Cardiomyopathy and related heart failure affect millions of Americans. Therefore, pathway-based therapies are highly desirable. The goal of this proposal is to leverage unique genetic tools in zebrafish to elucidate cardioprotective functions of target of rapamycin (TOR) signaling and develop novel therapeutic compounds via modifier screens. There are two obstacles prohibiting modifier screens from being conducted in adult zebrafish: the lack of adult assays to analyze cardiomyopathy-like phenotypes, and the difficulty to track adult mutant fish. To address the former challenge, we established and characterized first adult fish models of cardiomyopathy, including a model induced by Doxorubicin (DOX). To address the latter challenge, we adapted a transposon-based insertional mutagenesis strategy that facilitates the identification of all mutants by a RFP tag. We have conducted both phenotype-based insertional mutagenesis screens and chemical screens, and identified gene modifiers and compound modifiers of TOR signaling that sequentially affect DOX-induced cardiomyopathy. Preliminary studies using these genetic resources suggested that activated autophagy conveys the cardioprotective function of TOR inhibition. In this proposal, we will continue to leverage zebrafish genetics to test our central hypothesis that the cardioprotective functions of TOR inhibition are conferred by the activated autophagy, which can be harnessed by modifier screens in adult zebrafish to identify novel genes and therapeutics for treating cardiomyopathy.
In Specific Aim 1, we will determine the conservation of adult zebrafish as a model organism for cardiomyopathy.
In Specific Aim 2, we will discern functions of autophagy and pS6K subpathways in cardiomyopathy via phenotyping two modifier mutants that differentially affect TOR signaling.
In Specific Aim 3, we plan to discover novel compound modifiers of TOR signaling that could be of greater therapeutic value for cardiomyopathy. At the end of the project, we expect to validate a cardioprotective function of TOR inhibition, to define autophagy as the major downstream signaling branch that confers this cardioprotective function, and to identify compounds that specifically interfere with the TOR-autophagy subpathway that might be of better therapeutic value than rapamycin. Our studies will establish adult zebrafish as a conservative animal model to identify novel modifiers of cardiomyopathy, as well as a complete in vivo model organism to facilitate drug discovery.

Public Health Relevance

This proposal leverages the unique tools in zebrafish to seek TOR signaling-based therapies for cardiomyopathy and heart failure. We aim to use this unique animal model to identify gene modifiers of cardiomyopathy that will elucidate cardioprotective functions of TOR inhibition, and compounds in this pathway with therapeutic value for cardiomyopathy.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL107304-04
Application #
8600987
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Adhikari, Bishow B
Project Start
2011-04-01
Project End
2014-12-31
Budget Start
2014-01-01
Budget End
2014-12-31
Support Year
4
Fiscal Year
2014
Total Cost
$431,052
Indirect Cost
$157,715
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Long, Pamela A; Theis, Jeanne L; Shih, Yu-Huan et al. (2017) Recessive TAF1A mutations reveal ribosomopathy in siblings with end-stage pediatric dilated cardiomyopathy. Hum Mol Genet 26:2874-2881
Wang, Lei; Ma, Xiao; Xu, Xiaolei et al. (2017) Systematic identification and characterization of cardiac long intergenic noncoding RNAs in zebrafish. Sci Rep 7:1250
Ding, Yonghe; Long, Pamela A; Bos, J Martijn et al. (2017) A modifier screen identifies DNAJB6 as a cardiomyopathy susceptibility gene. JCI Insight 2:
Packard, René R Sevag; Baek, Kyung In; Beebe, Tyler et al. (2017) Automated Segmentation of Light-Sheet Fluorescent Imaging to Characterize Experimental Doxorubicin-Induced Cardiac Injury and Repair. Sci Rep 7:8603
Shih, Yu-Huan; Dvornikov, Alexey V; Zhu, Ping et al. (2016) Exon- and contraction-dependent functions of titin in sarcomere assembly. Development 143:4713-4722
Long, Pamela A; Zimmermann, Michael T; Kim, Maengjo et al. (2016) De novo RRAGC mutation activates mTORC1 signaling in syndromic fetal dilated cardiomyopathy. Hum Genet 135:909-917
Fei, Peng; Lee, Juhyun; Packard, René R Sevag et al. (2016) Cardiac Light-Sheet Fluorescent Microscopy for Multi-Scale and Rapid Imaging of Architecture and Function. Sci Rep 6:22489
Ding, Yonghe; Long, Pamela A; Bos, J Martijn et al. (2016) A modifier screen identifies DNAJB6 as a cardiomyopathy susceptibility gene. JCI Insight 1:
Yang, Jingchun; Shah, Sahrish; Olson, Timothy M et al. (2016) Modeling GATAD1-Associated Dilated Cardiomyopathy in Adult Zebrafish. J Cardiovasc Dev Dis 3:
Sun, Yanyi; Fang, Yuehua; Xu, Xiaolei et al. (2015) Evidence of an Association between Age-Related Functional Modifications and Pathophysiological Changes in Zebrafish Heart. Gerontology 61:435-47

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