Endocardial Notch Signaling Promotes Cardiomyocyte Proliferation in the Regenerating Zebrafish Heart through Wnt Pathway Antagonism

The newt and the zebrafish have the ability to regenerate many of their tissues and organs including the heart. Thus, a major goal in experimental medicine is to elucidate the molecular mechanisms underlying the regenerative capacity of these species. A wide variety of experiments have demonstrated that naturally occurring heart regeneration relies on cardiomyocyte proliferation. Thus, major efforts have been invested to induce proliferation of mammalian cardiomyocytes in order to improve cardiac function after injury or to protect the heart from further functional deterioration. In this review, we describe and analyze methods currently used to evaluate cardiomyocyte proliferation. In addition, we summarize the literature on naturally occurring heart regeneration. Our analysis highlights that newt and zebrafish heart regeneration relies on factors that are also utilized in cardiomyocyte proliferation during mammalian fetal development. Most of these factors have, however, failed to induce adult mammalian cardiomyocyte proliferation. Finally, our analysis of mammalian neonatal heart regeneration indicates experiments that could resolve conflicting results in the literature, such as binucleation assays and clonal analysis. Collectively, cardiac regeneration based on cardiomyocyte proliferation is a promising approach for improving adult human cardiac function after injury, but it is important to elucidate the mechanisms arresting mammalian cardiomyocyte proliferation after birth and to utilize better assays to determine formation of new muscle mass.

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Delineating the Dynamic Transcriptome Response of mRNA and microRNA during Zebrafish Heart Regeneration

Biomolecules ◽

10.3390/biom9010011 ◽

2018 ◽

Vol 9 (1) ◽

pp. 11 ◽

Cited By ~ 3

Author(s):

Hagen Klett ◽

Lonny Jürgensen ◽

Patrick Most ◽

Martin Busch ◽

Fabian Günther ◽

...

Keyword(s):

Heart Function ◽

Heart Diseases ◽

Expression Profiles ◽

Temporal Organization ◽

H9c2 Cell ◽

Specific Response ◽

Heart Regeneration ◽

Cardiomyocyte Proliferation ◽

Transcriptome Response ◽

Zebrafish Heart

Heart diseases are the leading cause of death for the vast majority of people around the world, which is often due to the limited capability of human cardiac regeneration. In contrast, zebrafish have the capacity to fully regenerate their hearts after cardiac injury. Understanding and activating these mechanisms would improve health in patients suffering from long-term consequences of ischemia. Therefore, we monitored the dynamic transcriptome response of both mRNA and microRNA in zebrafish at 1–160 days post cryoinjury (dpi). Using a control model of sham-operated and healthy fish, we extracted the regeneration specific response and further delineated the spatio-temporal organization of regeneration processes such as cell cycle and heart function. In addition, we identified novel (miR-148/152, miR-218b and miR-19) and previously known microRNAs among the top regulators of heart regeneration by using theoretically predicted target sites and correlation of expression profiles from both mRNA and microRNA. In a cross-species effort, we validated our findings in the dynamic process of rat myoblasts differentiating into cardiomyocytes-like cells (H9c2 cell line). Concluding, we elucidated different phases of transcriptomic responses during zebrafish heart regeneration. Furthermore, microRNAs showed to be important regulators in cardiomyocyte proliferation over time.

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Nrg1 is an injury-induced cardiomyocyte mitogen for the endogenous heart regeneration program in zebrafish

eLife ◽

10.7554/elife.05871 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 111

Author(s):

Matthew Gemberling ◽

Ravi Karra ◽

Amy L Dickson ◽

Kenneth D Poss

Keyword(s):

Cardiac Injury ◽

Heart Regeneration ◽

Cardiomyocyte Proliferation ◽

Adult Zebrafish ◽

Perivascular Cells ◽

Adult Heart ◽

Muscle Hyperplasia ◽

Zebrafish Heart

Heart regeneration is limited in adult mammals but occurs naturally in adult zebrafish through the activation of cardiomyocyte division. Several components of the cardiac injury microenvironment have been identified, yet no factor on its own is known to stimulate overt myocardial hyperplasia in a mature, uninjured animal. In this study, we find evidence that Neuregulin1 (Nrg1), previously shown to have mitogenic effects on mammalian cardiomyocytes, is sharply induced in perivascular cells after injury to the adult zebrafish heart. Inhibition of Erbb2, an Nrg1 co-receptor, disrupts cardiomyocyte proliferation in response to injury, whereas myocardial Nrg1 overexpression enhances this proliferation. In uninjured zebrafish, the reactivation of Nrg1 expression induces cardiomyocyte dedifferentiation, overt muscle hyperplasia, epicardial activation, increased vascularization, and causes cardiomegaly through persistent addition of wall myocardium. Our findings identify Nrg1 as a potent, induced mitogen for the endogenous adult heart regeneration program.

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Igf Signaling is Required for Cardiomyocyte Proliferation during Zebrafish Heart Development and Regeneration

PLoS ONE ◽

10.1371/journal.pone.0067266 ◽

2013 ◽

Vol 8 (6) ◽

pp. e67266 ◽

Cited By ~ 80

Author(s):

Ying Huang ◽

Michael R. Harrison ◽

Arthela Osorio ◽

Jieun Kim ◽

Aaron Baugh ◽

...

Keyword(s):

Heart Development ◽

Cardiomyocyte Proliferation ◽

Zebrafish Heart ◽

Igf Signaling

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CDK9 and its repressor LARP7 modulate cardiomyocyte proliferation and response to injury in the zebrafish heart

Development ◽

10.1242/dev.134148 ◽

2016 ◽

Vol 143 (1) ◽

pp. e1.2-e1.2

Author(s):

Gianfranco Matrone ◽

Kathryn S. Wilson ◽

Sana Maqsood ◽

John J. Mullins ◽

Carl S. Tucker ◽

...

Keyword(s):

Cardiomyocyte Proliferation ◽

Zebrafish Heart

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Abstract 13: Nkx2-5-notch Signaling Axis Regulates The Proliferation Of The Atrial Myocytes And Conduction System

Circulation Research ◽

10.1161/res.115.suppl_1.13 ◽

2014 ◽

Vol 115 (suppl_1) ◽

Author(s):

Austin Nakano ◽

Yasuhiro Nakashima ◽

Diana A Yanez ◽

Marlin Touma ◽

Haruko Nakano ◽

...

Keyword(s):

Notch Signaling ◽

Notch Pathway ◽

Conduction System ◽

Cardiomyocyte Proliferation ◽

Tight Control ◽

Septal Defects ◽

Signaling Axis ◽

Human Mutation ◽

Early Lethality

Rationale: Tight control of cardiomyocyte proliferation is essential for the formation of four-chambered heart. Although human mutation of NKX2-5 is linked to septal defects and atrioventricular conduction abnormalities, early lethality and hemodynamic alteration in the mutant models have caused controversy as to whether Nkx2-5 regulates cardiomyocyte proliferation. Objective: In this study, we circumvented these limitations by atrial-restricted deletion of Nkx2-5. Method and Results: Atrial-specific Nkx2-5 mutants died shortly after birth with hyperplastic working myocytes and conduction system including two nodes and internodal tracts. Multicolor reporter analysis revealed that Nkx2-5-null cardiomyocytes displayed clonal proliferative activity throughout the atria, indicating the suppressive role of Nkx2-5 in the cardiomyocyte proliferation after chamber ballooning stages. Transcriptome analysis revealed that aberrant activation of Notch signaling underlies hyperproliferation of mutant cardiomyocytes, and forced activation of Notch signaling recapitulates hyperproliferation of working myocytes but not conduction system. Conclusion: Collectively, these data suggest that Nkx2-5 regulates proliferation of atrial working and conduction myocardium in coordination with Notch pathway.

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Myocardial NF-κB activation is essential for zebrafish heart regeneration

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1511209112 ◽

2015 ◽

Vol 112 (43) ◽

pp. 13255-13260 ◽

Cited By ~ 54

Author(s):

Ravi Karra ◽

Anne K. Knecht ◽

Kazu Kikuchi ◽

Kenneth D. Poss

Keyword(s):

Tissue Regeneration ◽

Therapeutic Strategy ◽

Cardiac Injury ◽

Regulatory Sequences ◽

Heart Regeneration ◽

Cardiomyocyte Proliferation ◽

Developmental Program ◽

Lower Vertebrates ◽

Outstanding Question ◽

Zebrafish Heart

Heart regeneration offers a novel therapeutic strategy for heart failure. Unlike mammals, lower vertebrates such as zebrafish mount a strong regenerative response following cardiac injury. Heart regeneration in zebrafish occurs by cardiomyocyte proliferation and reactivation of a cardiac developmental program, as evidenced by induction of gata4 regulatory sequences in regenerating cardiomyocytes. Although many of the cellular determinants of heart regeneration have been elucidated, how injury triggers a regenerative program through dedifferentiation and epicardial activation is a critical outstanding question. Here, we show that NF-κB signaling is induced in cardiomyocytes following injury. Myocardial inhibition of NF-κB activity blocks heart regeneration with pleiotropic effects, decreasing both cardiomyocyte proliferation and epicardial responses. Activation of gata4 regulatory sequences is also prevented by NF-κB signaling antagonism, suggesting an underlying defect in cardiomyocyte dedifferentiation. Our results implicate NF-κB signaling as a key node between cardiac injury and tissue regeneration.

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