Because injury to the human heart results in irreversible loss of myocardium, insults such as infarction often lead to heart failure, susceptibility to arrhythmia, and death. In stark contrast, zebrafish are able to regenerate functional myocardium following injury by cardiomyocyte proliferation. Recently, a low grade of cardiomyocyte proliferation has been described in the adult mammalian heart. Therapies to augment cardiac regeneration following injury are attractive strategies to prevent human heart failure. However, the complement of factors that facilitate regeneration are unknown. Here, we propose the use of unbiased proteomic profiling and cell- type specific gene expression profiling to identify the extracellular factors that orchestrate zebrafish heart regeneration. Our preliminar work has identified brain natriuretic peptide (nppb) as a secreted factor that is spatiotemporally related to heart regeneration. We will generate novel transgenic fish to conditionally overexpress nppb and a dominant negative form of its receptor in specific cell lineages using Cre/Lox technology. These experiments will allow for the determination of autocrine and paracrine roles for nppb and serve as a template for future work to study the mechanism of action for other factors identified. Finally, we will assess conservation of these factors followin injury to the regenerative neonatal mouse heart and the poorly- regenerative adult mouse heart. Factors preferentially induced in regenerating neonatal mouse hearts compared to adult mouse hearts represent candidate biomarkers for heart regeneration. Markers of cardiac injury and regeneration that are conserved following cardiac injury in zebrafish and mice will then be measured in a repository of plasma obtained from patients following myocardial infarction. Marker levels will be tested for relation to human cardiovascular outcomes. The proposed experiments will identify factors that coordinate zebrafish heart regeneration and potential factors to therapeutically augment mammalian cardiomyocyte proliferation. In addition, our focus on secreted factors with regeneration will contribute to the development of a biomarker toolbox for future epidemiologic studies to understand the role of regeneration in human cardiovascular disease. Over the next several years, I hope to become an independent clinician-scientist focusing on heart regeneration. I ultimately hope to become an established investigator studying how variation in cardiac homeostasis affects the development of cardiovascular disease, specifically heart failure. The outlined experiments will provide a foundation for future mechanistic work to better understand the factors the facilitate regeneration and for a set biomarkers to understand how cardiac homeostasis affects cardiovascular outcomes following infarction. My work will be mentored by Dr. Kenneth Poss, PhD, a pioneer and leader in regenerative biology. We will collaborate with the Duke Clinical Research Institute, allowing for the ideal training experience for a translational research career.

Public Health Relevance

Heart failure is epidemic of increasing proportions. New markers to identify pre-clinical heart failure and novel treatment strategies are needed. In this proposal, we aim to use zebrafish heart regeneration to develop markers to better understand the role of cardiomyocyte homeostasis in the natural history of heart failure. Additionally, the candidates we identify are possible therapeutic targets following cardiac injury.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Clinical Investigator Award (CIA) (K08)
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Special Emphasis Panel (ZHL1-CSR-K (O2))
Program Officer
Wang, Wayne C
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Duke University
Internal Medicine/Medicine
Schools of Medicine
United States
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Karra, Ravi; Foglia, Matthew J; Choi, Wen-Yee et al. (2018) Vegfaa instructs cardiac muscle hyperplasia in adult zebrafish. Proc Natl Acad Sci U S A 115:8805-8810
Goldman, Joseph Aaron; Kuzu, Guray; Lee, Nutishia et al. (2017) Resolving Heart Regeneration by Replacement Histone Profiling. Dev Cell 40:392-404.e5
Karra, Ravi; Walter, Agoston O; Wu, Sean M (2017) The relationship between cardiac endothelium and fibroblasts: it's complicated. J Clin Invest 127:2892-2894
Karra, Ravi; Poss, Kenneth D (2017) Redirecting cardiac growth mechanisms for therapeutic regeneration. J Clin Invest 127:427-436
Kang, Junsu; Hu, Jianxin; Karra, Ravi et al. (2016) Modulation of tissue repair by regeneration enhancer elements. Nature 532:201-6
Cao, Jingli; Navis, Adam; Cox, Ben D et al. (2016) Single epicardial cell transcriptome sequencing identifies Caveolin 1 as an essential factor in zebrafish heart regeneration. Development 143:232-43
Kang, Junsu; Karra, Ravi; Poss, Kenneth D (2015) Back in Black. Dev Cell 33:623-4
Gemberling, Matthew; Karra, Ravi; Dickson, Amy L et al. (2015) Nrg1 is an injury-induced cardiomyocyte mitogen for the endogenous heart regeneration program in zebrafish. Elife 4:
Karra, Ravi; Knecht, Anne K; Kikuchi, Kazu et al. (2015) Myocardial NF-?B activation is essential for zebrafish heart regeneration. Proc Natl Acad Sci U S A 112:13255-60
Fang, Yi; Gupta, Vikas; Karra, Ravi et al. (2013) Translational profiling of cardiomyocytes identifies an early Jak1/Stat3 injury response required for zebrafish heart regeneration. Proc Natl Acad Sci U S A 110:13416-21

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