary to cardiovascular disease. In certain populations living with cardiovascular disease, SCD follows a distinct 24-hour pattern in occurrence, suggesting day/night rhythms in behavior, the environment, and endogenous circadian rhythms result in daily spans of increased vulnerability. The National Heart, Lung, and Blood Institute convened a workshop, Understanding Circadian Mechanisms of Sudden Cardiac Death to identify fundamental questions regarding the role of the circadian rhythms in SCD. Part 2 summarizes research gaps and opportunities in the areas of population and clinical research identified in the workshop. Established research supports a complex interaction between circadian rhythms and physiological responses that increase the risk for SCD. Moreover, these physiological responses themselves are influenced by several biological variables, including the type of cardiovascular disease, sex, age, and genetics, as well as environmental factors. The emergence of new noninvasive biotechnological tools that continuously measure key cardiovascular variables, as well as the identification of biomarkers to assess circadian rhythms, hold promise for generating large-scale human data sets that will delineate which subsets of individuals are most vulnerable to SCD. Additionally, these data will improve our understanding of how people who suffer from circadian disruptions develop cardiovascular diseases that increase the risk for SCD. Emerging strategies to identify new biomarkers that can quantify circadian health (eg, environmental, behavioral, and internal misalignment) may lead to new interventions and therapeutic targets to prevent the progression of cardiovascular diseases that cause SCD.
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Affiliation(s)
- Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington (B.P.D.)
| | - Alfred L George
- Department of Pharmacology (A.L.G.), Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Jeanne M Nerbonne
- Cardiovascular Division, and Developmental Biology, Departments of Medicine (J.M.N.), Washington University School of Medicine, St Louis, MO
| | - Joseph T Bass
- Department of Medicine (J.T.B.), Northwestern University, Feinberg School of Medicine, Chicago, IL
| | | | - Mukesh K Jain
- Department of Medicine, Case Western Reserve University, Cleveland, OH (M.K.J.)
| | - Tracey O Hermanstyne
- Department of Developmental Biology (T.O.H.), Washington University School of Medicine, St Louis, MO
| | - Martin E Young
- Department of Medicine, University of Alabama, Birmingham (M.E.Y.)
| | - Prince J Kannankeril
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (P.J.K.)
| | - Jeanne F Duffy
- Department of Medicine (J.F.D.), Harvard Medical School, Boston, MA
| | - Joshua I Goldhaber
- Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, CA (J.I.G.)
| | - Martica H Hall
- Department of Psychiatry, University of Pittsburgh, PA (M.H.H.)
| | | | | | | | - Ron C Anafi
- Department of Medicine and Center for Sleep and Circadian Neurobiology, University of Pennsylvania Perelman School of Medicine, Philadelphia (R.C.A.)
| | - Frank A J L Scheer
- Division of Sleep Medicine (F.A.J.L.S.), Harvard Medical School, Boston, MA
| | - Kalyanam Shivkumar
- Departement of Medicine, David Greffen School of Medicine, University of California, Los Angeles (K.S.)
| | - Steven A Shea
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland (S.A.S.)
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5
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Delisle BP, George AL, Nerbonne JM, Bass JT, Ripplinger CM, Jain MK, Hermanstyne TO, Young ME, Kannankeril PJ, Duffy JF, Goldhaber JI, Hall MH, Somers VK, Smolensky MH, Garnett CE, Anafi RC, Scheer FA, Shivkumar K, Shea SA, Balijepalli RC. Understanding Circadian Mechanisms of Sudden Cardiac Death: A Report From the National Heart, Lung, and Blood Institute Workshop, Part 1: Basic and Translational Aspects. Circ Arrhythm Electrophysiol 2021; 14:e010181. [PMID: 34719240 PMCID: PMC8815462 DOI: 10.1161/circep.121.010181] [Citation(s) in RCA: 3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Sudden cardiac death (SCD), the unexpected death due to acquired or genetic cardiovascular disease, follows distinct 24-hour patterns in occurrence. These 24-hour patterns likely reflect daily changes in arrhythmogenic triggers and the myocardial substrate caused by day/night rhythms in behavior, the environment, and endogenous circadian mechanisms. To better address fundamental questions regarding the circadian mechanisms, the National Heart, Lung, and Blood Institute convened a workshop, Understanding Circadian Mechanisms of Sudden Cardiac Death. We present a 2-part report of findings from this workshop. Part 1 summarizes the workshop and serves to identify research gaps and opportunities in the areas of basic and translational research. Among the gaps was the lack of standardization in animal studies for reporting environmental conditions (eg, timing of experiments relative to the light dark cycle or animal housing temperatures) that can impair rigor and reproducibility. Workshop participants also pointed to uncertainty regarding the importance of maintaining normal circadian rhythmic synchrony and the potential pathological impact of desynchrony on SCD risk. One related question raised was whether circadian mechanisms can be targeted to reduce SCD risk. Finally, the experts underscored the need for studies aimed at determining the physiological importance of circadian clocks in the many different cell types important to normal heart function and SCD. Addressing these gaps could lead to new therapeutic approaches/molecular targets that can mitigate the risk of SCD not only at certain times but over the entire 24-hour period.
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Affiliation(s)
| | - Alfred L. George
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Jeanne M. Nerbonne
- Departments of Medicine, Cardiovascular Division, and Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Joseph T. Bass
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | | | - Mukesh K. Jain
- Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Tracey O. Hermanstyne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Martin E. Young
- Department of Medicine, University of Alabama, Birmingham, AL
| | | | | | | | - Martica H. Hall
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA
| | | | | | | | - Ron C. Anafi
- Department of Medicine and Center for Sleep and Circadian Neurobiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | | | - Kalyanam Shivkumar
- Departement of Medicine, David Greffen School of Medicine at UCLA, Los Angeles, CA
| | - Steven A. Shea
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR
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6
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Wright PT, Bhogal NK, Diakonov I, Pannell LMK, Perera RK, Bork NI, Schobesberger S, Lucarelli C, Faggian G, Alvarez-Laviada A, Zaccolo M, Kamp TJ, Balijepalli RC, Lyon AR, Harding SE, Nikolaev VO, Gorelik J. Cardiomyocyte Membrane Structure and cAMP Compartmentation Produce Anatomical Variation in β 2AR-cAMP Responsiveness in Murine Hearts. Cell Rep 2019; 23:459-469. [PMID: 29642004 PMCID: PMC5912947 DOI: 10.1016/j.celrep.2018.03.053] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 02/02/2018] [Accepted: 03/13/2018] [Indexed: 01/19/2023] Open
Abstract
Cardiomyocytes from the apex but not the base of the heart increase their contractility in response to β2-adrenoceptor (β2AR) stimulation, which may underlie the development of Takotsubo cardiomyopathy. However, both cell types produce comparable cytosolic amounts of the second messenger cAMP. We investigated this discrepancy using nanoscale imaging techniques and found that, structurally, basal cardiomyocytes have more organized membranes (higher T-tubular and caveolar densities). Local membrane microdomain responses measured in isolated basal cardiomyocytes or in whole hearts revealed significantly smaller and more short-lived β2AR/cAMP signals. Inhibition of PDE4, caveolar disruption by removing cholesterol or genetic deletion of Cav3 eliminated differences in local cAMP production and equilibrated the contractile response to β2AR. We conclude that basal cells possess tighter control of cAMP because of a higher degree of signaling microdomain organization. This provides varying levels of nanostructural control for cAMP-mediated functional effects that orchestrate macroscopic, regional physiological differences within the heart. Cardiomyocyte membrane organization varies in degree between regions of the heart Differences in structural organization affect adrenergic signaling via β2AR Reduced organization allows β2AR-cAMP to influence contractility in myocardial apex Variability in cell structure may allow differential response of heart regions
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Affiliation(s)
- Peter T Wright
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Navneet K Bhogal
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Ivan Diakonov
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Laura M K Pannell
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Ruwan K Perera
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Nadja I Bork
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Sophie Schobesberger
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Carla Lucarelli
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK; Department of Cardiac Surgery, University of Verona School of Medicine, Azienda Ospedalieria Universitaria Integrata, Borgo Trento Piazzale A. Stefani, 37126 Verona, Italy
| | - Giuseppe Faggian
- Department of Cardiac Surgery, University of Verona School of Medicine, Azienda Ospedalieria Universitaria Integrata, Borgo Trento Piazzale A. Stefani, 37126 Verona, Italy
| | - Anita Alvarez-Laviada
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Timothy J Kamp
- Department of Medicine, University of Wisconsin Madison, 1111 Highland Ave., Madison, WI 53705-2275, USA
| | - Ravi C Balijepalli
- Department of Medicine, University of Wisconsin Madison, 1111 Highland Ave., Madison, WI 53705-2275, USA
| | - Alexander R Lyon
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK; NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London SW7 3AZ, UK
| | - Sian E Harding
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Julia Gorelik
- Myocardial Function, National Heart and Lung Institute, Imperial College London, ICTEM, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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7
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Tyan L, Foell JD, Vincent KP, Woon MT, Mesquitta WT, Lang D, Best JM, Ackerman MJ, McCulloch AD, Glukhov AV, Balijepalli RC, Kamp TJ. Long QT syndrome caveolin-3 mutations differentially modulate K v 4 and Ca v 1.2 channels to contribute to action potential prolongation. J Physiol 2019; 597:1531-1551. [PMID: 30588629 DOI: 10.1113/jp276014] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [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: 11/04/2018] [Accepted: 12/14/2018] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Mutations in the caveolae scaffolding protein, caveolin-3 (Cav3), have been linked to the long QT type 9 inherited arrhythmia syndrome (LQT9) and the cause of underlying action potential duration prolongation is incompletely understood. In the present study, we show that LQT9 Cav3 mutations, F97C and S141R, cause mutation-specific gain of function effects on Cav 1.2-encoded L-type Ca2+ channels responsible for ICa,L and also cause loss of function effects on heterologously expressed Kv 4.2 and Kv 4.3 channels responsible for Ito . A computational model of the human ventricular myocyte action potential suggests that the major ionic current change causing action potential duration prolongation in the presence of Cav3-F97C is the slowly inactivating ICa,L but, for Cav3-S141R, both increased ICa,L and increased late Na+ current contribute equally to action potential duration prolongation. Overall, the LQT9 Cav3-F97C and Cav3-S141R mutations differentially impact multiple ionic currents, highlighting the complexity of Cav3 regulation of cardiac excitability and suggesting mutation-specific therapeutic approaches. ABSTRACT Mutations in the CAV3 gene encoding caveolin-3 (Cav3), a scaffolding protein integral to caveolae in cardiomyocytes, have been associated with the congenital long-QT syndrome (LQT9). Initial studies demonstrated that LQT9-associated Cav3 mutations, F97C and S141R, increase late sodium current as a potential mechanism to prolong action potential duration (APD) and cause LQT9. Whether these Cav3 LQT9 mutations impact other caveolae related ion channels remains unknown. We used the whole-cell, patch clamp technique to characterize the effect of Cav3-F97C and Cav3-S141R mutations on heterologously expressed Cav 1.2+Cav β2cN4 channels, as well as Kv 4.2 and Kv 4.3 channels, in HEK 293 cells. Expression of Cav3-S141R increased ICa,L density without changes in gating properties, whereas expression of Cav3-F97C reduced Ca2+ -dependent inactivation of ICa,L without changing current density. The Cav3-F97C mutation reduced current density and altered the kinetics of IKv4.2 and IKv4.3 and also slowed recovery from inactivation. Cav3-S141R decreased current density and also slowed activation kinetics and recovery from inactivation of IKv4.2 but had no effect on IKv4.3 . Using the O'Hara-Rudy computational model of the human ventricular myocyte action potential, the Cav3 mutation-induced changes in Ito are predicted to have negligible effect on APD, whereas blunted Ca2+ -dependent inactivation of ICa,L by Cav3-F97C is predicted to be primarily responsible for APD prolongation, although increased ICa,L and late INa by Cav3-S141R contribute equally to APD prolongation. Thus, LQT9 Cav3-associated mutations, F97C and S141R, produce mutation-specific changes in multiple ionic currents leading to different primary causes of APD prolongation, which suggests the use of mutation-specific therapeutic approaches in the future.
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Affiliation(s)
- Leonid Tyan
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Jason D Foell
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Kevin P Vincent
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Marites T Woon
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Walatta T Mesquitta
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Di Lang
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Jabe M Best
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine, Pediatric and Adolescent Medicine and Molecular Pharmacology & Experimental Therapeutics, Divisions of Heart Rhythm Services and Pediatric Cardiology, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, 200 First Street SW, Rochester, MN, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA.,Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Alexey V Glukhov
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Ravi C Balijepalli
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
| | - Timothy J Kamp
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison, 1111, Highland Ave, Madison, WI, USA
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8
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Woon MT, Long PA, Reilly L, Evans JM, Keefe AM, Lea MR, Beglinger CJ, Balijepalli RC, Lee Y, Olson TM, Kamp TJ. Pediatric Dilated Cardiomyopathy-Associated LRRC10 (Leucine-Rich Repeat-Containing 10) Variant Reveals LRRC10 as an Auxiliary Subunit of Cardiac L-Type Ca 2+ Channels. J Am Heart Assoc 2018; 7:e006428. [PMID: 29431102 PMCID: PMC5850229 DOI: 10.1161/jaha.117.006428] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 11/10/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND Genetic causes of dilated cardiomyopathy (DCM) are incompletely understood. LRRC10 (leucine-rich repeat-containing 10) is a cardiac-specific protein of unknown function. Heterozygous mutations in LRRC10 have been suggested to cause DCM, and deletion of Lrrc10 in mice results in DCM. METHODS AND RESULTS Whole-exome sequencing was carried out on a patient who presented at 6 weeks of age with DCM and her unaffected parents, filtering for rare, deleterious, recessive, and de novo variants. Whole-exome sequencing followed by trio-based filtering identified a homozygous recessive variant in LRRC10, I195T. Coexpression of I195T LRRC10 with the L-type Ca2+ channel (Cav1.2, β2CN2, and α2δ subunits) in HEK293 cells resulted in a significant ≈0.5-fold decrease in ICa,L at 0 mV, in contrast to the ≈1.4-fold increase in ICa,L by coexpression of LRRC10 (n=9-12, P<0.05). Coexpression of LRRC10 or I195T LRRC10 did not alter the surface membrane expression of Cav1.2. LRRC10 coexpression with Cav1.2 in the absence of auxiliary β2CN2 and α2δ subunits revealed coassociation of Cav1.2 and LRRC10 and a hyperpolarizing shift in the voltage dependence of activation (n=6-9, P<0.05). Ventricular myocytes from Lrrc10-/- mice had significantly smaller ICa,L, and coimmunoprecipitation experiments confirmed association between LRRC10 and the Cav1.2 subunit in mouse hearts. CONCLUSIONS Examination of a patient with DCM revealed homozygosity for a previously unreported LRRC10 variant: I195T. Wild-type and I195T LRRC10 function as cardiac-specific subunits of L-type Ca2+ channels and exert dramatically different effects on channel gating, providing a potential link to DCM.
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Affiliation(s)
- Marites T Woon
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Pamela A Long
- Mayo Graduate School, Molecular Pharmacology and Experimental Therapeutics Track, Mayo Clinic, Rochester, MN
| | - Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Jared M Evans
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - Alexis M Keefe
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Martin R Lea
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Carl J Beglinger
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Ravi C Balijepalli
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Youngsook Lee
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Timothy M Olson
- Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN
| | - Timothy J Kamp
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
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9
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Woon MT, Long PA, Reilly L, Evans JM, Keefe AM, Lea MR, Beglinger CJ, Balijepalli RC, Lee Y, Olson TM, Kamp TJ. Abstract 409: LRRC10 Associates With and Regulates Cardiac Ca
V
1.2 L-type Ca
2+
Channels, and I195T LRRC10 Variant is Linked to Dilated Cardiomyopathy. Circ Res 2017. [DOI: 10.1161/res.121.suppl_1.409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/16/2022]
Abstract
Leucine-rich repeat containing (LRR) proteins facilitate protein-protein interactions critical in a number of cellular functions including ion channel regulation. Leucine-rich repeat containing protein 10 (LRRC10), a cardiac-specific protein expressed in zebrafish, mice and humans, is essential for normal cardiac physiology with loss of
Lrrc10
in
Lrrc10
-/-
mice resulting in dilated cardiomyopathy (DCM). However, the mechanism by which LRRC10 contributes to DCM is unknown. Further, the functional role of LRRC10 in the regulation of ion channels in the heart has not been explored. Here we recorded L-type Ca
2+
channel currents (I
Ca,L
) from isolated ventricular myocytes of WT and
Lrrc10
-/-
mice, demonstrating a significant reduction in I
Ca,L
in
Lrrc10
-/-
myocytes (-4.9 ± 0.19 pA/pF, n=10) compared to WT (-6.5 ± 0.24 pA/pF, n=8). Co-immunoprecipitation (co-IP) experiments showed an association between LRRC10 and Ca
v
1.2 in WT, but not
Lrrc10
-/-
mouse lysates, with immunocytochemistry studies further demonstrating colocalization of LRRC10 and Ca
v
1.2 in isolated ventricular myocytes from wild-type (WT) mice. Additionally, whole exome sequencing revealed a novel homozygous recessive missense variant in
LRRC10
, I195T, found in a pediatric DCM patient. To determine whether the I195T variant impacts Ca
v
1.2 L-type Ca
2+
channels, whole-cell patch clamp experiments were performed using HEK293 cells transiently expressing the L-type Ca
2+
channel complex (LTCC) alone or with WT or I195T LRRC10. These electrophysiology experiments demonstrated a significant increase in I
Ca,L
with WT LRRC10 coexpression (-81 ± 5.3 pA/pF, n=12), but a decrease in I
Ca,L
when I195T (-18.2 ± 3.3 pA/pF, n=9) was coexpressed compared to the LTCC alone (-34.1 ± 2.2 pA/pF, n=17). Parallel surface biotinylation experiments demonstrated that WT and I195T LRRC10 did not alter L-type Ca
2+
channel expression on the plasma membrane, while co-IP experiments using lysates prepared from the transiently transfected HEK293 cells showed the association between Ca
v
1.2 and I195T LRRC10 variant. Overall, these findings newly identify LRRC10 as a cardiac-specific component of the Ca
v
1.2 macromolecular complex and demonstrate dysregulation of I
Ca,L
by the DCM associated I195T LRRC10 variant.
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10
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Markandeya YS, Tsubouchi T, Hacker TA, Wolff MR, Belardinelli L, Balijepalli RC. Inhibition of late sodium current attenuates ionic arrhythmia mechanism in ventricular myocytes expressing LaminA-N195K mutation. Heart Rhythm 2016; 13:2228-2236. [PMID: 27498076 DOI: 10.1016/j.hrthm.2016.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [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: 03/22/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Lamin A and C are nuclear filament proteins encoded by the LMNA gene. Mutations in the LMNA gene cause many congenital diseases known as laminopathies, including Emery-Dreifuss muscular dystrophy, Hutchinson-Gilford progeria syndrome, and familial dilated cardiomyopathy (DCM) with conduction disease. A missense mutation (N195K) in the A-type lamins results in familial DCM and sudden arrhythmic death. OBJECTIVE The purpose of this study was to investigate the ion current mechanism of arrhythmia and DCM caused by the LaminA-N195K variant. METHODS A homozygous mouse line expressing the Lmna-N195K mutation (LmnaN195K/N195K) that exhibited arrhythmia, DCM, and sudden death was used. Using whole cell patch-clamp technique, we measured action potential duration (APD), Na+ currents (INa) in ventricular myocytes isolated from LmnaN195K/N195K, and wild-type mice. RESULTS Both peak and late INa were significantly (P <.05) increased in LmnaN195K/N195K ventricular myocytes. Similarly, LmnaN195K/N195K ventricular myocytes exhibited significant (P <.005) prolongation of APD (time to 50% [APD50] and 90% [APD90] repolarization) and triggered activity. Acute application of ranolazine inhibited late INa, shortened APD, and abolished triggered activity in LmnaN195K/N195K ventricular myocytes. CONCLUSION Inhibition of late INa may be an effective therapy in preventing arrhythmia in patients with LmnaN195K mutation-related DCM.
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Affiliation(s)
- Yogananda S Markandeya
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin
| | - Tadashi Tsubouchi
- Preclinical Research Laboratories, Sumitomo Dainippon Pharma Co. Ltd., Osaka, Japan
| | - Timothy A Hacker
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin
| | - Matthew R Wolff
- Meriter UnityPoint Heart and Vascular Institute, Madison, Wisconsin
| | | | - Ravi C Balijepalli
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin.
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11
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Schilling JM, Horikawa YT, Zemljic-Harpf AE, Vincent KP, Tyan L, Yu JK, McCulloch AD, Balijepalli RC, Patel HH, Roth DM. Electrophysiology and metabolism of caveolin-3-overexpressing mice. Basic Res Cardiol 2016; 111:28. [PMID: 27023865 DOI: 10.1007/s00395-016-0542-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [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: 12/04/2015] [Accepted: 02/17/2016] [Indexed: 10/22/2022]
Abstract
Caveolin-3 (Cav-3) plays a critical role in organizing signaling molecules and ion channels involved in cardiac conduction and metabolism. Mutations in Cav-3 are implicated in cardiac conduction abnormalities and myopathies. Additionally, cardiac-specific overexpression of Cav-3 (Cav-3 OE) is protective against ischemic and hypertensive injury, suggesting a potential role for Cav-3 in basal cardiac electrophysiology and metabolism involved in stress adaptation. We hypothesized that overexpression of Cav-3 may alter baseline cardiac conduction and metabolism. We examined: (1) ECG telemetry recordings at baseline and during pharmacological interventions, (2) ion channels involved in cardiac conduction with immunoblotting and computational modeling, and (3) baseline metabolism in Cav-3 OE and transgene-negative littermate control mice. Cav-3 OE mice had decreased heart rates, prolonged PR intervals, and shortened QTc intervals with no difference in activity compared to control mice. Dobutamine or propranolol did not cause significant changes between experimental groups in maximal (dobutamine) or minimal (propranolol) heart rate. Cav-3 OE mice had an overall lower chronotropic response to atropine. The expression of Kv1.4 and Kv4.3 channels, Nav1.5 channels, and connexin 43 were increased in Cav-3 OE mice. A computational model integrating the immunoblotting results indicated shortened action potential duration in Cav-3 OE mice linking the change in channel expression to the observed electrophysiology phenotype. Metabolic profiling showed no gross differences in VO2, VCO2, respiratory exchange ratio, heat generation, and feeding or drinking. In conclusion, Cav-3 OE mice have changes in ECG intervals, heart rates, and cardiac ion channel expression. These findings give novel mechanistic insights into previously reported Cav-3 dependent cardioprotection.
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Affiliation(s)
- Jan M Schilling
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Yousuke T Horikawa
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.,Department of Pediatrics, Sharp Rees-Stealy Medical Group, San Diego, CA, USA
| | - Alice E Zemljic-Harpf
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Kevin P Vincent
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Leonid Tyan
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Judith K Yu
- Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.,Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Hemal H Patel
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - David M Roth
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA. .,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA.
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12
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Brody MJ, Feng L, Grimes AC, Hacker TA, Olson TM, Kamp TJ, Balijepalli RC, Lee Y. LRRC10 is required to maintain cardiac function in response to pressure overload. Am J Physiol Heart Circ Physiol 2015; 310:H269-78. [PMID: 26608339 DOI: 10.1152/ajpheart.00717.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [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: 10/07/2014] [Accepted: 11/18/2015] [Indexed: 01/08/2023]
Abstract
We previously reported that the cardiomyocyte-specific leucine-rich repeat containing protein (LRRC)10 has critical functions in the mammalian heart. In the present study, we tested the role of LRRC10 in the response of the heart to biomechanical stress by performing transverse aortic constriction on Lrrc10-null (Lrrc10(-/-)) mice. Mild pressure overload induced severe cardiac dysfunction and ventricular dilation in Lrrc10(-/-) mice compared with control mice. In addition to dilation and cardiomyopathy, Lrrc10(-/-) mice showed a pronounced increase in heart weight with pressure overload stimulation and a more dramatic loss of cardiac ventricular performance, collectively suggesting that the absence of LRRC10 renders the heart more disease prone with greater hypertrophy and structural remodeling, although rates of cardiac fibrosis and myocyte dropout were not different from control mice. Lrrc10(-/-) cardiomyocytes also exhibited reduced contractility in response to β-adrenergic stimulation, consistent with loss of cardiac ventricular performance after pressure overload. We have previously shown that LRRC10 interacts with actin in the heart. Here, we show that His(150) of LRRC10 was required for an interaction with actin, and this interaction was reduced after pressure overload, suggesting an integral role for LRRC10 in the response of the heart to mechanical stress. Importantly, these experiments demonstrated that LRRC10 is required to maintain cardiac performance in response to pressure overload and suggest that dysregulated expression or mutation of LRRC10 may greatly sensitize human patients to more severe cardiac disease in conditions such as chronic hypertension or aortic stenosis.
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Affiliation(s)
- Matthew J Brody
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Molecular and Environmental Toxicology Center, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Li Feng
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Adrian C Grimes
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Timothy A Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Timothy M Olson
- Cardiovascular Genetics Research Laboratory and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy J Kamp
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Ravi C Balijepalli
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Youngsook Lee
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Molecular and Environmental Toxicology Center, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin;
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13
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Jiang M, Zhang M, Howren M, Wang Y, Tan A, Balijepalli RC, Huizar JF, Tseng GN. JPH-2 interacts with Cai-handling proteins and ion channels in dyads: Contribution to premature ventricular contraction-induced cardiomyopathy. Heart Rhythm 2015; 13:743-52. [PMID: 26538326 DOI: 10.1016/j.hrthm.2015.10.037] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [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: 09/01/2015] [Indexed: 12/28/2022]
Abstract
BACKGROUND In a canine model of premature ventricular contraction-induced cardiomyopathy (PVC-CM), Cav1.2 is downregulated and misplaced from transverse tubules (T tubules). Junctophilin-2 (JPH-2) is also downregulated. OBJECTIVES The objectives of this study were to understand the role of JPH-2 in PVC-CM and to probe changes in other proteins involved in dyad structure and function. METHODS We quantify T-tubule contents (di-8-ANEPPS fluorescence in live myocytes), examine myocyte ultrastructures (electron microscopy), probe JPH-2-interacting proteins (co-immunoprecipitation), quantify dyad and nondyad protein levels (immunoblotting), and examine subcellular distributions of dyad proteins (immunofluorescence/confocal microscopy). We also test direct JPH-2 modulation of channel function (vs indirect modulation through dyad formation) using heterologous expression. RESULTS PVC myocytes have reduced T-tubule contents but otherwise normal ultrastructures. Among 19 proteins examined, only JPH-2, bridging integrator-1 (BIN-1), and Cav1.2 are highly downregulated in PVC hearts. However, statistical analysis indicates a general reduction in dyad protein levels when JPH-2 is downregulated. Furthermore, several dyad proteins, including Na/Ca exchanger, are missing or shifted from dyads to the peripheral surface in PVC myocytes. JPH-2 directly or indirectly interacts with Cai-handling proteins, Cav1.2 and KCNQ1, although not BIN-1 or other scaffolding proteins tested. Expression in mammalian cells that do not have dyads confirms direct JPH-2 modulation of the L-type Ca channel current (Cav1.2/voltage-gated Ca channel β subunit 2) and slow delayed rectifier current (KCNQ1/KCNE1). CONCLUSION JPH-2 is more than a "dyad glue": it can modulate Cai handling and ion channel function in the dyad region. Downregulation of JPH-2, BIN-1, and Cav1.2 plays a deterministic role in PVC-CM. Dissecting the hierarchical relationship among the three is necessary for the design of therapeutic interventions to prevent the progression of PVC-CM.
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Affiliation(s)
- Min Jiang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Mei Zhang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Maureen Howren
- Department of Medicine/Cardiology Division, McGuire VA Medical Center, Richmond, Virginia
| | - Yuhong Wang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Alex Tan
- Department of Medicine/Cardiology Division, McGuire VA Medical Center, Richmond, Virginia
| | - Ravi C Balijepalli
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin
| | - Jose F Huizar
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Gea-Ny Tseng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia.
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14
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Markandeya YS, Phelan LJ, Woon MT, Keefe AM, Reynolds CR, August BK, Hacker TA, Roth DM, Patel HH, Balijepalli RC. Caveolin-3 Overexpression Attenuates Cardiac Hypertrophy via Inhibition of T-type Ca2+ Current Modulated by Protein Kinase Cα in Cardiomyocytes. J Biol Chem 2015; 290:22085-100. [PMID: 26170457 DOI: 10.1074/jbc.m115.674945] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [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: 06/25/2015] [Indexed: 12/24/2022] Open
Abstract
Pathological cardiac hypertrophy is characterized by subcellular remodeling of the ventricular myocyte with a reduction in the scaffolding protein caveolin-3 (Cav-3), altered Ca(2+) cycling, increased protein kinase C expression, and hyperactivation of calcineurin/nuclear factor of activated T cell (NFAT) signaling. However, the precise role of Cav-3 in the regulation of local Ca(2+) signaling in pathological cardiac hypertrophy is unclear. We used cardiac-specific Cav-3-overexpressing mice and in vivo and in vitro cardiac hypertrophy models to determine the essential requirement for Cav-3 expression in protection against pharmacologically and pressure overload-induced cardiac hypertrophy. Transverse aortic constriction and angiotensin-II (Ang-II) infusion in wild type (WT) mice resulted in cardiac hypertrophy characterized by significant reduction in fractional shortening, ejection fraction, and a reduced expression of Cav-3. In addition, association of PKCα and angiotensin-II receptor, type 1, with Cav-3 was disrupted in the hypertrophic ventricular myocytes. Whole cell patch clamp analysis demonstrated increased expression of T-type Ca(2+) current (ICa, T) in hypertrophic ventricular myocytes. In contrast, the Cav-3-overexpressing mice demonstrated protection from transverse aortic constriction or Ang-II-induced pathological hypertrophy with inhibition of ICa, T and intact Cav-3-associated macromolecular signaling complexes. siRNA-mediated knockdown of Cav-3 in the neonatal cardiomyocytes resulted in enhanced Ang-II stimulation of ICa, T mediated by PKCα, which caused nuclear translocation of NFAT. Overexpression of Cav-3 in neonatal myocytes prevented a PKCα-mediated increase in ICa, T and nuclear translocation of NFAT. In conclusion, we show that stable Cav-3 expression is essential for protecting the signaling mechanisms in pharmacologically and pressure overload-induced cardiac hypertrophy.
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Affiliation(s)
- Yogananda S Markandeya
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Laura J Phelan
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Marites T Woon
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Alexis M Keefe
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Courtney R Reynolds
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Benjamin K August
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Timothy A Hacker
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - David M Roth
- the Veterans Affairs San Diego Healthcare Systems, San Diego, California 92161, and the Department of Anesthesiology, University of California at San Diego, La Jolla, California 92161
| | - Hemal H Patel
- the Veterans Affairs San Diego Healthcare Systems, San Diego, California 92161, and the Department of Anesthesiology, University of California at San Diego, La Jolla, California 92161
| | - Ravi C Balijepalli
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706,
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15
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Ramchandran V, O’Hara T, Markandeya YS, Balijepalli RC, Kamp TJ, Trayanova NA. Ionic Mechanisms that Underlie Ventricular Action Potential Prolongation following Loss of Caveolin-3 in Adult Transgenic Mice. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1076] [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: 10/24/2022] Open
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16
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Woon MT, Grimes AC, Reynolds CR, Brody MJ, Lee Y, Balijepalli RC. Cardiac Specific Leucine-Rich Repeat Containing 10 (LRRC10) Protein Interacts with and Regulates the Cav1.2 L-Type Ca2+ Channels. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1078] [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
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17
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Reynolds CR, Feng L, Brody MJ, Youngsook L, Balijepalli RC. Leucine-Rich Repeat Containing 10 (Lrrc10) Protein is a Novel Regulator of Cardiac Cav1.2 L-Type Calcium Channels. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1891] [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: 10/23/2022] Open
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18
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Phelan L, Reynolds C, Markandeya Y, Roth DM, Patel HH, Balijepalli RC. Angiotensin‐II induced cardiac hypertrophic responses are mediated via PKC and NFAT signaling is attenuated by caveolin‐3 in ventricular myocytes. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1197.2] [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)
- Laura Phelan
- Medicine/CardiologyUniversity of WisconsinMadisonWI
| | | | | | - David M Roth
- AnesthesiologyUniversity of California San DiegoSan DiegoCA
| | - Hemal H Patel
- AnesthesiologyUniversity of California San DiegoSan DiegoCA
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19
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Woon MT, Markandeya YS, Reynolds CR, Balijepalli RC. Auxiliary Ca
v
β subunits of the high voltage L‐type Ca
2+
channels modulate the low voltage activated cardiac Ca
v
3.2 T‐type Ca
2+
channel currents. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1197.6] [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]
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20
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Devi S, Markandeya Y, Maddodi N, Dhingra A, Vardi N, Balijepalli RC, Setaluri V. Metabotropic glutamate receptor 6 signaling enhances TRPM1 calcium channel function and increases melanin content in human melanocytes. Pigment Cell Melanoma Res 2013; 26:348-56. [PMID: 23452348 DOI: 10.1111/pcmr.12083] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/19/2013] [Indexed: 12/23/2022]
Abstract
Mutations in TRPM1, a calcium channel expressed in retinal bipolar cells and epidermal melanocytes, cause complete congenital stationary night blindness with no discernible skin phenotype. In the retina, TRPM1 activity is negatively coupled to metabotropic glutamate receptor 6 (mGluR6) signaling through Gαo and TRPM1 mutations result in the loss of responsiveness of TRPM1 to mGluR6 signaling. Here, we show that human melanocytes express mGluR6, and treatment of melanocytes with L-AP4, a type III mGluR-selective agonist, enhances Ca(2+) uptake. Knockdown of TRPM1 or mGluR6 by shRNA abolished L-AP4-induced Ca(2+) influx and TRPM1 currents, showing that TRPM1 activity in melanocytes is positively coupled to mGluR6 signaling. Gαo protein is absent in melanocytes. However, forced expression of Gαo restored negative coupling of TRPM1 to mGluR6 signaling, but treatment with pertussis toxin, an inhibitor of Gi /Go proteins, did not affect basal or mGluR6-induced Ca(2+) uptake. Additionally, chronic stimulation of mGluR6 altered melanocyte morphology and increased melanin content. These data suggest differences in coupling of TRPM1 function to mGluR6 signaling explain different cellular responses to glutamate in the retina and the skin.
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Affiliation(s)
- Sulochana Devi
- Department of Dermatology, University of Wisconsin, School of Medicine and Public Health, Madison, WI, USA
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21
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Cheng J, Valdivia CR, Vaidyanathan R, Balijepalli RC, Ackerman MJ, Makielski JC. Caveolin-3 suppresses late sodium current by inhibiting nNOS-dependent S-nitrosylation of SCN5A. J Mol Cell Cardiol 2013; 61:102-10. [PMID: 23541953 DOI: 10.1016/j.yjmcc.2013.03.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [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: 10/10/2012] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 10/27/2022]
Abstract
AIMS Mutations in CAV3-encoding caveolin-3 (Cav3) have been implicated in type 9 long QT syndrome (LQT9) and sudden infant death syndrome (SIDS). When co-expressed with SCN5A-encoded cardiac sodium channels these mutations increased late sodium current (INa) but the mechanism was unclear. The present study was designed to address the mechanism by which the LQT9-causing mutant Cav3-F97C affects the function of caveolar SCN5A. METHODS AND RESULTS HEK-293 cells expressing SCN5A and LQT9 mutation Cav3-F97C resulted in a 2-fold increase in late INa compared to Cav3-WT. This increase was reversed by the neural nitric oxide synthase (nNOS) inhibitor L-NMMA. Based on these findings, we hypothesized that an nNOS complex mediated the effect of Cav3 on SCN5A. A SCN5A macromolecular complex was established in HEK-293 cells by transiently expressing SCN5A, α1-syntrophin (SNTA1), nNOS, and Cav3. Compared with Cav3-WT, Cav3-F97C produced significantly larger peak INa amplitudes, and showed 3.3-fold increase in the late INa associated with increased S-nitrosylation of SCN5A. L-NMMA reversed both the Cav3-F97C induced increase in late and peak INa and decreased S-nitrosylation of SCN5A. Overexpression of Cav3-F97C in adult rat cardiomyocytes caused a significant increase in late INa compared to Cav3-WT, and prolonged the action potential duration (APD90) in a nNOS-dependent manner. CONCLUSIONS Cav3 is identified as an important negative regulator for cardiac late INa via nNOS dependent direct S-nitrosylation of SCN5A. This provides a molecular mechanism for how Cav3 mutations increase late INa to cause LQT9. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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Affiliation(s)
- Jianding Cheng
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI 53792, USA
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22
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Markandeya YS, Feng L, Best JM, Lea Lea M, Buss CR, Kamp TJ, Balijepalli RC. Loss of Caveolin-3 Results in QtC Prolongation and Causes Delayed Cardiac Repolarization in a Cardiac-Specific Conditional CAV-3 Knockout Mouse Model. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1183] [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: 11/30/2022] Open
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23
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Balijepalli SY, Lim E, Concannon SP, Chew CL, Holzem KE, Tester DJ, Ackerman MJ, Delisle BP, Balijepalli RC, January CT. Mechanism of loss of Kv11.1 K+ current in mutant T421M-Kv11.1-expressing rat ventricular myocytes: interaction of trafficking and gating. Circulation 2012; 126:2809-18. [PMID: 23136156 DOI: 10.1161/circulationaha.112.118018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [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: 11/16/2022]
Abstract
BACKGROUND Type 2 long QT syndrome involves mutations in the human ether a-go-go-related gene (hERG or KCNH2). T421M, an S1 domain mutation in the Kv11.1 channel protein, was identified in a resuscitated patient. We assessed its biophysical, protein trafficking, and pharmacological mechanisms in adult rat ventricular myocytes. METHODS AND RESULTS Isolated adult rat ventricular myocytes were infected with wild-type (WT)-Kv11.1- and T421M-Kv11.1-expressing adenovirus and analyzed with the use of patch clamp, Western blot, and confocal imaging techniques. Expression of WT-Kv11.1 or T421M-Kv11.1 produced peak tail current (I(Kv11.1)) of 8.78±1.18 and 1.91±0.22 pA/pF, respectively. Loss of mutant I(Kv11.1) resulted from (1) a partially trafficking-deficient channel protein with reduced cell surface expression and (2) altered channel gating with a positive shift in the voltage dependence of activation and altered kinetics of activation and deactivation. Coexpression of WT+T421M-Kv11.1 resulted in heterotetrameric channels that remained partially trafficking deficient with only a minimal increase in peak I(Kv11.1) density, whereas the voltage dependence of channel gating became WT-like. In the adult rat ventricular myocyte model, both WT-Kv11.1 and T421M-Kv11.1 channels responded to β-adrenergic stimulation by increasing I(Kv11.1). CONCLUSIONS The T421M-Kv11.1 mutation caused a loss of I(Kv11.1) through interactions of abnormal protein trafficking and channel gating. Furthermore, for coexpressed WT+T421M-Kv11.1 channels, different dominant-negative interactions govern protein trafficking and ion channel gating, and these are likely to be reflected in the clinical phenotype. Our results also show that WT and mutant Kv11.1 channels responded to β-adrenergic stimulation.
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24
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Fridolfsson HN, Kawaraguchi Y, Ali SS, Panneerselvam M, Niesman IR, Finley JC, Kellerhals SE, Migita MY, Okada H, Moreno AL, Jennings M, Kidd MW, Bonds JA, Balijepalli RC, Ross RS, Patel PM, Miyanohara A, Chen Q, Lesnefsky EJ, Head BP, Roth DM, Insel PA, Patel HH. Mitochondria-localized caveolin in adaptation to cellular stress and injury. FASEB J 2012; 26:4637-49. [PMID: 22859372 DOI: 10.1096/fj.12-215798] [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] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We show here that the apposition of plasma membrane caveolae and mitochondria (first noted in electron micrographs >50 yr ago) and caveolae-mitochondria interaction regulates adaptation to cellular stress by modulating the structure and function of mitochondria. In C57Bl/6 mice engineered to overexpress caveolin specifically in cardiac myocytes (Cav-3 OE), localization of caveolin to mitochondria increases membrane rigidity (4.2%; P<0.05), tolerance to calcium, and respiratory function (72% increase in state 3 and 23% increase in complex IV activity; P<0.05), while reducing stress-induced generation of reactive oxygen species (by 20% in cellular superoxide and 41 and 28% in mitochondrial superoxide under states 4 and 3, respectively; P<0.05) in Cav-3 OE vs. TGneg. By contrast, mitochondrial function is abnormal in caveolin-knockout mice and Caenorhabditis elegans with null mutations in caveolin (60% increase free radical in Cav-2 C. elegans mutants; P<0.05). In human colon cancer cells, mitochondria with increased caveolin have a 30% decrease in apoptotic stress (P<0.05), but cells with disrupted mitochondria-caveolin interaction have a 30% increase in stress response (P<0.05). Targeted gene transfer of caveolin to mitochondria in C57Bl/6 mice increases cardiac mitochondria tolerance to calcium, enhances respiratory function (increases of 90% state 4, 220% state 3, 88% complex IV activity; P<0.05), and decreases (by 33%) cardiac damage (P<0.05). Physical association and apparently the transfer of caveolin between caveolae and mitochondria is thus a conserved cellular response that confers protection from cellular damage in a variety of tissues and settings.
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Affiliation(s)
- Heidi N Fridolfsson
- Department of Anesthesiology, University of California-San Diego, La Jolla, California 92161, USA
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25
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Markandeya YS, Saqib A, Phelan LJ, Buss CR, Hacker TA, Balijepalli RC. Cardiac Restricted Overexpression of Caveolin-3 Prevents Arrhythmia, Ventricular Hypertrophy and Cardiac Dysfunction in Aging Mice. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1721] [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: 11/30/2022] Open
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26
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Horikawa YT, Panneerselvam M, Kawaraguchi Y, Tsutsumi YM, Ali SS, Balijepalli RC, Murray F, Head BP, Niesman IR, Rieg T, Vallon V, Insel PA, Patel HH, Roth DM. Cardiac-specific overexpression of caveolin-3 attenuates cardiac hypertrophy and increases natriuretic peptide expression and signaling. J Am Coll Cardiol 2011; 57:2273-83. [PMID: 21616289 DOI: 10.1016/j.jacc.2010.12.032] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [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] [Received: 11/05/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 02/04/2023]
Abstract
OBJECTIVES We hypothesized that cardiac myocyte-specific overexpression of caveolin-3 (Cav-3), a muscle-specific caveolin, would alter natriuretic peptide signaling and attenuate cardiac hypertrophy. BACKGROUND Natriuretic peptides modulate cardiac hypertrophy and are potential therapeutic options for patients with heart failure. Caveolae, microdomains in the plasma membrane that contain caveolin proteins and natriuretic peptide receptors, have been implicated in cardiac hypertrophy and natriuretic peptide localization. METHODS We generated transgenic mice with cardiac myocyte-specific overexpression of caveolin-3 (Cav-3 OE) and also used an adenoviral construct to increase Cav-3 in cardiac myocytes. RESULTS The Cav-3 OE mice subjected to transverse aortic constriction had increased survival, reduced cardiac hypertrophy, and maintenance of cardiac function compared with control mice. In left ventricle at baseline, messenger ribonucleic acid for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were increased 7- and 3-fold, respectively, in Cav-3 OE mice compared with control subjects and were accompanied by increased protein expression for ANP and BNP. In addition, ventricles from Cav-3 OE mice had greater cyclic guanosine monophosphate levels, less nuclear factor of activated T-cell nuclear translocation, and more nuclear Akt phosphorylation than ventricles from control subjects. Cardiac myocytes incubated with Cav-3 adenovirus showed increased expression of Cav-3, ANP, and Akt phosphorylation. Incubation with methyl-β-cyclodextrin, which disrupts caveolae, or with wortmannin, a PI3K inhibitor, blocked the increase in ANP expression. CONCLUSIONS These results imply that cardiac myocyte-specific Cav-3 OE is a novel strategy to enhance natriuretic peptide expression, attenuate hypertrophy, and possibly exploit the therapeutic benefits of natriuretic peptides in cardiac hypertrophy and heart failure.
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Affiliation(s)
- Yousuke T Horikawa
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA
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27
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Abstract
Evaluation of: Wei S, Guo A, Chen B et al.: T-tubule remodeling during transition from hypertrophy to heart failure. Circ. Res. 107(4), 520-531 (2010). The highly organized transverse (T)-tubule membrane system in ventricular myocytes plays an integral role in excitation-contraction coupling, and disruption of this T-tubule network has been implicated in contractile dysfunction in heart failure. Wei and colleagues used advanced confocal imaging techniques to evaluate cardiomyocyte membrane structure in intact rat hearts following surgically induced pressure overload, and demonstrated a loss of integrity of the T-tubule system. Importantly, this T-tubule dropout was detected early in the disease process, at the stage of compensated hypertrophy before observable ventricular dysfunction, and then progressed in proportion to the severity of the systolic dysfunction. These findings provide a new insight into the critical transition from compensated hypertrophy to heart failure and suggests important future areas for investigation.
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
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28
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Best JM, Foell JD, Buss CR, Delisle BP, Balijepalli RC, January CT, Kamp TJ. Small GTPase Rab11b regulates degradation of surface membrane L-type Cav1.2 channels. Am J Physiol Cell Physiol 2011; 300:C1023-33. [PMID: 21248079 DOI: 10.1152/ajpcell.00288.2010] [Citation(s) in RCA: 30] [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: 01/07/2023]
Abstract
L-type Ca(2+) channels (LTCCs) play a critical role in Ca(2+)-dependent signaling processes in a variety of cell types. The number of functional LTCCs at the plasma membrane strongly influences the strength and duration of Ca(2+) signals. Recent studies demonstrated that endosomal trafficking provides a mechanism for dynamic changes in LTCC surface membrane density. The purpose of the current study was to determine whether the small GTPase Rab11b, a known regulator of endosomal recycling, impacts plasmalemmal expression of Ca(v)1.2 LTCCs. Disruption of endogenous Rab11b function with a dominant negative Rab11b S25N mutant led to a significant 64% increase in peak L-type Ba(2+) current (I(Ba,L)) in human embryonic kidney (HEK)293 cells. Short-hairpin RNA (shRNA)-mediated knockdown of Rab11b also significantly increased peak I(Ba,L) by 66% compared when with cells transfected with control shRNA, whereas knockdown of Rab11a did not impact I(Ba,L). Rab11b S25N led to a 1.7-fold increase in plasma membrane density of hemagglutinin epitope-tagged Ca(v)1.2 expressed in HEK293 cells. Cell surface biotinylation experiments demonstrated that Rab11b S25N does not significantly impact anterograde trafficking of LTCCs to the surface membrane but rather slows degradation of plasmalemmal Ca(v)1.2 channels. We further demonstrated Rab11b expression in ventricular myocardium and showed that Rab11b S25N significantly increases peak I(Ba,L) by 98% in neonatal mouse cardiac myocytes. These findings reveal a novel role for Rab11b in limiting, rather than promoting, the plasma membrane expression of Ca(v)1.2 LTCCs in contrast to its effects on other ion channels including human ether-a-go-go-related gene (hERG) K(+) channels and cystic fibrosis transmembrane conductance regulator. This suggests Rab11b differentially regulates the trafficking of distinct cargo and extends our understanding of how endosomal transport impacts the functional expression of LTCCs.
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Affiliation(s)
- Jabe M Best
- University of Wisconsin School of Medicine and Public Health, H6/370 Clinical Science Center, 600 Highland Ave., Madison, WI 53792-3248, USA
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29
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Markandeya YS, Fahey JM, Pluteanu F, Cribbs LL, Balijepalli RC. Caveolin-3 regulates protein kinase A modulation of the Ca(V)3.2 (alpha1H) T-type Ca2+ channels. J Biol Chem 2010; 286:2433-44. [PMID: 21084288 DOI: 10.1074/jbc.m110.182550] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated T-type Ca(2+) channel Ca(v)3.2 (α(1H)) subunit, responsible for T-type Ca(2+) current, is expressed in different tissues and participates in Ca(2+) entry, hormonal secretion, pacemaker activity, and arrhythmia. The precise subcellular localization and regulation of Ca(v)3.2 channels in native cells is unknown. Caveolae containing scaffolding protein caveolin-3 (Cav-3) localize many ion channels, signaling proteins and provide temporal and spatial regulation of intracellular Ca(2+) in different cells. We examined the localization and regulation of the Ca(v)3.2 channels in cardiomyocytes. Immunogold labeling and electron microscopy analysis demonstrated co-localization of the Ca(v)3.2 channel and Cav-3 relative to caveolae in ventricular myocytes. Co-immunoprecipitation from neonatal ventricular myocytes or transiently transfected HEK293 cells demonstrated that Ca(v)3.1 and Ca(v)3.2 channels co-immunoprecipitate with Cav-3. GST pulldown analysis confirmed that the N terminus region of Cav-3 closely interacts with Ca(v)3.2 channels. Whole cell patch clamp analysis demonstrated that co-expression of Cav-3 significantly decreased the peak Ca(v)3.2 current density in HEK293 cells, whereas co-expression of Cav-3 did not alter peak Ca(v)3.1 current density. In neonatal mouse ventricular myocytes, overexpression of Cav-3 inhibited the peak T-type calcium current (I(Ca,T)) and adenovirus (AdCa(v)3.2)-mediated increase in peak Ca(v)3.2 current, but did not affect the L-type current. The protein kinase A-dependent stimulation of I(Ca,T) by 8-Br-cAMP (membrane permeable cAMP analog) was abolished by siRNA directed against Cav-3. Our findings on functional modulation of the Ca(v)3.2 channels by Cav-3 is important for understanding the compartmentalized regulation of Ca(2+) signaling during normal and pathological processes.
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Affiliation(s)
- Yogananda S Markandeya
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, Wisconsin 53706, USA
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30
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Lin EC, Holzem KM, Anson BD, Moungey BM, Balijepalli SY, Tester DJ, Ackerman MJ, Delisle BP, Balijepalli RC, January CT. Properties of WT and mutant hERG K(+) channels expressed in neonatal mouse cardiomyocytes. Am J Physiol Heart Circ Physiol 2010; 298:H1842-9. [PMID: 20363883 DOI: 10.1152/ajpheart.01236.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [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: 11/22/2022]
Abstract
Mutations in human ether-a-go-go-related gene 1 (hERG) are linked to long QT syndrome type 2 (LQT2). hERG encodes the pore-forming alpha-subunits that coassemble to form rapidly activating delayed rectifier K(+) current in the heart. LQT2-linked missense mutations have been extensively studied in noncardiac heterologous expression systems, where biogenic (protein trafficking) and biophysical (gating and permeation) abnormalities have been postulated to underlie the loss-of-function phenotype associated with LQT2 channels. Little is known about the properties of LQT2-linked hERG channel proteins in native cardiomyocyte systems. In this study, we expressed wild-type (WT) hERG and three LQT2-linked mutations in neonatal mouse cardiomyocytes and studied their electrophysiological and biochemical properties. Compared with WT hERG channels, the LQT2 missense mutations G601S and N470D hERG exhibited altered protein trafficking and underwent pharmacological correction, and N470D hERG channels gated at more negative voltages. The DeltaY475 hERG deletion mutation trafficked similar to WT hERG channels, gated at more negative voltages, and had rapid deactivation kinetics, and these properties were confirmed in both neonatal mouse cardiomyocyte and human embryonic kidney (HEK)-293 cell expression systems. Differences between the cardiomyocytes and HEK-293 cell expression systems were that hERG current densities were reduced 10-fold and deactivation kinetics were accelerated 1.5- to 2-fold in neonatal mouse cardiomyocytes. An important finding of this work is that pharmacological correction of trafficking-deficient LQT2 mutations, as a potential innovative approach to therapy, is possible in native cardiac tissue.
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Affiliation(s)
- Eric C Lin
- Section of Cardiovascular Medicine, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin, USA
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31
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Balijepalli RC, Foell JD, Best JM, Kamp TJ. Cavβ2 Subunit Associates with Caveolin-3 and Regulates Trafficking and β2adrenergic Receptor Regulation of the Caveolar L-Type Ca2+ Channels. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.092] [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: 11/24/2022] Open
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32
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Reuter H, Louch WE, Brette F, Sham JSK, Sun H, Yang XR, Soeller C, Lakatta EG, Balijepalli RC. Commentaries on viewpoint: The cardiac contraction cycle: is Ca2+ going local? Counterpoint. J Appl Physiol (1985) 2009; 107:1985-7; author reply 1988. [PMID: 19952386 DOI: 10.1152/japplphysiol.01028.2009] [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: 11/22/2022] Open
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33
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Abstract
Caveolae are specialized membrane microdomains enriched in cholesterol and sphingolipids which are present in multiple cell types including cardiomyocytes. Along with the essential scaffolding protein caveolin-3, a number of different ion channels and transporters have been localized to caveolae in cardiac myocytes including L-type Ca2+ channels (Ca(v)1.2), Na+ channels (Na(v)1.5), pacemaker channels (HCN4), Na+/Ca2+ exchanger (NCX1) and others. Closely associated with these channels are specific macromolecular signaling complexes that provide highly localized regulation of the channels. Mutations in the caveolin-3 gene (CAV3) have been linked with the congenital long QT syndrome (LQT9), and mutations in caveolar-localized ion channels may contribute to other inherited arrhythmias. Changes in the caveolar microdomain in acquired heart disease may also lead to dysregulation and dysfunction of ion channels, altering the risk of arrhythmias in conditions such as heart failure. This review highlights the existing evidence identifying and characterizing ion channels localized to caveolae in cardiomyocytes and their role in arrhythmogenesis.
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI 53792, USA
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34
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Ye B, Balijepalli RC, Foell JD, Kroboth S, Ye Q, Luo YH, Shi NQ. Caveolin-3 associates with and affects the function of hyperpolarization-activated cyclic nucleotide-gated channel 4. Biochemistry 2008; 47:12312-12318. [PMID: 19238754 PMCID: PMC2803323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Targeting of ion channels to caveolae, a subset of lipid rafts, allow cells to respond efficiently to extracellular signals. Hyperpolarization-activated cyclic nucleotide-gated channel (HCN) 4 is a major subunit for the cardiac pacemaker. Caveolin-3 (Cav3), abundantly expressed in muscle cells, is responsible for forming caveolae. P104L, a Cav3 mutant, has a dominant negative effect on wild type (WT) Cav3 and associates with limb-girdle muscular dystrophy and cardiomyopathy. HCN4 was previously shown to localize to lipid rafts, but how caveolae regulate the function of HCN4 is unknown. We hypothesize that Cav3 associates with HCN4 and regulates the function of HCN4 channel. In this study, we applied whole-cell patch clamp analysis, immunostaining, biotinylation, and immunoprecipitation methods to investigate this hypothesis. The immunoprecipitation results indicated an association of HCN4 and Cav3 in the heart and in HEK293 cells. Our immunostaining results showed that HCN4 colocalized with Cav3 but only partially colocalized with P104L in HEK293 cells. Transient expression of Cav3, but not P104L, in HEK 293 cells stably expressing HCN4 caused a 45% increase in HCN4 current (IHCN4) density. Transient expression of P104L caused a two-fold increase in the activation time constant for IHCN4 and shifted the voltage of the steady-state inactivation to a more negative potential. We conclude that HCN4 associates with Cav3 to form a HCN4 macromolecular complex. Our results indicated that disruption of caveolae using P104L alters HCN4 function and could cause a reduction of cardiac pacemaker activity.
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Affiliation(s)
- Bin Ye
- To whom correspondence should be addressed. Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin–Madison, Room 24, 1300 University Avenue Madison, WI 53706. Phone: (608)239-9779. Fax: (608)263-1144. (B.Y.); (R.C.B.)
| | - Ravi C. Balijepalli
- To whom correspondence should be addressed. Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin–Madison, Room 24, 1300 University Avenue Madison, WI 53706. Phone: (608)239-9779. Fax: (608)263-1144. (B.Y.); (R.C.B.)
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35
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Delisle BP, Underkofler HAS, Moungey BM, Slind JK, Kilby JA, Best JM, Foell JD, Balijepalli RC, Kamp TJ, January CT. Small GTPase determinants for the Golgi processing and plasmalemmal expression of human ether-a-go-go related (hERG) K+ channels. J Biol Chem 2008; 284:2844-2853. [PMID: 19029296 DOI: 10.1074/jbc.m807289200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pro-arrhythmic Long QT syndrome (LQT) is linked to 10 different genes (LQT1-10). Approximately 40% of genotype-positive LQT patients have LQT2, which is characterized by mutations in the human ether-a-go-go related gene (hERG). hERG encodes the voltage-gated K(+) channel alpha-subunits that form the pore of the rapidly activating delayed rectifier K(+) current in the heart. The purpose of this study was to elucidate the mechanisms that regulate the intracellular transport or trafficking of hERG, because trafficking is impaired for about 90% of LQT2 missense mutations. Protein trafficking is regulated by small GTPases. To identify the small GTPases that are critical for hERG trafficking, we coexpressed hERG and dominant negative (DN) GTPase mutations in HEK293 cells. The GTPases Sar1 and ARF1 regulate the endoplasmic reticulum (ER) export of proteins in COPII and COPI vesicles, respectively. Expression of DN Sar1 inhibited the Golgi processing of hERG, decreased hERG current (I(hERG)) by 85% (n > or = 8 cells per group, *, p < 0.01), and reduced the plasmalemmal staining of hERG. The coexpression of DN ARF1 had relatively small effects on hERG trafficking. Surprisingly, the coexpression of DN Rab11B, which regulates the endosomal recycling, inhibited the Golgi processing of hERG, decreased I(hERG) by 79% (n > or = 8 cells per group; *, p < 0.01), and reduced the plasmalemmal staining of hERG. These data suggest that hERG undergoes ER export in COPII vesicles and endosomal recycling prior to being processed in the Golgi. We conclude that hERG trafficking involves a pathway between the ER and endosomal compartments that influences expression in the plasmalemma.
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Affiliation(s)
- Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536.
| | - Heather A S Underkofler
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Brooke M Moungey
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Jessica K Slind
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Jennifer A Kilby
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Jabe M Best
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Jason D Foell
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Ravi C Balijepalli
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Timothy J Kamp
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706
| | - Craig T January
- Cellular and Molecular Arrhythmia Research Program, Departments of Medicine and Physiology, University of Wisconsin, Madison, Wisconsin 53706.
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36
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Ye B, Balijepalli RC, Foell JD, Kroboth S, Ye Q, Luo YH, Shi NQ. Caveolin-3 Associates with and Affects the Function of Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel 4. Biochemistry 2008; 47:12476-82. [DOI: 10.1021/bi8009295] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Bin Ye
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Ravi C. Balijepalli
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Jason D. Foell
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Stacie Kroboth
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Qi Ye
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Yu-Hong Luo
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
| | - Nian-Qing Shi
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, and Jinan University, Guangzhou, Guangdong Province, China
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Balijepalli RC, Delisle BP, Balijepalli SY, Foell JD, Slind JK, Kamp TJ, January CT. Kv11.1 (ERG1) K+ channels localize in cholesterol and sphingolipid enriched membranes and are modulated by membrane cholesterol. Channels (Austin) 2007; 1:263-72. [PMID: 18708743 DOI: 10.4161/chan.4946] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The localization of ion channels to specific membrane microdomains can impact the functional properties of channels and their role in cellular physiology. We determined the membrane localization of human Kv11.1 (hERG1) alpha-subunit protein, which underlies the rapidly activating, delayed rectifier K(+) current (I(Kr)) in the heart. Immunocytochemistry and membrane fractionation using discontinuous sucrose density gradients of adult canine ventricular tissue showed that Kv11.1 channel protein localized to both the cell surface and T-tubular sarcolemma. Furthermore, density gradient membrane fractionation using detergent (Triton X-100) and non-detergent (OptiPrep) methods from canine ventricular myocytes or HEK293 cells demonstrated that Kv11.1 protein, along with MiRP1 and Kv7.1 (KCNQ1) proteins, localize in cholesterol and sphingolipid enriched membrane fractions. In HEK293 cells, Kv11.1 channels, but not long QT-associated mutant G601S-Kv11.1 channels, also localized to cholesterol and sphingolipid enriched membrane fractions. Depletion of membrane cholesterol from HEK293 cells expressing Kv11.1 channels using methyl-beta-cyclodextrin (MbetaCD) caused a positive shift of the voltage dependence of activation and an acceleration of deactivation kinetics of Kv11.1 current (I(Kv11.1)). Cholesterol loading of HEK293 cells reduced the steep voltage dependence of I(Kv11.1) activation and accelerated the inactivation kinetics of I(Kv11.1). Incubation of neonatal mouse myocytes in MbetaCD also accelerated the deactivation kinetics of I(Kr). We conclude that Kv11.1 protein localizes in cholesterol and sphingolipid enriched membranes and that membrane cholesterol can modulate I(Kv11.1) and I(Kr).
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, Wisconsin, USA
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38
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Vatta M, Ackerman MJ, Ye B, Makielski JC, Ughanze EE, Taylor EW, Tester DJ, Balijepalli RC, Foell JD, Li Z, Kamp TJ, Towbin JA. Mutant caveolin-3 induces persistent late sodium current and is associated with long-QT syndrome. Circulation 2006; 114:2104-12. [PMID: 17060380 DOI: 10.1161/circulationaha.106.635268] [Citation(s) in RCA: 345] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Congenital long-QT syndrome (LQTS) is a primary arrhythmogenic syndrome stemming from perturbed cardiac repolarization. LQTS, which affects approximately 1 in 3000 persons, is 1 of the most common causes of autopsy-negative sudden death in the young. Since the sentinel discovery of cardiac channel gene mutations in LQTS in 1995, hundreds of mutations in 8 LQTS susceptibility genes have been identified. All 8 LQTS genotypes represent primary cardiac channel defects (ie, ion channelopathy) except LQT4, which is a functional channelopathy because of mutations in ankyrin-B. Approximately 25% of LQTS remains unexplained pathogenetically. We have pursued a "final common pathway" hypothesis to elicit novel LQTS-susceptibility genes. With the recent observation that the LQT3-associated, SCN5A-encoded cardiac sodium channel localizes in caveolae, which are known membrane microdomains whose major component in the striated muscle is caveolin-3, we hypothesized that mutations in caveolin-3 may represent a novel pathogenetic mechanism for LQTS. METHODS AND RESULTS Using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing, we performed open reading frame/splice site mutational analysis on CAV3 in 905 unrelated patients referred for LQTS genetic testing. CAV3 mutations were engineered by site-directed mutagenesis and the molecular phenotype determined by transient heterologous expression into cell lines that stably express the cardiac sodium channel hNa(v)1.5. We identified 4 novel mutations in CAV3-encoded caveolin-3 that were absent in >1000 control alleles. Electrophysiological analysis of sodium current in HEK293 cells stably expressing hNa(v)1.5 and transiently transfected with wild-type and mutant caveolin-3 demonstrated that mutant caveolin-3 results in a 2- to 3-fold increase in late sodium current compared with wild-type caveolin-3. Our observations are similar to the increased late sodium current associated with LQT3-associated SCN5A mutations. CONCLUSIONS The present study reports the first CAV3 mutations in subjects with LQTS, and we provide functional data demonstrating a gain-of-function increase in late sodium current.
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Affiliation(s)
- Matteo Vatta
- Department of Pediatrics (Cardiology), Baylor College of Medicine, Texas Children's Hospital, Houston, TX 77030, USA.
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39
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Balijepalli RC, Foell JD, Hall DD, Hell JW, Kamp TJ. Localization of cardiac L-type Ca(2+) channels to a caveolar macromolecular signaling complex is required for beta(2)-adrenergic regulation. Proc Natl Acad Sci U S A 2006; 103:7500-5. [PMID: 16648270 PMCID: PMC1564282 DOI: 10.1073/pnas.0503465103] [Citation(s) in RCA: 320] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
L-type Ca(2+) channels play a critical role in regulating Ca(2+)-dependent signaling in cardiac myocytes, including excitation-contraction coupling; however, the subcellular localization of cardiac L-type Ca(2+) channels and their regulation are incompletely understood. Caveolae are specialized microdomains of the plasmalemma rich in signaling molecules and supported by the structural protein caveolin-3 in muscle. Here we demonstrate that a subpopulation of L-type Ca(2+) channels is localized to caveolae in ventricular myocytes as part of a macromolecular signaling complex necessary for beta(2)-adrenergic receptor (AR) regulation of I(Ca,L). Immunofluorescence studies of isolated ventricular myocytes using confocal microscopy detected extensive colocalization of caveolin-3 and the major pore-forming subunit of the L-type Ca channel (Ca(v)1.2). Immunogold electron microscopy revealed that these proteins colocalize in caveolae. Immunoprecipitation from ventricular myocytes using anti-Ca(v)1.2 or anti-caveolin-3 followed by Western blot analysis showed that caveolin-3, Ca(v)1.2, beta(2)-AR (not beta(1)-AR), G protein alpha(s), adenylyl cyclase, protein kinase A, and protein phosphatase 2a are closely associated. To determine the functional impact of the caveolar-localized beta(2)-AR/Ca(v)1.2 signaling complex, beta(2)-AR stimulation (salbutamol plus atenolol) of I(Ca,L) was examined in pertussis toxin-treated neonatal mouse ventricular myocytes. The stimulation of I(Ca,L) in response to beta(2)-AR activation was eliminated by disruption of caveolae with 10 mM methyl beta-cyclodextrin or by small interfering RNA directed against caveolin-3, whereas beta(1)-AR stimulation (norepinephrine plus prazosin) of I(Ca,L) was not altered. These findings demonstrate that subcellular localization of L-type Ca(2+) channels to caveolar macromolecular signaling complexes is essential for regulation of the channels by specific signaling pathways.
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Affiliation(s)
| | - Jason D. Foell
- *Department of Medicine, University of Wisconsin, Madison, WI 53706 and
| | - Duane D. Hall
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242
| | - Johannes W. Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242
| | - Timothy J. Kamp
- *Department of Medicine, University of Wisconsin, Madison, WI 53706 and
- To whom correspondence should be addressed at:
H6/343 Clinical Science Center, Box 3248, 600 Highland Avenue, Madison, WI 53792. E-mail:
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40
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He JQ, Balijepalli RC, Haworth RA, Kamp TJ. Crosstalk of β-Adrenergic Receptor Subtypes Through G
i
Blunts β-Adrenergic Stimulation of L-Type Ca
2+
Channels in Canine Heart Failure. Circ Res 2005; 97:566-73. [PMID: 16100050 DOI: 10.1161/01.res.0000181160.31851.05] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The mechanisms underlying the blunted contractile response to β-adrenergic receptor (β-AR) stimulation in heart failure (HF) are incompletely understood, especially with regard to β-AR subtype–specific regulation of L-type Ca
2+
channels. We evaluated the impact of HF induced by pacing tachycardia on β-AR regulation of L-type Ca
2+
channels in a canine model. To evaluate changes in the relative subcellular distribution of β-AR subtypes, left ventricular membranes enriched in surface sarcolemma and T-tubular sarcolemma were prepared. Radioligand binding using [
125
I]cyanopindolol revealed that HF resulted in a comparable decrease in the density of β
1
-ARs in both surface and T-tubule sarcolemma (55±4%, n=7,
P
<0.001; and 45±10%, n=7,
P
<0.01, respectively), but no significant change in β
2
-AR density was observed. Whole-cell patch clamp studies demonstrated a markedly blunted increase in
I
Ca,L
in response to saturating concentrations of the nonselective β-AR agonist isoproterenol (0.1 μmol/L) in failing myocytes compared with control (129±20%, n=11, versus 332±35%, n=7;
P
<0.001). Experiments testing β
1
-AR– and β
2
-AR–selective stimulation showed that the major component of the blunted response to nonselective β-AR stimulation in HF was caused by β
2
-AR activation, resulting in a pertussis toxin–sensitive, G
i
-mediated inhibition of the β
1
-AR–induced increase in
I
Ca,L
. In conclusion, canine HF results in the following: (1) a uniform reduction in β
1
-AR density in surface and T-tubule membrane fractions without a change in β
2
-AR density; and (2) the emergence of distinct G
i
-coupling to β
2
-ARs resulting in accentuated antagonism of β
1
-AR–mediated stimulation of
I
Ca,L
. These results have implications for optimizing the use of β-AR drugs in HF.
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MESH Headings
- Albuterol/pharmacology
- Animals
- Calcium Channels, L-Type/physiology
- Dogs
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Heart Failure/physiopathology
- Isoproterenol/pharmacology
- Pertussis Toxin/pharmacology
- Propanolamines/pharmacology
- Receptors, Adrenergic, beta-1/analysis
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/analysis
- Receptors, Adrenergic, beta-2/physiology
- Sarcolemma/chemistry
- Signal Transduction/physiology
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Affiliation(s)
- Jia-Qiang He
- Department of Physiology, University of Wisconsin, Madison, WI 53792, USA
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41
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Cohen RM, Foell JD, Balijepalli RC, Shah V, Hell JW, Kamp TJ. Unique modulation of L-type Ca2+channels by short auxiliary β1dsubunit present in cardiac muscle. Am J Physiol Heart Circ Physiol 2005; 288:H2363-74. [PMID: 15615847 DOI: 10.1152/ajpheart.00348.2004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies have identified a growing diversity of splice variants of auxiliary Ca2+channel Cavβ subunits. The Cavβ1disoform encodes a putative protein composed of the amino-terminal half of the full-length Cavβ1isoform and thus lacks the known high-affinity binding site that recognizes the Ca2+channel α1-subunit, the α-binding pocket. The present study investigated whether the Cavβ1dsubunit is expressed at the protein level in heart, and whether it exhibits any of the functional properties typical of full-length Cavβ subunits. On Western blots, an antibody directed against the unique carboxyl terminus of Cavβ1didentified a protein of the predicted molecular mass of 23 kDa from canine and human hearts. Immunocytochemistry and surface-membrane biotinylation experiments in transfected HEK-293 cells revealed that the full-length Cavβ1bsubunit promoted membrane trafficking of the pore-forming α1C(Cav1.2)-subunit to the surface membrane, whereas the Cavβ1dsubunit did not. Whole cell patch-clamp analysis of transfected HEK-293 cells demonstrated no effect of coexpression of the Cavβ1dwith the α1C-subunit compared with the 15-fold larger currents and leftward shift in voltage-dependent activation induced by full-length Cavβ1bcoexpression. In contrast, cell-attached patch single-channel studies demonstrated that coexpression of either Cavβ1bor Cavβ1dsignificantly increased mean open probability four- to fivefold relative to the α1C-channels alone, but only Cavβ1bcoexpression increased the number of channels observed per patch. In conclusion, the Cavβ1disoform is expressed in heart and can modulate the gating of L-type Ca2+channels, but it does not promote membrane trafficking of the channel complex.
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Affiliation(s)
- Risa M Cohen
- Department of Medicine, University of Wisconsin, Madison, Wisconsin 53792, USA
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42
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Delisle BP, Slind JK, Kilby JA, Anderson CL, Anson BD, Balijepalli RC, Tester DJ, Ackerman MJ, Kamp TJ, January CT. Intragenic suppression of trafficking-defective KCNH2 channels associated with long QT syndrome. Mol Pharmacol 2005; 68:233-40. [PMID: 15851652 DOI: 10.1124/mol.105.012914] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the KCNH2 or human ether-a-go-go-related gene-encoded K(+) channel reduce functional KCNH2 current (I(KCNH2)) to cause long QT syndrome (LQT2) by multiple mechanisms, including defects in intracellular transport (trafficking). Trafficking-deficient, or class 2, LQT2 mutations reduce the Golgi processing and surface membrane expression of KCNH2 channel proteins. Drugs that associate with pore-S6 intracellular drug binding domain of KCNH2 channel proteins to cause high-affinity block of I(KCNH2) also can increase the processing of class 2 LQT2 channel proteins through the secretory pathway. We used a strategy of intragenic suppression to test the hypothesis that amino acid substitutions in the putative drug binding domain at residue Y652 could compensate for protein folding abnormalities caused by class 2 LQT2 mutations. We found that the Y652C substitution, and to lesser extent the Y652S substitution, resulted in intragenic suppression of the class 2 LQT2 G601S phenotype; these substitutions increased Golgi processing of G601S channel proteins. The Y652C substitution also caused intragenic suppression of the class 2 LQT2 V612L and F640V phenotypes but not the LQT2 N470D or F805C phenotypes. These are the first findings to demonstrate that a single amino acid substitution in the putative KCNH2 drug binding domain can cause intragenic suppression of several LQT2 mutations.
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Affiliation(s)
- Brian P Delisle
- Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706, USA
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44
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Foell JD, Balijepalli RC, Delisle BP, Yunker AMR, Robia SL, Walker JW, McEnery MW, January CT, Kamp TJ. Molecular heterogeneity of calcium channel beta-subunits in canine and human heart: evidence for differential subcellular localization. Physiol Genomics 2004; 17:183-200. [PMID: 14762176 DOI: 10.1152/physiolgenomics.00207.2003] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple Ca2+ channel beta-subunit (Ca(v)beta) isoforms are known to differentially regulate the functional properties and membrane trafficking of high-voltage-activated Ca2+ channels, but the precise isoform expression pattern of Ca(v)beta subunits in ventricular muscle has not been fully characterized. Using sequence data from the Human Genome Project to define the intron/exon structure of the four known Ca(v)beta genes, we designed a systematic RT-PCR strategy to screen human and canine left ventricular myocardial samples for all known Ca(v)beta isoforms. A total of 18 different Ca(v)beta isoforms were detected in both canine and human ventricles including splice variants from all four Ca(v)beta genes. Six of these isoforms have not previously been described. Western blots of ventricular membrane fractions and immunocytochemistry demonstrated that all four Ca(v)beta subunit genes are expressed at the protein level, and the Ca(v)beta subunits show differential subcellular localization with Ca(v)beta1b, Ca(v)beta2, and Ca(v)beta3 predominantly localized to the T-tubule sarcolemma, whereas Ca(v)beta1a and Ca(v)beta4 are more prevalent in the surface sarcolemma. Coexpression of the novel Ca(v)beta2c subunits (Ca(v)beta(2cN1), Ca(v)beta(2cN2), Ca(v)beta(2cN4)) with the pore-forming alpha1C (Ca(v)1.2) and Ca(v)alpha2delta subunits in HEK 293 cells resulted in a marked increase in ionic current and Ca(v)beta2c isoform-specific modulation of voltage-dependent activation. These results demonstrate a previously unappreciated heterogeneity of Ca(v)beta subunit isoforms in ventricular myocytes and suggest the presence of different subcellular populations of Ca2+ channels with distinct functional properties.
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Affiliation(s)
- Jason D Foell
- Department of Medicine, University of Wisconsin, Madison 53792, USA
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45
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Robu VG, Pfeiffer ES, Robia SL, Balijepalli RC, Pi Y, Kamp TJ, Walker JW. Localization of functional endothelin receptor signaling complexes in cardiac transverse tubules. J Biol Chem 2003; 278:48154-61. [PMID: 12972433 DOI: 10.1074/jbc.m304396200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin-1 (ET-1) is an autocrine factor in the mammalian heart important in enhancing cardiac performance, protecting against myocardial ischemia, and initiating the development of cardiac hypertrophy. The ETA receptor is a seven-transmembrane G-protein-coupled receptor whose precise subcellular localization in cardiac muscle is unknown. Here we used fluorescein ET-1 and 125I-ET-1 to provide evidence for ET-1 receptors in cardiac transverse tubules (T-tubules). Moreover, the ETA receptor and downstream effector phospholipase C-beta 1 were co-localized within T-tubules using standard immunofluorescence techniques, and protein kinase C (PKC)-epsilon-enhanced green fluorescent protein bound reversibly to T-tubules upon activation. Localized photorelease of diacylglycerol further suggested compartmentation of PKC signaling, with release at the myocyte "surface" mimicking the negative inotropic effects of bath-applied PKC activators and "deep" release mimicking the positive inotropic effect of ET-1. The functional significance of T-tubular ET-1 receptors was further tested by rendering the T-tubule lumen inaccessible to bath-applied ET-1. Such "detubulated" cardiac myocytes showed no positive inotropic response to 20 nM ET-1, despite retaining both a nearly normal twitch response to field stimulation and a robust positive inotropic response to 20 nm isoproterenol. We propose that ET-1 enhances myocyte contractility by activating ETA receptor-phospholipase C-beta 1-PKC-epsilon signaling complexes preferentially localized in cardiac T-tubules. Compartmentation of ET-1 signaling complexes may explain the discordant effects of ET-1 versus bath applied PKC activators and may contribute to both the specificity and diversity of the cardiac actions of ET-1.
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Affiliation(s)
- Valentin G Robu
- Department of Physiology, University of Wisconsin, Madison, Wisconsin 53706, USA
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Delisle BP, Anderson CL, Balijepalli RC, Anson BD, Kamp TJ, January CT. Thapsigargin selectively rescues the trafficking defective LQT2 channels G601S and F805C. J Biol Chem 2003; 278:35749-54. [PMID: 12837749 DOI: 10.1074/jbc.m305787200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several mutations in the human ether-a-go-go-related K+ channel gene (HERG or KCNH2) cause long QT syndrome (LQT2) by reducing the intracellular transport (trafficking) of the channel protein to the cell surface. Drugs that bind to and block HERG channels (i.e. E4031) rescue the surface expression of some trafficking defective LQT2 mutations. Because these drugs potently block HERG current, their ability to correct congenital LQT is confounded by their risk of causing acquired LQT. We tested the hypothesis that pharmacological rescue can occur without HERG channel block. Thapsigargin (1 microM), a sarcoplasmic/endoplasmic reticulum Ca2+-ATPase inhibitor, rescued the surface expression of G601S, and it did so without blocking current. Thapsigargin-induced rescue and E4031-induced rescue caused complex glycosylation that was evident within 3 h of drug exposure. Disruption of the Golgi apparatus with brefeldin A prevented thapsigargin- and E4031-induced rescue of IG01S. Confocal imaging showed that G601S protein is predominantly "trapped" intracellularly and that both thapsigargin and E4031 promote its relocation to the surface membrane. We also studied two other trafficking defective LQT2 mutations. Thapsigargin rescued the C terminus mutation F805C but not N470D, whereas E4031 rescued N470D but not F805C. Other sarcoplasmic/endoplasmic reticulum Ca2+-ATPase inhibitors did not rescue G601S or F805C. This study 1) supports the hypothesis that the LQT2 trafficking defective phenotype can be reversed without blocking the channel; 2) demonstrates pharmacological rescue of a C terminus LQT2 mutation; and 3) shows that thapsigargin can correct trafficking defective phenotypes in more than one channel type and disease (i.e. LQT2 and cystic fibrosis).
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Affiliation(s)
- Brian P Delisle
- Department of Medicine (Cardiology), University of Wisconsin, Madison, Wisconsin 53706, USA
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Balijepalli RC, Lokuta AJ, Maertz NA, Buck JM, Haworth RA, Valdivia HH, Kamp TJ. Depletion of T-tubules and specific subcellular changes in sarcolemmal proteins in tachycardia-induced heart failure. Cardiovasc Res 2003; 59:67-77. [PMID: 12829177 DOI: 10.1016/s0008-6363(03)00325-0] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE The T-tubule membrane network is integrally involved in excitation-contraction coupling in ventricular myocytes. Ventricular myocytes from canine hearts with tachycardia-induced dilated cardiomyopathy exhibit a decrease in accessible T-tubules to the membrane-impermeant dye, di8-ANNEPs. The present study investigated the mechanism of loss of T-tubule staining and examined for changes in the subcellular distribution of membrane proteins essential for excitation-contraction coupling. METHODS Isolated ventricular myocytes from canine hearts with and without tachycardia-induced heart failure were studied using fluorescence confocal microscopy and membrane fractionation techniques using a variety of markers specific for sarcolemmal and sarcoplasmic reticulum proteins. RESULTS Probes for surface glycoproteins, Na/K ATPase, Na/Ca exchanger and Ca(v)1.2 demonstrated a prominent but heterogeneous reduction in T-tubule labeling in both intact and permeabilised failing myocytes, indicating a true depletion of T-tubules and associated membrane proteins. Membrane fractionation studies showed reductions in L-type Ca(2+) channels and beta-adrenergic receptors but increased levels of Na/Ca exchanger protein in both surface sarcolemma and T-tubular sarcolemma-enriched fractions; however, the membrane fraction enriched in junctional complexes of sarcolemma and junctional sarcoplasmic reticulum demonstrated no significant changes in the density of any sarcolemmal protein or sarcoplasmic reticulum protein assayed. CONCLUSION Failing canine ventricular myocytes exhibit prominent depletion of T-tubules and changes in the density of a variety of proteins in both surface and T-tubular sarcolemma but with preservation of the protein composition of junctional complexes. This subcellular remodeling contributes to abnormal excitation-contraction coupling in heart failure.
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Balijepalli RC, Foell JD, Robia SL, Walker JW, Kamp TJ. 11 Subcellular distribution of cardiac β-adrenergic receptor subtypes in canine tachycardia-induced heart failure. J Mol Cell Cardiol 2002. [DOI: 10.1016/s0022-2828(02)90117-3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Robu VG, Balijepalli RC, Pfeiffer ES, Robia SL, Kamp TJ, Walker JW. 06 Localization of endothelin a receptor in the transverse tubules of cardiac myocytes. J Mol Cell Cardiol 2002. [DOI: 10.1016/s0022-2828(02)90214-2] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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