1
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Waddingham MT, Sequeira V, Kuster DWD, Dal Canto E, Handoko ML, de Man FS, da Silva Gonçalves Bós D, Ottenheijm CA, Shen S, van der Pijl RJ, van der Velden J, Paulus WJ, Eringa EC. Geranylgeranylacetone reduces cardiomyocyte stiffness and attenuates diastolic dysfunction in a rat model of cardiometabolic syndrome. Physiol Rep 2023; 11:e15788. [PMID: 37985159 PMCID: PMC10659935 DOI: 10.14814/phy2.15788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 11/22/2023] Open
Abstract
Titin-dependent stiffening of cardiomyocytes is a significant contributor to left ventricular (LV) diastolic dysfunction in heart failure with preserved LV ejection fraction (HFpEF). Small heat shock proteins (HSPs), such as HSPB5 and HSPB1, protect titin and administration of HSPB5 in vitro lowers cardiomyocyte stiffness in pressure-overload hypertrophy. In humans, oral treatment with geranylgeranylacetone (GGA) increases myocardial HSP expression, but the functional implications are unknown. Our objective was to investigate whether oral GGA treatment lowers cardiomyocyte stiffness and attenuates LV diastolic dysfunction in a rat model of the cardiometabolic syndrome. Twenty-one-week-old male lean (n = 10) and obese (n = 20) ZSF1 rats were studied, and obese rats were randomized to receive GGA (200 mg/kg/day) or vehicle by oral gavage for 4 weeks. Echocardiography and cardiac catheterization were performed before sacrifice at 25 weeks of age. Titin-based stiffness (Fpassive ) was determined by force measurements in relaxing solution with 100 nM [Ca2+ ] in permeabilized cardiomyocytes at sarcomere lengths (SL) ranging from 1.8 to 2.4 μm. In obese ZSF1 rats, GGA reduced isovolumic relaxation time of the LV without affecting blood pressure, EF or LV weight. In cardiomyocytes, GGA increased myofilament-bound HSPB5 and HSPB1 expression. Vehicle-treated obese rats exhibited higher cardiomyocyte stiffness at all SLs compared to lean rats, while GGA reduced stiffness at SL 2.0 μm. In obese ZSF1 rats, oral GGA treatment improves cardiomyocyte stiffness by increasing myofilament-bound HSPB1 and HSPB5. GGA could represent a potential novel therapy for the early stage of diastolic dysfunction in the cardiometabolic syndrome.
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Affiliation(s)
- Mark T. Waddingham
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
- Department of Cardiac PhysiologyNational Cerebral and Cardiovascular CenterSuitaJapan
| | - Vasco Sequeira
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | - Diederik W. D. Kuster
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | - Elisa Dal Canto
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
- Laboratory of Experimental CardiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
- Julius Center for Health Sciences and Primary CareUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - M. Louis Handoko
- Department of Cardiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | - Frances S. de Man
- Department of Pulmonology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | | | - Coen A. Ottenheijm
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
- Cellular and Molecular MedicineUniversity of ArizonaTucsonArizonaUSA
| | - Shengyi Shen
- Cellular and Molecular MedicineUniversity of ArizonaTucsonArizonaUSA
| | | | - Jolanda van der Velden
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | - Walter J. Paulus
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
| | - Etto C. Eringa
- Department of Physiology, Amsterdam Cardiovascular SciencesAmsterdam University Medical CentersAmsterdamThe Netherlands
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2
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de Winter JM, Bouman K, Strom J, Methawasin M, Jongbloed JDH, van der Roest W, Wijngaarden JV, Timmermans J, Nijveldt R, van den Heuvel F, Kamsteeg EJ, van Engelen BG, Galli R, Bogaards SJP, Boon RA, van der Pijl RJ, Granzier H, Koeleman B, Amin AS, van der Velden J, van Tintelen JP, van den Berg MP, van Spaendonck-Zwarts KY, Voermans NC, Ottenheijm CAC. KBTBD13 is a novel cardiomyopathy gene. Hum Mutat 2022; 43:1860-1865. [PMID: 36335629 PMCID: PMC10100581 DOI: 10.1002/humu.24499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 08/22/2022] [Accepted: 09/12/2022] [Indexed: 11/08/2022]
Abstract
KBTBD13 variants cause nemaline myopathy type 6 (NEM6). The majority of NEM6 patients harbors the Dutch founder variant, c.1222C>T, p.Arg408Cys (KBTBD13 p.R408C). Although KBTBD13 is expressed in cardiac muscle, cardiac involvement in NEM6 is unknown. Here, we constructed pedigrees of three families with the KBTBD13 p.R408C variant. In 65 evaluated patients, 12% presented with left ventricle dilatation, 29% with left ventricular ejection fraction< 50%, 8% with atrial fibrillation, 9% with ventricular tachycardia, and 20% with repolarization abnormalities. Five patients received an implantable cardioverter defibrillator, three cases of sudden cardiac death were reported. Linkage analysis confirmed cosegregation of the KBTBD13 p.R408C variant with the cardiac phenotype. Mouse studies revealed that (1) mice harboring the Kbtbd13 p.R408C variant display mild diastolic dysfunction; (2) Kbtbd13-deficient mice have systolic dysfunction. Hence, (1) KBTBD13 is associated with cardiac dysfunction and cardiomyopathy; (2) KBTBD13 should be added to the cardiomyopathy gene panel; (3) NEM6 patients should be referred to the cardiologist.
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Affiliation(s)
| | - Karlijn Bouman
- Department of Neurology, Radboudumc, Nijmegen, The Netherlands
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Jan D H Jongbloed
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Wilma van der Roest
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | | | | | - Robin Nijveldt
- Department of Cardiology, Radboudumc, Nijmegen, The Netherlands
| | | | | | | | - Ricardo Galli
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | | | - Reinier A Boon
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Robbert J van der Pijl
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
| | - Bobby Koeleman
- Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands
| | - Ahmad S Amin
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - J Peter van Tintelen
- Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cardiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Maarten P van den Berg
- Department of Cardiology, University Medical Centre Groningen, Groningen, The Netherlands
| | - Karin Y van Spaendonck-Zwarts
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands.,Department of Human Genetics, Amsterdam UMC, Amsterdam, The Netherlands
| | | | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA
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3
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Kelley RC, Betancourt L, Noriega AM, Brinson SC, Curbelo-Bermudez N, Hahn D, Kumar RA, Balazic E, Muscato DR, Ryan TE, van der Pijl RJ, Shen S, Ottenheijm CAC, Ferreira LF. Skeletal myopathy in a rat model of postmenopausal heart failure with preserved ejection fraction. J Appl Physiol (1985) 2022; 132:106-125. [PMID: 34792407 PMCID: PMC8742741 DOI: 10.1152/japplphysiol.00170.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 11/01/2021] [Accepted: 11/11/2021] [Indexed: 01/03/2023] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) accounts for ∼50% of all patients with heart failure and frequently affects postmenopausal women. The HFpEF condition is phenotype-specific, with skeletal myopathy that is crucial for disease development and progression. However, most of the current preclinical models of HFpEF have not addressed the postmenopausal phenotype. We sought to advance a rodent model of postmenopausal HFpEF and examine skeletal muscle abnormalities therein. Female, ovariectomized, spontaneously hypertensive rats (SHRs) were fed a high-fat, high-sucrose diet to induce HFpEF. Controls were female sham-operated Wistar-Kyoto rats on a lean diet. In a complementary, longer-term cohort, controls were female sham-operated SHRs on a lean diet to evaluate the effect of strain difference in the model. Our model developed key features of HFpEF that included increased body weight, glucose intolerance, hypertension, cardiac hypertrophy, diastolic dysfunction, exercise intolerance, and elevated plasma cytokines. In limb skeletal muscle, HFpEF decreased specific force by 15%-30% (P < 0.05) and maximal mitochondrial respiration by 40%-55% (P < 0.05), increased oxidized glutathione by approximately twofold (P < 0.05), and tended to increase mitochondrial H2O2 emission (P = 0.10). Muscle fiber cross-sectional area, markers of mitochondrial content, and indices of capillarity were not different between control and HFpEF in our short-term cohort. Overall, our preclinical model of postmenopausal HFpEF recapitulates several key features of the disease. This new model reveals contractile and mitochondrial dysfunction and redox imbalance that are potential contributors to abnormal metabolism, exercise intolerance, and diminished quality of life in patients with postmenopausal HFpEF.NEW & NOTEWORTHY Heart failure with preserved ejection fraction (HFpEF) is a condition with phenotype-specific features highly prevalent in postmenopausal women and skeletal myopathy contributing to disease development and progression. We advanced a rat model of postmenopausal HFpEF with key cardiovascular and systemic features of the disease. Our study shows that the skeletal myopathy of postmenopausal HFpEF includes loss of limb muscle-specific force independent of atrophy, mitochondrial dysfunction, and oxidized shift in redox balance.
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Affiliation(s)
- Rachel C Kelley
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Lauren Betancourt
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Andrea M Noriega
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Suzanne C Brinson
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Nuria Curbelo-Bermudez
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Dongwoo Hahn
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Ravi A Kumar
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Eliza Balazic
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Derek R Muscato
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Terence E Ryan
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Robbert J van der Pijl
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Shengyi Shen
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Coen A C Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology, Amsterdam UMC, Amsterdam, The Netherlands
| | - Leonardo F Ferreira
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
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4
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van der Pijl RJ, Domenighetti AA, Sheikh F, Ehler E, Ottenheijm CAC, Lange S. The titin N2B and N2A regions: biomechanical and metabolic signaling hubs in cross-striated muscles. Biophys Rev 2021; 13:653-677. [PMID: 34745373 PMCID: PMC8553726 DOI: 10.1007/s12551-021-00836-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 02/07/2023] Open
Abstract
Muscle specific signaling has been shown to originate from myofilaments and their associated cellular structures, including the sarcomeres, costameres or the cardiac intercalated disc. Two signaling hubs that play important biomechanical roles for cardiac and/or skeletal muscle physiology are the N2B and N2A regions in the giant protein titin. Prominent proteins associated with these regions in titin are chaperones Hsp90 and αB-crystallin, members of the four-and-a-half LIM (FHL) and muscle ankyrin repeat protein (Ankrd) families, as well as thin filament-associated proteins, such as myopalladin. This review highlights biological roles and properties of the titin N2B and N2A regions in health and disease. Special emphasis is placed on functions of Ankrd and FHL proteins as mechanosensors that modulate muscle-specific signaling and muscle growth. This region of the sarcomere also emerged as a hotspot for the modulation of passive muscle mechanics through altered titin phosphorylation and splicing, as well as tethering mechanisms that link titin to the thin filament system.
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Affiliation(s)
| | - Andrea A. Domenighetti
- Shirley Ryan AbilityLab, Chicago, IL USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL USA
| | - Farah Sheikh
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King’s College London, London, UK
| | - Coen A. C. Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ USA
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Stephan Lange
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
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5
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Affiliation(s)
- Robbert J van der Pijl
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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6
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van der Pijl RJ, van den Berg M, van de Locht M, Shen S, Bogaards SJP, Conijn S, Langlais P, Hooijman PE, Labeit S, Heunks LMA, Granzier H, Ottenheijm CAC. Muscle ankyrin repeat protein 1 (MARP1) locks titin to the sarcomeric thin filament and is a passive force regulator. J Gen Physiol 2021; 153:212403. [PMID: 34152365 PMCID: PMC8222902 DOI: 10.1085/jgp.202112925] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/19/2021] [Indexed: 12/12/2022] Open
Abstract
Muscle ankyrin repeat protein 1 (MARP1) is frequently up-regulated in stressed muscle, but its effect on skeletal muscle function is poorly understood. Here, we focused on its interaction with the titin–N2A element, found in titin’s molecular spring region. We show that MARP1 binds to F-actin, and that this interaction is stronger when MARP1 forms a complex with titin–N2A. Mechanics and super-resolution microscopy revealed that MARP1 “locks” titin–N2A to the sarcomeric thin filament, causing increased extension of titin’s elastic PEVK element and, importantly, increased passive force. In support of this mechanism, removal of thin filaments abolished the effect of MARP1 on passive force. The clinical relevance of this mechanism was established in diaphragm myofibers of mechanically ventilated rats and of critically ill patients. Thus, MARP1 regulates passive force by locking titin to the thin filament. We propose that in stressed muscle, this mechanism protects the sarcomere from mechanical damage.
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Affiliation(s)
- Robbert J van der Pijl
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Marloes van den Berg
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Martijn van de Locht
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Shengyi Shen
- Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Sylvia J P Bogaards
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Stefan Conijn
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Paul Langlais
- Division of Endocrinology, University of Arizona, Tucson, AZ
| | - Pleuni E Hooijman
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Siegfried Labeit
- Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Leo M A Heunks
- Intensive Care Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
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7
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 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.
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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
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8
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Abstract
The diaphragm, the main muscle of inspiration, is constantly subjected to mechanical loading. Only during controlled mechanical ventilation, as occurs during thoracic surgery and in the intensive care unit, is mechanical loading of the diaphragm arrested. Animal studies indicate that the diaphragm is highly sensitive to unloading, causing rapid muscle fiber atrophy and contractile weakness; unloading-induced diaphragm atrophy and contractile weakness have been suggested to contribute to the difficulties in weaning patients from ventilator support. The molecular triggers that initiate the rapid unloading atrophy of the diaphragm are not well understood, although proteolytic pathways and oxidative signaling have been shown to be involved. Mechanical stress is known to play an important role in the maintenance of muscle mass. Within the muscle's sarcomere, titin is considered to play an important role in the stress-response machinery. Titin is a giant protein that acts as a mechanosensor regulating muscle protein expression in a sarcomere strain-dependent fashion. Thus titin is an attractive candidate for sensing the sudden mechanical arrest of the diaphragm when patients are mechanically ventilated, leading to changes in muscle protein expression. Here, we provide a novel perspective on how titin and its biomechanical sensing and signaling might be involved in the development of mechanical unloading-induced diaphragm weakness.
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Affiliation(s)
- Robbert J van der Pijl
- Department of Cellular and Molecular Medicine, University of Arizona , Tucson, Arizona.,Department of Physiology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona , Tucson, Arizona
| | - Coen A C Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona , Tucson, Arizona.,Department of Physiology, Amsterdam University Medical Center, Amsterdam, The Netherlands
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