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Strom J, Bull M, Gohlke J, Saripalli C, Methawasin M, Gotthardt M, Granzier H. Titin's cardiac-specific N2B element is critical to mechanotransduction during volume overload of the heart. J Mol Cell Cardiol 2024; 191:40-49. [PMID: 38604403 DOI: 10.1016/j.yjmcc.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 03/09/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024]
Abstract
The heart has the ability to detect and respond to changes in mechanical load through a process called mechanotransduction. In this study, we focused on investigating the role of the cardiac-specific N2B element within the spring region of titin, which has been proposed to function as a mechanosensor. To assess its significance, we conducted experiments using N2B knockout (KO) mice and wildtype (WT) mice, subjecting them to three different conditions: 1) cardiac pressure overload induced by transverse aortic constriction (TAC), 2) volume overload caused by aortocaval fistula (ACF), and 3) exercise-induced hypertrophy through swimming. Under conditions of pressure overload (TAC), both genotypes exhibited similar hypertrophic responses. In contrast, WT mice displayed robust left ventricular hypertrophy after one week of volume overload (ACF), while the KO mice failed to undergo hypertrophy and experienced a high mortality rate. Similarly, swim exercise-induced hypertrophy was significantly reduced in the KO mice. RNA-Seq analysis revealed an abnormal β-adrenergic response to volume overload in the KO mice, as well as a diminished response to isoproterenol-induced hypertrophy. Because it is known that the N2B element interacts with the four-and-a-half LIM domains 1 and 2 (FHL1 and FHL2) proteins, both of which have been associated with mechanotransduction, we evaluated these proteins. Interestingly, while volume-overload resulted in FHL1 protein expression levels that were comparable between KO and WT mice, FHL2 protein levels were reduced by over 90% in the KO mice compared to WT. This suggests that in response to volume overload, FHL2 might act as a signaling mediator between the N2B element and downstream signaling pathways. Overall, our study highlights the importance of the N2B element in mechanosensing during volume overload, both in physiological and pathological settings.
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Affiliation(s)
- Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Mathew Bull
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Chandra Saripalli
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Michael Gotthardt
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Department of Cardiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
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Lancaster JJ, Grijalva A, Fink J, Ref J, Daugherty S, Whitman S, Fox K, Gorman G, Lancaster LD, Avery R, Acharya T, McArthur A, Strom J, Pierce MK, Moukabary T, Borgstrom M, Benson D, Mangiola M, Pandey AC, Zile MR, Bradshaw A, Koevary JW, Goldman S. Biologically derived epicardial patch induces macrophage mediated pathophysiologic repair in chronically infarcted swine hearts. Commun Biol 2023; 6:1203. [PMID: 38007534 PMCID: PMC10676365 DOI: 10.1038/s42003-023-05564-w] [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] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 11/09/2023] [Indexed: 11/27/2023] Open
Abstract
There are nearly 65 million people with chronic heart failure (CHF) globally, with no treatment directed at the pathologic cause of the disease, the loss of functioning cardiomyocytes. We have an allogeneic cardiac patch comprised of cardiomyocytes and human fibroblasts on a bioresorbable matrix. This patch increases blood flow to the damaged heart and improves left ventricular (LV) function in an immune competent rat model of ischemic CHF. After 6 months of treatment in an immune competent Yucatan mini swine ischemic CHF model, this patch restores LV contractility without constrictive physiology, partially reversing maladaptive LV and right ventricular remodeling, increases exercise tolerance, without inducing any cardiac arrhythmias or a change in myocardial oxygen consumption. Digital spatial profiling in mice with patch placement 3 weeks after a myocardial infarction shows that the patch induces a CD45pos immune cell response that results in an infiltration of dendritic cells and macrophages with high expression of macrophages polarization to the anti-inflammatory reparative M2 phenotype. Leveraging the host native immune system allows for the potential use of immunomodulatory therapies for treatment of chronic inflammatory diseases not limited to ischemic CHF.
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Affiliation(s)
- J J Lancaster
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - A Grijalva
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - J Fink
- Division of Blood & Marrow Transplant & Cellular Therapy, Department of Pediatrics, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55455, USA
| | - J Ref
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - S Daugherty
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - S Whitman
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - K Fox
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
- Division of Cardiothoracic Surgery, Department of Surgery, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - G Gorman
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - L D Lancaster
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - R Avery
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - T Acharya
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - A McArthur
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - J Strom
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - M K Pierce
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - T Moukabary
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - M Borgstrom
- Research & Discovery Tech, Research Computing Specialist, Principal, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - D Benson
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - M Mangiola
- Department of Pathology, NYU Grossman School of Medicine, New York City, NY, 11016, USA
| | - A C Pandey
- Section of Cardiology, Tulane University Heart and Vascular Institute, John W. Deming Department of Medicine, Section of Cardiology, Department of Medicine, Southeast Louisiana Veterans Healthcare System, Tulane University School of Medicine, New Orleans, LA, 70122, USA
| | - M R Zile
- Ralph H. Johnson VA Medical Center, Division of Cardiology, Medical University of South Carolina, Thurmond/Gazes Building, 30 Courtenay Drive, Charleston, SC, 29425, USA
| | - A Bradshaw
- Ralph H. Johnson VA Medical Center, Division of Cardiology, Medical University of South Carolina, Thurmond/Gazes Building, 30 Courtenay Drive, Charleston, SC, 29425, USA
| | - J W Koevary
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
- Biomedical Engineering, College of Engineering, University of Arizona, 1127 E. James E. Rogers Way, Tucson, AZ, 85721, USA
| | - S Goldman
- Sarver Heart Center, Department of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA.
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Hoyer-Kimura C, Hay M, Konhilas JP, Morrison HW, Methajit M, Strom J, Polt R, Salcedo V, Fricks JP, Kalya A, Pires PW. PNA5, A Novel Mas Receptor Agonist, Improves Neurovascular and Blood-Brain-Barrier Function in a Mouse Model of Vascular Cognitive Impairment and Dementia. Aging Dis 2023:AD.2023.0928. [PMID: 37815905 DOI: 10.14336/ad.2023.0928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 09/28/2023] [Indexed: 10/12/2023] Open
Abstract
It is well established that decreased brain blood flow, increased reactive oxygen species production (ROS), and pro-inflammatory mechanisms accelerate neurodegenerative disease progressions, including vascular cognitive impairment and dementia (VCID). Previous studies in our laboratory have shown that our novel glycosylated Angiotensin-(1-7) Mas receptor agonist PNA5 reverses cognitive deficits, decreases ROS production, and inhibits inflammatory cytokine production in our preclinical mouse model of VCID that is induced by chronic heart failure (VCID-HF). In the present study, the effects of VCID-HF and treatment with PNA5 on microglia activation, blood-brain-barrier (BBB) integrity, and neurovascular coupling were assessed in our mouse model of VCID-HF. Three-month-old male C57BL/6J mice were subjected to myocardial infarction (MI) to induce heart failure for four weeks and then treated with subcutaneous injections of extended-release PNA5. Microglia activation, BBB permeability, cerebral perfusion, and neurovascular coupling were assessed. Results show that in our VCID-HF model, there was an increase in microglial activation and recruitment within the CA1 and CA3 regions of the hippocampus, a disruption in BBB integrity, and a decrease in neurovascular coupling. Treatment with PNA5 reversed these neuropathological effects of VCID-HF, suggesting that PNA5 may be an effective disease-modifying therapy to treat and prevent VCID. This study identifies potential mechanisms by which heart failure may induce VCID and highlights the possible mechanisms by which treatment with our novel glycosylated Angiotensin-(1-7) Mas receptor agonist, PNA5, may protect cognitive function in our model of VCID.
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Affiliation(s)
| | - Meredith Hay
- Department of Physiology, The University of Arizona, Tucson, AZ 85724, USA
- Evelyn F. McKnight Brain Institute, The University of Arizona, Tucson, AZ 85724, USA
- ProNeurogen, Inc, Tucson, AZ, USA
| | - John P Konhilas
- Department of Physiology, The University of Arizona, Tucson, AZ 85724, USA
| | - Helena W Morrison
- College of Nursing, The University of Arizona, Tucson, AZ 85724, USA
| | - Methawasin Methajit
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, AZ 85724, USA
| | - Robin Polt
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ 85724, USA
| | - Victoria Salcedo
- Department of Physiology, The University of Arizona, Tucson, AZ 85724, USA
| | | | - Anjna Kalya
- Department of Physiology, The University of Arizona, Tucson, AZ 85724, USA
| | - Paulo W Pires
- Department of Physiology, The University of Arizona, Tucson, AZ 85724, USA
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de Winter JM, Bouman K, Strom J, Methawasin M, Jongbloed JDH, van der Roest W, Wijngaarden JV, Timmermans J, Nijveldt R, van den Heuvel F, Kamsteeg EJ, van Engelen BG, Galli R, Bogaards SJP, Boon RA, van der Pijl RJ, Granzier H, Koeleman B, Amin AS, van der Velden J, van Tintelen JP, van den Berg MP, van Spaendonck-Zwarts KY, Voermans NC, Ottenheijm CAC. KBTBD13 is a novel cardiomyopathy gene. Hum Mutat 2022; 43:1860-1865. [PMID: 36335629 PMCID: PMC10100581 DOI: 10.1002/humu.24499] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 08/22/2022] [Accepted: 09/12/2022] [Indexed: 11/08/2022]
Abstract
KBTBD13 variants cause nemaline myopathy type 6 (NEM6). The majority of NEM6 patients harbors the Dutch founder variant, c.1222C>T, p.Arg408Cys (KBTBD13 p.R408C). Although KBTBD13 is expressed in cardiac muscle, cardiac involvement in NEM6 is unknown. Here, we constructed pedigrees of three families with the KBTBD13 p.R408C variant. In 65 evaluated patients, 12% presented with left ventricle dilatation, 29% with left ventricular ejection fraction< 50%, 8% with atrial fibrillation, 9% with ventricular tachycardia, and 20% with repolarization abnormalities. Five patients received an implantable cardioverter defibrillator, three cases of sudden cardiac death were reported. Linkage analysis confirmed cosegregation of the KBTBD13 p.R408C variant with the cardiac phenotype. Mouse studies revealed that (1) mice harboring the Kbtbd13 p.R408C variant display mild diastolic dysfunction; (2) Kbtbd13-deficient mice have systolic dysfunction. Hence, (1) KBTBD13 is associated with cardiac dysfunction and cardiomyopathy; (2) KBTBD13 should be added to the cardiomyopathy gene panel; (3) NEM6 patients should be referred to the cardiologist.
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Affiliation(s)
| | - Karlijn Bouman
- Department of Neurology, Radboudumc, Nijmegen, The Netherlands
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Jan D H Jongbloed
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Wilma van der Roest
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | | | | | - Robin Nijveldt
- Department of Cardiology, Radboudumc, Nijmegen, The Netherlands
| | | | | | | | - Ricardo Galli
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | | | - Reinier A Boon
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Robbert J van der Pijl
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Bobby Koeleman
- Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands
| | - Ahmad S Amin
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - J Peter van Tintelen
- Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cardiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Maarten P van den Berg
- Department of Cardiology, University Medical Centre Groningen, Groningen, The Netherlands
| | - Karin Y van Spaendonck-Zwarts
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands.,Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands
| | | | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
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Strom J, Xu J, Sun T, Song Y, Sevilla-Cazes J, Wadhera R, Yeh R. Ascertainment of aortic valve disease using administrative claims. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.2857] [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: 11/14/2022] Open
Abstract
Abstract
Background
Administrative claims may be useful for characterizing patients with aortic stenosis (AS) and aortic regurgitation (AR) and estimating disease prevalence. However, the accuracy of diagnostic codes for aortic valve disease has not been well studied.
Purpose
To evaluate the validity of International Classification of Diseases, 10th Revision (ICD-10) codes for identification of AS and AR.
Methods
Using a large, transthoracic echocardiographic (TTE) report dataset linked to Medicare Fee-for-service (FFS) claims, 2017–2018, the performance of candidate claims to ascertain AS/AR status using standard TTE definitions was evaluated. Recursive partitioning with 10-fold cross validation was used to build the optimal prediction tree for AS/AR status using all ICD-10 codes as candidate predictors. The optimal performing claims algorithm was tested against patient outcomes in a separate 100% sample of Medicare FFS inpatient and outpatient claims, 2017–2019.
Results
Of those included in the derivation dataset (N=5497, mean age 74.4±11.0 years, 49.7% female), any AS or AR was present in 24% and 38.8%, respectively. The code I35.0 was optimal for identification of any AS with a sensitivity and specificity for any AS of 53.1% and 94.8%, respectively (Table 1). Amongst those with an I35.0 code, 40.3% had severe AS. Claims were unable to distinguish disease severity (i.e. severe vs. non-severe) or subtypes (e.g. bicuspid or rheumatic AS), and were insensitive and nonspecific for AR of any severity. Among all Medicare beneficiaries who received an TTE (N=3,783,249), those with an I35.0 code, compared to those without, had a higher risk of all-cause mortality (HR 1.65, 95% CI 1.63–1.67), heart failure hospitalization (HR 2.17, 95% CI 2.11–2.24), and aortic valve replacement (HR 32.35, 95% CI 31.46–33.27) (Table 2).
Conclusions
Amongst those receiving TTE, the ICD-10 code I35.0 in any position was optimal for identification of AS and identified a population at significant greater risk of all-cause mortality, heart failure hospitalization, and receipt of aortic valve replacement. Though 40.3% of those with I35.0 had severe AS, claims were unable to distinguish disease severity of subtype. Claims may be feasibly used to identify those with AS who may be at risk for adverse valve-related cardiovascular events and require future treatment.
Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): National, Heart, Lung, and Blood Institute
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Affiliation(s)
- J Strom
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
| | - J Xu
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
| | - T Sun
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
| | - Y Song
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
| | - J Sevilla-Cazes
- Beth Israel Deaconess Medical Center , Boston , United States of America
| | - R Wadhera
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
| | - R Yeh
- Beth Israel Deaconess Medical Center & Harvard Medical School, Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology , Boston , United States of America
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Fregosi R, Strom J, Wollman L. Perinatal nicotine exposure alters development of cardiac performance. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r5840] [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)
| | - Joshua Strom
- Cell & Molecular MedicineUniversity of ArizonaTucsonAZ
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Bruggink S, Xiao Y, Geisler C, Ghimire S, Strom J, Renquist B. An Underlying Mechanism by which Hepatic Steatosis Drives the Development of Hypertension. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.l7531] [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)
| | - Yao Xiao
- Animal and Comparative Biomedical SciencesUniversity of ArizonaTucsonAZ
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Sullivan J, Sadler R, Strom J, Harris S. In situ replacement of slow skeletal myosin binding protein-c. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Sadler R, Strom J, Fan J, Harris SP. A homozygous missense mutation in the M-domain of cardiac myosin binding protein-C is lethal in a CRISPR-gene edited mouse model. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Wang C, Zhang Y, Methawasin M, Braz CU, Gao-Hu J, Yang B, Strom J, Gohlke J, Hacker T, Khatib H, Granzier H, Guo W. RBM20 S639G mutation is a high genetic risk factor for premature death through RNA-protein condensates. J Mol Cell Cardiol 2022; 165:115-129. [PMID: 35041844 PMCID: PMC8940686 DOI: 10.1016/j.yjmcc.2022.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/03/2022] [Accepted: 01/09/2022] [Indexed: 12/13/2022]
Abstract
Dilated cardiomyopathy (DCM) is a heritable and genetically heterogenous disease often idiopathic and a leading cause of heart failure with high morbidity and mortality. DCM caused by RNA binding motif protein 20 (RBM20) mutations is diverse and needs a more complete mechanistic understanding. RBM20 mutation S637G (S639G in mice) is linked to severe DCM and early death in human patients. In this study, we generated a RBM20 S639G mutation knock-in (KI) mouse model to validate the function of S639G mutation and examine the underlying mechanisms. KI mice exhibited severe DCM and premature death with a ~ 50% mortality in two months old homozygous (HM) mice. KI mice had enlarged atria and increased ANP and BNP biomarkers. The S639G mutation promoted RBM20 trafficking and ribonucleoprotein (RNP) granules in the sarcoplasm. RNA Seq data revealed differentially expressed and spliced genes were associated with arrhythmia, cardiomyopathy, and sudden death. KI mice also showed a reduction of diastolic stiffness and impaired contractility at both the left ventricular (LV) chamber and cardiomyocyte levels. Our results indicate that the RBM20 S639G mutation leads to RNP granules causing severe heart failure and early death and this finding strengthens the novel concept that RBM20 cardiomyopathy is a RNP granule disease.
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Affiliation(s)
- Chunyan Wang
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Yanghai Zhang
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Camila Urbano Braz
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Jeffrey Gao-Hu
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Betty Yang
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Timothy Hacker
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - Hasan Khatib
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Wei Guo
- Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA.
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11
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Methawasin M, Farman GP, Granzier-Nakajima S, Strom J, Kiss B, Smith JE, Granzier H. Shortening the thick filament by partial deletion of titin's C-zone alters cardiac function by reducing the operating sarcomere length range. J Mol Cell Cardiol 2022; 165:103-114. [PMID: 35031281 PMCID: PMC8940690 DOI: 10.1016/j.yjmcc.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 10/19/2022]
Abstract
Titin's C-zone is an inextensible segment in titin, comprised of 11 super-repeats and located in the cMyBP-C-containing region of the thick filament. Previously we showed that deletion of titin's super-repeats C1 and C2 (TtnΔC1-2 model) results in shorter thick filaments and contractile dysfunction of the left ventricular (LV) chamber but that unexpectedly LV diastolic stiffness is normal. Here we studied the contraction-relaxation kinetics from the time-varying elastance of the LV and intact cardiomyocyte, cellular work loops of intact cardiomyocytes, Ca2+ transients, cross-bridge kinetics, and myofilament Ca2+ sensitivity. Intact cardiomyocytes of TtnΔC1-2 mice exhibit systolic dysfunction and impaired relaxation. The time-varying elastance at both LV and single-cell levels showed that activation kinetics are normal in TtnΔC1-2 mice, but that relaxation is slower. The slowed relaxation is, in part, attributable to an increased myofilament Ca2+ sensitivity and slower early Ca2+ reuptake. Cross-bridge dynamics showed that cross-bridge kinetics are normal but that the number of force-generating cross-bridges is reduced. In vivo sarcomere length (SL) measurements revealed that in TtnΔC1-2 mice the operating SL range of the LV is shifted towards shorter lengths. This normalizes the apparent cell and LV diastolic stiffness but further reduces systolic force as systole occurs further down on the ascending limb of the force-SL relation. We propose that the reduced working SLs reflect titin's role in regulating diastolic stiffness by altering the number of sarcomeres in series. Overall, our study reveals that thick filament length regulation by titin's C-zone is critical for normal cardiac function.
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Affiliation(s)
- Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
| | - Gerrie P Farman
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Shawtaroh Granzier-Nakajima
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Balazs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
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12
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Stewart S, Afokwah C, Playford D, Strom J, Chan Y, Schuffham P, Strange G. Calculating the Cost Burden of Progressive Aortic Stenosis: Insight From an International Observational Clinical Cohort Study. Heart Lung Circ 2022. [DOI: 10.1016/j.hlc.2022.06.067] [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: 11/26/2022]
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13
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Biquand A, Spinozzi S, Tonino P, Cosette J, Strom J, Elbeck Z, Knöll R, Granzier H, Lostal W, Richard I. Titin M-line insertion sequence 7 is required for proper cardiac function in mice. J Cell Sci 2021; 134:271843. [PMID: 34401916 DOI: 10.1242/jcs.258684] [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] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 08/06/2021] [Indexed: 11/20/2022] Open
Abstract
Titin is a giant sarcomeric protein that is involved in a large number of functions, with a primary role in skeletal and cardiac sarcomere organization and stiffness. The titin gene (TTN) is subject to various alternative splicing events, but in the region that is present at the M-line, the only exon that can be spliced out is Mex5, which encodes for the insertion sequence 7 (is7). Interestingly, in the heart, the majority of titin isoforms are Mex5+, suggesting a cardiac role for is7. Here, we performed comprehensive functional, histological, transcriptomic, microscopic and molecular analyses of a mouse model lacking the Ttn Mex5 exon (ΔMex5), and revealed that the absence of the is7 is causative for dilated cardiomyopathy. ΔMex5 mice showed altered cardiac function accompanied by increased fibrosis and ultrastructural alterations. Abnormal expression of excitation-contraction coupling proteins was also observed. The results reported here confirm the importance of the C-terminal region of titin in cardiac function and are the first to suggest a possible relationship between the is7 and excitation-contraction coupling. Finally, these findings give important insights for the identification of new targets in the treatment of titinopathies.
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Affiliation(s)
- Ariane Biquand
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Simone Spinozzi
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | | | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Zaher Elbeck
- Department of Medicine, Integrated Cardio Metabolic Centre (ICMC), Heart and Vascular Theme, Karolinska Institutet, 141 57 Huddinge, Sweden
| | - Ralph Knöll
- Department of Medicine, Integrated Cardio Metabolic Centre (ICMC), Heart and Vascular Theme, Karolinska Institutet, 141 57 Huddinge, Sweden.,Bioscience Cardiovascular, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, 431 50 Gothenburg, Sweden
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - William Lostal
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Isabelle Richard
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
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14
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Kiss B, Gohlke J, Tonino P, Hourani Z, Kolb J, Strom J, Alekhina O, Smith JE, Ottenheijm C, Gregorio C, Granzier H. Nebulin and Lmod2 are critical for specifying thin-filament length in skeletal muscle. Sci Adv 2020; 6:6/46/eabc1992. [PMID: 33177085 PMCID: PMC7673738 DOI: 10.1126/sciadv.abc1992] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 09/23/2020] [Indexed: 06/07/2023]
Abstract
Regulating the thin-filament length in muscle is crucial for controlling the number of myosin motors that generate power. The giant protein nebulin forms a long slender filament that associates along the length of the thin filament in skeletal muscle with functions that remain largely obscure. Here nebulin's role in thin-filament length regulation was investigated by targeting entire super-repeats in the Neb gene; nebulin was either shortened or lengthened by 115 nm. Its effect on thin-filament length was studied using high-resolution structural and functional techniques. Results revealed that thin-filament length is strictly regulated by the length of nebulin in fast muscles. Nebulin's control is less tight in slow muscle types where a distal nebulin-free thin-filament segment exists, the length of which was found to be regulated by leiomodin-2 (Lmod2). We propose that strict length control by nebulin promotes high-speed shortening and that dual-regulation by nebulin/Lmod2 enhances contraction efficiency.
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Affiliation(s)
- Balázs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Olga Alekhina
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Carol Gregorio
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA.
- Allan and Alfie Endowed Chair for Heart Disease in Women Research, Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, USA
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15
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Abstract
BACKGROUND Low myocardial cGMP-PKG (cyclic guanosine monophosphate-protein kinase G) activity has been associated with increased cardiomyocyte diastolic stiffness in heart failure with preserved ejection fraction. Cyclic guanosine monophosphate is mainly hydrolyzed by PDE (phosphodiesterases) 5a and 9a. Importantly, PDE9a expression has been reported to be upregulated in human heart failure with preserved ejection fraction myocardium and chronic administration of a PDE9a inhibitor reverses preestablished cardiac hypertrophy and systolic dysfunction in mice subjected to transverse aortic constriction (TAC). We hypothesized that inhibiting PDE9a activity ameliorates diastolic dysfunction. METHODS To examine the effect of chronic PDE9a inhibition, 2 diastolic dysfunction mouse models were studied: (1) TAC-deoxycorticosterone acetate and (2) Leprdb/db. PDE9a inhibitor (5 and 8 mg/kg per day) was administered to the mice via subcutaneously implanted osmotic minipumps for 28 days. The effect of acute PDE9a inhibition was investigated in intact cardiomyocytes isolated from TAC-deoxycorticosterone acetate mice. Atrial natriuretic peptide together with PDE9a inhibitor were administered to the isolated intact cardiomyocytes through the cell perfusate. RESULTS For acute inhibition, no cellular stiffness reduction was found, whereas chronic PDE9a inhibition resulted in reduced left ventricular chamber stiffness in TAC-deoxycorticosterone acetate, but not in Leprdb/db mice. Passive cardiomyocyte stiffness was reduced by chronic PDE9a inhibition, with no differences in myocardial fibrosis or cardiac morphometry. PDE9a inhibition increased the ventricular-arterial coupling ratio, reflecting impaired systolic function. CONCLUSIONS Chronic PDE9a inhibition lowers left ventricular chamber stiffness in TAC-deoxycorticosterone acetate mice. However, the usefulness of PDE9a inhibition to treat high-diastolic stiffness may be limited as the required PDE9a inhibitor dose also impairs systolic function, observed as a decline in ventricular-arterial coordination, in this model.
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Affiliation(s)
- Mei Methawasin
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Joshua Strom
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Tomasz Borkowski
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Ray Runyan
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - John E Smith
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Henk Granzier
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
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16
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Napierski NC, Granger K, Langlais PR, Moran HR, Strom J, Touma K, Harris SP. A Novel "Cut and Paste" Method for In Situ Replacement of cMyBP-C Reveals a New Role for cMyBP-C in the Regulation of Contractile Oscillations. Circ Res 2020; 126:737-749. [PMID: 32078438 DOI: 10.1161/circresaha.119.315760] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE cMyBP-C (cardiac myosin-binding protein-C) is a critical regulator of heart contraction, but the mechanisms by which cMyBP-C affects actin and myosin are only partly understood. A primary obstacle is that cMyBP-C localization on thick filaments may be a key factor defining its interactions, but most in vitro studies cannot duplicate the unique spatial arrangement of cMyBP-C within the sarcomere. OBJECTIVE The goal of this study was to validate a novel hybrid genetic/protein engineering approach for rapid manipulation of cMyBP-C in sarcomeres in situ. METHODS AND RESULTS We designed a novel cut and paste approach for removal and replacement of cMyBP-C N'-terminal domains (C0-C7) in detergent-permeabilized cardiomyocytes from gene-edited Spy-C mice. Spy-C mice express a TEVp (tobacco etch virus protease) cleavage site and a SpyTag (st) between cMyBP-C domains C7 and C8. A cut is achieved using TEVp which cleaves cMyBP-C to create a soluble N'-terminal γC0C7 (endogenous [genetically encoded] N'-terminal domains C0 to C7 of cardiac myosin binding protein-C) fragment and an insoluble C'-terminal SpyTag-C8-C10 fragment that remains associated with thick filaments. Paste of new recombinant (r)C0C7 domains is achieved by a covalent bond formed between SpyCatcher (-sc; encoded at the C'-termini of recombinant proteins) and SpyTag. Results show that loss of γC0C7 reduced myofilament Ca2+ sensitivity and increased cross-bridge cycling (ktr) at submaximal [Ca2+]. Acute loss of γC0C7 also induced auto-oscillatory contractions at submaximal [Ca2+]. Ligation of rC0C7 (exogenous [recombinant] N'-terminal domains C0 to C7 of cardiac myosin binding protein-C)-sc returned pCa50 and ktr to control values and abolished oscillations, but phosphorylated (p)-rC0C7-sc did not completely rescue these effects. CONCLUSIONS We describe a robust new approach for acute removal and replacement of cMyBP-C in situ. The method revealed a novel role for cMyBP-C N'-terminal domains to damp sarcomere-driven contractile waves (so-called spontaneous oscillatory contractions). Because phosphorylated (p)-rC0C7-sc was less effective at damping contractile oscillations, results suggest that spontaneous oscillatory contractions may contribute to enhanced contractility in response to inotropic stimuli.
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Affiliation(s)
- Nathaniel C Napierski
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Kevin Granger
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Paul R Langlais
- Division of Endocrinology, Department of Medicine (P.R.L.), University of Arizona College of Medicine, Tucson
| | - Hannah R Moran
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | - Joshua Strom
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
| | | | - Samantha P Harris
- From the Department of Cellular and Molecular Medicine (N.C.N., K.G., H.R.M, J.S., S.P.H.), University of Arizona College of Medicine, Tucson
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17
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Mi-Mi L, Farman GP, Mayfield RM, Strom J, Chu M, Pappas CT, Gregorio CC. In vivo elongation of thin filaments results in heart failure. PLoS One 2020; 15:e0226138. [PMID: 31899774 PMCID: PMC6941805 DOI: 10.1371/journal.pone.0226138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 11/20/2019] [Indexed: 12/20/2022] Open
Abstract
A novel cardiac-specific transgenic mouse model was generated to identify the physiological consequences of elongated thin filaments during post-natal development in the heart. Remarkably, increasing the expression levels in vivo of just one sarcomeric protein, Lmod2, results in ~10% longer thin filaments (up to 26% longer in some individual sarcomeres) that produce up to 50% less contractile force. Increasing the levels of Lmod2 in vivo (Lmod2-TG) also allows us to probe the contribution of Lmod2 in the progression of cardiac myopathy because Lmod2-TG mice present with a unique cardiomyopathy involving enlarged atrial and ventricular lumens, increased heart mass, disorganized myofibrils and eventually, heart failure. Turning off of Lmod2 transgene expression at postnatal day 3 successfully prevents thin filament elongation, as well as gross morphological and functional disease progression. We show here that Lmod2 has an essential role in regulating cardiac contractile force and function.
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Affiliation(s)
- Lei Mi-Mi
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Gerrie P. Farman
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Rachel M. Mayfield
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Joshua Strom
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Miensheng Chu
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Christopher T. Pappas
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
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18
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Lehman SJ, Tal-Grinspan L, Lynn ML, Strom J, Benitez GE, Anderson ME, Tardiff JC. Chronic Calmodulin-Kinase II Activation Drives Disease Progression in Mutation-Specific Hypertrophic Cardiomyopathy. Circulation 2019; 139:1517-1529. [PMID: 30586744 PMCID: PMC6461395 DOI: 10.1161/circulationaha.118.034549] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Although the genetic causes of hypertrophic cardiomyopathy (HCM) are widely recognized, considerable lag in the development of targeted therapeutics has limited interventions to symptom palliation. This is in part attributable to an incomplete understanding of how point mutations trigger pathogenic remodeling. As a further complication, similar mutations within sarcomeric genes can result in differential disease severity, highlighting the need to understand the mechanism of progression at the molecular level. One pathway commonly linked to HCM progression is calcium homeostasis dysregulation, though how specific mutations disrupt calcium homeostasis remains unclear. METHODS To evaluate the effects of early intervention in calcium homeostasis, we used 2 mouse models of sarcomeric HCM (cardiac troponin T R92L and R92W) with differential myocellular calcium dysregulation and disease presentation. Two modes of intervention were tested: inhibition of the autoactivated calcium-dependent kinase (calmodulin kinase II [CaMKII]) via the AC3I peptide and diltiazem, an L-type calcium channel antagonist. Two-dimensional echocardiography was used to determine cardiac function and left ventricular remodeling, and atrial remodeling was monitored via atrial mass. Sarcoplasmic reticulum Ca2+ATPase activity was measured as an index of myocellular calcium handling and coupled to its regulation via the phosphorylation status of phospholamban. RESULTS We measured an increase in phosphorylation of CaMKII in R92W animals by 6 months of age, indicating increased autonomous activity of the kinase in these animals. Inhibition of CaMKII led to recovery of diastolic function and partially blunted atrial remodeling in R92W mice. This improved function was coupled to increased sarcoplasmic reticulum Ca2+ATPase activity in the R92W animals despite reduction of CaMKII activation, likely indicating improvement in myocellular calcium handling. In contrast, inhibition of CaMKII in R92L animals led to worsened myocellular calcium handling, remodeling, and function. Diltiazem-HCl arrested diastolic dysfunction progression in R92W animals only, with no improvement in cardiac remodeling in either genotype. CONCLUSIONS We propose a highly specific, mutation-dependent role of activated CaMKII in HCM progression and a precise therapeutic target for clinical management of HCM in selected cohorts. Moreover, the mutation-specific response elicited with diltiazem highlights the necessity to understand mutation-dependent progression at a molecular level to precisely intervene in disease progression.
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Affiliation(s)
- Sarah J. Lehman
- Department of Physiological Sciences, University of Arizona, Tucson, Arizona 85724, USA
| | - Lauren Tal-Grinspan
- Department of Medicine, Columbia University Medical Center, New York, New York 10032, USA
| | - Melissa L. Lynn
- Department of Medicine, University of Arizona, Tucson, Arizona, 85724, USA
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85724, USA
| | - Grace E. Benitez
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, 85724, USA
| | - Mark E. Anderson
- Department of Medicine, Johns Hopkins University, Baltimore, Maryland 21287, USA
| | - Jil C. Tardiff
- Department of Medicine, University of Arizona, Tucson, Arizona, 85724, USA
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19
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Brynnel A, Hernandez Y, Kiss B, Lindqvist J, Adler M, Kolb J, Van der Pijl R, Gohlke J, Strom J, Smith JE, Granzier HL. Downsizing the Giant Titin Reveals its Dominant Roles in Skeletal Muscle Passive Stiffness and Longitudinal Hypertrophy. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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20
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Brynnel A, Hernandez Y, Kiss B, Lindqvist J, Adler M, Kolb J, van der Pijl R, Gohlke J, Strom J, Smith J, Ottenheijm C, Granzier HL. Downsizing the molecular spring of the giant protein titin reveals that skeletal muscle titin determines passive stiffness and drives longitudinal hypertrophy. eLife 2018; 7:40532. [PMID: 30565562 PMCID: PMC6300359 DOI: 10.7554/elife.40532] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/26/2018] [Indexed: 12/25/2022] Open
Abstract
Titin, the largest protein known, forms an elastic myofilament in the striated muscle sarcomere. To establish titin’s contribution to skeletal muscle passive stiffness, relative to that of the extracellular matrix, a mouse model was created in which titin’s molecular spring region was shortened by deleting 47 exons, the TtnΔ112-158 model. RNA sequencing and super-resolution microscopy predicts a much stiffer titin molecule. Mechanical studies with this novel mouse model support that titin is the main determinant of skeletal muscle passive stiffness. Unexpectedly, the in vivo sarcomere length working range was shifted to shorter lengths in TtnΔ112-158 mice, due to a ~ 30% increase in the number of sarcomeres in series (longitudinal hypertrophy). The expected effect of this shift on active force generation was minimized through a shortening of thin filaments that was discovered in TtnΔ112-158 mice. Thus, skeletal muscle titin is the dominant determinant of physiological passive stiffness and drives longitudinal hypertrophy. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Ambjorn Brynnel
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Yaeren Hernandez
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Balazs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Maya Adler
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Robbert van der Pijl
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - John Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
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21
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van der Pijl R, Strom J, Conijn S, Lindqvist J, Labeit S, Granzier H, Ottenheijm C. Titin-based mechanosensing modulates muscle hypertrophy. J Cachexia Sarcopenia Muscle 2018; 9:947-961. [PMID: 29978560 PMCID: PMC6204599 DOI: 10.1002/jcsm.12319] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [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: 01/08/2018] [Revised: 04/30/2018] [Accepted: 05/22/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Titin is an elastic sarcomeric filament that has been proposed to play a key role in mechanosensing and trophicity of muscle. However, evidence for this proposal is scarce due to the lack of appropriate experimental models to directly test the role of titin in mechanosensing. METHODS We used unilateral diaphragm denervation (UDD) in mice, an in vivo model in which the denervated hemidiaphragm is passively stretched by the contralateral, innervated hemidiaphragm and hypertrophy rapidly occurs. RESULTS In wildtype mice, the denervated hemidiaphragm mass increased 48 ± 3% after 6 days of UDD, due to the addition of both sarcomeres in series and in parallel. To test whether titin stiffness modulates the hypertrophy response, RBM20ΔRRM and TtnΔIAjxn mouse models were used, with decreased and increased titin stiffness, respectively. RBM20ΔRRM mice (reduced stiffness) showed a 20 ± 6% attenuated hypertrophy response, whereas the TtnΔIAjxn mice (increased stiffness) showed an 18 ± 8% exaggerated response after UDD. Thus, muscle hypertrophy scales with titin stiffness. Protein expression analysis revealed that titin-binding proteins implicated previously in muscle trophicity were induced during UDD, MARP1 & 2, FHL1, and MuRF1. CONCLUSIONS Titin functions as a mechanosensor that regulates muscle trophicity.
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Affiliation(s)
- Robbert van der Pijl
- Department of Cellular and Molecular MedicineUniversity of ArizonaTucsonAZUSA
- Dept of PhysiologyVU University Medical CenterAmsterdamThe Netherlands
| | - Joshua Strom
- Department of Cellular and Molecular MedicineUniversity of ArizonaTucsonAZUSA
| | - Stefan Conijn
- Dept of PhysiologyVU University Medical CenterAmsterdamThe Netherlands
| | - Johan Lindqvist
- Department of Cellular and Molecular MedicineUniversity of ArizonaTucsonAZUSA
| | - Siegfried Labeit
- Department of Integrative PathophysiologyMedical Faculty MannheimMannheimGermany
- Myomedix GmbHNeckargemuendGermany
| | - Henk Granzier
- Department of Cellular and Molecular MedicineUniversity of ArizonaTucsonAZUSA
| | - Coen Ottenheijm
- Department of Cellular and Molecular MedicineUniversity of ArizonaTucsonAZUSA
- Dept of PhysiologyVU University Medical CenterAmsterdamThe Netherlands
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22
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Lindqvist J, van den Berg M, van der Pijl R, Hooijman PE, Beishuizen A, Elshof J, de Waard M, Girbes A, Spoelstra-de Man A, Shi ZH, van den Brom C, Bogaards S, Shen S, Strom J, Granzier H, Kole J, Musters RJP, Paul MA, Heunks LMA, Ottenheijm CAC. Positive End-Expiratory Pressure Ventilation Induces Longitudinal Atrophy in Diaphragm Fibers. Am J Respir Crit Care Med 2018; 198:472-485. [PMID: 29578749 PMCID: PMC6118031 DOI: 10.1164/rccm.201709-1917oc] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 03/26/2018] [Indexed: 01/11/2023] Open
Abstract
RATIONALE Diaphragm weakness in critically ill patients prolongs ventilator dependency and duration of hospital stay and increases mortality and healthcare costs. The mechanisms underlying diaphragm weakness include cross-sectional fiber atrophy and contractile protein dysfunction, but whether additional mechanisms are at play is unknown. OBJECTIVES To test the hypothesis that mechanical ventilation with positive end-expiratory pressure (PEEP) induces longitudinal atrophy by displacing the diaphragm in the caudal direction and reducing the length of fibers. METHODS We studied structure and function of diaphragm fibers of mechanically ventilated critically ill patients and mechanically ventilated rats with normal and increased titin compliance. MEASUREMENTS AND MAIN RESULTS PEEP causes a caudal movement of the diaphragm, both in critically ill patients and in rats, and this caudal movement reduces fiber length. Diaphragm fibers of 18-hour mechanically ventilated rats (PEEP of 2.5 cm H2O) adapt to the reduced length by absorbing serially linked sarcomeres, the smallest contractile units in muscle (i.e., longitudinal atrophy). Increasing the compliance of titin molecules reduces longitudinal atrophy. CONCLUSIONS Mechanical ventilation with PEEP results in longitudinal atrophy of diaphragm fibers, a response that is modulated by the elasticity of the giant sarcomeric protein titin. We postulate that longitudinal atrophy, in concert with the aforementioned cross-sectional atrophy, hampers spontaneous breathing trials in critically ill patients: during these efforts, end-expiratory lung volume is reduced, and the shortened diaphragm fibers are stretched to excessive sarcomere lengths. At these lengths, muscle fibers generate less force, and diaphragm weakness ensues.
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Affiliation(s)
- Johan Lindqvist
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | - Robbert van der Pijl
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology
| | | | - Albertus Beishuizen
- Department of Intensive Care, Medisch Spectrum Twente, Enschede, the Netherlands; and
| | | | | | | | | | - Zhong-Hua Shi
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China
| | | | | | - Shengyi Shen
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Joshua Strom
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Henk Granzier
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | | | - Marinus A. Paul
- Department of Cardiothoracic Surgery, Vrije Universiteit Medical Center, Amsterdam, the Netherlands
| | | | - Coen A. C. Ottenheijm
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology
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Strom J, Bull M, Saripalli C, Gohlke J, Gotthardt M, Granzier H. Abstract 532: Titin’s N2B Element is Critical to Cardiac Mechanotransduction during Volume Overload, but not Pressure Overload. Circ Res 2018. [DOI: 10.1161/res.123.suppl_1.532] [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
The heart senses and responds to changes in mechanical loading conditions by initiating signaling events to produce structural and functional remodeling through a process known as mechanotransduction. Within cardiac myocytes, the giant protein titin has been implicated as a key player in the conversion of mechanical stimuli into downstream signaling events as part of the adaptive responses of mechanotransduction. The N2B element within the extensible I-band of titin has been proposed to be a stretch sensor and signaling hot spot important to titin’s role as a mechanosensor. To investigate the role of the N2B element in mechanotransduction, N2B knockout (N2BKO) mice were subjected to cardiac pressure overload by transverse aortic constriction (TAC) or volume overload by aortocaval fistula (ACF). Following 4 weeks TAC, WT mice respond with 37% LV hypertrophy (4.0 ± 0.1 mg/gBW for TAC vs 2.9 ± 0.1 mg/gBW for sham) compared to 51% (3.8 ± 0.1 mg/gBW for TAC vs 2.5 ± 0.1 mg/gBW for sham) in N2BKO. In contrast, N2BKO mice demonstrated a severe lack of a hypertrophic response following 1-week ACF with 26% (4.0 ± 0.1 mg/gBW for ACF vs 3.1 ± 0.1 mg/gBW for sham) LV hypertrophy in WT compared to -2% (2.8 ± 0.1 mg/gBW for ACF vs 2.8 ± 0.1 mg/gBW for sham) in N2BKO. Additionally, while there was no incidence of mortality in WT mice subjected to ACF, approximately 36% (5 of 14) of N2BKO mice died within 1 week following ACF. Western blot analysis of canonical hypertrophy signaling kinases revealed no differences between WT and N2BKO mice at baseline or 1 week post-ACF. Four-and-a half LIM domains 1 and 2 (FHL1 and FHL2) have previously been shown to localize to the N2B element and FHL1 has been linked to mechanotransduction in TAC. In N2BKO, FHL1 protein is expressed at levels comparable to WT in both TAC and ACF; however, FHL2 protein levels are reduced by ~98% compared to WT (1.00 ± 0.26 for WT vs 0.02 ± 0.01% for N2BKO). These data indicate that while the N2B element is not required for mechanotransduction in pressure overload of the LV, it is critical for mechanosensing and the adaptive hypertrophy response during volume overload. FHL2 is an attractive candidate as a link between titin’s N2B element and the hypertrophy response following ACF and further work will critical examine its involvement.
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Methawasin M, Strom J, Helmes M, Granzier H. Abstract 440: The Cardiomyocyte Diastolic Stiffness and Contractility are Inversely Related to the Size of Titin: A Cellular Work Loop Study of Single Intact Cardiomyocytes. Circ Res 2018. [DOI: 10.1161/res.123.suppl_1.440] [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
Studying cardiac titin under physiological conditions can be at the level of the left ventricular (LV) chamber and the multicellular muscle level. However, those preparations are influenced by neurohormonal reflex, preload-afterload status and extracellular matrix. In this study, cellular work loop force measurement of the single intact cardiomyocyte was conducted under physiological conditions. Intact cell experiments were performed at 37°C under field-stimulation at 2 Hz frequency. The cell was attached to the force transducer and the piezo length controller which modulates the cell length by the feedback control system based on developed force. The force length relation (cellular work loop) of the single cell was generated. The end diastolic force length relation (EDFLR), the end systolic force length relation (ESFLR) and the preload recruitable stroke work (PRSW) were obtained. The
Ttn
ΔIAjxn
-/-
(
IA
-/-
) mice, in which the I-band/A-band region of titin’s spring has been deleted were studied in comparison to
α-MHC-Cre
;
cRbm20
ΔRRM +/-
(
cRbm20
+/-
) mice which are deficient in titin splicing and express large titin isoforms in the heart. The cellular diastolic stiffness (slope of EDFLR) was increased in
IA
-/-
and was reduced in
cRbm20
+/-
(151.3, 104.0 and 91.5 μN/mm
2
in
IA
-/-
, WT and
cRbm20
+/-
respectively). The contractility (slopes of ESFLR and PRSW) were 233.5 and 1215.6 uN/mm
2
in WT, and were increased in
IA
-/-
(371.2 and 2076 μN/mm
2
) but attenuated in
cRbm20
+/-
(202.9 and 907.7 μN/mm
2
). Cellular work loop studies were also conducted in intact cells isolated from the mice that underwent transverse aortic constriction (TAC) surgery with deoxycorticosterone acetate (DOCA) implantation. TAC DOCA mice developed diastolic dysfunction at the LV chamber level. The result showed that the cells from TAC DOCA hearts had increased slopes of EDFLR, ESFLR and PRSW ( 157.9, 378.9 and 1699.0 μN/mm
2
) compared to the cells from sham mice (98.6, 230.3, and 1203.9 μN/mm
2
).
Conclusions:
Cellular work loops recapitulated the cardiac physiology at the LV chamber level. The result showed that the cellular diastolic stiffness and contractility were inversely related to the size of titin and that titin stiffness plays an important roles in both diastolic and systolic function.
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Touma K, van Dijk SJ, Strom J, Harris SP. In Situ Replacement of cMyBP-C N'-Terminal Domains using the Novel Spy-C Method. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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26
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Granzier H, Tonino P, Kiss B, Strom J, Smith J, Methawasin M, Kolb J. The Giant Protein Titin Regulates the Length of the Striated Muscle Thick Filament-Titin Rules. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Lopez-Pier MA, Koppinger M, Royal Harris P, Strom J, Mayfield RM, Gregorio CC, Konhilas JP. Abstract 267: Activation of Non-canonical Estrogen-dependent Pathways to Mitigate Pathological Cardiac Remodeling. Circ Res 2017. [DOI: 10.1161/res.121.suppl_1.267] [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
Prior to menopause, women are protected against cardiovascular disease (CVD) compared to age-matched men; this protection is gradually lost after menopause. Mechanisms responsible for loss of CVD protection are unknown. We previously demonstrated that menopause and CVD suppress the AMP-activated protein kinase (AMPK) signaling pathway in mice. We also validated the cellular mechanism by which estrogen (E2) potentiates AMPK activity through a direct interaction of estrogen receptors (ER) with members of the AMPK kinase complex. Because AMPK signaling is down in CVD and menopause, we hypothesized that activation of AMPK will prevent pathological cardiac remodeling in menopausal female mice. First, we demonstrated that E2 potentiates AMPK activity in neonatal rat cardiomyocytes (NRCMs) subjected to energy stress. NRCMs, cultured in estrogen-free media, were treated (10-30 minutes at 100nm) with the electron transport chain uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenyphydrazone (FCCP). As expected, AMPK activity determined by phosphorylation of threonine 172 (p-AMPK172) was increased over controls. Adding 1-100nm of E2 potentiated p-AMPK172 over control-treated NRCMs by 5-fold. Next, we used our novel model of menopause with 4-vinylcyclohexene diepoxide (VCD), which induces gradual ovarian failure, preserving the perimenopause transitional period and androgen secreting capacity of residual ovarian tissue. Starting at 2 months, females received daily (i.p.) injections of VCD (160mg/kg, 20 consecutive days) or sesame oil as vehicle. Peri/menopause were confirmed by vaginal cytology. Menopausal females receiving angiotensin II (Ang II, 800 ng/kg/min via alzet s.c. mini-pump, 14 days) demonstrated exacerbation of hypertension and pathological cardiac remodeling compared to pre- and peri-menopausal mice. Female mice treated with Ang II following surgical removal of ovaries (OVX) experienced a similar exacerbation of cardiac remodeling. Daily adminstration of the AMPK activator (A-769662, s.c. 30mg/kg) prevented pathological remodeling in menopausal and OVX female mice subjected to Ang II. We conclude that AMPK represents a non-canonical target for the mitigation of menopausal susceptibly to CVD.
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29
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Strom J, Chen QM. Loss of Nrf2 promotes rapid progression to heart failure following myocardial infarction. Toxicol Appl Pharmacol 2017; 327:52-58. [DOI: 10.1016/j.taap.2017.03.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/03/2017] [Accepted: 03/30/2017] [Indexed: 12/24/2022]
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Lynn ML, Tal Grinspan L, Holeman TA, Jimenez J, Strom J, Tardiff JC. The structural basis of alpha-tropomyosin linked (Asp230Asn) familial dilated cardiomyopathy. J Mol Cell Cardiol 2017; 108:127-137. [PMID: 28600229 DOI: 10.1016/j.yjmcc.2017.06.001] [Citation(s) in RCA: 13] [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: 04/18/2017] [Revised: 05/31/2017] [Accepted: 06/02/2017] [Indexed: 01/05/2023]
Abstract
Recently, linkage analysis of two large unrelated multigenerational families identified a novel dilated cardiomyopathy (DCM)-linked mutation in the gene coding for alpha-tropomyosin (TPM1) resulting in the substitution of an aspartic acid for an asparagine (at residue 230). To determine how a single amino acid mutation in α-tropomyosin (Tm) can lead to a highly penetrant DCM we generated a novel transgenic mouse model carrying the D230N mutation. The resultant mouse model strongly phenocopied the early onset of cardiomyopathic remodeling observed in patients as significant systolic dysfunction was observed by 2months of age. To determine the precise cellular mechanism(s) leading to the observed cardiac pathology we examined the effect of the mutation on Ca2+ handling in isolated myocytes and myofilament activation in vitro. D230N-Tm filaments exhibited a reduced Ca2+ sensitivity of sliding velocity. This decrease in sensitivity was coupled to increase in the peak amplitude of Ca2+ transients. While significant, and consistent with other DCMs, these measurements are comprised of complex inputs and did not provide sufficient experimental resolution. We then assessed the primary structural effects of D230N-Tm. Measurements of the thermal unfolding of D230N-Tm vs WT-Tm revealed an increase in stability primarily affecting the C-terminus of the Tm coiled-coil. We conclude that the D230N-Tm mutation induces a decrease in flexibility of the C-terminus via propagation through the helical structure of the protein, thus decreasing the flexibility of the Tm overlap and impairing its ability to regulate contraction. Understanding this unique structural mechanism could provide novel targets for eventual therapeutic interventions in patients with Tm-linked cardiomyopathies.
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Affiliation(s)
- M L Lynn
- Department of Physiological Sciences, University of Arizona, Tucson, AZ 85724, United States
| | - L Tal Grinspan
- Department of Medicine, Columbia University, New York, NY 10032, United States
| | - T A Holeman
- Department of Physiological Sciences, University of Arizona, Tucson, AZ 85724, United States; Department of Chemistry, University of Arizona, Tucson, AZ 85721, United States
| | - J Jimenez
- Department of Medicine, Washington University in Saint Louis, St. Louis, MO 63130, United States
| | - J Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - J C Tardiff
- Department of Physiological Sciences, University of Arizona, Tucson, AZ 85724, United States; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States; Department of Medicine, University of Arizona, Tucson, AZ 85724, United States.
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Bull M, Methawasin M, Strom J, Nair P, Hutchinson K, Granzier H. Alternative Splicing of Titin Restores Diastolic Function in an HFpEF-Like Genetic Murine Model (TtnΔIAjxn). Circ Res 2016; 119:764-72. [PMID: 27470639 DOI: 10.1161/circresaha.116.308904] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [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: 04/13/2016] [Accepted: 07/28/2016] [Indexed: 12/15/2022]
Abstract
RATIONALE Patients with heart failure with preserved ejection fraction (HFpEF) experience elevated filling pressures and reduced ventricular compliance. The splicing factor RNA-binding motif 20 (RBM20) regulates the contour length of titin's spring region and thereby determines the passive stiffness of cardiomyocytes. Inhibition of RBM20 leads to super compliant titin isoforms (N2BAsc) that reduce passive stiffness. OBJECTIVE To determine the therapeutic potential of upregulating compliant titin isoforms in an HFpEF-like state in the mouse. METHODS AND RESULTS Constitutive and inducible cardiomyocyte-specific RBM20-inhibited mice were produced on a Ttn(ΔIAjxn) background to assess the effect of upregulating compliant titin at the cellular and organ levels. Genetic deletion of the I-band-A-band junction (IAjxn) in titin increases strain on the spring region and causes a HFpEF-like syndrome in the mouse without pharmacological or surgical intervention. The increased strain represents a mechanical analog of deranged post-translational modification of titin that results in increased passive myocardial stiffness in patients with HFpEF. On inhibition of RBM20 in Ttn(ΔIAjxn) mice, compliant titin isoforms were expressed, diastolic function was normalized, exercise performance was improved, and pathological hypertrophy was attenuated. CONCLUSIONS We report for the first time a benefit from upregulating compliant titin isoforms in a murine model with HFpEF-like symptoms. Constitutive and inducible RBM20 inhibition improves diastolic function resulting in greater tolerance to exercise. No effective therapies exists for treating this pervasive syndrome; therefore, our data on RBM20 inhibition are clinically significant.
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Affiliation(s)
- Mathew Bull
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson
| | - Mei Methawasin
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson
| | - Joshua Strom
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson
| | - Pooja Nair
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson
| | - Kirk Hutchinson
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson
| | - Henk Granzier
- From the Department of Cellular and Molecular Medicine (M.B., M.M., J.S., P.N., K.H., H.G.) and Sarver Molecular Cardiovascular Research Program (M.B., M.M., J.S., P.N., K.H., H.G.), University of Arizona, Tucson.
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32
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Bull M, Methawasin M, Strom J, Nair P, Hutchinson K, Granzier H. Abstract 398: Alternative Splicing of Titin Restores Diastolic Function and Improves HFpEF Associated Symptoms. Circ Res 2016. [DOI: 10.1161/res.119.suppl_1.398] [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
Greater than half of all heart failure (HF) patients suffer from increased diastolic stiffness and impaired relaxation of the left ventricle while their ejection fraction (EF) is preserved (HFpEF). HFpEF is a complex disease characterized by diastolic dysfunction, exercise intolerance, and concentric hypertrophic remodeling. No effective therapy exists for treating this pervasive disease due in part to our limited understanding of the underlying pathophysiology. Titin, the largest known protein and molecular spring in the heart, has emerged as a prime candidate for therapeutic targets aimed at restoring compliance to the sarcomere in order to improve diastolic function.
Titin has two main cardiac isoforms; the smaller N2B isoform (~3.0 MDa) and the larger more compliant N2BA isoform (~3.3 MDa). Diastolic stiffness of the left ventricle is in large part dependent upon the N2BA:N2B isoform ratio. Modification of these two primary isoforms can be achieved post-transcriptionally through inhibiting the known titin splicing factor Rbm20. Alternative splicing of messenger RNA occurs primarily in the spring region of titin and therefore regulates the elastic property of titin through changes in contour length of the spring.
The current study evaluates whether reduction of titin splicing factor Rbm20 has a beneficial effect on the diastolic function of mice with restrictive cardiomyopathy. A previously published mouse model deficient in titin’s IA junction (
Ttn
ΔIAjxn
) places increased strain on the spring region of titin and acts as a mechanical analogue of the titin-based increase in passive myocardial stiffness found in HFpEF patients. This model exhibits a HFpEF-like phenotype apparent as early as 3 months in the adult mouse that becomes exaggerated with age apart from pharmacological or surgical intervention. We report for the first time a rescue of HFpEF in the mouse through inhibiting Rbm20. We demonstrate that Rbm20 reduction restores diastolic function, improves exercise tolerance and attenuates afterload induced pathologic remodeling of the left ventricle. No specific FDA approved therapies exist to treat the pathologically stiff left ventricle, therefore our findings on Rbm20 inhibition are clinically significant.
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33
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Morrissy SJ, Sun H, Zhang J, Strom J, Chen QM. Differential Regulation of Bcl-xL Gene Expression by Corticosterone, Progesterone, and Retinoic Acid. J Biochem Mol Toxicol 2016; 30:309-16. [PMID: 26915917 DOI: 10.1002/jbt.21795] [Citation(s) in RCA: 2] [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] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/13/2016] [Accepted: 01/15/2016] [Indexed: 01/13/2023]
Abstract
Corticosterone (CT), progesterone (PG), and retinoic acid (RA) are capable of inhibiting Doxorubicin (Dox) from inducing apoptosis in rat cardiomyocytes. Mechanistically, CT, PG, and RA induce increases of Bcl-xL protein and mRNA, and activate a 3.2 kb bcl-x gene promoter. CT and RA, but not PG, induced the activity of a 0.9 kb bcl-x promoter, containing sequences for AP-1 and NF-kB binding. RA, but not CT or PG, induced NF-kB activation. CT, but not PG or RA, induced AP-1 activation, and induction of the 0.9 kb bcl-x reporter by CT was inhibited by dominant negative c-Jun TAM-67 or removal of AP-1 binding site. Therefore, although CT, PG, and RA all induce Bcl-xL mRNA and protein, three independent mechanisms are in operation: while CT induces Bcl-xL via AP-1 transcription factor, and RA induces NF-kB activation and bcl-x promoter activity, PG induces Bcl-xL via a mechanism independent of NF-kB or AP-1.
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Affiliation(s)
- Steve J Morrissy
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - Haipeng Sun
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - Jack Zhang
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - Joshua Strom
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - Qin M Chen
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, 85724, USA.
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Abstract
Sublethal levels of oxidative stress are commonly associated with various pathophysiological conditions. Cardiomyocytes have the highest content of mitochondria among all cell types, allowing the study of mitochondria in cells surviving oxidative stress and address whether nuclear factor-erythroid-derived 2-related factor 2 (Nrf2) can reverse these changes. Mitochondria normally exist in elaborated networks, which were replaced by predominately individual punctuate mitochondria 24 h after exposure to a nonlethal dose of H2O2. Electron microscopy revealed that cells surviving H2O2 show swelling of mitochondria with disorganized cristae and areas of condensation. Measurements of functional mitochondria showed a H2O2 dose-dependent decrease over a course of 5 d. At the protein and mRNA levels, cells surviving H2O2 treatment show a reduction of mitochondrial components, cytochrome c, and cytochrome b. Nrf2 overexpression prevented H2O2 from inducing mitochondria morphologic changes and reduction of cytochrome b/c. Although Nrf2 is known as a transcription factor regulating antioxidant and detoxification genes, Nrf2 overexpression did not significantly reduce the level of protein oxidation. Instead, Nrf2 was found to associate with the outer mitochondrial membrane. Mitochondria prepared from the myocardium of Nrf2 knockout mice are more sensitive to permeability transition. Our data suggest that Nrf2 protects mitochondria from oxidant injury likely through direct interaction with mitochondria.
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Affiliation(s)
- Joshua Strom
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, USA
| | - Beibei Xu
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, USA
| | - Xiuqing Tian
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, USA
| | - Qin M Chen
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, USA
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Bull M, Nair P, Strom J, Gotthardt M, Granzier H. Abstract 375: Mechanotransduction via Titin’s N2B Element Contributes to Cardiac Remodeling. Circ Res 2015. [DOI: 10.1161/res.117.suppl_1.375] [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
Pathological remodeling is responsible for the functional deficits characteristic of heart failure patients. Understanding mechanotransduction is limited, but holds potential to provide novel therapeutic targets to treat patients with heart failure, especially those with diastolic dysfunction and preserved ejection fraction (HFpEF). Titin is the largest known protein and is abundant in muscle. It is the main contributor of passive stiffness in the heart and functions as a molecular mechano-sensor for stress and strain in the myocyte. Titin is composed of four distinct regions, (N-terminal Z-line, I-band, A-band, and C-terminal M-line), and acts as a molecular spring that is responsible for the assembly and maintenance of ultrastructure in the sarcomere. The elastic N2B element found in titin’s I-band region has been proposed as a mechano-sensor and signaling “hot spot” in the sarcomere. This study investigates the role of titin’s cardiac specific N2B element as sensor for stress and strain induced remodeling in the heart. The previously published N2B knock out (KO) mouse was subjected to a variety of stressors including transverse aortic constriction (TAC), aorto-caval fistula (ACF), chronic swimming, voluntary running and isoproterenol injections. Through chronic pathologic stress, pressure overload (TAC) and chronic volume overload (ACF), we found that the N2B element is necessary for the response to volume overload but not pressure overload as determined by changes in cardiac remodeling. Furthermore, the response to exercise either by chronic swimming or voluntary running was reduced in the N2B KO mouse. Finally, unlike the wild-type (WT) mouse, the N2B KO mouse did not respond to isoproterenol injections with hypertrophic remodeling. Ongoing work to elucidate the molecular pathways involving the N2B element and response to stress, is focused on its binding protein Four-and-a-half-LIM domains 2 (FHL2) and the mitogen activated protein kinase (MAPK) pathway. Taken together our data suggest that the N2B element contributes significantly to mechanotransduction in the heart.
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Kaiser C, Klestinski K, Tsuji J, Sabatino T, Yorke N, Johnson R, Arnhold K, Otten J, Ahn P, Cephus K, Dittlof A, Ortega L, Foster H, Hernandez M, Rivera M, Strom D, Strom J, Yang N, Dittrich N, Waas M. Nicotinamide Phosphoribosyltransferase (NAMPT) Inhibition Yields Promising Future Implications. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.lb61] [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)
- Carl Kaiser
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - Keith Klestinski
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - J Tsuji
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - T Sabatino
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - N Yorke
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - R Johnson
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - K Arnhold
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - J Otten
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - P Ahn
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - K Cephus
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - A Dittlof
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - L Ortega
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - H Foster
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - M Hernandez
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - M Rivera
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - D Strom
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - J Strom
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - N Yang
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - N Dittrich
- Science Marquette University High SchoolMilwaukeeWIUnited States
| | - Matthew Waas
- BiochemistryMedical College of WisconsinMilwaukeeWIUnited States
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Xu B, Zhang J, Strom J, Lee S, Chen QM. Myocardial ischemic reperfusion induces de novo Nrf2 protein translation. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1638-47. [PMID: 24915518 DOI: 10.1016/j.bbadis.2014.06.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 12/15/2022]
Abstract
Nrf2 is a bZIP transcription factor regulating the expression of antioxidant and detoxification genes. We have found that Nrf2 knockout mice have an increased infarction size in response to regional ischemic reperfusion and have a reduced degree of cardiac protection by means of ischemic preconditioning. With cycles of brief ischemia and reperfusion (5'I/5'R) that induce cardiac protection in wild type mice, an elevated Nrf2 protein was observed without prior increases of Nrf2 mRNA. When an mRNA species is being translated into a protein, it is occupied by multiple ribosomes. The level of ribosome-associated Nrf2 mRNA increased following cycles of 5'I/5'R, supporting de novo Nrf2 protein translation. A dicistronic reporter assay indicated a role of the 5' untranslated region (5' UTR) of Nrf2 mRNA in oxidative stress induced Nrf2 protein translation in isolated cardiomyocytes. Western blot analyses after isolation of proteins binding to biotinylated Nrf2 5' UTR from the myocardium or cultured cardiomyocytes demonstrated that cycles of 5'I/5'R or oxidants caused an increased association of La protein with Nrf2 5' UTR. Ribonucleoprotein complex immunoprecipitation assays confirmed such association indeed occurring in vivo. Knocking down La using siRNA was able to prevent Nrf2 protein elevation by oxidants in cultured cardiomyocytes and by cycles of 5'I/5'R in the myocardium. Our data point out a novel mechanism of cardiac protection by de novo Nrf2 protein translation involving interaction of La protein with 5' UTR of Nrf2 mRNA in cardiomyocytes.
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Affiliation(s)
- Beibei Xu
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA
| | - Jack Zhang
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA
| | - Joshua Strom
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA
| | - Sang Lee
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA
| | - Qin M Chen
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA.
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Abstract
Objective: Currently there are no medications that can be administered to help deliver more oxygen to the myocardial region experiencing abnormal perfusion. The purpose of this study was to look at the nanoparticle dodecafluoropentane in an emulsion as an oxygen carrier. Using nanoparticles as an oxygen carrier is advantageous because they are able to carry oxygen past blockages that are obstructing red blood cells (6-8 µm) due to their smaller size (250 nm). With the reintroduction of oxygen to the ischemic muscle tissue, a reduced infarct size should be seen. Methods: Male C57BL/6J mice underwent left anterior descending artery (LAD) ligation using 8-0 monofilament nylon suture. Immediately after ligation of the LAD, the control group received a 200-µl intravenous injection of phosphate buffered saline (PBS). The treated group received a dose of 0.6 ml/kg of dodecafluoropentane diluted to a total volume of 200 µl in PBS. The mice were then allowed to recover from anesthesia and were sacrificed 24 hours after the time of ligation. After the mice were sacrificed, the heart was excised and placed at -20°C for 20 minutes. The heart was then sliced into 1-mm sections and stained with tetrazolium red to identify the infarcted area. The area of infarct and ventricle were then analyzed using ImageJ software. Results: The average area of infarct in comparison to the ventricle for the control mice was 29.3±0.04% compared to 11.7±0.02% for the dodecafluoropentane-treated mice. Conclusion: The use of dodecafluoropentane in this murine model of myocardial infarction showed a 60% reduction in infarct size (p<0.01). The possibility of using nanoparticles to deliver oxygen to hypoxic tissues has interesting implications and justifies further study.
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Affiliation(s)
- TW Swyer
- Sarver Heart Center, College of Medicine, The University of Arizona, Tucson, AZ, USA
| | - J Strom
- Sarver Heart Center, College of Medicine, The University of Arizona, Tucson, AZ, USA
| | - DF Larson
- Sarver Heart Center, College of Medicine, The University of Arizona, Tucson, AZ, USA
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Abstract
NAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes two-electron reduction of various quinones by utilizing NAD(P)H as an electron donor. Our previous study found that progesterone (PG) can protect cardiomyocytes from apoptosis induced by doxorubicin (Dox). Microarray analyses of genes induced by PG had led to the discovery of induction of NQO1 mRNA. We report here that PG induces NQO1 protein and its activity in a dose-dependent manner. Whereas NQO1 is well known as a target gene of Nrf2 transcription factor due to the presence of antioxidant response element (ARE) in the promoter, PG did not activate the ARE, suggesting Nrf2-independent induction of NQO1. To address the role of NQO1 induction in PG-induced cytoprotection, we tested the effect of NQO1 inducer β-naphthoflavone and inhibitor dicoumarol. Induction of NQO1 by β-naphthoflavone decreased Dox-induced apoptosis and potentiated the protective effect of PG as measured by caspase-3 activity. PG-induced NQO1 activity was inhibited with dicoumarol, which did not affect PG-induced cytoprotection. Dicoumarol treatment alone potentiated Dox-induced caspase-3 activity. These data suggest that while NQO1 plays a role in PG-induced cytoprotection, there are additional components contributing to PG-induced cytoprotection.
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Affiliation(s)
- Stephen Morrissy
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724, USA
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Sterrett JR, Strom J, Stummvoll HK, Bahner U, Disney A, Soroka SD, Corpier C, Arruda JA, Schwanauer LE, Klassen PS, Olson KA, Block GA. Cinacalcet HCl (Sensipar/ Mimpara) is an effective chronic therapy for hemodialysis patients with secondary hyperparathyroidism. Clin Nephrol 2007; 68:10-7. [PMID: 17703830 DOI: 10.5414/cnp68010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
AIMS This 1-year double-blind, placebo-controlled, multicenter study evaluated the long-term safety and efficacy of cinacalcet for the treatment of secondary hyperparathyroidism in patients receiving hemodialysis. METHOD Patients were randomly assigned in a 1:1 ratio to cinacalcet or control treatment groups. The initial dose of cinacalcet (or matching placebo) was 30 mg. Doses were titrated every 3 or 4 weeks based on the intact parathyroid hormone (iPTH) response and safety profile. Sequential doses included 30, 60, 90, 120 and 180 mg/d. Phosphate binders and vitamin D sterols were adjusted per protocol as needed to control levels of calcium and phosphorus. Efficacy and safety were compared between treatment groups among patients who completed the study (52 total weeks of treatment). Reasons for withdrawal are presented for patients who did not complete the study. RESULTS A total of 210 patients completed 52 weeks of double-blinded treatment with cinacalcet (n = 99) or placebo (n = 111). Over the last 6 months of the study, a greater proportion of patients in the cinacalcet group than the control group achieved an iPTH level < or = 250 pg/ml (61.6 vs. 9.9%, p < 0.001) or a > or = 30% decrease in iPTH from baseline (81.8 vs. 21.6%, p < 0.001). Mean iPTH levels decreased by -47.8% in the cinacalcet group and increased by +12.9% in the control group. Mean percentage changes in other laboratory values in the cinacalcet and control groups included the following: serum calcium -6.5 vs. +0.9% (p < 0.001), serum phosphorus -3.6 vs. -1.1% (p = 0.465), and Ca x P -9.9 vs. -0.3% (p = 0.006). The most commonly reported adverse events related to study drug by the investigators included nausea (13% cinacalcet, 5% control), investigator-reported hypocalcemia (11% cinacalcet, 1% control), vomiting (9% cinacalcet, 2% control), dyspepsia (5% cinacalcet, 4% control), and diarrhea (5% cinacalcet, 2% control). CONCLUSIONS Treatment with cinacalcet is a safe and effective therapy for long-term control of secondary hyperparathyroidism. 1-year therapy with cinacalcet was associated with sustained, clinically significant reductions in calcium, Ca x P and iPTH which allowed a greater percentage of patients to achieve NKF-KDOQI target goals for PTH and Ca x P.
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Affiliation(s)
- J R Sterrett
- St. Joseph Regional Medical Center, Paterson, NJ, USA.
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41
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Hood E, Gonzalez M, Plaas A, Strom J, VanAuker M. 44 IMMUNONIOSOMES TARGETED TO VASCULAR INFLAMMATION. J Investig Med 2006. [DOI: 10.2310/6650.2005.x0008.43] [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: 11/18/2022]
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Quinn G, Bepler G, Bell M, Carroway V, Powell-Stafford V, Schmizu C, Strom J, Vaughn J, William C. O-066 Patient's perceptions of thoracic clinical trials: Methods toimprove accrual. Lung Cancer 2005. [DOI: 10.1016/s0169-5002(05)80198-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Jacobson Z, Strom J. Pericardial tamponade complicating central venous catheterization in an infant with very low birth weight: the role of echocardiography in diagnosis and treatment. Heart Dis 1999; 1:133-5. [PMID: 11720615] [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] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A case involving an infant with very low birth weight in whom an umbilical venous catheter led to pericardial tamponade, a rare but commonly fatal complication, is reported. This is one of only six reported cases in which the infant survived such a complication. Usage of echocardiographically guided pericardiocentesis under similar circumstances has only been documented once before. In the case of this 2-week old infant (birth weight 495 g), prompt diagnosis and treatment using echocardiography resulted in his survival.
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Affiliation(s)
- Z Jacobson
- Department of Pediatrics, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York, USA
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Demopoulos L, Bijou R, Fergus I, Jones M, Strom J, LeJemtel TH. Exercise training in patients with severe congestive heart failure: enhancing peak aerobic capacity while minimizing the increase in ventricular wall stress. J Am Coll Cardiol 1997; 29:597-603. [PMID: 9060899 DOI: 10.1016/s0735-1097(96)00526-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES The aims of the study were to 1) assess the effects of 12 weeks of exercise training at low work loads (i.e., corresponding to < or = 50% of peak oxygen consumption [Vo2]) on peak Vo2 and hyperemic calf blood flow in patients with severe congestive heart failure; and 2) evaluate left ventricular diastolic pressure and wall stress during exercise performed at work loads corresponding to < or = 50% and 70% to 80% of peak Vo2. BACKGROUND Whether the benefits of exercise training can be achieved at work loads that result in lower left ventricular diastolic wall stress than those associated with conventional work loads is unknown in patients with severe congestive heart failure. METHODS Sixteen patients with severe congestive heart failure trained at low work loads for 1 h/day, four times a week, for 12 weeks. Peak Vo2 and calf and forearm reactive hyperemia were measured before and during training. Nine of the 16 patients underwent right heart catheterization and echocardiography during bicycle exercise at low and conventional work loads (i.e., 50% and 70% to 80% of peak Vo2, respectively). RESULTS The increase in left ventricular diastolic wall stress was substantially lower during exercise at low work loads than during exercise at conventional work loads, (i.e., [mean +/- SEM] 23.3 +/- 7.4 vs. 69.6 +/- 8.1 dynes/cm2 (p < 0.001). After 6 and 12 weeks of training, peak Vo2 increased from 11.5 +/- 0.4 to 14.0 +/- 0.5 and 15.0 +/- 0.5 ml/kg per min, respectively (p < 0.0001 vs. baseline for both). Peak reactive hyperemia significantly increased in the calf but not in the forearm. The increases in peak Vo2 and calf peak reactive hyperemia correlated closely (r = 0.61, p < 0.02). CONCLUSIONS In patients with severe congestive heart failure, peak Vo2 is enhanced by exercise training at work loads that result in smaller increases in left ventricular diastolic wall stress than those observed at conventional work loads.
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Affiliation(s)
- L Demopoulos
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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45
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Abstract
Cystinosis is a lysosomal storage disease classically associated with renal failure, photophobia, and hypothyroidism. Multi-organ dysfunction tends to develop over time, a factor of increasing significance as patient survival improves. Herein, we describe a male patient with cystinosis who developed a restrictive cardiomyopathy associated with myocardial cystine deposition and an ap-proximately 1000-fold elevation in myocardial cystine levels. Renal failure necessitated a kidney transplant at age 12. At age 31, the patient was diagnosed with progressive cardiac failure poorly responsive to aggressive antifailure therapy and risk factor modification. The patient died at age 33 in hypovolemic shock due to a ruptured pseudoaneurysm at an old renal transplant site.
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Affiliation(s)
- M Edelman
- Departments of, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York USA
| | - D Silverstein
- Pediatrics (Nephrology), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York USA
| | - J Strom
- Medicine (Cardiology), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York USA
| | - S M Factor
- Pathology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York USA
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46
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Elitsur Y, Strom J, Luk GD. Inhibition of ornithine decarboxylase activity decreases polyamines and suppresses DNA synthesis in human colonic lamina propria lymphocytes. Immunopharmacology 1993; 25:253-60. [PMID: 8354641 DOI: 10.1016/0162-3109(93)90053-s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Ornithine decarboxylase (ODC) and the polyamines are essential for cell proliferation in a variety of cells including lymphocytes. In this study, we investigated the potential role of ODC and polyamines in human colonic lamina propria lymphocytes (LPL) compared to peripheral blood lymphocytes (PBL). Our results show that con A stimulation of LPL and PBL was associated with marked increases in ODC and polyamines. The specific inhibitor of ODC, alpha-difluoromethylornithine (DFMO), resulted in a complete inhibition of ODC activity and depletion of putrescine, spermidine and spermine levels. DFMO also suppressed DNA synthesis of LPL and PBL by up to 48% and 62% respectively. This antiproliferative effect was reversed by adding back the polyamines putrescine (1 mM), spermidine (10 microM) or spermine (10 microM) to the culture medium. We conclude that ODC and the polyamines are important for human LPL proliferation, and hence may play a role in human mucosal immune function.
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Affiliation(s)
- Y Elitsur
- Department of Pediatrics, Marshall University School of Medicine, Huntington, WV 25701
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47
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Frishman WH, Giles T, Greenberg S, Heiman M, Raffidal L, Soberman J, Laifer L, Nadelmann J, Lazar E, Strom J. Sustained high-dose nitroglycerin transcutaneous patch therapy in angina pectoris: evidence for attenuation of effect over time. J Clin Pharmacol 1989; 29:1097-105. [PMID: 2515215 DOI: 10.1002/j.1552-4604.1989.tb03285.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The safety and efficacy of using continuous high-dose transcutaneous nitroglycerin in doses up to 100 mg/24 hours in chronic stable angina was assessed in 20 patients using serial treadmill testing. Patients had first to show a response to sublingual nitroglycerin with a 20% improvement in exercise time. All patients were then titrated with 20 mg (40 cm2), 60 mg (120 cm2), 80 mg (160 cm2) or 100 mg (200 cm2) patches, until intolerable headache in association with a 10 mmHg reduction in blood pressure and a ten-beat increment in heart rate. Drug was then discontinued for 2 days and patients underwent three repeat stress tests to reestablish a consistent drug-free baseline. Patients were then randomized in double-blind fashion to receive either active patch (N = 11) in previous titration dose or placebo patch (N = 9), with treadmill tests performed at 0 (1 hour after previous patch removal), 4, and 24 hours after patch application at baseline and at weeks 1 and 2. Venous blood was obtained for measurement of plasma nitroglycerin levels. After the first 24 hours of active patch therapy, there was a significant reduction in systolic blood pressure (P = .05), a significant increase in heart rate (P = .01), and a minor increase in exercise tolerance (P = .06) compared to placebo. At weeks 1 and 2, there was an attenuation of drug effect in all of these parameters. Plasma nitroglycerin levels demonstrated consistently high plasma levels over each 24-hour dosing interval, on day 1, week 1, and week 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W H Frishman
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
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48
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Keren G, Katz S, Gage J, Strom J, Sonnenblick EH, LeJemtel TH. Effect of isometric exercise on cardiac performance and mitral regurgitation in patients with severe congestive heart failure. Am Heart J 1989; 118:973-9. [PMID: 2816708 DOI: 10.1016/0002-8703(89)90232-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Left ventricular performance was studied during isometric exercise in 17 patients with severe congestive heart failure, combining invasive hemodynamic and echo-Doppler techniques. Isometric exercise at 30% of maximum resulted in a decrease in stroke volume index (27.4 +/- 7.1 to 22.7 +/- 7.4 ml/m2), with a significant increase in heart rate from 81 +/- 10 to 92 +/- 14 beats/min and in systemic vascular resistance from 1827 +/- 527 to 2372 +/- 737 dyne.sec.cm-5. A significant rise in pulmonary capillary wedge pressure (18 +/- 9 to 31 +/- 10 mm Hg) was associated with a marked increase in mitral regurgitant volume (14 +/- 11 to 27 +/- 15 ml), calculated as the difference between total stroke volume obtained by two-dimensional echocardiography and forward stroke volume measured by pulsed Doppler at the aortic anulus. During isometric exercise, left ventricular end-diastolic and end-systolic volumes did not change markedly, but the total stroke volume tended to increase from 62 +/- 13 to 67 +/- 13 ml. The increase in mitral regurgitant volume induced by isometric exercise was correlated with the fall in forward stroke volume (r = 0.7, p less than 0.01). Thus a rise in systemic arterial pressure induced by isometric exercise is associated with a decrease in cardiac performance attributable to redistribution of total left ventricular output with an increase in mitral regurgitation and a simultaneous decrease in forward cardiac output.
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Affiliation(s)
- G Keren
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
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Keren G, Katz S, Strom J, Sonnenblick EH, LeJemtel TH. Dynamic mitral regurgitation. An important determinant of the hemodynamic response to load alterations and inotropic therapy in severe heart failure. Circulation 1989; 80:306-13. [PMID: 2502326 DOI: 10.1161/01.cir.80.2.306] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cardiac performance and mitral regurgitation were measured by Doppler echocardiography and right heart catheterization in 12 patients with severe congestive heart failure who performed isometric exercise during control and intravenous administration of dobutamine and nitroglycerin. During control isometric exercise, mitral regurgitant volume increased from 18 +/- 13 to 31 +/- 17 ml (p less than 0.01), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially decreased. At rest, dobutamine decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 10 ml (p less than 0.05), while forward stroke volume increased from 46 +/- 13 to 55 +/- 15 ml (p less than 0.05). During isometric exercise, dobutamine tended to decrease mitral regurgitant volume (24 +/- 12 vs. 31 +/- 17 ml; NS) when compared with control exercise. At rest, nitroglycerin decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 11 ml (p less than 0.05), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially increased. Similarly, during isometric exercise, nitroglycerin decreased mitral regurgitant volume from 31 +/- 17 to 20 +/- 14 ml (p less than 0.05), while significantly increasing forward stroke volume. At control rest, the median mitral regurgitant fraction was 24% for the 12 patients. Neither dobutamine nor nitroglycerin changed significantly forward stroke and mitral regurgitant volumes at rest and during isometric exercise in the six patients with resting mitral regurgitant fraction below the median. In contrast, dobutamine and nitroglycerin significantly decreased mitral regurgitant volume and increased forward stroke volume both at rest and during isometric exercise in the six patients with mitral regurgitant fraction greater than the median.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G Keren
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
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50
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Keren G, Katz S, Strom J, Sonnenblick EH, LeJemtel TH. Noninvasive quantification of mitral regurgitation in dilated cardiomyopathy: correlation of two Doppler echocardiographic methods. Am Heart J 1988; 116:758-64. [PMID: 3414490 DOI: 10.1016/0002-8703(88)90334-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The presence and severity of functional mitral regurgitation were quantified by Doppler echocardiography in 17 patients with dilated cardiomyopathy and no evidence of primary valvular disease. Mitral regurgitant fraction was greater than 20% in 11 of the 17 patients, and exceeded 40% in four patients. Total stroke volume, calculated from the difference between end-diastolic and end-systolic volumes obtained by two-dimensional echocardiography, correlated well with mitral valve inflow determined by Doppler echocardiography (r = 0.90, p less than 0.001). Similarly, mitral regurgitant volume, calculated as the difference between echocardiographic total stroke volume and forward aortic volume obtained by Doppler echocardiography, correlated well with regurgitant volume calculated as the difference between mitral valve inflow and forward aortic flow, both determined by Doppler echocardiography (r = 0.90, p less than 0.001). Accordingly, functional mitral regurgitation can be conveniently demonstrated in patients with dilated cardiomyopathy by two different Doppler echocardiography methods, whose results are closely correlated. Mitral regurgitant fraction is greater than 20% in two thirds of the patients with a dilated cardiomyopathy.
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Affiliation(s)
- G Keren
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
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