1
|
Li Y, Yao M, Xie F, Qiu Y, Zhao X, Li R. Gut microbiota as a residual risk factor causally influencing cardiac structure and function: Mendelian randomization analysis and biological annotation. Front Microbiol 2024; 15:1410272. [PMID: 39132134 PMCID: PMC11316272 DOI: 10.3389/fmicb.2024.1410272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 07/04/2024] [Indexed: 08/13/2024] Open
Abstract
Background The gut microbiota (GM) is widely acknowledged to have a significant impact on cardiovascular health and may act as a residual risk factor affecting cardiac structure and function. However, the causal relationship between GM and cardiac structure and function remains unclear. Objective This study aims to employ a two-sample Mendelian randomization (MR) approach to investigate the causal association between GM and cardiac structure and function. Methods Data on 119 GM genera were sourced from a genome-wide association study (GWAS) meta-analysis (13,266 European participants) conducted by the MiBioGen consortium, while data on 16 parameters of cardiac structure and function were obtained from the UK Biobank's GWAS of cardiac magnetic resonance imaging (up to 41,135 European participants). Inverse variance weighted (IVW), MR-Egger, and weighted median (WM) methods were utilized for causal association assessments, with sensitivity analyses conducted to reinforce the findings. Finally, biological annotation was performed on the GWAS data of GM and cardiac phenotypes with causal associations to explore potential mechanisms. Results The MR analysis, predominantly based on the IVW model, revealed 93 causal associations between the genetically predicted abundance of 44 GM genera and 16 cardiac structure and function parameters. These associations maintained consistent directions in MR-Egger and WM models, with no evidence of pleiotropy detected. Biological annotations suggest that GM may influence cardiac structure and function through pathways involved in myocardial cell development, cardiac contractility, and apoptosis. Conclusion The MR analysis supports a causal association between certain abundances of genetically predicted GM and cardiac structure and function, suggesting that GM could be a residual risk factor impacting cardiac phenotypes.
Collapse
Affiliation(s)
- Yihua Li
- The First Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Meidan Yao
- The First Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- National Key Laboratory of Chinese Medicine Evidence, Guangzhou, China
- Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Fei Xie
- The First Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yijun Qiu
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xinjun Zhao
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Rong Li
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| |
Collapse
|
2
|
Zhang W, Zhang L, Wen Z, Liang J, Wang Y, Wang Z, Yin Z, Fan L. Clear-cell papillary renal cell tumour: New insights into clinicopathological features and molecular landscape after renaming by 5th WHO classification. Pathol Res Pract 2024; 255:155167. [PMID: 38324963 DOI: 10.1016/j.prp.2024.155167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/09/2024]
Abstract
OBJECTIVE Clear cell papillary renal cell tumour (CCPRCT) is a kind of renal epithelial cell tumor, and was renamed by the 5th WHO due to its specific epidemiology and clinicopathological characteristics. However, the biological mechanism and molecular basis of CCPRCT still need to be further clarified. This study aims to comprehensively evaluate clinicopathologic and molecular characteristics of CCPRCC, and particularly compare it with other more prevalent subtypes of renal cell carcinoma. METHODS 12 cases of CCPRCT were collected for analyzing the clinicopathological characteristics. Then, whole-exome sequencing (WES) was employed to reveal the genetic profiles, followed by comparison with the molecular genetic alterations identified in ccRCC (341) and pRCC (200) datasets obtained from the TCGA database. RESULTS Of the 12 CCPRCT cases, the male-to-female ratio was 4:1 with a mean age of 49.5 years (48.5 ± 10.5) at diagnosis. All patients were diagnosed accidentally during routine physical examinations. All tumors (12/12, 100%)had a solid-cystic appearance with a well-defined fibrous capsule. The median size of the tumors was 3 cm (2.98 ± 1.2). Histologically, the cystic papillary structures were considered to be prominent, lined with cuboidal tumor cells away from basement membrane. The tumor cells were moderately atypia equivalent to grade 1 or grade 2 according to the ISUP nuclear grading system. Typically, the tumor cell diffusely positive for CK7 and CAIX in a "cup-like" pattern. The results of WES revealed recurrent gene alterations (mainly missense mutation) of TTN and FLT in 4 cases (4/12, 33.3%), respectively, of which, the alteration of FLT was not observed in ccRCC and pRCC of the TCGA database. Other gene alterations including POTEC (1 cases), PRADC1 (1 cases), ZZZ3 (1 case) and PTPRZ1 (1 case), etc. Moreover, all of the CCPRCT cases displayed a lower tumor mutation burden (TMB) compared to ccRCC and pRCC with median TMB of 1.04 (range: 1.94 ± 2.74). None of the patients experienced tumor metastasis, recurrence, or tumor-related deaths. CONCLUSION CCPRCT is a renal epithelial cell tumor characterized by specific clinical and pathological features. Our study provides additional evidence supporting the favorable prognosis of CCPRCT. Furthermore, the potential molecular alterations were uncovered by this study in CCPRCT such as the FLT family and TTN. However, due to the limited sample size, larger studies are required to validate these findings.
Collapse
Affiliation(s)
- Wenhui Zhang
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Liang Zhang
- Department of Pathology, The First Affiliated Hospital of University of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230036, China
| | - Zhu Wen
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jiayi Liang
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yingmei Wang
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Zhe Wang
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China.
| | - Zhiyong Yin
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
| | - Linni Fan
- State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, School of Basic Medicine and Xijing Hospital, Fourth Military Medical University, Xi'an, China.
| |
Collapse
|
3
|
Garg A, Lavine KJ, Greenberg MJ. Assessing Cardiac Contractility From Single Molecules to Whole Hearts. JACC Basic Transl Sci 2024; 9:414-439. [PMID: 38559627 PMCID: PMC10978360 DOI: 10.1016/j.jacbts.2023.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/14/2023] [Accepted: 07/14/2023] [Indexed: 04/04/2024]
Abstract
Fundamentally, the heart needs to generate sufficient force and power output to dynamically meet the needs of the body. Cardiomyocytes contain specialized structures referred to as sarcomeres that power and regulate contraction. Disruption of sarcomeric function or regulation impairs contractility and leads to cardiomyopathies and heart failure. Basic, translational, and clinical studies have adapted numerous methods to assess cardiac contraction in a variety of pathophysiological contexts. These tools measure aspects of cardiac contraction at different scales ranging from single molecules to whole organisms. Moreover, these studies have revealed new pathogenic mechanisms of heart disease leading to the development of novel therapies targeting contractility. In this review, the authors explore the breadth of tools available for studying cardiac contractile function across scales, discuss their strengths and limitations, highlight new insights into cardiac physiology and pathophysiology, and describe how these insights can be harnessed for therapeutic candidate development and translational.
Collapse
Affiliation(s)
- Ankit Garg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kory J. Lavine
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| |
Collapse
|
4
|
Baban A, Cicenia M, Magliozzi M, Parlapiano G, Cirillo M, Pascolini G, Fattori F, Gnazzo M, Bruno P, De Luca L, Di Chiara L, Francalanci P, Udd B, Secinaro A, Amodeo A, Bertini ES, Savarese M, Drago F, Novelli A. Biallelic truncating variants in children with titinopathy represent a recognizable condition with distinctive muscular and cardiac characteristics: a report on five patients. Front Cardiovasc Med 2023; 10:1210378. [PMID: 37576110 PMCID: PMC10415037 DOI: 10.3389/fcvm.2023.1210378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 07/10/2023] [Indexed: 08/15/2023] Open
Abstract
Background Monoallelic and biallelic TTN truncating variants (TTNtv) may be responsible for a wide spectrum of musculoskeletal and cardiac disorders with different age at onset. Although the prevalence of heterozygous TTNtv is relatively high in the general population, cardiac phenotyping (mainly cardiomyopathies, CMPs) in biallelic titinopathy has rarely been described in children. Methods We reviewed the medical records of pediatric patients with biallelic TTNtv and cardiac involvement. Clinical exome sequencing excluded pathogenic/likely pathogenic variants in major CMP genes. Results Five pediatric patients (four male) with biallelic TTNtv were included. Major arthrogryposis multiplex was observed in four patients; no patient showed intellectual disability. At a cardiac level, congenital heart defects (atrial and ventricular septal defects, n = 3) and left ventricular non-compaction (n = 1) were reported. All patients had dilated cardiomyopathy (DCM) diagnosed at birth in one patient and at the age of 10, 13, 14, and 17 years in the other four patients. Heart rhythm monitoring showed tachyarrhythmias (premature ventricular contractions, n = 2; non-sustained ventricular tachycardia, n = 2) and nocturnal first-degree atrio-ventricular block (n = 2). Cardiac magnetic resonance (CMR) imaging was performed in all patients and revealed a peculiar late gadolinium enhancement distribution in three patients. HyperCKemia was present in two patients and end-stage heart failure in four. End-organ damage requiring heart transplantation (HT) was indicated in two patients, who were operated on successfully. Conclusion Biallelic TTNtv should be considered when evaluating children with severe and early-onset DCM, particularly if skeletal and muscular abnormalities are present, e.g., arthrogryposis multiplex and congenital progressive myopathy. End-stage heart failure is common and may require HT.
Collapse
Affiliation(s)
- Anwar Baban
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marianna Cicenia
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Monia Magliozzi
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Giovanni Parlapiano
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marco Cirillo
- Department of Imaging, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Giulia Pascolini
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Fabiana Fattori
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Maria Gnazzo
- Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, Rome, Italy
| | - Pasqualina Bruno
- Department of Cardiac Surgery, Cardiology, Heart and Lung Transplantation, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Lorenzo De Luca
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Luca Di Chiara
- Pediatric Cardiac Intensive Care Unit, Department of Cardiology and Cardiac Surgery, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Paola Francalanci
- Department of Pathology, Bambino Gesù Children’s Hospital and Research Institute, IRCCS, Rome, Italy
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Aurelio Secinaro
- Advanced Cardiothoracic Imaging Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Antonio Amodeo
- Heart Failureand Transplant, Mechanical Circulatory Support Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Enrico Silvio Bertini
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Fabrizio Drago
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| |
Collapse
|
5
|
Liu T, Simakov S, Liang F. An idealized human cardiomyocyte finite element model for studying the interaction between the cross-bridge state and cell mechanical response . ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-5. [PMID: 38082753 DOI: 10.1109/embc40787.2023.10341055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
The mechanical state of cardiomyocyte is directly related to the structure and function of internal sarcomeres. In the field of computational cardiac mechanics, attempts to establish models of human cardiomyocyte with a detailed representation of sarcomere cross-bridge (XB) are rare. In this study, we established a computational model for a cardiomyocyte with idealized geometry while containing a representative sarcomere composed of thick filament, thin filament, titin filament, and Z-disc. The formation of XB with passive tension in the model was simulated with the finite element (FE) method, and stochastic FE analyses were further carried out in conjunction with six sigma analysis to explore the interaction between the S1 power stroke and the twitch mechanics of cardiomyocyte. The proposed modeling method may help us better understand the working state of cardiomyocyte, and offer a potential means for exploring the cell-level mechanisms of cardiac diseases.
Collapse
|
6
|
Banga S, Cardoso R, Castellani C, Srivastava S, Watkins J, Lima J. Cardiac MRI as an Imaging Tool in Titin Variant-Related Dilated Cardiomyopathy. CARDIOVASCULAR REVASCULARIZATION MEDICINE 2023; 52:86-93. [PMID: 36934006 DOI: 10.1016/j.carrev.2023.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 02/05/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023]
Abstract
Dilated Cardiomyopathy is a common myocardial disease characterized by dilation and loss of function of one or both ventricles. A variety of etiologies have been implicated including genetic variation. Advancement in genetic sequencing, and diagnostic imaging allows for detection of genetic mutations in sarcomere protein titin (TTN) and high resolution assessment of cardiac function. This review article discusses the role of cardiac MRI in diagnosing dilated cardiomyopathy in patients with TTN variant related cardiomyopathy.
Collapse
Affiliation(s)
- Sandeep Banga
- Division of Cardiology, Michigan State University, Sparrow Hospital, Lansing, MI, USA.
| | | | - Carson Castellani
- Division of Internal Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Shaurya Srivastava
- Division of Internal Medicine, Michigan State University, Lansing, MI, USA
| | - Jennifer Watkins
- Division of Cardiology, Michigan State University, Sparrow Hospital, Lansing, MI, USA
| | - Joao Lima
- Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| |
Collapse
|
7
|
Dominic KL, Choi J, Holmes JB, Singh M, Majcher MJ, Stelzer JE. The contribution of N-terminal truncated cMyBPC to in vivo cardiac function. J Gen Physiol 2023; 155:e202213318. [PMID: 37067542 PMCID: PMC10114924 DOI: 10.1085/jgp.202213318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/13/2023] [Accepted: 03/24/2023] [Indexed: 04/18/2023] Open
Abstract
Cardiac myosin binding protein C (cMyBPC) is an 11-domain sarcomeric protein (C0-C10) integral to cardiac muscle regulation. In vitro studies have demonstrated potential functional roles for regions beyond the N-terminus. However, the in vivo contributions of these domains are mostly unknown. Therefore, we examined the in vivo consequences of expression of N-terminal truncated cMyBPC (C3C10). Neonatal cMyBPC-/- mice were injected with AAV9-full length (FL), C3C10 cMyBPC, or saline, and echocardiography was performed 6 wk after injection. We then isolated skinned myocardium from virus-treated hearts and performed mechanical experiments. Our results show that expression of C3C10 cMyBPC in cMyBPC-/- mice resulted in a 28% increase in systolic ejection fraction compared to saline-injected cMyBPC-/- mice and a 25% decrease in left ventricle mass-to-body weight ratio. However, unlike expression of FL cMyBPC, there was no prolongation of ejection time compared to saline-injected mice. In vitro mechanical experiments demonstrated that functional improvements in cMyBPC-/- mice expressing C3C10 were primarily due to a 35% reduction in the rate of cross-bridge recruitment at submaximal Ca2+ concentrations when compared to hearts from saline-injected cMyBPC-/- mice. However, unlike the expression of FL cMyBPC, there was no change in the rate of cross-bridge detachment when compared to saline-injected mice. Our data demonstrate that regions of cMyBPC beyond the N-terminus are important for in vivo cardiac function, and have divergent effects on cross-bridge behavior. Elucidating the molecular mechanisms of cMyBPC region-specific function could allow for development of targeted approaches to manipulate specific aspects of cardiac contractile function.
Collapse
Affiliation(s)
- Katherine L. Dominic
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joohee Choi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joshua B. Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Mandeep Singh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Michael J. Majcher
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| |
Collapse
|
8
|
Kanashiro-Takeuchi RM, Takeuchi LM, Dulce RA, Kazmierczak K, Balkan W, Cai R, Sha W, Schally AV, Hare JM. Efficacy of a growth hormone-releasing hormone agonist in a murine model of cardiometabolic heart failure with preserved ejection fraction. Am J Physiol Heart Circ Physiol 2023; 324:H739-H750. [PMID: 36897749 PMCID: PMC10151038 DOI: 10.1152/ajpheart.00601.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 02/27/2023] [Accepted: 02/27/2023] [Indexed: 03/11/2023]
Abstract
Heart failure (HF) with preserved ejection fraction (HFpEF) represents a major unmet medical need owing to its diverse pathophysiology and lack of effective therapies. Potent synthetic, agonists (MR-356 and MR-409) of growth hormone-releasing hormone (GHRH) improve the phenotype of models of HF with reduced ejection fraction (HFrEF) and in cardiorenal models of HFpEF. Endogenous GHRH exhibits a broad range of regulatory influences in the cardiovascular (CV) system and aging and plays a role in several cardiometabolic conditions including obesity and diabetes. Whether agonists of GHRH can improve the phenotype of cardiometabolic HFpEF remains untested and unknown. Here we tested the hypothesis that MR-356 can mitigate/reverse the cardiometabolic HFpEF phenotype. C57BL6N mice received a high-fat diet (HFD) plus the nitric oxide synthase inhibitor (l-NAME) for 9 wk. After 5 wk of HFD + l-NAME regimen, animals were randomized to receive daily injections of MR-356 or placebo during a 4-wk period. Control animals received no HFD + l-NAME or agonist treatment. Our results showed the unique potential of MR-356 to treat several HFpEF-like features including cardiac hypertrophy, fibrosis, capillary rarefaction, and pulmonary congestion. MR-356 improved cardiac performance by improving diastolic function, global longitudinal strain (GLS), and exercise capacity. Importantly, the increased expression of cardiac pro-brain natriuretic peptide (pro-BNP), inducible nitric oxide synthase (iNOS), and vascular endothelial growth factor-A (VEGF-A) was restored to normal levels suggesting that MR-356 reduced myocardial stress associated with metabolic inflammation in HFpEF. Thus, agonists of GHRH may be an effective therapeutic strategy for the treatment of cardiometabolic HFpEF phenotype.NEW & NOTEWORTHY This randomized study used rigorous hemodynamic tools to test the efficacy of a synthetic GHRH agonist to improve cardiac performance in a cardiometabolic HFpEF. Daily injection of the GHRH agonist, MR-356, reduced the HFpEF-like effects as evidenced by improved diastolic dysfunction, reduced cardiac hypertrophy, fibrosis, and pulmonary congestion. Notably, end-diastolic pressure and end-diastolic pressure-volume relationship were reset to control levels. Moreover, treatment with MR-356 increased exercise capacity and reduced myocardial stress associated with metabolic inflammation in HFpEF.
Collapse
Affiliation(s)
- Rosemeire M Kanashiro-Takeuchi
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Lauro M Takeuchi
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Raul A Dulce
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Wayne Balkan
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
- Division of Cardiology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Renzhi Cai
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, Florida, United States
| | - Wei Sha
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, Florida, United States
- Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida, United States
| | - Andrew V Schally
- Division of Oncology, Department of Medicine and Endocrinology, University of Miami Miller School of Medicine, Miami, Florida, United States
- Division of Endocrinology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, Florida, United States
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, United States
- Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida, United States
| | - Joshua M Hare
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States
- Division of Cardiology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| |
Collapse
|
9
|
Han SW, Boldt K, Joumaa V, Herzog W. Characterizing residual and passive force enhancements in cardiac myofibrils. Biophys J 2023; 122:1538-1547. [PMID: 36932677 PMCID: PMC10147830 DOI: 10.1016/j.bpj.2023.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 11/07/2022] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Residual force enhancement (RFE), an increase in isometric force after active stretching of a muscle compared with the purely isometric force at the corresponding length, has been consistently observed throughout the structural hierarchy of skeletal muscle. Similar to RFE, passive force enhancement (PFE) is also observable in skeletal muscle and is defined as an increase in passive force when a muscle is deactivated after it has been actively stretched compared with the passive force following deactivation of a purely isometric contraction. These history-dependent properties have been investigated abundantly in skeletal muscle, but their presence in cardiac muscle remains unresolved and controversial. The purpose of this study was to investigate whether RFE and PFE exist in cardiac myofibrils and whether the magnitudes of RFE and PFE increase with increasing stretch magnitudes. Cardiac myofibrils were prepared from the left ventricles of New Zealand White rabbits, and the history-dependent properties were tested at three different final average sarcomere lengths (n = 8 for each), 1.8, 2, and 2.2 μm, while the stretch magnitude was kept at 0.2 μm/sarcomere. The same experiment was repeated with a final average sarcomere length of 2.2 μm and a stretching magnitude of 0.4 μm/sarcomere (n = 8). All 32 cardiac myofibrils exhibited increased forces after active stretching compared with the corresponding purely isometric reference conditions (p < 0.05). Furthermore, the magnitude of RFE was greater when myofibrils were stretched by 0.4 compared with 0.2 μm/sarcomere (p < 0.05). We conclude that, like in skeletal muscle, RFE and PFE are properties of cardiac myofibrils and are dependent on stretch magnitude.
Collapse
Affiliation(s)
- Seong-Won Han
- Institute of Physiology II, Faculty of Medicine, University of Münster, Münster, Germany; Faculty of Kinesiology, University of Calgary, Calgary, Canada.
| | - Kevin Boldt
- Faculty of Kinesiology, University of Calgary, Calgary, Canada; Kinesiology Program, Trent University, Peterborough, ON, Canada; Department of Human Health and Nutritional Science, University of Guelph, Guelph, ON, Canada
| | - Venus Joumaa
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Walter Herzog
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| |
Collapse
|
10
|
Soetkamp D, Gallet R, Parker SJ, Holewinski R, Venkatraman V, Peck K, Goldhaber JI, Marbán E, Van Eyk JE. Myofilament Phosphorylation in Stem Cell Treated Diastolic Heart Failure. Circ Res 2021; 129:1125-1140. [PMID: 34641704 DOI: 10.1161/circresaha.119.316311] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
RATIONALE Phosphorylation of sarcomeric proteins has been implicated in heart failure with preserved ejection fraction (HFpEF); such changes may contribute to diastolic dysfunction by altering contractility, cardiac stiffness, Ca2+-sensitivity, and mechanosensing. Treatment with cardiosphere-derived cells (CDCs) restores normal diastolic function, attenuates fibrosis and inflammation, and improves survival in a rat HFpEF model. OBJECTIVE Phosphorylation changes that underlie HFpEF and those reversed by CDC therapy, with a focus on the sarcomeric subproteome were analyzed. METHODS AND RESULTS Dahl salt-sensitive rats fed a high-salt diet, with echocardiographically verified diastolic dysfunction, were randomly assigned to either intracoronary CDCs or placebo. Dahl salt-sensitive rats receiving low salt diet served as controls. Protein and phosphorylated Ser, Thr, and Tyr residues from left ventricular tissue were quantified by mass spectrometry. HFpEF hearts exhibited extensive hyperphosphorylation with 98% of the 529 significantly changed phospho-sites increased compared with control. Of those, 39% were located within the sarcomeric subproteome, with a large group of proteins located or associated with the Z-disk. CDC treatment partially reverted the hyperphosphorylation, with 85% of the significantly altered 76 residues hypophosphorylated. Bioinformatic upstream analysis of the differentially phosphorylated protein residues revealed PKC as the dominant putative regulatory kinase. PKC isoform analysis indicated increases in PKC α, β, and δ concentration, whereas CDC treatment led to a reversion of PKCβ. Use of PKC isoform specific inhibition and overexpression of various PKC isoforms strongly suggests that PKCβ is the dominant kinase involved in hyperphosphorylation in HFpEF and is altered with CDC treatment. CONCLUSIONS Increased protein phosphorylation at the Z-disk is associated with diastolic dysfunction, with PKC isoforms driving most quantified phosphorylation changes. Because CDCs reverse the key abnormalities in HFpEF and selectively reverse PKCβ upregulation, PKCβ merits being classified as a potential therapeutic target in HFpEF, a disease notoriously refractory to medical intervention.
Collapse
Affiliation(s)
- Daniel Soetkamp
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Romain Gallet
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Sarah J Parker
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | | | | | - Kiel Peck
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | | | - Eduardo Marbán
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | | |
Collapse
|
11
|
Lopez-Bravo A, Roche-Bueno JC, Romera-López A, Larrode-Pellicer P. A novel TTN variant in a patient with distal myopathy of lower limbs and dilated cardiomyopathy. NEUROLOGÍA (ENGLISH EDITION) 2021; 36:721-723. [PMID: 34247971 DOI: 10.1016/j.nrleng.2021.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/10/2021] [Indexed: 11/29/2022] Open
Affiliation(s)
- A Lopez-Bravo
- Sección de Neurología, Hospital Reina Sofía, Tudela, Navarra, Spain; Instituto de Investigación Sanitaria Aragón (IIS-A), Spain.
| | - J C Roche-Bueno
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
| | - A Romera-López
- Unidad de Genética Médica, Sistemas Genómicos, Valencia, Spain
| | - P Larrode-Pellicer
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
| |
Collapse
|
12
|
Sheldon H, Alexander J, Bridges E, Moreira L, Reilly S, Ang KH, Wang D, Lin S, Haider S, Banham AH, Harris AL. ELTD1 Activation Induces an Endothelial-EMT Transition to a Myofibroblast Phenotype. Int J Mol Sci 2021; 22:11293. [PMID: 34681953 PMCID: PMC8539764 DOI: 10.3390/ijms222011293] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/13/2022] Open
Abstract
ELTD1 is expressed in endothelial and vascular smooth muscle cells and has a role in angiogenesis. It has been classified as an adhesion GPCR, but as yet, no ligand has been identified and its function remains unknown. To establish its role, ELTD1 was overexpressed in endothelial cells. Expression and consequently ligand independent activation of ELTD1 results in endothelial-mesenchymal transistion (EndMT) with a loss of cell-cell contact, formation of stress fibres and mature focal adhesions and an increased expression of smooth muscle actin. The effect was pro-angiogenic, increasing Matrigel network formation and endothelial sprouting. RNA-Seq analysis after the cells had undergone EndMT revealed large increases in chemokines and cytokines involved in regulating immune response. Gene set enrichment analysis of the data identified a number of pathways involved in myofibroblast biology suggesting that the endothelial cells had undergone a type II EMT. This type of EMT is involved in wound repair and is closely associated with inflammation implicating ELTD1 in these processes.
Collapse
Affiliation(s)
- Helen Sheldon
- Cancer Research UK Molecular Oncology Laboratories, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (E.B.); (K.H.A.); (S.L.)
| | - John Alexander
- The Breast Cancer Now Toby Robins Research Centre, Division of Breast Cancer Research, The Institute of Cancer Research, London SM2 5NG, UK; (J.A.); (S.H.)
| | - Esther Bridges
- Cancer Research UK Molecular Oncology Laboratories, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (E.B.); (K.H.A.); (S.L.)
| | - Lucia Moreira
- Cardiovascular Medicine, RDM John Radcliffe Hospital, Oxford OX3 9DU, UK; (L.M.); (S.R.)
| | - Svetlana Reilly
- Cardiovascular Medicine, RDM John Radcliffe Hospital, Oxford OX3 9DU, UK; (L.M.); (S.R.)
| | - Koon Hwee Ang
- Cancer Research UK Molecular Oncology Laboratories, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (E.B.); (K.H.A.); (S.L.)
| | - Dian Wang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (D.W.); (A.H.B.)
| | - Salwa Lin
- Cancer Research UK Molecular Oncology Laboratories, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (E.B.); (K.H.A.); (S.L.)
| | - Syed Haider
- The Breast Cancer Now Toby Robins Research Centre, Division of Breast Cancer Research, The Institute of Cancer Research, London SM2 5NG, UK; (J.A.); (S.H.)
| | - Alison H. Banham
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (D.W.); (A.H.B.)
| | - Adrian L. Harris
- Cancer Research UK Molecular Oncology Laboratories, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK; (E.B.); (K.H.A.); (S.L.)
| |
Collapse
|
13
|
The Sarcomeric Spring Protein Titin: Biophysical Properties, Molecular Mechanisms, and Genetic Mutations Associated with Heart Failure and Cardiomyopathy. Curr Cardiol Rep 2021; 23:121. [PMID: 34269900 DOI: 10.1007/s11886-021-01550-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/07/2021] [Indexed: 01/06/2023]
Abstract
PURPOSE OF REVIEW The giant protein titin forms the "elastic" filament of the sarcomere, essential for the mechanical compliance of the heart muscle. Titin serves a biological spring, and therefore structural modifications of titin affect function of the myocardium and are associated with heart failure and cardiomyopathy. RECENT FINDINGS In this review, we discuss the current understanding of titin's biophysical properties and how modifications contribute to cardiac function and heart failure. In addition, we review the most recent data on the clinical impact and phenotype heterogeneity of TTN truncating variants, including diseases involving striated muscles, and prospects for future therapies. Because of the giant structure of the titin protein and the complexity of its function, titin's role in health and disease is not yet completely understood. Future research efforts need to focus on novel therapeutic approaches able to modulate titin transcriptional and post-translational modification.
Collapse
|
14
|
Abstract
PURPOSE OF REVIEW This review aims to give an update on recent findings related to the cardiac splicing factor RNA-binding motif protein 20 (RBM20) and RBM20 cardiomyopathy, a form of dilated cardiomyopathy caused by mutations in RBM20. RECENT FINDINGS While most research on RBM20 splicing targets has focused on titin (TTN), multiple studies over the last years have shown that other splicing targets of RBM20 including Ca2+/calmodulin-dependent kinase IIδ (CAMK2D) might be critically involved in the development of RBM20 cardiomyopathy. In this regard, loss of RBM20 causes an abnormal intracellular calcium handling, which may relate to the arrhythmogenic presentation of RBM20 cardiomyopathy. In addition, RBM20 presents clinically in a highly gender-specific manner, with male patients suffering from an earlier disease onset and a more severe disease progression. Further research on RBM20, and treatment of RBM20 cardiomyopathy, will need to consider both the multitude and relative contribution of the different splicing targets and related pathways, as well as gender differences.
Collapse
|
15
|
Lopez-Bravo A, Roche-Bueno JC, Romera-López A, Larrode-Pellicer P. A novel TTN variant in a patient with distal myopathy of lower limbs and dilated cardiomyopathy. Neurologia 2021; 36:S0213-4853(21)00004-9. [PMID: 33558083 DOI: 10.1016/j.nrl.2021.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 12/26/2020] [Accepted: 01/10/2021] [Indexed: 10/22/2022] Open
Affiliation(s)
- A Lopez-Bravo
- Sección de Neurología, Hospital Reina Sofía, Tudela, Navarra, España; Instituto de Investigación Sanitaria Aragón (IIS-A), España.
| | - J C Roche-Bueno
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, España
| | - A Romera-López
- Unidad de Genética Médica, Sistemas Genómicos, Valencia, España
| | - P Larrode-Pellicer
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, España
| |
Collapse
|
16
|
Modifications of Titin Contribute to the Progression of Cardiomyopathy and Represent a Therapeutic Target for Treatment of Heart Failure. J Clin Med 2020; 9:jcm9092770. [PMID: 32859027 PMCID: PMC7564493 DOI: 10.3390/jcm9092770] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 12/20/2022] Open
Abstract
Titin is the largest human protein and an essential component of the cardiac sarcomere. With multiple immunoglobulin(Ig)-like domains that serve as molecular springs, titin contributes significantly to the passive tension, systolic function, and diastolic function of the heart. Mutations leading to early termination of titin are the most common genetic cause of dilated cardiomyopathy. Modifications of titin, which change protein length, and relative stiffness affect resting tension of the ventricle and are associated with acquired forms of heart failure. Transcriptional and post-translational changes that increase titin’s length and extensibility, making the sarcomere longer and softer, are associated with systolic dysfunction and left ventricular dilation. Modifications of titin that decrease its length and extensibility, making the sarcomere shorter and stiffer, are associated with diastolic dysfunction in animal models. There has been significant progress in understanding the mechanisms by which titin is modified. As molecular pathways that modify titin’s mechanical properties are elucidated, they represent therapeutic targets for treatment of both systolic and diastolic dysfunction. In this article, we review titin’s contribution to normal cardiac physiology, the pathophysiology of titin truncation variations leading to dilated cardiomyopathy, and transcriptional and post-translational modifications of titin. Emphasis is on how modification of titin can be utilized as a therapeutic target for treatment of heart failure.
Collapse
|
17
|
van der Pijl RJ, Hudson B, Granzier-Nakajima T, Li F, Knottnerus AM, Smith J, Chung CS, Gotthardt M, Granzier HL, Ottenheijm CAC. Deleting Titin's C-Terminal PEVK Exons Increases Passive Stiffness, Alters Splicing, and Induces Cross-Sectional and Longitudinal Hypertrophy in Skeletal Muscle. Front Physiol 2020; 11:494. [PMID: 32547410 PMCID: PMC7274174 DOI: 10.3389/fphys.2020.00494] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022] Open
Abstract
The Proline, Glutamate, Valine and Lysine-rich (PEVK) region of titin constitutes an entropic spring that provides passive tension to striated muscle. To study the functional and structural repercussions of a small reduction in the size of the PEVK region, we investigated skeletal muscles of a mouse with the constitutively expressed C-terminal PEVK exons 219-225 deleted, the TtnΔ219-225 model (MGI: TtnTM 2.1Mgot ). Based on this deletion, passive tension in skeletal muscle was predicted to be increased by ∼17% (sarcomere length 3.0 μm). In contrast, measured passive tension (sarcomere length 3.0 μm) in both soleus and EDL muscles was increased 53 ± 11% and 62 ± 4%, respectively. This unexpected increase was due to changes in titin, not to alterations in the extracellular matrix, and is likely caused by co-expression of two titin isoforms in TtnΔ219-225 muscles: a larger isoform that represents the TtnΔ219-225 N2A titin and a smaller isoform, referred to as N2A2. N2A2 represents a splicing adaption with reduced expression of spring element exons, as determined by titin exon microarray analysis. Maximal tetanic tension was increased in TtnΔ219-225 soleus muscle (WT 240 ± 9; TtnΔ219-225 276 ± 17 mN/mm2), but was reduced in EDL muscle (WT 315 ± 9; TtnΔ219-225 280 ± 14 mN/mm2). The changes in active tension coincided with a switch toward slow fiber types and, unexpectedly, faster kinetics of tension generation and relaxation. Functional overload (FO; ablation) and hindlimb suspension (HS; unloading) experiments were also conducted. TtnΔ219-225 mice showed increases in both longitudinal hypertrophy (increased number of sarcomeres in series) and cross-sectional hypertrophy (increased number of sarcomeres in parallel) in response to FO and attenuated cross-sectional atrophy in response to HS. In summary, slow- and fast-twitch muscles in a mouse model devoid of titin's PEVK exons 219-225 have high passive tension, due in part to alterations elsewhere in splicing of titin's spring region, increased kinetics of tension generation and relaxation, and altered trophic responses to both functional overload and unloading. This implicates titin's C-terminal PEVK region in regulating passive and active muscle mechanics and muscle plasticity.
Collapse
Affiliation(s)
- Robbert J van der Pijl
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Amsterdam UMC, Amsterdam, Netherlands
| | - Brian Hudson
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | | | - Frank Li
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Anne M Knottnerus
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - John Smith
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Charles S Chung
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Michael Gotthardt
- Max-Delbruck-Center for Molecular Medicine, Berlin, Germany.,Cardiology, Virchow Klinikum, Charité University Medicine, Berlin, Germany
| | - Henk L Granzier
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Coen A C Ottenheijm
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Amsterdam UMC, Amsterdam, Netherlands
| |
Collapse
|
18
|
The effect of calcium binding on the unfolding force of mutated and healthy titin I10 domain: A steered molecular dynamics simulation study. J Mol Graph Model 2020; 96:107534. [DOI: 10.1016/j.jmgm.2020.107534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/03/2019] [Accepted: 01/08/2020] [Indexed: 01/03/2023]
|
19
|
Kelly CM, Manukian S, Kim E, Gage MJ. Differences in stability and calcium sensitivity of the Ig domains in titin's N2A region. Protein Sci 2020; 29:1160-1171. [PMID: 32112607 DOI: 10.1002/pro.3848] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 11/11/2022]
Abstract
Titin is a large filamentous protein that spans half a sarcomere, from Z-disk to M-line. The N2A region within the titin molecule exists between the proximal immunoglobulin (Ig) region and the PEVK region and protein-protein interactions involving this region are required for normal muscle function. The N2A region consists of four Ig domains (I80-I83) with a 105 amino acid linker region between I80 and I81 that has a helical nature. Using chemical stability measurements, we show that predicted differences between the adjacent Ig domains (I81-I83) correlate with experimentally determined differences in chemical stability and refolding kinetics. Our work further shows that I83 has the lowest ΔGunfolding , which is increased in the presence of calcium (pCa 4.3), indicating that Ca2+ plays a role in stabilizing this immunoglobulin domain. The characteristics of N2A's three Ig domains provide insight into the stability of the binding sites for proteins that interact with the N2A region. This work also provides insights into how Ca2+ might influence binding events involving N2A.
Collapse
Affiliation(s)
- Colleen M Kelly
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA.,UMass Movement Center, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Sophia Manukian
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Emily Kim
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Matthew J Gage
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA.,UMass Movement Center, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| |
Collapse
|
20
|
Tharp CA, Haywood ME, Sbaizero O, Taylor MRG, Mestroni L. The Giant Protein Titin's Role in Cardiomyopathy: Genetic, Transcriptional, and Post-translational Modifications of TTN and Their Contribution to Cardiac Disease. Front Physiol 2019; 10:1436. [PMID: 31849696 PMCID: PMC6892752 DOI: 10.3389/fphys.2019.01436] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023] Open
Abstract
Dilated cardiomyopathy (DCM) is a leading cause of heart failure, sudden cardiac death and heart transplant. DCM is inherited in approximately 50% of cases, in which the most frequent genetic defects are truncation variants of the titin gene (TTNtv). TTN encodes titin, which is the largest protein in the body and is an essential component of the sarcomere. Titin serves as a biological spring, spanning half of the sarcomere and connecting the Z-disk to the M-line, with scaffold and signaling functions. Truncations of titin are believed to lead to either haploinsufficiency and loss-of-function, or to a “poison peptide” effect. However, other titin mechanisms are postulated to influence cardiac function including post-translational modifications, in particular changes in titin phosphorylation that alters the stiffness of the protein, and diversity of alternative splicing that generates different titin isoforms. In this article, we review the role of TTN mutations in development of DCM, how differential expression of titin isoforms relate to DCM pathophysiology, and discuss how post-translational modifications of titin can affect cardiomyocyte function. Current research efforts aim to elucidate the contribution of titin to myofibril assembly, stability, and signal transduction, and how mutant titin leads to cardiac dysfunction and human disease. Future research will need to translate this knowledge toward novel therapeutic approaches that can modulate titin transcriptional and post-translational defects to treat DCM and heart failure.
Collapse
Affiliation(s)
- Charles A Tharp
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Mary E Haywood
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Orfeo Sbaizero
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Matthew R G Taylor
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Luisa Mestroni
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| |
Collapse
|
21
|
Koser F, Loescher C, Linke WA. Posttranslational modifications of titin from cardiac muscle: how, where, and what for? FEBS J 2019; 286:2240-2260. [PMID: 30989819 PMCID: PMC6850032 DOI: 10.1111/febs.14854] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Accepted: 04/13/2019] [Indexed: 12/11/2022]
Abstract
Titin is a giant elastic protein expressed in the contractile units of striated muscle cells, including the sarcomeres of cardiomyocytes. The last decade has seen enormous progress in our understanding of how titin molecular elasticity is modulated in a dynamic manner to help cardiac sarcomeres adjust to the varying hemodynamic demands on the heart. Crucial events mediating the rapid modulation of cardiac titin stiffness are post‐translational modifications (PTMs) of titin. In this review, we first recollect what is known from earlier and recent work on the molecular mechanisms of titin extensibility and force generation. The main goal then is to provide a comprehensive overview of current insight into the relationship between titin PTMs and cardiomyocyte stiffness, notably the effect of oxidation and phosphorylation of titin spring segments on titin stiffness. A synopsis is given of which type of oxidative titin modification can cause which effect on titin stiffness. A large part of the review then covers the mechanically relevant phosphorylation sites in titin, their location along the elastic segment, and the protein kinases and phosphatases known to target these sites. We also include a detailed coverage of the complex changes in phosphorylation at specific titin residues, which have been reported in both animal models of heart disease and in human heart failure, and their correlation with titin‐based stiffness alterations. Knowledge of the relationship between titin PTMs and titin elasticity can be exploited in the search for therapeutic approaches aimed at softening the pathologically stiffened myocardium in heart failure patients.
Collapse
|
22
|
Rodrigues PG, Miranda-Silva D, Costa SM, Barros C, Hamdani N, Moura C, Mendes MJ, Sousa-Mendes C, Trindade F, Fontoura D, Vitorino R, Linke WA, Leite-Moreira AF, Falcão-Pires I. Early myocardial changes induced by doxorubicin in the nonfailing dilated ventricle. Am J Physiol Heart Circ Physiol 2019; 316:H459-H475. [DOI: 10.1152/ajpheart.00401.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several studies have demonstrated that administration of doxorubicin (DOXO) results in cardiotoxicity, which eventually progresses to dilated cardiomyopathy. The present work aimed to evaluate the early myocardial changes of DOXO-induced cardiotoxicity. Male New Zealand White rabbits were injected intravenously with DOXO twice weekly for 8 wk [DOXO-induced heart failure (DOXO-HF)] or with an equivolumetric dose of saline (control). Echocardiographic evaluation was performed, and myocardial samples were collected to evaluate myocardial cellular and molecular modifications. The DOXO-HF group presented cardiac hypertrophy and higher left ventricular cavity diameters, showing a dilated phenotype but preserved ejection fraction. Concerning cardiomyocyte function, the DOXO-HF group presented a trend toward increased active tension without significant differences in passive tension. The myocardial GSSG-to-GSH ratio and interstitial fibrosis were increased and Bax-to- Bcl-2 ratio presented a trend toward an increase, suggesting the activation of apoptosis signaling pathways. The macromolecule titin shifted toward the more compliant isoform (N2BA), whereas the stiffer one (N2B) was shown to be hypophosphorylated. Differential protein analysis from the aggregate-enriched fraction through gel liquid chromatography-tandem mass spectrometry revealed an increase in the histidine-rich glycoprotein fragment in DOXO-HF animals. This work describes novel and early myocardial effects of DOXO-induced cardiotoxicity. Thus, tracking these changes appears to be of extreme relevance for the early detection of cardiac damage (as soon as ventricular dilation becomes evident) before irreversible cardiac function deterioration occurs (reduced ejection fraction). Moreover, it allows for the adjustment of the therapeutic approach and thus the prevention of cardiomyopathy progression. NEW & NOTEWORTHY Identification of early myocardial effects of doxorubicin in the heart is essential to hinder the development of cardiac complications and adjust the therapeutic approach. This study describes doxorubicin-induced cellular and molecular modifications before the onset of dilated cardiomyopathy. Myocardial samples from doxorubicin-treated rabbits showed a tendency for higher cardiomyocyte active tension, titin isoform shift from N2B to N2BA, hypophosphorylation of N2B, increased apoptotic genes, left ventricular interstitial fibrosis, and increased aggregation of histidine-rich glycoprotein.
Collapse
Affiliation(s)
- Patricia G. Rodrigues
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Daniela Miranda-Silva
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Sofia M. Costa
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Carla Barros
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Nazha Hamdani
- Department of Systems Physiology, Ruhr University, Bochum, Germany
| | - Cláudia Moura
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Maria J. Mendes
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Cláudia Sousa-Mendes
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Fábio Trindade
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
- Department of Medical Sciences, Institute of Biomedicine, University of Aveiro, Aveiro, Portugal
| | - Dulce Fontoura
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| | - Rui Vitorino
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
- Department of Medical Sciences, Institute of Biomedicine, University of Aveiro, Aveiro, Portugal
| | - Wolfgang A. Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Adelino F. Leite-Moreira
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
- Department of Cardiothoracic Surgery, São João Hospital Centre, Porto, Portugal
| | - Inês Falcão-Pires
- Department of Surgery and Physiology, Faculty of Medicine, Unidade de Investigação Cardiovascular, Universidade do Porto, Porto, Portugal
| |
Collapse
|
23
|
Watanabe T, Kimura A, Kuroyanagi H. Alternative Splicing Regulator RBM20 and Cardiomyopathy. Front Mol Biosci 2018; 5:105. [PMID: 30547036 PMCID: PMC6279932 DOI: 10.3389/fmolb.2018.00105] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/09/2018] [Indexed: 12/17/2022] Open
Abstract
RBM20 is a vertebrate-specific RNA-binding protein with two zinc finger (ZnF) domains, one RNA-recognition motif (RRM)-type RNA-binding domain and an arginine/serine (RS)-rich region. RBM20 has initially been identified as one of dilated cardiomyopathy (DCM)-linked genes. RBM20 is a regulator of heart-specific alternative splicing and Rbm20ΔRRM mice lacking the RRM domain are defective in the splicing regulation. The Rbm20ΔRRM mice, however, do not exhibit a characteristic DCM-like phenotype such as dilatation of left ventricles or systolic dysfunction. Considering that most of the RBM20 mutations identified in familial DCM cases were heterozygous missense mutations in an arginine-serine-arginine-serine-proline (RSRSP) stretch whose phosphorylation is crucial for nuclear localization of RBM20, characterization of a knock-in animal model is awaited. One of the major targets for RBM20 is the TTN gene, which is comprised of the largest number of exons in mammals. Alternative splicing of the TTN gene is exceptionally complicated and RBM20 represses >160 of its consecutive exons, yet detailed mechanisms for such extraordinary regulation are to be elucidated. The TTN gene encodes the largest known protein titin, a multi-functional sarcomeric structural protein specific to striated muscles. As titin is the most important factor for passive tension of cardiomyocytes, extensive heart-specific and developmentally regulated alternative splicing of the TTN pre-mRNA by RBM20 plays a critical role in passive stiffness and diastolic function of the heart. In disease models with diastolic dysfunctions, the phenotypes were rescued by increasing titin compliance through manipulation of the Ttn pre-mRNA splicing, raising RBM20 as a potential therapeutic target.
Collapse
Affiliation(s)
- Takeshi Watanabe
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Department of Psychosomatic Dentistry, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Akinori Kimura
- Division of Pathology, Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Laboratory for Integrated Research Projects on Intractable Diseases Advanced Technology Laboratories, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Laboratory for Integrated Research Projects on Intractable Diseases Advanced Technology Laboratories, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, United States
| |
Collapse
|
24
|
Four and a half LIM domain protein signaling and cardiomyopathy. Biophys Rev 2018; 10:1073-1085. [PMID: 29926425 DOI: 10.1007/s12551-018-0434-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 06/06/2018] [Indexed: 01/10/2023] Open
Abstract
Four and a half LIM domain (FHL) protein family members, FHL1 and FHL2, are multifunctional proteins that are enriched in cardiac muscle. Although they both localize within the cardiomyocyte sarcomere (titin N2B), they have been shown to have important yet unique functions within the context of cardiac hypertrophy and disease. Studies in FHL1-deficient mice have primarily uncovered mitogen-activated protein kinase (MAPK) scaffolding functions for FHL1 as part of a novel biomechanical stretch sensor within the cardiomyocyte sarcomere, which acts as a positive regulator of pressure overload-mediated cardiac hypertrophy. New data have highlighted a novel role for the serine/threonine protein phosphatase (PP5) as a deactivator of the FHL1-based biomechanical stretch sensor, which has implications in not only cardiac hypertrophy but also heart failure. In contrast, studies in FHL2-deficient mice have primarily uncovered an opposing role for FHL2 as a negative regulator of adrenergic-mediated signaling and cardiac hypertrophy, further suggesting unique functions targeted by FHL proteins in the "stressed" cardiomyocyte. In this review, we provide current knowledge of the role of FHL1 and FHL2 in cardiac muscle as it relates to their actions in cardiac hypertrophy and cardiomyopathy. A specific focus will be to dissect the pathways and protein-protein interactions that underlie FHLs' signaling role in cardiac hypertrophy as well as provide a comprehensive list of FHL mutations linked to cardiac disease, using evidence gained from genetic mouse models and human genetic studies.
Collapse
|
25
|
Phosphorylation of the RSRSP stretch is critical for splicing regulation by RNA-Binding Motif Protein 20 (RBM20) through nuclear localization. Sci Rep 2018; 8:8970. [PMID: 29895960 PMCID: PMC5997748 DOI: 10.1038/s41598-018-26624-w] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/14/2018] [Indexed: 11/08/2022] Open
Abstract
RBM20 is a major regulator of heart-specific alternative pre-mRNA splicing of TTN encoding a giant sarcomeric protein titin. Mutation in RBM20 is linked to autosomal-dominant familial dilated cardiomyopathy (DCM), yet most of the RBM20 missense mutations in familial and sporadic cases were mapped to an RSRSP stretch in an arginine/serine-rich region of which function remains unknown. In the present study, we identified an R634W missense mutation within the stretch and a G1031X nonsense mutation in cohorts of DCM patients. We demonstrate that the two serine residues in the RSRSP stretch are constitutively phosphorylated and mutations in the stretch disturb nuclear localization of RBM20. Rbm20S637A knock-in mouse mimicking an S635A mutation reported in a familial case showed a remarkable effect on titin isoform expression like in a patient carrying the mutation. These results revealed the function of the RSRSP stretch as a critical part of a nuclear localization signal and offer the Rbm20S637A mouse as a good model for in vivo study.
Collapse
|
26
|
Mannacio V, Mannacio L, Antignano A, De Amicis V, Musumeci F, Iannelli G. Aortic stenosis and aortic regurgitation express different titin isoforms: Differences and relationships with functional and geometric characteristics. Int J Cardiol 2018; 259:138-144. [PMID: 29472025 DOI: 10.1016/j.ijcard.2018.01.136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/17/2017] [Accepted: 01/31/2018] [Indexed: 10/18/2022]
Abstract
Background-Titin represents an important biomechanical sensor which determines compliance and diastolic/systolic function of the left ventricle (LV). To assess the different titin-isoform expression and the relationships with functional and geometric patterns, we analyzed titin-isoform expression and cardiomyocytes contractile function in myocardial biopsy samples of patients undergoing aortic valve replacement (AVR) for aortic stenosis (AS) and for aortic regurgitation (AR). Method -Specimens, collected from the LV of 35 with AS and 35 with AR undergoing AVR were analyzed for titin-isoform expression and cardiomyocytes force measurement. Ten donor hearts were analyzed as controls for normal values. Results were implemented with preoperative geometry and function assessed by Doppler echocardiography. Results-Compared to controls, N2BA/N2B titin-isoforms ratio was reduced to 0.24 in AS (p < 0.001) but increased to 0.51 in AR (p < 0.001). N2BA/N2B titin-isoforms ratio was further reduced in 8 patients with severe (restrictive) diastolic dysfunction (0.17 ± 0.03, p < 0.001) but was increased in patients with severe systolic dysfunction (0.58 ± 0.07, p < 0.001). As compared to controls, Fpasive was higher in AS (6.7 ± 0.2 vs 4.4 ± 0.4 kN/m2, p < 0.001) but was lower in AR (3.7 ± 0.2 vs 4.4 ± 0.4 kN/m2, p < 0.001). Total force was comparable. Fpassive was significantly higher in AS patients with severe than with moderate LV diastolic dysfunction (7.1 ± 0.5 vs 6.6. ± 0.6, p = 0.004). Conclusions-titin-isoform expression differs in AS and AR as adaptive response to different pathophysiologic scenarios. Co-expressing isoforms at varying ratios results in modulation of the passive mechanical behavior of the LV at different degree of dysfunction and allows for compensative adjustment of the diastolic/systolic properties of the myocardium.
Collapse
Affiliation(s)
- Vito Mannacio
- Department of Cardiac Surgery, University Federico II, School of Medicine, Naples, Italy.
| | - Luigi Mannacio
- Department of Cardiac Surgery, University Federico II, School of Medicine, Naples, Italy
| | - Anita Antignano
- Department of Cardiology, Azienda Ospedaliera Santobono-Pausillipon, Naples, Italy
| | - Vincenzo De Amicis
- Department of Cardiac Surgery, University Federico II, School of Medicine, Naples, Italy
| | - Francesco Musumeci
- Department of Cardiac Surgery, Azienda Ospedaliera S. Camillo Forlanini, Rome, Italy
| | - Gabriele Iannelli
- Department of Cardiac Surgery, University Federico II, School of Medicine, Naples, Italy
| |
Collapse
|
27
|
Guo W, Zhu C, Yin Z, Wang Q, Sun M, Cao H, Greaser ML. Splicing Factor RBM20 Regulates Transcriptional Network of Titin Associated and Calcium Handling Genes in The Heart. Int J Biol Sci 2018; 14:369-380. [PMID: 29725258 PMCID: PMC5930469 DOI: 10.7150/ijbs.24117] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/27/2018] [Indexed: 01/28/2023] Open
Abstract
RNA binding motif 20 (RBM20) regulates pre-mRNA splicing of over thirty genes, among which titin is a major target. With RBM20 expression, titin expresses a larger isoform at fetal stage to a smaller isoform at adult resulting from alternative splicing, while, without RBM20, titin expresses exclusively a larger isoform throughout all ages. In addition to splicing regulation, it is unknown whether RBM20 also regulates gene expression. In this study, we employed Rbm20 knockout rats to investigate gene expression profile using Affymetrix expression array. We compared wild type to Rbm20 knockout at day1, 20 and 49. Bioinformatics analysis showed RBM20 regulates fewer genes expression at younger age and more at older age and commonly expressed genes have the same trends. GSEA indicated up-regulated genes are associated with heart failure. We examined titin binding partners. All titin direct binding partners are up-regulated and their increased expression is associated with dilated cardiomyopathy. Particularly, we found that genes involving calcium handling and muscle contraction are changed by RBM20. Intracellular calcium level measurement with individual cardiomyocytes further confirmed that changes of these proteins impact calcium handling. Selected genes from titin binding partners and calcium handling were validated with QPCR and western blotting. These data demonstrate that RBM20 regulates gene splicing as well as gene expression. Altered gene expression by RBM20 influences protein-protein interaction, calcium releasing and thus muscle contraction. Our results first reported gene expression impacted by RBM20 with heart maturation, and provided new insights into the role of RBM20 in the progression of heart failure.
Collapse
Affiliation(s)
- Wei Guo
- Animal Science, University of Wyoming, Laramie, WY 82071, USA.,Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA
| | - Chaoqun Zhu
- Animal Science, University of Wyoming, Laramie, WY 82071, USA.,Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA
| | - Zhiyong Yin
- Animal Science, University of Wyoming, Laramie, WY 82071, USA.,Department of Cardiology, Xi Jing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Qiurong Wang
- Animal Science, University of Wyoming, Laramie, WY 82071, USA.,Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA
| | - Mingming Sun
- Animal Science, University of Wyoming, Laramie, WY 82071, USA.,Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA
| | - Huojun Cao
- Iowa Institute for Oral Health Research, College of Dentistry.,Craniofacial Anomalies Research Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Marion L Greaser
- Animal Science, University of Wisconsin-Madison, Madison, WI 53705, USA
| |
Collapse
|
28
|
Frank(ly), Star(t)ling: A structural protein contributes to changes in left ventricular performance with cardiomyopathies? J Thorac Cardiovasc Surg 2018; 156:215-216. [PMID: 29395195 DOI: 10.1016/j.jtcvs.2017.12.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 12/18/2017] [Indexed: 11/22/2022]
|
29
|
Popović ZB, Sato K, Desai MY. Is universal grading of diastolic function by echocardiography feasible? Cardiovasc Diagn Ther 2018. [PMID: 29541608 DOI: 10.21037/cdt.2017.07.02] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Quantitation of diastolic function centers on the assessment of active and passive ventricular properties, and involves measurement estimates of ventricular relaxation, and chamber and myocardial stiffness. Diastolic dysfunction is a propensity to develop increased left ventricular (LV) end-diastolic pressure. Recently American Society of Echocardiography and European Association of Cardiovascular Imaging (ASE/EACVI) proposed a new grading system. While the new guidelines are ambiguous and with cutoff points that may misclassify patients as both sicker and healthier than they are. This article outlines the pathophysiology behind the diastolic dysfunction and role and limitation of echocardiographic assessment in predicting LV diastolic dysfunction.
Collapse
Affiliation(s)
- Zoran B Popović
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA
| | - Kimi Sato
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA
| | - Milind Y Desai
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA
| |
Collapse
|
30
|
Tonino P, Kiss B, Strom J, Methawasin M, Smith JE, Kolb J, Labeit S, Granzier H. The giant protein titin regulates the length of the striated muscle thick filament. Nat Commun 2017; 8:1041. [PMID: 29051486 PMCID: PMC5648799 DOI: 10.1038/s41467-017-01144-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/22/2017] [Indexed: 01/13/2023] Open
Abstract
The contractile machinery of heart and skeletal muscles has as an essential component the thick filament, comprised of the molecular motor myosin. The thick filament is of a precisely controlled length, defining thereby the force level that muscles generate and how this force varies with muscle length. It has been speculated that the mechanism by which thick filament length is controlled involves the giant protein titin, but no conclusive support for this hypothesis exists. Here we show that in a mouse model in which we deleted two of titin’s C-zone super-repeats, thick filament length is reduced in cardiac and skeletal muscles. In addition, functional studies reveal reduced force generation and a dilated cardiomyopathy (DCM) phenotype. Thus, regulation of thick filament length depends on titin and is critical for maintaining muscle health. Thick filaments in skeletal muscle and heart are composed of myosin. The authors show that the length of thick filaments is defined by titin, and that alterations in titin length affect force generation and lead to dilated cardiomyopathy in mice.
Collapse
Affiliation(s)
- Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - Balazs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - Josh Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA
| | - Siegfried Labeit
- Department of Integrative Pathophysiology, Medical Faculty Mannheim, Mannheim, 68167, Germany.,DZHK, Mannheim-Heidelberg, 68167, Germany
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, 85721, USA. .,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, 85721, USA.
| |
Collapse
|
31
|
Leg Lifting in HFrEF, Frank-Starling, and Mitral Regurgitation. JACC Cardiovasc Imaging 2017; 10:619-621. [DOI: 10.1016/j.jcmg.2016.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/12/2016] [Indexed: 11/24/2022]
|
32
|
Li X, Zhang P. Genetic determinants of myocardial dysfunction. J Med Genet 2016; 54:1-10. [DOI: 10.1136/jmedgenet-2016-104308] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 12/30/2022]
|
33
|
Pulcastro HC, Awinda PO, Methawasin M, Granzier H, Dong W, Tanner BCW. Increased Titin Compliance Reduced Length-Dependent Contraction and Slowed Cross-Bridge Kinetics in Skinned Myocardial Strips from Rbm (20ΔRRM) Mice. Front Physiol 2016; 7:322. [PMID: 27524973 PMCID: PMC4966298 DOI: 10.3389/fphys.2016.00322] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/14/2016] [Indexed: 01/12/2023] Open
Abstract
Titin is a giant protein spanning from the Z-disk to the M-band of the cardiac sarcomere. In the I-band titin acts as a molecular spring, contributing to passive mechanical characteristics of the myocardium throughout a heartbeat. RNA Binding Motif Protein 20 (RBM20) is required for normal titin splicing, and its absence or altered function leads to greater expression of a very large, more compliant N2BA titin isoform in Rbm20 homozygous mice (Rbm20ΔRRM) compared to wild-type mice (WT) that almost exclusively express the stiffer N2B titin isoform. Prior studies using Rbm20ΔRRM animals have shown that increased titin compliance compromises muscle ultrastructure and attenuates the Frank-Starling relationship. Although previous computational simulations of muscle contraction suggested that increasing compliance of the sarcomere slows the rate of tension development and prolongs cross-bridge attachment, none of the reported effects of Rbm20ΔRRM on myocardial function have been attributed to changes in cross-bridge cycling kinetics. To test the relationship between increased sarcomere compliance and cross-bridge kinetics, we used stochastic length-perturbation analysis in Ca2+-activated, skinned papillary muscle strips from Rbm20ΔRRM and WT mice. We found increasing titin compliance depressed maximal tension, decreased Ca2+-sensitivity of the tension-pCa relationship, and slowed myosin detachment rate in myocardium from Rbm20ΔRRM vs. WT mice. As sarcomere length increased from 1.9 to 2.2 μm, length-dependent activation of contraction was eliminated in the Rbm20ΔRRM myocardium, even though myosin MgADP release rate decreased ~20% to prolong strong cross-bridge binding at longer sarcomere length. These data suggest that increasing N2BA expression may alter cardiac performance in a length-dependent manner, showing greater deficits in tension production and slower cross-bridge kinetics at longer sarcomere length. This study also supports the idea that passive mechanical characteristics of the myocardium influence ensemble cross-bridge behavior and maintenance of tension generation throughout the sarcomere.
Collapse
Affiliation(s)
- Hannah C Pulcastro
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
| | - Peter O Awinda
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona Tucson, AZ, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona Tucson, AZ, USA
| | - Wenji Dong
- Department of Integrative Physiology and Neuroscience, Washington State UniversityPullman, WA, USA; Voiland School of Chemical Engineering and Bioengineering, Washington State UniversityPullman, WA, USA
| | - Bertrand C W Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
| |
Collapse
|
34
|
Gramlich M, Pane LS, Zhou Q, Chen Z, Murgia M, Schötterl S, Goedel A, Metzger K, Brade T, Parrotta E, Schaller M, Gerull B, Thierfelder L, Aartsma-Rus A, Labeit S, Atherton JJ, McGaughran J, Harvey RP, Sinnecker D, Mann M, Laugwitz KL, Gawaz MP, Moretti A. Antisense-mediated exon skipping: a therapeutic strategy for titin-based dilated cardiomyopathy. EMBO Mol Med 2016; 7:562-76. [PMID: 25759365 PMCID: PMC4492817 DOI: 10.15252/emmm.201505047] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Frameshift mutations in the TTN gene encoding titin are a major cause for inherited forms of dilated cardiomyopathy (DCM), a heart disease characterized by ventricular dilatation, systolic dysfunction, and progressive heart failure. To date, there are no specific treatment options for DCM patients but heart transplantation. Here, we show the beneficial potential of reframing titin transcripts by antisense oligonucleotide (AON)-mediated exon skipping in human and murine models of DCM carrying a previously identified autosomal-dominant frameshift mutation in titin exon 326. Correction of TTN reading frame in patient-specific cardiomyocytes derived from induced pluripotent stem cells rescued defective myofibril assembly and stability and normalized the sarcomeric protein expression. AON treatment in Ttn knock-in mice improved sarcomere formation and contractile performance in homozygous embryos and prevented the development of the DCM phenotype in heterozygous animals. These results demonstrate that disruption of the titin reading frame due to a truncating DCM mutation can be restored by exon skipping in both patient cardiomyocytes in vitro and mouse heart in vivo, indicating RNA-based strategies as a potential treatment option for DCM.
Collapse
Affiliation(s)
- Michael Gramlich
- Department of Cardiology and Cardiovascular Diseases, Eberhard Karls University, Tübingen, Germany Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Luna Simona Pane
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany
| | - Qifeng Zhou
- Department of Cardiology and Cardiovascular Diseases, Eberhard Karls University, Tübingen, Germany
| | - Zhifen Chen
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany
| | - Marta Murgia
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Sonja Schötterl
- Department of Cardiology and Cardiovascular Diseases, Eberhard Karls University, Tübingen, Germany
| | - Alexander Goedel
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany
| | - Katja Metzger
- Department of Cardiology and Cardiovascular Diseases, Eberhard Karls University, Tübingen, Germany
| | - Thomas Brade
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany
| | - Elvira Parrotta
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Martin Schaller
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Brenda Gerull
- Libin Cardiovascular Institute of Alberta and University of Calgary, Calgary, AB, Canada
| | | | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Siegfried Labeit
- Institute for Integrative Pathophysiology, Universitätsmedizin Mannheim, Mannheim, Germany
| | - John J Atherton
- Department of Cardiology, Royal Brisbane and Women's Hospital and University of Queensland School of Medicine, Brisbane, Australia
| | - Julie McGaughran
- Genetic Health Queensland, Royal Brisbane and Women's Hospital, Brisbane, Qld, Australia
| | - Richard P Harvey
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia St Vincent's Clinical School, University of New South Wales, Kensington, NSW, Australia
| | - Daniel Sinnecker
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Karl-Ludwig Laugwitz
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Meinrad Paul Gawaz
- Department of Cardiology and Cardiovascular Diseases, Eberhard Karls University, Tübingen, Germany
| | - Alessandra Moretti
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, Munich, Germany DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| |
Collapse
|
35
|
Stadler AM, Karmazin L, Bailly C. Eine Ca2+-, Mg2+- und Zn2+-basierte dendritische kontraktile Nanovorrichtung mit zwei pH-abhängigen Bewegungsfunktionen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
36
|
Stadler A, Karmazin L, Bailly C. A Ca
2+
‐, Mg
2+
‐, and Zn
2+
‐Based Dendritic Contractile Nanodevice with Two pH‐Dependent Motional Functions. Angew Chem Int Ed Engl 2015; 54:14570-4. [DOI: 10.1002/anie.201506474] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Indexed: 01/27/2023]
Affiliation(s)
- Adrian‐Mihail Stadler
- Institut de Science et d'Ingénierie Supramoléculaires (UMR 7006), CNRS and Université de Strasbourg, 8 Allée Gaspard Monge, 67000 Strasbourg (France)
- Institut für Nanotechnologie (INT), Karlsruhe Institut für Technologie (KIT), 76344 Eggenstein‐Leopoldshafen (Germany)
| | - Lydia Karmazin
- Service de Radiocristallographie, Université de Strasbourg, 1, rue Blaise Pascal, 67000 Strasbourg (France)
| | - Corinne Bailly
- Service de Radiocristallographie, Université de Strasbourg, 1, rue Blaise Pascal, 67000 Strasbourg (France)
| |
Collapse
|
37
|
Mannacio V, Mottola M, Mannacio L, Antignano A, Pinna GB, Musumeci F, Gagliardi C, Vosa C. WITHDRAWN: Titin Isoform Expression in Aortic Stenosis and Aortic Regurgitation: Differences and Relationships with Functional and Geometric Characteristics. Can J Cardiol 2015. [DOI: 10.1016/j.cjca.2015.08.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
38
|
Yang C, Zhang X, Guo Y, Meng F, Sachs F, Guo J. Mechanical dynamics in live cells and fluorescence-based force/tension sensors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1889-904. [PMID: 25958335 DOI: 10.1016/j.bbamcr.2015.05.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 04/07/2015] [Accepted: 05/01/2015] [Indexed: 01/13/2023]
Abstract
Three signaling systems play the fundamental roles in modulating cell activities: chemical, electrical, and mechanical. While the former two are well studied, the mechanical signaling system is still elusive because of the lack of methods to measure structural forces in real time at cellular and subcellular levels. Indeed, almost all biological processes are responsive to modulation by mechanical forces that trigger dispersive downstream electrical and biochemical pathways. Communication among the three systems is essential to make cells and tissues receptive to environmental changes. Cells have evolved many sophisticated mechanisms for the generation, perception and transduction of mechanical forces, including motor proteins and mechanosensors. In this review, we introduce some background information about mechanical dynamics in live cells, including the ubiquitous mechanical activity, various types of mechanical stimuli exerted on cells and the different mechanosensors. We also summarize recent results obtained using genetically encoded FRET (fluorescence resonance energy transfer)-based force/tension sensors; a new technique used to measure mechanical forces in structural proteins. The sensors have been incorporated into many specific structural proteins and have measured the force gradients in real time within live cells, tissues, and animals.
Collapse
Affiliation(s)
- Chao Yang
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing 210029, PR China
| | - Xiaohan Zhang
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing 210029, PR China
| | - Yichen Guo
- The University of Alabama, Tuscaloosa, AL, 35401, USA
| | - Fanjie Meng
- Physiology and Biophysics Department, Center for Single Molecule Studies, University at Buffalo, The State University of New York at Buffalo, Buffalo, NY, 14214, USA
| | - Frederick Sachs
- Physiology and Biophysics Department, Center for Single Molecule Studies, University at Buffalo, The State University of New York at Buffalo, Buffalo, NY, 14214, USA
| | - Jun Guo
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing 210029, PR China.
| |
Collapse
|
39
|
Yang J, Shih YH, Xu X. Understanding cardiac sarcomere assembly with zebrafish genetics. Anat Rec (Hoboken) 2015; 297:1681-93. [PMID: 25125181 DOI: 10.1002/ar.22975] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 01/06/2023]
Abstract
Mutations in sarcomere genes have been found in many inheritable human diseases, including hypertrophic cardiomyopathy. Elucidating the molecular mechanisms of sarcomere assembly shall facilitate understanding of the pathogenesis of sarcomere-based cardiac disease. Recently, biochemical and genomic studies have identified many new genes encoding proteins that localize to the sarcomere. However, their precise functions in sarcomere assembly and sarcomere-based cardiac disease are unknown. Here, we review zebrafish as an emerging vertebrate model for these studies. We summarize the techniques offered by this animal model to manipulate genes of interest, annotate gene expression, and describe the resulting phenotypes. We survey the sarcomere genes that have been investigated in zebrafish and discuss the potential of applying this in vivo model for larger-scale genetic studies.
Collapse
Affiliation(s)
- Jingchun Yang
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota; Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | | |
Collapse
|
40
|
Deleting titin's I-band/A-band junction reveals critical roles for titin in biomechanical sensing and cardiac function. Proc Natl Acad Sci U S A 2014; 111:14589-94. [PMID: 25246556 DOI: 10.1073/pnas.1411493111] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Titin, the largest protein known, forms a giant filament in muscle where it spans the half sarcomere from Z disk to M band. Here we genetically targeted a stretch of 14 immunoglobulin-like and fibronectin type 3 domains that comprises the I-band/A-band (IA) junction and obtained a viable mouse model. Super-resolution optical microscopy (structured illumination microscopy, SIM) and electron microscopy were used to study the thick filament length and titin's molecular elasticity. SIM showed that the IA junction functionally belongs to the relatively stiff A-band region of titin. The stiffness of A-band titin was found to be high, relative to that of I-band titin (∼ 40-fold higher) but low, relative to that of the myosin-based thick filament (∼ 70-fold lower). Sarcomere stretch therefore results in movement of A-band titin with respect to the thick filament backbone, and this might constitute a novel length-sensing mechanism. Findings disproved that titin at the IA junction is crucial for thick filament length control, settling a long-standing hypothesis. SIM also showed that deleting the IA junction moves the attachment point of titin's spring region away from the Z disk, increasing the strain on titin's molecular spring elements. Functional studies from the cellular to ex vivo and in vivo left ventricular chamber levels showed that this causes diastolic dysfunction and other symptoms of heart failure with preserved ejection fraction (HFpEF). Thus, our work supports titin's important roles in diastolic function and disease of the heart.
Collapse
|
41
|
Clowes C, Boylan MGS, Ridge LA, Barnes E, Wright JA, Hentges KE. The functional diversity of essential genes required for mammalian cardiac development. Genesis 2014; 52:713-37. [PMID: 24866031 PMCID: PMC4141749 DOI: 10.1002/dvg.22794] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 05/22/2014] [Accepted: 05/23/2014] [Indexed: 01/04/2023]
Abstract
Genes required for an organism to develop to maturity (for which no other gene can compensate) are considered essential. The continuing functional annotation of the mouse genome has enabled the identification of many essential genes required for specific developmental processes including cardiac development. Patterns are now emerging regarding the functional nature of genes required at specific points throughout gestation. Essential genes required for development beyond cardiac progenitor cell migration and induction include a small and functionally homogenous group encoding transcription factors, ligands and receptors. Actions of core cardiogenic transcription factors from the Gata, Nkx, Mef, Hand, and Tbx families trigger a marked expansion in the functional diversity of essential genes from midgestation onwards. As the embryo grows in size and complexity, genes required to maintain a functional heartbeat and to provide muscular strength and regulate blood flow are well represented. These essential genes regulate further specialization and polarization of cell types along with proliferative, migratory, adhesive, contractile, and structural processes. The identification of patterns regarding the functional nature of essential genes across numerous developmental systems may aid prediction of further essential genes and those important to development and/or progression of disease. genesis 52:713–737, 2014.
Collapse
Affiliation(s)
- Christopher Clowes
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, United Kingdom
| | | | | | | | | | | |
Collapse
|
42
|
Abstract
The giant protein titin forms a unique filament network in cardiomyocytes, which engages in both mechanical and signaling functions of the heart. TTN, which encodes titin, is also a major human disease gene. In this review, we cover the roles of cardiac titin in normal and failing hearts, with a special emphasis on the contribution of titin to diastolic stiffness. We provide an update on disease-associated titin mutations in cardiac and skeletal muscles and summarize what is known about the impact of protein-protein interactions on titin properties and functions. We discuss the importance of titin-isoform shifts and titin phosphorylation, as well as titin modifications related to oxidative stress, in adjusting the diastolic stiffness of the healthy and the failing heart. Along the way we distinguish among titin alterations in systolic and in diastolic heart failure and ponder the evidence for titin stiffness as a potential target for pharmacological intervention in heart disease.
Collapse
Affiliation(s)
- Wolfgang A Linke
- From the Department of Cardiovascular Physiology, Ruhr University Bochum, Bochum, Germany
| | | |
Collapse
|
43
|
Xiao D, Dasgupta C, Chen M, Zhang K, Buchholz J, Xu Z, Zhang L. Inhibition of DNA methylation reverses norepinephrine-induced cardiac hypertrophy in rats. Cardiovasc Res 2014; 101:373-82. [PMID: 24272874 PMCID: PMC3927999 DOI: 10.1093/cvr/cvt264] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 10/15/2013] [Accepted: 11/08/2013] [Indexed: 12/20/2022] Open
Abstract
AIMS The mechanisms of heart failure remain largely elusive. The present study determined a causative role of DNA methylation in norepinephrine-induced heart hypertrophy and reduced cardiac contractility. METHODS AND RESULTS Male adult rats were subjected to norepinephrine infusion for 28 days, some of which were treated with 5-aza-2'-deoxycytidine for the last 6 days of norepinephrine treatment. At the end of the treatment, hearts were isolated and left ventricular morphology and function as well as molecular assessments was determined. Animals receiving chronic norepinephrine infusion showed a sustained increase in blood pressure, heightened global genomic DNA methylation and changes in the expression of subsets of proteins in the left ventricle, left ventricular hypertrophy, and impaired contractility with an increase in the susceptibility to ischaemic injury. Treatment of animals with 5-aza-2'-deoxycytidine for the last 6 days of norepinephrine infusion reversed norepinephrine-induced hypermethylation, corrected protein expression patterns, and rescued the phenotype of heart hypertrophy and failure. CONCLUSIONS The findings provide novel evidence of a causative role of increased DNA methylation in programming of heart hypertrophy and reduced cardiac contractility, and suggest potential therapeutic targets of demethylation in the treatment of failing heart and ischaemic heart disease.
Collapse
Affiliation(s)
- DaLiao Xiao
- Institute for Fetology and Reproductive Medicine Center, First Hospital of Soochow University, Suzhou 215006, China
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Chiranjib Dasgupta
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Man Chen
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Kangling Zhang
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - John Buchholz
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Zhice Xu
- Institute for Fetology and Reproductive Medicine Center, First Hospital of Soochow University, Suzhou 215006, China
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Lubo Zhang
- Institute for Fetology and Reproductive Medicine Center, First Hospital of Soochow University, Suzhou 215006, China
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| |
Collapse
|
44
|
Kaushik G, Engler AJ. From stem cells to cardiomyocytes: the role of forces in cardiac maturation, aging, and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:219-42. [PMID: 25081620 DOI: 10.1016/b978-0-12-394624-9.00009-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Stem cell differentiation into a variety of lineages is known to involve signaling from the extracellular niche, including from the physical properties of that environment. What regulates stem cell responses to these cues is there ability to activate different mechanotransductive pathways. Here, we will review the structures and pathways that regulate stem cell commitment to a cardiomyocyte lineage, specifically examining proteins within muscle sarcomeres, costameres, and intercalated discs. Proteins within these structures stretch, inducing a change in their phosphorylated state or in their localization to initiate different signals. We will also put these changes in the context of stem cell differentiation into cardiomyocytes, their subsequent formation of the chambered heart, and explore negative signaling that occurs during disease.
Collapse
Affiliation(s)
- Gaurav Kaushik
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Adam J Engler
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| |
Collapse
|
45
|
Pathophysiological defects and transcriptional profiling in the RBM20-/- rat model. PLoS One 2013; 8:e84281. [PMID: 24367651 PMCID: PMC3868568 DOI: 10.1371/journal.pone.0084281] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 11/21/2013] [Indexed: 12/20/2022] Open
Abstract
Our recent study indicated that RNA binding motif 20 (Rbm20) alters splicing of titin and other genes. The current goals were to understand how the Rbm20(-/-) rat is related to physiological, structural, and molecular changes leading to heart failure. We quantitatively and qualitatively compared the expression of titin isoforms between Rbm20(-/-) and wild type rats by real time RT-PCR and SDS agarose electrophoresis. Isoform changes were linked to alterations in transcription as opposed to translation of titin messages. Reduced time to exhaustion with running in knockout rats also suggested a lower maximal cardiac output or decreased skeletal muscle performance. Electron microscopic observations of the left ventricle from knockout animals showed abnormal myofibril arrangement, Z line streaming, and lipofuscin deposits. Mutant skeletal muscle ultrastructure appeared normal. The results suggest that splicing alterations in Rbm20(-/-) rats resulted in pathogenic changes in physiology and cardiac ultrastructure. Secondary changes were observed in message levels for many genes whose splicing was not directly affected. Gene and protein expression data indicated the activation of pathophysiological and muscle stress-activated pathways. These data provide new insights on Rbm20 function and how its malfunction leads to cardiomyopathy.
Collapse
|
46
|
Vikhlyantsev IM, Podlubnaya ZA. New titin (connectin) isoforms and their functional role in striated muscles of mammals: facts and suppositions. BIOCHEMISTRY (MOSCOW) 2013; 77:1515-35. [PMID: 23379526 DOI: 10.1134/s0006297912130093] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This review summarizes results of our studies on titin isoform composition in vertebrate striated muscles under normal conditions, during hibernation, real and simulated microgravity, and under pathological conditions (stiff-person syndrome, post-apoplectic spasticity, dilated cardiomyopathy, cardiac hypertrophy). Experimental evidence for the existence in mammalian striated muscles of higher molecular weight isoforms of titin (NT-isoforms) in addition to the known N2A-, N2BA-, and N2B-titin isoforms was obtained. Comparative studies of changes in titin isoform composition and structure-functional properties of human and animal striated muscles during adaptive and pathological processes led to a conclusion about the key role of NT-isoforms of titin in maintenance of sarcomere structure and contractile function of these muscles.
Collapse
Affiliation(s)
- I M Vikhlyantsev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | | |
Collapse
|
47
|
Yamamoto S, Iida H, Yashima E. Guest-Induced Unidirectional Dual Rotary and Twisting Motions of a Spiroborate-Based Double-Stranded Helicate Containing a Bisporphyrin Unit. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
48
|
Guest-Induced Unidirectional Dual Rotary and Twisting Motions of a Spiroborate-Based Double-Stranded Helicate Containing a Bisporphyrin Unit. Angew Chem Int Ed Engl 2013; 52:6849-53. [DOI: 10.1002/anie.201302560] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Indexed: 11/07/2022]
|
49
|
Coelho Ribeiro MDL, Espinosa J, Islam S, Martinez O, Thanki JJ, Mazariegos S, Nguyen T, Larina M, Xue B, Uversky VN. Malleable ribonucleoprotein machine: protein intrinsic disorder in the Saccharomyces cerevisiae spliceosome. PeerJ 2013; 1:e2. [PMID: 23638354 PMCID: PMC3628832 DOI: 10.7717/peerj.2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 12/01/2012] [Indexed: 12/29/2022] Open
Abstract
Recent studies revealed that a significant fraction of any given proteome is presented by proteins that do not have unique 3D structures as a whole or in significant parts. These intrinsically disordered proteins possess dramatic structural and functional variability, being especially enriched in signaling and regulatory functions since their lack of fixed structure defines their ability to be involved in interaction with several proteins and allows them to be re-used in multiple pathways. Among recognized disorder-based protein functions are interactions with nucleic acids and multi-target binding; i.e., the functions ascribed to many spliceosomal proteins. Therefore, the spliceosome, a multimegadalton ribonucleoprotein machine catalyzing the excision of introns from eukaryotic pre-mRNAs, represents an attractive target for the focused analysis of the abundance and functionality of intrinsic disorder in its proteinaceous components. In yeast cells, spliceosome consists of five small nuclear RNAs (U1, U2, U4, U5, and U6) and a range of associated proteins. Some of these proteins constitute cores of the corresponding snRNA-protein complexes known as small nuclear ribonucleoproteins (snRNPs). Other spliceosomal proteins have various auxiliary functions. To gain better understanding of the functional roles of intrinsic disorder, we have studied the prevalence of intrinsically disordered proteins in the yeast spliceosome using a wide array of bioinformatics methods. Our study revealed that similar to the proteins associated with human spliceosomes (Korneta & Bujnicki, 2012), proteins found in the yeast spliceosome are enriched in intrinsic disorder.
Collapse
Affiliation(s)
- Maria de Lourdes Coelho Ribeiro
- Cancer Imaging Metabolism, H. Lee Moffitt Cancer Center & Research Institute , United States ; Department of Molecular Medicine, University of South Florida , Tampa, Florida , United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Tuning the molecular giant titin through phosphorylation: role in health and disease. Trends Cardiovasc Med 2013; 23:165-71. [PMID: 23295080 DOI: 10.1016/j.tcm.2012.10.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/22/2012] [Accepted: 10/23/2012] [Indexed: 01/05/2023]
Abstract
Titin is a giant multi-functional filament that spans half of the sarcomere. Titin's extensible I-band region functions as a molecular spring that provides passive stiffness to cardiac myocytes. Elevated diastolic stiffness is found in a large fraction of heart failure patients and thus understanding the normal mechanisms and pathophysiology of passive stiffness modulation is clinically important. Here we provide first a brief general background on titin including what is known about titin isoforms and then focus on recently discovered post-translational modifications of titin that alter passive stiffness. We discuss the various kinases that have been shown to phosphorylate titin and address the possible roles of titin phosphorylation in cardiac disease, including heart failure with preserved ejection fraction (HFpEF).
Collapse
|