Many pathways have been implicated in heart disease, but less is understood about what keeps the heart healthy. Clinical and experimental studies document the impact of exercise in both preventing and treating heart disease, including ischemic injury and heart failure (HF). Prior work from our laboratory identified a distinct "physiological gene set" induced by exercise, as well as key transcription factor nodes in this network. Remarkably, exercise also activated a proliferative and potentially regenerative gene program in the heart. Genetically mimicking exercise-induced changes was sufficient to recapitulate many phenotypic features of the exercised heart, as well as to protect against HF. Like transcription factors, micro-RNAs (miRs) also regulate large gene expression networks and modify complex cardiovascular phenotypes but little is known about their role in exercise. We recently performed a comprehensive screen for miRs differentially expressed in hearts of exercised mice. Sixteen miRs were identified and validated as differentially regulated in exercised hearts, and then subjected to in vitro and in vivo functional assays. Our preliminary data demonstrate that cardiac miR-222 is robustly upregulated in two independent exercise models and appears to drive a proliferative response in cardiomyocytes (CMs). The overall goals of this R21 are to examine the functional roles of miR-222 in CMs in vitro and in vivo, and determine the downstream mechanisms. We hypothesize that exercise induces intrinsic signaling changes that promote cardiac health, in part by promoting regeneration, and that miR-222 is an important contributor to these benefits. We will use a combination of genetic and pharmacological interventions to test these hypotheses in vivo, while identifying the responsible mechanisms. If successful, we anticipate that these studies will provide new insights into the benefits of exercise and pathways controlling the regenerative capacity of the heart. In addition, the unique animal models generated will provide a foundation for validating miR-222 as a therapeutic target in cardiac disease.

Public Health Relevance

We are studying changes induced by exercise in the heart to identify beneficial pathways that could help mitigate the progression of heart failure, a growing clinical problem throughout the world. This grant is focused on micro-RNA, a class of non-coding RNA that negatively regulates gene expression and has been shown to be important in the heart. Identifying the pathways that mediate the benefits of exercise in the heart could lay a foundation for the development of new therapeutic approaches for heart failure and other cardiac diseases.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21HL114352-02
Application #
8606241
Study Section
Special Emphasis Panel (ZRG1-CVRS-F (02))
Program Officer
Wang, Lan-Hsiang
Project Start
2013-02-01
Project End
2015-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
2
Fiscal Year
2014
Total Cost
$195,750
Indirect Cost
$83,250
Name
Beth Israel Deaconess Medical Center
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02215