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Hashimoto K, Ohira M, Kodama A, Kimoto M, Inoue M, Toné S, Usui Y, Hanashima A, Goto T, Ogura Y, Ujihara Y, Mohri S. Loss of connectin novex-3 leads to heart dysfunction associated with impaired cardiomyocyte proliferation and abnormal nuclear mechanics. Sci Rep 2024; 14:13727. [PMID: 38877142 PMCID: PMC11178842 DOI: 10.1038/s41598-024-64608-1] [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: 08/31/2023] [Accepted: 06/11/2024] [Indexed: 06/16/2024] Open
Abstract
Connectin (also known as titin) is a giant striated muscle protein that functions as a molecular spring by providing elasticity to the sarcomere. Novex-3 is a short splice variant of connectin whose physiological function remains unknown. We have recently demonstrated using in vitro analyses that in addition to sarcomere expression, novex-3 was also expressed in cardiomyocyte nuclei exclusively during fetal life, where it provides elasticity/compliance to cardiomyocyte nuclei and promotes cardiomyocyte proliferation in the fetus, suggesting a non-sarcomeric function. Here, we analyzed novex-3 knockout mice to assess the involvement of this function in cardiac pathophysiology in vivo. Deficiency of novex-3 compromised fetal cardiomyocyte proliferation and induced the enlargement of individual cardiomyocytes in neonates. In adults, novex-3 deficiency resulted in chamber dilation and systolic dysfunction, associated with Ca2+ dysregulation, resulting in a reduced life span. Mechanistic analyses revealed a possible association between impaired proliferation and abnormal nuclear mechanics, including stiffer nuclei positioned peripherally with stabilized circumnuclear microtubules in knockout cardiomyocytes. Although the underlying causal relationships were not fully elucidated, these data show that novex-3 has a vital non-sarcomeric function in cardiac pathophysiology and serves as an early contributor to cardiomyocyte proliferation.
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Affiliation(s)
- Ken Hashimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan.
| | - Momoko Ohira
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Aya Kodama
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Misaki Kimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Mariko Inoue
- Central Research Institute, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Shigenobu Toné
- Laboratory of Molecular Developmental Biology, Graduate School of Science and Engineering, Tokyo Denki University, Hatoyama, Saitama, 350-0394, Japan
| | - Yuu Usui
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Akira Hanashima
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Takato Goto
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Yuhei Ogura
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Yoshihiro Ujihara
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Satoshi Mohri
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
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Usui Y, Hanashima A, Hashimoto K, Kimoto M, Ohira M, Mohri S. Comparative analysis of ventricular stiffness across species. Physiol Rep 2024; 12:e16013. [PMID: 38644486 PMCID: PMC11033294 DOI: 10.14814/phy2.16013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 04/01/2024] [Accepted: 04/01/2024] [Indexed: 04/23/2024] Open
Abstract
Investigating ventricular diastolic properties is crucial for understanding the physiological cardiac functions in organisms and unraveling the pathological mechanisms of cardiovascular disorders. Ventricular stiffness, a fundamental parameter that defines ventricular diastolic functions in chordates, is typically analyzed using the end-diastolic pressure-volume relationship (EDPVR). However, comparing ventricular stiffness accurately across chambers of varying maximum volume capacities has been a long-standing challenge. As one of the solutions to this problem, we propose calculating a relative ventricular stiffness index by applying an exponential approximation formula to the EDPVR plot data of the relationship between ventricular pressure and values of normalized ventricular volume by the ventricular weight. This article reviews the potential, utility, and limitations of using normalized EDPVR analysis in recent studies. Herein, we measured and ranked ventricular stiffness in differently sized and shaped chambers using ex vivo ventricular pressure-volume analysis data from four animals: Wistar rats, red-eared slider turtles, masu salmon, and cherry salmon. Furthermore, we have discussed the mechanical effects of intracellular and extracellular viscoelastic components, Titin (Connectin) filaments, collagens, physiological sarcomere length, and other factors that govern ventricular stiffness. Our review provides insights into the comparison of ventricular stiffness in different-sized ventricles between heterologous and homologous species, including non-model organisms.
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Grants
- JP22K15155 Japan Society for the Promotion of Science, Grant/Award Number
- JP20K21453 Japan Society for the Promotion of Science, Grant/Award Number
- JP20H04508 Japan Society for the Promotion of Science, Grant/Award Number
- JP21K19933 Japan Society for the Promotion of Science, Grant/Award Number
- JP20H04521 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H02092 Japan Society for the Promotion of Science, Grant/Award Number
- JP23H00556 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H06272 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H00859 Japan Society for the Promotion of Science, Grant/Award Number
- JP25560214 Japan Society for the Promotion of Science, Grant/Award Number
- JP16K01385 Japan Society for the Promotion of Science, Grant/Award Number
- JP26282127 Japan Society for the Promotion of Science, Grant/Award Number
- The Futaba research grant program
- Research Grant from the Kawasaki Foundation in 2016 from Medical Science and Medical Welfare
- Medical Research Grant in 2010 from Takeda Science Foundation
- R03S005 Research Project Grant from Kawasaki Medical School
- R03B050 Research Project Grant from Kawasaki Medical School
- R01B054 Research Project Grant from Kawasaki Medical School
- H30B041 Research Project Grant from Kawasaki Medical School
- H30B016 Research Project Grant from Kawasaki Medical School
- H27B10 Research Project Grant from Kawasaki Medical School
- R02B039 Research Project Grant from Kawasaki Medical School
- H28B80 Research Project Grant from Kawasaki Medical School
- R05B016 Research Project Grant from Kawasaki Medical School
- Japan Society for the Promotion of Science, Grant/Award Number
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Affiliation(s)
- Yuu Usui
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Akira Hanashima
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Ken Hashimoto
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Misaki Kimoto
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Momoko Ohira
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Satoshi Mohri
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
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Usui Y, Kimoto M, Hanashima A, Hashimoto K, Mohri S. Cardiac hemodynamics and ventricular stiffness of sea-run cherry salmon (Oncorhynchus masou masou) differ critically from those of landlocked masu salmon. PLoS One 2022; 17:e0267264. [PMID: 36331913 PMCID: PMC9635730 DOI: 10.1371/journal.pone.0267264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
Ventricular diastolic mechanical properties are important determinants of cardiac function and are optimized by changes in cardiac structure and physical properties. Oncorhynchus masou masou is an anadromous migratory fish of the Salmonidae family, and several ecological studies on it have been conducted; however, the cardiac functions of the fish are not well known. Therefore, we investigated ventricular diastolic function in landlocked (masu salmon) and sea-run (cherry salmon) types at 29–30 months post fertilization. Pulsed-wave Doppler echocardiography showed that the atrioventricular inflow waveforms of cherry salmon were biphasic with early diastolic filling and atrial contraction, whereas those of masu salmon were monophasic with atrial contraction. In addition, end-diastolic pressure–volume relationship analysis revealed that the dilatability per unit myocardial mass of the ventricle in cherry salmon was significantly suppressed compared to that in masu salmon, suggesting that the ventricle of the cherry salmon was relatively stiffer (relative ventricular stiffness index; p = 0.0263). Contrastingly, the extensibility of cardiomyocytes, characterized by the expression pattern of Connectin isoforms in their ventricles, was similar in both types. Histological analysis showed that the percentage of the collagen accumulation area in the compact layer of cherry salmon increased compared with that of the masu salmon, which may contribute to ventricle stiffness. Although the heart mass of cherry salmon was about 11-fold greater than that of masu salmon, there was no difference in the morphology of the isolated cardiomyocytes, suggesting that the heart of the cherry salmon grows by cardiomyocyte proliferation, but not cell hypertrophy. The cardiac physiological function of the teleosts varies with differences in their developmental processes and life history. Our multidimensional analysis of the O. masou heart may provide a clue to the process by which the heart acquires a biphasic blood-filling pattern, i.e., a ventricular diastolic suction.
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Affiliation(s)
- Yuu Usui
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
- * E-mail:
| | - Misaki Kimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Akira Hanashima
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Ken Hashimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Satoshi Mohri
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
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Comparison of the histology and stiffness of ventricles in Anura of different habitats. J Biol Phys 2021; 47:287-300. [PMID: 34515919 DOI: 10.1007/s10867-021-09579-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/21/2021] [Indexed: 01/08/2023] Open
Abstract
Vertebrate hearts have undergone marked morphological and structural changes to adapt to different environments and lifestyles as part of the evolutionary process. Amphibians were the first vertebrates to migrate to land. Transition from aquatic to terrestrial environments required the ability to circulate blood against the force of gravity. In this study, we investigated the passive mechanical properties and histology of the ventricles of three species of Anura (frogs and toads) from different habitats, Xenopus laevis (aquatic), Pelophylax nigromaculatus (semiaquatic), and Bufo japonicus formosus (terrestrial). Pressure-loading tests demonstrated stiffer ventricles of P. nigromaculatus and B. j. formosus compared X. laevis ventricles. Histological analysis revealed a remarkable difference in the structure of cardiac tissue: thickening of the compact myocardium layer of P. nigromaculatus and B. j. formosus and enrichment of the collagen fibers of B. j. formosus. The amount of collagen fibers differed among the species, as quantitatively confirmed by second-harmonic generation light microscopy. No significant difference was observed in cardiomyocytes isolated from each animal, and the sarcomere length was almost the same. The results indicate that the ventricles of Anura stiffen during adaptation to life on land.
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Nuclear connectin novex-3 promotes proliferation of hypoxic foetal cardiomyocytes. Sci Rep 2018; 8:12337. [PMID: 30120340 PMCID: PMC6098106 DOI: 10.1038/s41598-018-30886-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/08/2018] [Indexed: 12/15/2022] Open
Abstract
Loss of cardiomyocyte proliferative capacity after birth is a major obstacle for therapeutic heart regeneration in adult mammals. We and others have recently shown the importance of hypoxic in utero environments for active foetal cardiomyocyte proliferation. Here, we report the unexpected expression of novex-3, the short splice variant of the giant sarcomeric protein connectin (titin), in the cardiomyocyte nucleus specifically during the hypoxic foetal stage in mice. This nuclear localisation appeared to be regulated by the N-terminal region of novex-3, which contains the nuclear localisation signal. Importantly, the nuclear expression of novex-3 in hypoxic foetal cardiomyocytes was repressed at the postnatal stage following the onset of breathing and the resulting elevation of oxygen tension, whereas the sarcomeric expression remained unchanged. Novex-3 knockdown in foetal cardiomyocytes repressed cell cycle-promoting genes and proliferation, whereas novex-3 overexpression enhanced proliferation. Mechanical analysis by atomic force microscopy and microneedle-based tensile tests demonstrated that novex-3 expression in hypoxic foetal cardiomyocytes contributes to the elasticity/compliance of the nucleus at interphase and facilitates proliferation, by promoting phosphorylation-induced disassembly of multimer structures of nuclear lamins. We propose that novex-3 has a previously unrecognised role in promoting cardiomyocyte proliferation specifically at the hypoxic foetal stage.
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