Details of a Researcher - Hashimoto, Hisayuki

Papers - Hashimoto, Hisayuki

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Endothelial-fibroblast interactions during Scarb1 accelerate heart failure

Toshiomi Katsuki, Dai Kusumoto, Yohei Akiba, Mai Kimura, Jin Komuro, Takahiro Nakamura, Hisayuki Hashimoto, Thukaa Kuoka, Yutaka Suzuki, Yoshiaki Kubota, Keiichi Fukuda, Shinsuke Yuasa, Masaki Ieda

(Cold Spring Harbor Laboratory) 2023.09

Summary

Endothelial cells (ECs) maintain cardiac homeostasis and EC dysfunction causes heart failure progression. Moreover, pathological changes occur via interactions between multiple cells, including ECs. Here, we conducted single-cell RNA-seq analysis of non-cardiomyocytes in mouse hearts during heart failure progression to elucidate the pathological changes in ECs and fibroblasts (FBs) mediated by cell-cell interactions. We show that capillary and arterial ECs exhibit mesenchymal gene expression changes with heart failure progression, indicating that endothelial-to-mesenchymal transition (EndMT) is a major pathological alteration in ECs. We also found that the interaction between ECs and FBs was enriched during heart failure, particularly when involving Scavenger Receptor Class B Member 1 (Scarb1) in ECs. FBs induce mesenchymal gene alterations in ECs in the EC-FB co-culture system, which is inhibited by blocking SCARB1. RNA-seq analysis showed that administration of a SCARB1 inhibitor blocked mesenchymal gene expression, and inflammatory changes, suggesting that the EC-FB interaction via Scarb1 is important for EndMT induction in ECs. Systemic administration of a SCARB1 inhibitor attenuated heart failure progression and cardiac fibrosis. EC-specificScarb1knockout mouse showed improved cardiac function, suggesting a crucial role of Scarb1 in heart failure progression. Our results suggest that Scarb1 is a promising candidate for novel heart failure treatments that target ECs.

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Machine learning in cardiology: Clinical application and basic research

Jin Komuro, Dai Kusumoto, Hisayuki Hashimoto, Shinsuke Yuasa

Journal of Cardiology (Elsevier BV) 82 ( 2 ) 128 - 133 2023.08

ISSN 0914-5087

Machine learning is a subfield of artificial intelligence. The quality and versatility of machine learning have been rapidly improving and playing a critical role in many aspects of social life. This trend is also observed in the medical field. Generally, there are three main types of machine learning: supervised, unsupervised, and reinforcement learning. Each type of learning is adequately selected for the purpose and type of data. In the field of medicine, various types of information are collected and used, and research using machine learning is becoming increasingly relevant. Many clinical studies are conducted using electronic health and medical records, including in the cardiovascular area. Machine learning has also been applied in basic research. Machine learning has been widely used for several types of data analysis, such as clustering of microarray analysis and RNA sequence analysis. Machine learning is essential for genome and multi-omics analyses. This review summarizes the recent advancements in the use of machine learning in clinical applications and basic cardiovascular research.

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MEF2C/p300-mediated epigenetic remodeling promotes the maturation of induced cardiomyocytes

Hidenori Kojima, Taketaro Sadahiro, Naoto Muraoka, Hiroyuki Yamakawa, Hisayuki Hashimoto, Ryota Ishii, Masahiko Gosho, Yuto Abe, Yu Yamada, Koji Nakano, Seiichiro Honda, Ryo Fujita, Tatsuya Akiyama, Yoichi Sunagawa, Tatsuya Morimoto, Toshifumi Tsukahara, Hiroyuki Hirai, Keiichi Fukuda, Masaki Ieda

Stem Cell Reports (Elsevier BV) 18 ( 6 ) 1274 - 1283 2023.06

ISSN 2213-6711

Cardiac transcription factors (TFs) directly reprogram fibroblasts into induced cardiomyocytes (iCMs), where MEF2C acts as a pioneer factor with GATA4 and TBX5 (GT). However, the generation of functional and mature iCMs is inefficient, and the molecular mechanisms underlying this process remain largely unknown. Here, we found that the overexpression of transcriptionally activated MEF2C via fusion of the powerful MYOD transactivation domain combined with GT increased the generation of beating iCMs by 30-fold. Activated MEF2C with GT generated iCMs that were transcriptionally, structurally, and functionally more mature than those generated by native MEF2C with GT. Mechanistically, activated MEF2C recruited p300 and multiple cardiogenic TFs to cardiac loci to induce chromatin remodeling. In contrast, p300 inhibition suppressed cardiac gene expression, inhibited iCM maturation, and decreased the beating iCM numbers. Splicing isoforms of MEF2C with similar transcriptional activities did not promote functional iCM generation. Thus, MEF2C/p300-mediated epigenetic remodeling promotes iCM maturation.

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Development of non-bias phenotypic drug screening for cardiomyocyte hypertrophy by image segmentation using deep learning

Jin Komuro, Yuta Tokuoka, Tomohisa Seki, Dai Kusumoto, Hisayuki Hashimoto, Toshiomi Katsuki, Takahiro Nakamura, Yohei Akiba, Thukaa Kuoka, Mai Kimura, Takahiro Yamada, Keiichi Fukuda, Akira Funahashi, Shinsuke Yuasa

Biochemical and Biophysical Research Communications (Elsevier BV) 632 181 - 188 2022.12

ISSN 0006-291X

The number of patients with heart failure and related deaths is rapidly increasing worldwide, making it a major problem. Cardiac hypertrophy is a crucial preliminary step in heart failure, but its treatment has not yet been fully successful. In this study, we established a system to evaluate cardiomyocyte hypertrophy using a deep learning-based high-throughput screening system and identified drugs that inhibit it. First, primary cultured cardiomyocytes from neonatal rats were stimulated by both angiotensin II and endothelin-1, and cellular images were captured using a phase-contrast microscope. Subsequently, we used a deep learning model for instance segmentation and established a system to automatically and unbiasedly evaluate the cardiomyocyte size and perimeter. Using this system, we screened 100 FDA-approved drugs library and identified 12 drugs that inhibited cardiomyocyte hypertrophy. We focused on ezetimibe, a cholesterol absorption inhibitor, that inhibited cardiomyocyte hypertrophy in a dose-dependent manner in vitro. Additionally, ezetimibe improved the cardiac dysfunction induced by pressure overload in mice. These results suggest that the deep learning-based system is useful for the evaluation of cardiomyocyte hypertrophy and drug screening, leading to the development of new treatments for heart failure.

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Single cell解析に基づく心不全特異的な線維芽細胞集団を標的とした心不全の新規治療戦略

小室仁, 橋本寿之, 勝木俊臣, 楠本大, 湯浅慎介, 福田恵一

心臓 ((公財)日本心臓財団) 54 ( 12 ) 1405 - 1405 2022.12

ISSN 0586-4488

The complement C3-complement factor D-C3a receptor signalling axis regulates cardiac remodelling in right ventricular failure.

Shogo Ito, Hisayuki Hashimoto, Hiroyuki Yamakawa, Dai Kusumoto, Yohei Akiba, Takahiro Nakamura, Mizuki Momoi, Jin Komuro, Toshiomi Katsuki, Mai Kimura, Yoshikazu Kishino, Shin Kashimura, Akira Kunitomi, Mark Lachmann, Masaya Shimojima, Gakuto Yozu, Chikaaki Motoda, Tomohisa Seki, Tsunehisa Yamamoto, Yoshiki Shinya, Takahiro Hiraide, Masaharu Kataoka, Takashi Kawakami, Kunimichi Suzuki, Kei Ito, Hirotaka Yada, Manabu Abe, Mizuko Osaka, Hiromi Tsuru, Masayuki Yoshida, Kenji Sakimura, Yoshihiro Fukumoto, Michisuke Yuzaki, Keiichi Fukuda, Shinsuke Yuasa

Nature communications (Nature Communications) 13 ( 1 ) 5409 - 5409 2022.09

Failure of the right ventricle plays a critical role in any type of heart failure. However, the mechanism remains unclear, and there is no specific therapy. Here, we show that the right ventricle predominantly expresses alternative complement pathway-related genes, including Cfd and C3aR1. Complement 3 (C3)-knockout attenuates right ventricular dysfunction and fibrosis in a mouse model of right ventricular failure. C3a is produced from C3 by the C3 convertase complex, which includes the essential component complement factor D (Cfd). Cfd-knockout mice also show attenuation of right ventricular failure. Moreover, the plasma concentration of CFD correlates with the severity of right ventricular failure in patients with chronic right ventricular failure. A C3a receptor (C3aR) antagonist dramatically improves right ventricular dysfunction in mice. In summary, we demonstrate the crucial role of the C3-Cfd-C3aR axis in right ventricular failure and highlight potential therapeutic targets for right ventricular failure.

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Single cell解析に基づく心不全特異的な線維芽細胞集団を標的とした心不全の新規治療戦略

小室仁, 橋本寿之, 楠本大, 湯浅慎介

大和証券ヘルス財団研究業績集 ((公財)大和証券ヘルス財団) ( 45 ) 36 - 41 2022.03

心臓線維芽細胞に発現する転写因子c-Mycの心臓における役割を、single cell解析に基づいて調べ、心臓線維芽細胞が心不全の治療標的となり得るか検証した。心不全時に特異的に出現する心臓線維芽細胞集団を見つけ、その細胞集団ではc-Mycが特徴的に発現していることを見出した。さらに、その線維芽細胞においてc-Mycは心不全の進行に寄与していることが示唆された。一方、c-Mycを心臓線維芽細胞で過剰発現させ、その遺伝子発現を網羅的に解析したところ、その細胞自体は炎症や線維化に関連した遺伝子の発現が低下しており、心不全の進行を抑制する働きが予想された。これらのことから、in vivoではc-Myc陽性心不全特異的心臓線維芽細胞は別の細胞と相互作用することにより、心不全の進行に寄与しているという仮説が立てられた。

The histone reader PHF7 cooperates with the SWI/SNF complex at cardiac super enhancers to promote direct reprogramming.

Glynnis A Garry, Svetlana Bezprozvannaya, Kenian Chen, Huanyu Zhou, Hisayuki Hashimoto, Maria Gabriela Morales, Ning Liu, Rhonda Bassel-Duby, Eric N Olson

Nature cell biology (Nature Cell Biology) 23 ( 5 ) 467 - 475 2021.05

ISSN 1465-7392

Direct cardiac reprogramming of fibroblasts to cardiomyocytes presents an attractive therapeutic strategy to restore cardiac function following injury. Cardiac reprogramming was initially achieved through overexpression of the transcription factors Gata4, Mef2c and Tbx5; later, Hand2 and Akt1 were found to further enhance this process1-5. Yet, staunch epigenetic barriers severely limit the ability of these cocktails to reprogramme adult fibroblasts6,7. We undertook a screen of mammalian gene regulatory factors to discover novel regulators of cardiac reprogramming in adult fibroblasts and identified the histone reader PHF7 as the most potent activating factor8. Mechanistically, PHF7 localizes to cardiac super enhancers in fibroblasts, and through cooperation with the SWI/SNF complex, it increases chromatin accessibility and transcription factor binding at these sites. Furthermore, PHF7 recruits cardiac transcription factors to activate a positive transcriptional autoregulatory circuit in reprogramming. Importantly, PHF7 achieves efficient reprogramming in the absence of Gata4. Here, we highlight the underexplored necessity of cardiac epigenetic readers, such as PHF7, in harnessing chromatin remodelling and transcriptional complexes to overcome critical barriers to direct cardiac reprogramming.

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Anti-senescent drug screening by deep learning-based morphology senescence scoring.

Dai Kusumoto, Tomohisa Seki, Hiromune Sawada, Akira Kunitomi, Toshiomi Katsuki, Mai Kimura, Shogo Ito, Jin Komuro, Hisayuki Hashimoto, Keiichi Fukuda, Shinsuke Yuasa

Nature communications (Nature Communications) 12 ( 1 ) 257 - 257 2021.01

Advances in deep learning technology have enabled complex task solutions. The accuracy of image classification tasks has improved owing to the establishment of convolutional neural networks (CNN). Cellular senescence is a hallmark of ageing and is important for the pathogenesis of ageing-related diseases. Furthermore, it is a potential therapeutic target. Specific molecular markers are used to identify senescent cells. Moreover senescent cells show unique morphology, which can be identified. We develop a successful morphology-based CNN system to identify senescent cells and a quantitative scoring system to evaluate the state of endothelial cells by senescence probability output from pre-trained CNN optimised for the classification of cellular senescence, Deep Learning-Based Senescence Scoring System by Morphology (Deep-SeSMo). Deep-SeSMo correctly evaluates the effects of well-known anti-senescent reagents. We screen for drugs that control cellular senescence using a kinase inhibitor library by Deep-SeSMo-based drug screening and identify four anti-senescent drugs. RNA sequence analysis reveals that these compounds commonly suppress senescent phenotypes through inhibition of the inflammatory response pathway. Thus, morphology-based CNN system can be a powerful tool for anti-senescent drug screening.

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Dermal fibroblast-like cells reprogrammed directly from adipocytes in mouse.

Mitsunobu Toyosaki, Koichiro Homma, Sayuri Suzuki, Naoto Muraoka, Hisayuki Hashimoto, Naoki Goshima, Masaki Ieda, Junichi Sasaki

Scientific reports (Scientific Reports) 10 ( 1 ) 21467 - 21467 2020.12

In deep burns, early wound closure is important for healing, and skin grafting is mainly used for wound closure. However, it is difficult to achieve early wound closure in extensive total body surface area deep burns due to the lack of donor sites. Dermal fibroblasts, responsible for dermis formation, may be lost in deep burns. However, fat layers composed of adipocytes, lying underneath the dermis, are retained even in such cases. Direct reprogramming is a novel method for directly reprograming some cells into other types by introducing specific master regulators; it has exhibited appreciable success in various fields. In this study, we aimed to assess whether the transfection of master regulators (ELF4, FOXC2, FOXO1, IRF1, PRRX1, and ZEB1) could reprogram mouse adipocytes into dermal fibroblast-like cells. Our results indicated the shrinkage of fat droplets in reprogrammed mouse adipocytes and their transformation into spindle-shaped dermal fibroblasts. Reduced expression of PPAR-2, c/EBP, aP2, and leptin, the known markers of adipocytes, in RT-PCR, and enhanced expression of anti-ER-TR7, the known anti-fibroblast marker, in immunocytochemistry, were confirmed in the reprogrammed mouse adipocytes. The dermal fibroblast-like cells, reported here, may open up a new treatment mode for enabling early closure of deep burn wounds.

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Stem Cell Aging in Skeletal Muscle Regeneration and Disease.

Yamakawa H, Kusumoto D, Hashimoto H, Yuasa S

International journal of molecular sciences 21 ( 5 ) 2020.03

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補体副経路を標的とした右心不全および心室性不整脈に対する新たな治療法の開発

伊藤章吾, 湯浅慎介, 小室仁, 勝木俊臣, 木村舞, 岸野喜一, 楠本大, 橋本寿之, 鈴木邦道, 柚崎通介, 福田恵一

補体 ((一社)日本補体学会) 56 ( 1 ) 55 - 56 2019.07

ISSN 2188-8205

Cardiac Reprogramming Factors Synergistically Activate Genome-wide Cardiogenic Stage-Specific Enhancers.

Hashimoto H, Wang Z, Garry GA, Malladi VS, Botten GA, Ye W, Zhou H, Osterwalder M, Dickel DE, Visel A, Liu N, Bassel-Duby R, Olson EN

Cell stem cell (Elsevier BV) 25 ( 1 ) 69 - 86.e5 2019.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 1934-5909

The cardiogenic transcription factors (TFs) Mef2c, Gata4, and Tbx5 can directly reprogram fibroblasts to induced cardiac-like myocytes (iCLMs), presenting a potential source of cells for cardiac repair. While activity of these TFs is enhanced by Hand2 and Akt1, their genomic targets and interactions during reprogramming are not well studied. We performed genome-wide analyses of cardiogenic TF binding and enhancer profiling during cardiac reprogramming. We found that these TFs synergistically activate enhancers highlighted by Mef2c binding sites and that Hand2 and Akt1 coordinately recruit other TFs to enhancer elements. Intriguingly, these enhancer landscapes collectively resemble patterns of enhancer activation during embryonic cardiogenesis. We further constructed a cardiac reprogramming gene regulatory network and found repression of EGFR signaling pathway genes. Consistently, chemical inhibition of EGFR signaling augmented reprogramming. Thus, by defining epigenetic landscapes these findings reveal synergistic transcriptional activation across a broad landscape of cardiac enhancers and key signaling pathways that govern iCLM reprogramming.

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Therapeutic approaches for cardiac regeneration and repair.

Hashimoto H, Olson EN, Bassel-Duby R

Nature reviews. Cardiology (Springer Science and Business Media LLC) 15 ( 10 ) 585 - 600 2018.10

Research paper (scientific journal), Joint Work, Accepted, ISSN 17595002

Ischaemic heart disease is a leading cause of death worldwide. Injury to the heart is followed by loss of the damaged cardiomyocytes, which are replaced with fibrotic scar tissue. Depletion of cardiomyocytes results in decreased cardiac contraction, which leads to pathological cardiac dilatation, additional cardiomyocyte loss, and mechanical dysfunction, culminating in heart failure. This sequential reaction is defined as cardiac remodelling. Many therapies have focused on preventing the progressive process of cardiac remodelling to heart failure. However, after patients have developed end-stage heart failure, intervention is limited to heart transplantation. One of the main reasons for the dramatic injurious effect of cardiomyocyte loss is that the adult human heart has minimal regenerative capacity. In the past 2 decades, several strategies to repair the injured heart and improve heart function have been pursued, including cellular and noncellular therapies. In this Review, we discuss current therapeutic approaches for cardiac repair and regeneration, describing outcomes, limitations, and future prospects of preclinical and clinical trials of heart regeneration. Substantial progress has been made towards understanding the cellular and molecular mechanisms regulating heart regeneration, offering the potential to control cardiac remodelling and redirect the adult heart to a regenerative state.

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Epigenetic barrier against the propagation of fluctuating gene expression in embryonic stem cells.

Saito Y, Kunitomi A, Seki T, Tohyama S, Kusumoto D, Takei M, Kashimura S, Hashimoto H, Yozu G, Motoda C, Shimojima M, Egashira T, Oda M, Fukuda K, Yuasa S

FEBS letters (WILEY) 591 ( 18 ) 2879 - 2889 2017.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 0014-5793

The expression of pluripotency genes fluctuates in a population of embryonic stem (ES) cells and the fluctuations in the expression of some pluripotency genes correlate. However, no correlation in the fluctuation of Pou5f1, Zfp42, and Nanog expression was observed in ES cells. Correlation between Pou5f1 and Zfp42 fluctuations was demonstrated in ES cells containing a knockout in the NuRD component Mbd3. ES cells containing a triple knockout in the DNA methyltransferases Dnmt1, Dnmt3a, and Dnmt3b showed correlation between the fluctuation of Pou5f1, Zfp42, and Nanog gene expression. We suggest that an epigenetic barrier is key to preventing the propagation of fluctuating pluripotency gene expression in ES cells.

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ZNF281 enhances cardiac reprogramming by modulating cardiac and inflammatory gene expression.

Zhou H, Morales MG, Hashimoto H, Dickson ME, Song K, Ye W, Kim MS, Niederstrasser H, Wang Z, Chen B, Posner BA, Bassel-Duby R, Olson EN

Genes & development (COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT) 31 ( 17 ) 1770 - 1783 2017.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 0890-9369

Direct reprogramming of fibroblasts to cardiomyocytes represents a potential means of restoring cardiac function following myocardial injury. AKT1 in the presence of four cardiogenic transcription factors, GATA4, HAND2, MEF2C, and TBX5 (AGHMT), efficiently induces the cardiac gene program in mouse embryonic fibroblasts but not adult fibroblasts. To identify additional regulators of adult cardiac reprogramming, we performed an unbiased screen of transcription factors and cytokines for those that might enhance or suppress the cardiogenic activity of AGHMT in adult mouse fibroblasts. Among a collection of inducers and repressors of cardiac reprogramming, we discovered that the zinc finger transcription factor 281 (ZNF281) potently stimulates cardiac reprogramming by genome-wide association with GATA4 on cardiac enhancers. Concomitantly, ZNF281 suppresses expression of genes associated with inflammatory signaling, suggesting the antagonistic convergence of cardiac and inflammatory transcriptional programs. Consistent with an inhibitory influence of inflammatory pathways on cardiac reprogramming, blockade of these pathways with anti-inflammatory drugs or components of the nucleosome remodeling deacetylase (NuRD) complex, which associate with ZNF281, stimulates cardiac gene expression. We conclude that ZNF281 acts at a nexus of cardiac and inflammatory gene programs, which exert opposing influences on fibroblast to cardiac reprogramming.

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Emerin plays a crucial role in nuclear invagination and in the nuclear calcium transient.

Shimojima M, Yuasa S, Motoda C, Yozu G, Nagai T, Ito S, Lachmann M, Kashimura S, Takei M, Kusumoto D, Kunitomi A, Hayashiji N, Seki T, Tohyama S, Hashimoto H, Kodaira M, Egashira T, Hayashi K, Nakanishi C, Sakata K, Yamagishi M, Fukuda K

Scientific reports (NATURE PUBLISHING GROUP) 7 44312 - 44312 2017.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 2045-2322

Alteration of the nuclear Ca2+ transient is an early event in cardiac remodeling. Regulation of the nuclear Ca2+ transient is partly independent of the cytosolic Ca2+ transient in cardiomyocytes. One nuclear membrane protein, emerin, is encoded by EMD, and an EMD mutation causes Emery-Dreifuss muscular dystrophy (EDMD). It remains unclear whether emerin is involved in nuclear Ca2+ homeostasis. The aim of this study is to elucidate the role of emerin in rat cardiomyocytes by means of hypertrophic stimuli and in EDMD induced pluripotent stem (iPS) cell-derived cardiomyocytes in terms of nuclear structure and the Ca2+ transient. The cardiac hypertrophic stimuli increased the nuclear area, decreased nuclear invagination, and increased the half-decay time of the nuclear Ca2+ transient in cardiomyocytes. Emd knockdown cardiomyocytes showed similar properties after hypertrophic stimuli. The EDMD-iPS cell-derived cardiomyocytes showed increased nuclear area, decreased nuclear invagination, and increased half-decay time of the nuclear Ca2+ transient. An autopsied heart from a patient with EDMD also showed increased nuclear area and decreased nuclear invagination. These data suggest that Emerin plays a crucial role in nuclear structure and in the nuclear Ca2+ transient. Thus, emerin and the nuclear Ca2+ transient are possible therapeutic targets in heart failure and EDMD.

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Notch Inhibition Enhances Cardiac Reprogramming by Increasing MEF2C Transcriptional Activity.

Abad M, Hashimoto H, Zhou H, Morales MG, Chen B, Bassel-Duby R, Olson EN

Stem cell reports (CELL PRESS) 8 ( 3 ) 548 - 560 2017.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 22136711

Conversion of fibroblasts into functional cardiomyocytes represents a potential means of restoring cardiac function after myocardial infarction, but so far this process remains inefficient and little is known about its molecular mechanisms. Here we show that DAPT, a classical Notch inhibitor, enhances the conversion of mouse fibroblasts into induced cardiac-like myocytes by the transcription factors GATA4, HAND2, MEF2C, and TBX5. DAPT cooperates with AKT kinase to further augment this process, resulting in up to 70% conversion efficiency. Moreover, DAPT promotes the acquisition of specific cardiomyocyte features, substantially increasing calcium flux, sarcomere structure, and the number of spontaneously beating cells. Transcriptome analysis shows that DAPT induces genetic programs related to muscle development, differentiation, and excitation-contraction coupling. Mechanistically, DAPT increases binding of the transcription factor MEF2C to the promoter regions of cardiac structural genes. These findings provide mechanistic insights into the reprogramming process and may have important implications for cardiac regeneration therapies.

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Flecainide ameliorates arrhythmogenicity through NCX flux in Andersen-Tawil syndrome-iPS cell-derived cardiomyocytes.

Kuroda Y, Yuasa S, Watanabe Y, Ito S, Egashira T, Seki T, Hattori T, Ohno S, Kodaira M, Suzuki T, Hashimoto H, Okata S, Tanaka A, Aizawa Y, Murata M, Aiba T, Makita N, Furukawa T, Shimizu W, Kodama I, Ogawa S, Kokubun N, Horigome H, Horie M, Kamiya K, Fukuda K

Biochemistry and biophysics reports (Biochemistry and Biophysics Reports) 9 245 - 256 2017.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 2405-5808

Andersen-Tawil syndrome (ATS) is a rare inherited channelopathy. The cardiac phenotype in ATS is typified by a prominent U wave and ventricular arrhythmia. An effective treatment for this disease remains to be established. We reprogrammed somatic cells from three ATS patients to generate induced pluripotent stem cells (iPSCs). Multi-electrode arrays (MEAs) were used to record extracellular electrograms of iPSC-derived cardiomyocytes, revealing strong arrhythmic events in the ATS-iPSC-derived cardiomyocytes. Ca2+ imaging of cells loaded with the Ca2+ indicator Fluo-4 enabled us to examine intracellular Ca2+ handling properties, and we found a significantly higher incidence of irregular Ca2+ release in the ATS-iPSC-derived cardiomyocytes than in control-iPSC-derived cardiomyocytes. Drug testing using ATS-iPSC-derived cardiomyocytes further revealed that antiarrhythmic agent, flecainide, but not the sodium channel blocker, pilsicainide, significantly suppressed these irregular Ca2+ release and arrhythmic events, suggesting that flecainide's effect in these cardiac cells was not via sodium channels blocking. A reverse-mode Na+/Ca2+exchanger (NCX) inhibitor, KB-R7943, was also found to suppress the irregular Ca2+ release, and whole-cell voltage clamping of isolated guinea-pig cardiac ventricular myocytes confirmed that flecainide could directly affect the NCX current (INCX). ATS-iPSC-derived cardiomyocytes recapitulate abnormal electrophysiological phenotypes and flecainide suppresses the arrhythmic events through the modulation of INCX.

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Embryonic type Na⁺ channel β-subunit, SCN3B masks the disease phenotype of Brugada syndrome.

Okata S, Yuasa S, Suzuki T, Ito S, Makita N, Yoshida T, Li M, Kurokawa J, Seki T, Egashira T, Aizawa Y, Kodaira M, Motoda C, Yozu G, Shimojima M, Hayashiji N, Hashimoto H, Kuroda Y, Tanaka A, Murata M, Aiba T, Shimizu W, Horie M, Kamiya K, Furukawa T, Fukuda K

Scientific reports (NATURE PUBLISHING GROUP) 6 34198 - 34198 2016.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 2045-2322

SCN5A is abundant in heart and has a major role in I-Na. Loss-of-function mutation in SCN5A results in Brugada syndrome (BrS), which causes sudden death in adults. It remains unclear why disease phenotype does not manifest in the young even though mutated SCN5A is expressed in the young. The aim of the present study is to elucidate the timing of the disease manifestation in BrS. A gain-of-function mutation in SCN5A also results in Long QT syndrome type 3 (LQTS3), leading to sudden death in the young. Induced pluripotent stem cells (iPSCs) were generated from a patient with a mixed phenotype of LQTS3 and BrS with the E1784K SCN5A mutation. Here we show that electrophysiological analysis revealed that LQTS3/BrS iPSC-derived cardiomyocytes recapitulate the phenotype of LQTS3 but not BrS. Each beta-subunit of the sodium channel is differentially expressed in embryonic and adult hearts. SCN3B is highly expressed in embryonic hearts and iPSC-derived cardiomyocytes. A heterologous expression system revealed that I-Na of mutated SCN5A is decreased and SCN3B augmented INa of mutated SCN5A. Knockdown of SCN3B in LQTS3/BrS iPSC-derived cardiomyocytes successfully unmasked the phenotype of BrS. Isogenic control of LQTS3/BrS (corrected-LQTS3/BrS) iPSC-derived cardiomyocytes gained the normal electrophysiological properties.

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