Ischemic injury in the heart induces an inflammatory cascade that both repairs damage and exacerbates scar tissue formation. Cardiosphere-derived cells (CDCs) are a stem-like population that is derived ex vivo from cardiac biopsies; they confer both cardioprotection and regeneration in acute myocardial infarction (MI). While the regenerative effects of CDCs in chronic settings have been studied extensively, little is known about how CDCs confer the cardioprotective process known as cellular postconditioning. Here, we used an in vivo rat model of ischemia/reperfusion (IR) injury–induced MI and in vitro coculture assays to investigate how CDCs protect stressed cardiomyocytes. Compared with control animals, animals that received CDCs 20 minutes after IR had reduced infarct size when measured at 48 hours. CDCs modified the myocardial leukocyte population after ischemic injury. Specifically, introduction of CDCs reduced the number of CD68+ macrophages, and these CDCs secreted factors that polarized macrophages toward a distinctive cardioprotective phenotype that was not M1 or M2. Systemic depletion of macrophages with clodronate abolished CDC-mediated cardioprotection. Using both in vitro coculture assays and a rat model of adoptive transfer after IR, we determined that CDC-conditioned macrophages attenuated cardiomyocyte apoptosis and reduced infarct size, thereby recapitulating the beneficial effects of CDC therapy. Together, our data indicate that CDCs limit acute injury by polarizing an effector macrophage population within the heart.
Geoffrey de Couto, Weixin Liu, Eleni Tseliou, Baiming Sun, Nupur Makkar, Hideaki Kanazawa, Moshe Arditi, Eduardo Marbán
The sinoatrial node (SAN) maintains a rhythmic heartbeat; therefore, a better understanding of factors that drive SAN development and function is crucial to generation of potential therapies, such as biological pacemakers, for sinus arrhythmias. Here, we determined that the LIM homeodomain transcription factor ISL1 plays a key role in survival, proliferation, and function of pacemaker cells throughout development. Analysis of several
Xingqun Liang, Qingquan Zhang, Paola Cattaneo, Shaowei Zhuang, Xiaohui Gong, Nathanael J. Spann, Cizhong Jiang, Xinkai Cao, Xiaodong Zhao, Xiaoli Zhang, Lei Bu, Gang Wang, H.S. Vincent Chen, Tao Zhuang, Jie Yan, Peng Geng, Lina Luo, Indroneal Banerjee, Yihan Chen, Christopher K. Glass, Alexander C. Zambon, Ju Chen, Yunfu Sun, Sylvia M. Evans
Stephen E. Boag, Rajiv Das, Evgeniya V. Shmeleva, Alan Bagnall, Mohaned Egred, Nicholas Howard, Karim Bennaceur, Azfar Zaman, Bernard Keavney, Ioakim Spyridopoulos
Macrophages clear millions of apoptotic cells daily and, during this process, take up large quantities of cholesterol. The membrane transporter ABCA1 is a key player in cholesterol efflux from macrophages and has been shown via human genetic studies to provide protection against cardiovascular disease. How the apoptotic cell clearance process is linked to macrophage ABCA1 expression is not known. Here, we identified a plasma membrane–initiated signaling pathway that drives a rapid upregulation of
Aaron M. Fond, Chang Sup Lee, Ira G. Schulman, Robert S. Kiss, Kodi S. Ravichandran
Ischemic heart disease is the leading cause of heart failure. Both clinical trials and experimental animal studies demonstrate that chronic hypoxia can induce contractile dysfunction even before substantial ventricular damage, implicating a direct role of oxygen in the regulation of cardiac contractile function. Prolyl hydroxylase domain (PHD) proteins are well recognized as oxygen sensors and mediate a wide variety of cellular events by hydroxylating a growing list of protein substrates. Both PHD2 and PHD3 are highly expressed in the heart, yet their functional roles in modulating contractile function remain incompletely understood. Here, we report that combined deletion of
Liang Xie, Xinchun Pi, W.H. Davin Townley-Tilson, Na Li, Xander H.T. Wehrens, Mark L. Entman, George E. Taffet, Ashutosh Mishra, Junmin Peng, Jonathan C. Schisler, Gerhard Meissner, Cam Patterson
The cGMP-dependent protein kinase-1α (PKG1α) transduces NO and natriuretic peptide signaling; therefore, PKG1α activation can benefit the failing heart. Disease modifiers such as oxidative stress may depress the efficacy of PKG1α pathway activation and underlie variable clinical results. PKG1α can also be directly oxidized, forming a disulfide bond between homodimer subunits at cysteine 42 to enhance oxidant-stimulated vasorelaxation; however, the impact of PKG1α oxidation on myocardial regulation is unknown. Here, we demonstrated that PKG1α is oxidized in both patients with heart disease and in rodent disease models. Moreover, this oxidation contributed to adverse heart remodeling following sustained pressure overload or Gq agonist stimulation. Compared with control hearts and myocytes, those expressing a redox-dead protein (PKG1αC42S) better adapted to cardiac stresses at functional, histological, and molecular levels. Redox-dependent changes in PKG1α altered intracellular translocation, with the activated, oxidized form solely located in the cytosol, whereas reduced PKG1αC42S translocated to and remained at the outer plasma membrane. This altered PKG1α localization enhanced suppression of transient receptor potential channel 6 (TRPC6), thereby potentiating antihypertrophic signaling. Together, these results demonstrate that myocardial PKG1α oxidation prevents a beneficial response to pathological stress, may explain variable responses to PKG1α pathway stimulation in heart disease, and indicate that maintaining PKG1α in its reduced form may optimize its intrinsic cardioprotective properties.
Taishi Nakamura, Mark J. Ranek, Dong I. Lee, Virginia Shalkey Hahn, Choel Kim, Philip Eaton, David A. Kass
Arrhythmogenic cardiomyopathy (AC) is associated with mutations in genes encoding intercalated disc proteins and ultimately results in sudden cardiac death. A subset of patients with AC have the autosomal recessive cardiocutaneous disorder Naxos disease, which is caused by a 2–base pair deletion in the plakoglobin-encoding gene
Zhiwei Zhang, Matthew J. Stroud, Jianlin Zhang, Xi Fang, Kunfu Ouyang, Kensuke Kimura, Yongxin Mu, Nancy D. Dalton, Yusu Gu, William H. Bradford, Kirk L. Peterson, Hongqiang Cheng, Xinmin Zhou, Ju Chen
David S. Park, Marina Cerrone, Gregory Morley, Carolina Vasquez, Steven Fowler, Nian Liu, Scott A. Bernstein, Fang-Yu Liu, Jie Zhang, Christopher S. Rogers, Silvia G. Priori, Larry A. Chinitz, Glenn I. Fishman
Acute stimulation of cardiac β-adrenoceptors is crucial to increasing cardiac function under stress; however, sustained β-adrenergic stimulation has been implicated in pathological myocardial remodeling and heart failure. Here, we have demonstrated that export of cAMP from cardiac myocytes is an intrinsic cardioprotective mechanism in response to cardiac stress. We report that infusion of cAMP into mice averted myocardial hypertrophy and fibrosis in a disease model of cardiac pressure overload. The protective effect of exogenous cAMP required adenosine receptor signaling. This observation led to the identification of a potent paracrine mechanism that is dependent on secreted cAMP. Specifically, FRET-based imaging of cAMP formation in primary cells and in myocardial tissue from murine hearts revealed that cardiomyocytes depend on the transporter ABCC4 to export cAMP as an extracellular signal. Extracellular cAMP, through its metabolite adenosine, reduced cardiomyocyte cAMP formation and hypertrophy by activating A1 adenosine receptors while delivering an antifibrotic signal to cardiac fibroblasts by A2 adenosine receptor activation. Together, our data reveal a paracrine role for secreted cAMP in intercellular signaling in the myocardium, and we postulate that secreted cAMP may also constitute an important signal in other tissues.
Yassine Sassi, Andrea Ahles, Dong-Jiunn Jeffery Truong, Younis Baqi, Sang-Yong Lee, Britta Husse, Jean-Sébastien Hulot, Ariana Foinquinos, Thomas Thum, Christa E. Müller, Andreas Dendorfer, Bernhard Laggerbauer, Stefan Engelhardt
Atrial fibrillation (AF) is characterized by sustained high atrial activation rates and arrhythmogenic cellular Ca2+ signaling instability; however, it is not clear how a high atrial rate and Ca2+ instability may be related. Here, we characterized subcellular Ca2+ signaling after 5 days of high atrial rates in a rabbit model. While some changes were similar to those in persistent AF, we identified a distinct pattern of stabilized subcellular Ca2+ signaling. Ca2+ sparks, arrhythmogenic Ca2+ waves, sarcoplasmic reticulum (SR) Ca2+ leak, and SR Ca2+ content were largely unaltered. Based on computational analysis, these findings were consistent with a higher Ca2+ leak due to PKA-dependent phosphorylation of SR Ca2+ channels (RyR2s), fewer RyR2s, and smaller RyR2 clusters in the SR. We determined that less Ca2+ release per [Ca2+]i transient, increased Ca2+ buffering strength, shortened action potentials, and reduced L-type Ca2+ current contribute to a stunning reduction of intracellular Na+ concentration following rapid atrial pacing. In both patients with AF and in our rabbit model, this silencing led to failed propagation of the [Ca2+]i signal to the myocyte center. We conclude that sustained high atrial rates alone silence Ca2+ signaling and do not produce Ca2+ signaling instability, consistent with an adaptive molecular and cellular response to atrial tachycardia.
Maura Greiser, Benoît-Gilles Kerfant, George S.B. Williams, Niels Voigt, Erik Harks, Katharine M. Dibb, Anne Giese, Janos Meszaros, Sander Verheule, Ursula Ravens, Maurits A. Allessie, James S. Gammie, Jolanda van der Velden, W. Jonathan Lederer, Dobromir Dobrev, Ulrich Schotten
Patients with type 2 diabetes often present with cardiovascular complications; however, it is not clear how diabetes promotes cardiac dysfunction. In murine models, deletion of the gene encoding aryl hydrocarbon nuclear translocator (ARNT, also known as HIF1β) in the liver or pancreas leads to a diabetic phenotype; however, the role of ARNT in cardiac metabolism is unknown. Here, we determined that cardiac-specific deletion of
Rongxue Wu, Hsiang-Chun Chang, Arineh Khechaduri, Kusum Chawla, Minh Tran, Xiaomeng Chai, Cory Wagg, Mohsen Ghanefar, Xinghang Jiang, Marina Bayeva, Frank Gonzalez, Gary Lopaschuk, Hossein Ardehali
Cardiac Purkinje cells are important triggers of ventricular arrhythmias associated with heritable and acquired syndromes; however, the mechanisms responsible for this proarrhythmic behavior are incompletely understood. Here, through transcriptional profiling of genetically labeled cardiomyocytes, we identified expression of Purkinje cell protein-4 (
Eugene E. Kim, Akshay Shekhar, Jia Lu, Xianming Lin, Fang-Yu Liu, Jie Zhang, Mario Delmar, Glenn I. Fishman
The cellular response to stress involves the recruitment and coordination of molecular signaling pathways that prevent cell death. D-dopachrome tautomerase (DDT) is an enzyme that lacks physiologic substrates in mammalian cells, but shares partial sequence and structural homology with macrophage migration inhibitory factor (MIF). Here, we observed that DDT is highly expressed in murine cardiomyocytes and secreted by the heart after ischemic stress. Antibody-dependent neutralization of secreted DDT exacerbated both ischemia-induced cardiac contractile dysfunction and necrosis. We generated cardiomyocyte-specific DDT knockout mice (
Dake Qi, Kwame Atsina, Lintao Qu, Xiaoyue Hu, Xiaohong Wu, Bin Xu, Marta Piecychna, Lin Leng, Günter Fingerle-Rowson, Jiasheng Zhang, Richard Bucala, Lawrence H. Young
Mutations in the gene encoding the RNA-binding protein RBM20 have been implicated in dilated cardiomyopathy (DCM), a major cause of chronic heart failure, presumably through altering cardiac RNA splicing. Here, we combined transcriptome-wide crosslinking immunoprecipitation (CLIP-seq), RNA-seq, and quantitative proteomics in cell culture and rat and human hearts to examine how RBM20 regulates alternative splicing in the heart. Our analyses revealed the presence of a distinct RBM20 RNA-recognition element that is predominantly found within intronic binding sites and linked to repression of exon splicing with RBM20 binding near 3′ and 5′ splice sites. Proteomic analysis determined that RBM20 interacts with both U1 and U2 small nuclear ribonucleic particles (snRNPs) and suggested that RBM20-dependent splicing repression occurs through spliceosome stalling at complex A. Direct RBM20 targets included several genes previously shown to be involved in DCM as well as genes not typically associated with this disease. In failing human hearts, reduced expression of RBM20 affected alternative splicing of several direct targets, indicating that differences in RBM20 expression may affect cardiac function. Together, these findings identify RBM20-regulated targets and provide insight into the pathogenesis of human heart failure.
Henrike Maatz, Marvin Jens, Martin Liss, Sebastian Schafer, Matthias Heinig, Marieluise Kirchner, Eleonora Adami, Carola Rintisch, Vita Dauksaite, Michael H. Radke, Matthias Selbach, Paul J.R. Barton, Stuart A. Cook, Nikolaus Rajewsky, Michael Gotthardt, Markus Landthaler, Norbert Hubner
Inhibition of cGMP-specific phosphodiesterase 5 (PDE5) ameliorates pathological cardiac remodeling and has been gaining attention as a potential therapy for heart failure. Despite promising results in males, the efficacy of the PDE5 inhibitor sildenafil in female cardiac pathologies has not been determined and might be affected by estrogen levels, given the hormone’s involvement in cGMP synthesis. Here, we determined that the heart-protective effect of sildenafil in female mice depends on the presence of estrogen via a mechanism that involves myocyte eNOS–dependent cGMP synthesis and the cGMP-dependent protein kinase Iα (PKGIα). Sildenafil treatment failed to exert antiremodeling properties in female pathological hearts from Gαq-overexpressing or pressure-overloaded mice after ovary removal; however, estrogen replacement restored the effectiveness of sildenafil in these animals. In females, sildenafil-elicited myocardial PKG activity required estrogen, which stimulated tonic cardiomyocyte cGMP synthesis via an eNOS/soluble guanylate cyclase pathway. In contrast, eNOS activation, cGMP synthesis, and sildenafil efficacy were not estrogen dependent in male hearts. Estrogen and sildenafil had no impact on pressure-overloaded hearts from animals expressing dysfunctional PKGIα, indicating that PKGIα mediates antiremodeling effects. These results support the importance of sex differences in the use of PDE5 inhibitors for treating heart disease and the critical role of estrogen status when these agents are used in females.
Hideyuki Sasaki, Takahiro Nagayama, Robert M. Blanton, Kinya Seo, Manling Zhang, Guangshuo Zhu, Dong I. Lee, Djahida Bedja, Steven Hsu, Osamu Tsukamoto, Seiji Takashima, Masafumi Kitakaze, Michael E. Mendelsohn, Richard H. Karas, David A. Kass, Eiki Takimoto
Cardiomyocyte proteostasis is mediated by the ubiquitin/proteasome system (UPS) and autophagy/lysosome system and is fundamental for cardiac adaptation to both physiologic (e.g., exercise) and pathologic (e.g., pressure overload) stresses. Both the UPS and autophagy/lysosome system exhibit reduced efficiency as a consequence of aging, and dysfunction in these systems is associated with cardiomyopathies. The muscle-specific ubiquitin ligase atrogin-1 targets signaling proteins involved in cardiac hypertrophy for degradation. Here, using atrogin-1 KO mice in combination with in vivo pulsed stable isotope labeling of amino acids in cell culture proteomics and biochemical and cellular analyses, we identified charged multivesicular body protein 2B (CHMP2B), which is part of an endosomal sorting complex (ESCRT) required for autophagy, as a target of atrogin-1–mediated degradation. Mice lacking atrogin-1 failed to degrade CHMP2B, resulting in autophagy impairment, intracellular protein aggregate accumulation, unfolded protein response activation, and subsequent cardiomyocyte apoptosis, all of which increased progressively with age. Cellular proteostasis alterations resulted in cardiomyopathy characterized by myocardial remodeling with interstitial fibrosis, with reduced diastolic function and arrhythmias. CHMP2B downregulation in atrogin-1 KO mice restored autophagy and decreased proteotoxicity, thereby preventing cell death. These data indicate that atrogin-1 promotes cardiomyocyte health through mediating the interplay between UPS and autophagy/lysosome system and its alteration promotes development of cardiomyopathies.
Tania Zaglia, Giulia Milan, Aaron Ruhs, Mauro Franzoso, Enrico Bertaggia, Nicola Pianca, Andrea Carpi, Pierluigi Carullo, Paola Pesce, David Sacerdoti, Cristiano Sarais, Daniele Catalucci, Marcus Krüger, Marco Mongillo, Marco Sandri
PKA phosphorylates multiple molecules involved in calcium (Ca2+) handling in cardiac myocytes and is considered to be the predominant regulator of β-adrenergic receptor–mediated enhancement of cardiac contractility; however, recent identification of exchange protein activated by cAMP (EPAC), which is independently activated by cAMP, has challenged this paradigm. Mice lacking
Satoshi Okumura, Takayuki Fujita, Wenqian Cai, Meihua Jin, Iyuki Namekata, Yasumasa Mototani, Huiling Jin, Yoshiki Ohnuki, Yayoi Tsuneoka, Reiko Kurotani, Kenji Suita, Yuko Kawakami, Shogo Hamaguchi, Takaya Abe, Hiroshi Kiyonari, Takashi Tsunematsu, Yunzhe Bai, Sayaka Suzuki, Yuko Hidaka, Masanari Umemura, Yasuhiro Ichikawa, Utako Yokoyama, Motohiko Sato, Fumio Ishikawa, Hiroko Izumi-Nakaseko, Satomi Adachi-Akahane, Hikaru Tanaka, Yoshihiro Ishikawa
In response to stress, the heart undergoes extensive cardiac remodeling that results in cardiac fibrosis and pathological growth of cardiomyocytes (hypertrophy), which contribute to heart failure. Alterations in microRNA (miRNA) levels are associated with dysfunctional gene expression profiles associated with many cardiovascular disease conditions; however, miRNAs have emerged recently as paracrine signaling mediators. Thus, we investigated a potential paracrine miRNA crosstalk between cardiac fibroblasts and cardiomyocytes and found that cardiac fibroblasts secrete miRNA-enriched exosomes. Surprisingly, evaluation of the miRNA content of cardiac fibroblast–derived exosomes revealed a relatively high abundance of many miRNA passenger strands (“star” miRNAs), which normally undergo intracellular degradation. Using confocal imaging and coculture assays, we identified fibroblast exosomal–derived miR-21_3p (miR-21*) as a potent paracrine-acting RNA molecule that induces cardiomyocyte hypertrophy. Proteome profiling identified sorbin and SH3 domain-containing protein 2 (SORBS2) and PDZ and LIM domain 5 (PDLIM5) as miR-21* targets, and silencing SORBS2 or PDLIM5 in cardiomyocytes induced hypertrophy. Pharmacological inhibition of miR-21* in a mouse model of Ang II–induced cardiac hypertrophy attenuated pathology. These findings demonstrate that cardiac fibroblasts secrete star miRNA–enriched exosomes and identify fibroblast-derived miR-21* as a paracrine signaling mediator of cardiomyocyte hypertrophy that has potential as a therapeutic target.
Claudia Bang, Sandor Batkai, Seema Dangwal, Shashi Kumar Gupta, Ariana Foinquinos, Angelika Holzmann, Annette Just, Janet Remke, Karina Zimmer, Andre Zeug, Evgeni Ponimaskin, Andreas Schmiedl, Xiaoke Yin, Manuel Mayr, Rashi Halder, Andre Fischer, Stefan Engelhardt, Yuanyuan Wei, Andreas Schober, Jan Fiedler, Thomas Thum
Diabetic cardiomyopathy is a secondary complication of diabetes with an unclear etiology. Based on a functional genomic evaluation of obesity-associated cardiac gene expression, we previously identified and cloned the gene encoding apolipoprotein O (APOO), which is overexpressed in hearts from diabetic patients. Here, we generated APOO-Tg mice, transgenic mouse lines that expresses physiological levels of human APOO in heart tissue. APOO-Tg mice fed a high-fat diet exhibited depressed ventricular function with reduced fractional shortening and ejection fraction, and myocardial sections from APOO-Tg mice revealed mitochondrial degenerative changes. In vivo fluorescent labeling and subcellular fractionation revealed that APOO localizes with mitochondria. Furthermore, APOO enhanced mitochondrial uncoupling and respiration, both of which were reduced by deletion of the N-terminus and by targeted knockdown of APOO. Consequently, fatty acid metabolism and ROS production were enhanced, leading to increased AMPK phosphorylation and
Annie Turkieh, Céline Caubère, Manon Barutaut, Franck Desmoulin, Romain Harmancey, Michel Galinier, Matthieu Berry, Camille Dambrin, Carlo Polidori, Louis Casteilla, François Koukoui, Philippe Rouet, Fatima Smih
Malou van den Boogaard, Scott Smemo, Ozanna Burnicka-Turek, David E. Arnolds, Harmen J.G. van de Werken, Petra Klous, David McKean, Jochen D. Muehlschlegel, Julia Moosmann, Okan Toka, Xinan H. Yang, Tamara T. Koopmann, Michiel E. Adriaens, Connie R. Bezzina, Wouter de Laat, Christine Seidman, J.G. Seidman, Vincent M. Christoffels, Marcelo A. Nobrega, Phil Barnett, Ivan P. Moskowitz