Calcineurin is a calcium-activated protein phosphatase that is both necessary and sufficient for the development of a cardiac hypertrophic phenotype. In mammals, calcineurin-dependent dephosphorylation of nuclear factor of activated T cells (NFAT) transcription factors lead to the induction of hypertrophic genes. In contrast, Drosophila do not contain calcineurin-regulated isoforms of NFAT suggesting the idea that NFAT-independent mechanisms exist. Indeed, another transcription factor, myocyte enhancer factor 2 (MEF2), has also been implicated in calcineurin-mediated cardiac hypertrophy. In this competing renewal we propose to carry out a deficiency and EMS mutagenesis screen in Drosophila to identify novel NFAT-independent enhancer and suppressor genes of the calcineurin signaling pathway. To accomplish this goal we will use information already available from screens performed by Sullivan and Rubin and Gajewski and Schulz who have identified large regions of fly genome that act as suppressor and enhancer loci in a Drosophila screen sensitized by constitutive active calcineurin (CanAAct). Accordingly, we hypothesize that calcineurin-mediated cardiac hypertrophy can develop through an NFAT-independent pathway, and that a genetic screen in the fly will identify new molecular mechanisms that induce cardiac hypertrophy. We propose the following specific aims:
Aim 1. Identify novel Suppressor genes of Calcineurin-induced hypertrophic signaling in Drosophila. NFAT-independent calcineurin signaling genes will be identified by a deficiency screen of previously mapped suppressor loci using a sensitized fly expressing cardiac-specific CanAAct.
Aim 2. Identify novel Enhancer genes of Calcineurin-induced hypertrophic signaling in Drosophila. NFAT-independent calcineurin signaling genes will be identified with by a deficiency screen of previously mapped enhancer loci using a sensitized fly expressing cardiac-specific CanAAct.
Aim 3. Identify novel genetic modifiers of Calcineurin-induced hypertrophic signaling induced by EMS mutagenesis in Drosophila. EMS chemical mutagenesis screen to induce mutations across the entire Drosophila genome in a sensitized fly expressing actin- CanAAct. We anticipate that the proposed investigation will identify novel genes and pathways that lead to cardiac hypertrophy and will better define the role of calcineurin in the hypertrophic process. Furthermore, the proposed studies will lead to new targets to treat cardiac hypertrophy and heart failure in humans.

Public Health Relevance

The proposed experiments will expand our knowledge of the molecular mechanisms of cardiac hypertrophy, which we believe will lead to new targets for the identification and treatment of patients with heart failure. Calcineurin is a nodal signaling pathway for cardiac hypertrophy. Simpler model systems, such as Drosophila, provide the unique ability to perform genetic screens to identify genetic modifiers of the Calcineurin pathway that otherwise would be very difficult to do in mammalian systems.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL083065-08
Application #
8518440
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Evans, Frank
Project Start
2005-12-01
Project End
2015-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
8
Fiscal Year
2013
Total Cost
$362,931
Indirect Cost
$127,311
Name
Duke University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
Lee, Teresa E; Yu, Lin; Wolf, Matthew J et al. (2014) Galactokinase is a novel modifier of calcineurin-induced cardiomyopathy in Drosophila. Genetics 198:591-603
Lin, Na; Badie, Nima; Yu, Lin et al. (2011) A method to measure myocardial calcium handling in adult Drosophila. Circ Res 108:1306-15
Acehan, Devrim; Malhotra, Ashim; Xu, Yang et al. (2011) Cardiolipin affects the supramolecular organization of ATP synthase in mitochondria. Biophys J 100:2184-92
Kim, Byung-Eun; Turski, Michelle L; Nose, Yasuhiro et al. (2010) Cardiac copper deficiency activates a systemic signaling mechanism that communicates with the copper acquisition and storage organs. Cell Metab 11:353-63
Kim, Il-Man; Wolf, Matthew J; Rockman, Howard A (2010) Gene deletion screen for cardiomyopathy in adult Drosophila identifies a new notch ligand. Circ Res 106:1233-43
Fernandez, Liliana; Marchuk, Douglas A; Moran, Jennifer L et al. (2009) An N-ethyl-N-nitrosourea mutagenesis recessive screen identifies two candidate regions for murine cardiomyopathy that map to chromosomes 1 and 15. Mamm Genome 20:296-304
Acehan, Devrim; Khuchua, Zaza; Houtkooper, Riekelt H et al. (2009) Distinct effects of tafazzin deletion in differentiated and undifferentiated mitochondria. Mitochondrion 9:86-95
Wolf, Matthew J; Rockman, Howard A (2008) Drosophila melanogaster as a model system for genetics of postnatal cardiac function. Drug Discov Today Dis Models 5:117-123