Therapeutic manipulation of caspases or their regulators offers significant promise in controlling cellular injury in ischemia/reperfusion. Because blockade of specific caspases can result in apoptotic progression via alternative or compensatory pathways, however, it is critical to understand the roles of individual caspases and those molecules which directly control caspase activities or which provide """"""""short-circuits"""""""" leading to so-called """"""""caspase independent"""""""" downstream mechanisms of cell death. The central hypothesis of this proposal is that following ischemia/reperfusion (I/R) in cardiomyocytes, generation of reactive oxygen species (ROS) and caspase-2 activation lead to mitochondrial perturbations resulting in release of cytochrome c (cyt c) and disruption of the electron transport chain and apoptotic cell death. Using a combination of cellular and animal models, depletion of specific proteins via RNA interference and specific knockout mice, we propose to study the roles of specific caspases and their regulators, including Smac/DIABLO and inhibitor of apoptosis proteins (IAPs) in two major specific aims: 1) Determine the interactive roles of caspase-2, mitochondrial ROS, and Bax and Bid ininitiating ischemia/reperfusion-induced injury to cardiomyocytes. We hypothesize that IR results in generation of mitochondrial ROS and the activation of Bax and caspase-2. In these studies we will examine also the effects of specific ROS, such as superoxide and hydrogen peroxide, and antioxidant treatment on the activation of Bax and caspase-2. Further, we postulate that active caspase-2 acts directly on the mitochondria and/or via Bid cleavage to cause the release of cyt c and further ROS generation; 2) Determine the role of caspase-2 in the release of pro-apoptotic mitochiondrial protein Smac/DIABLO, its effects on IAP blockade of caspase activity and their relative roles in amplification of I/R-induced apoptosis. We hypothesize that in I/Rstimulated cardiomyocytes, caspases can cause differential release of apoptogenic mitochondrial proteins, such as cyt c and the IAP-inhibiting Smac/DIABLO, and that these affect caspase-mediated amplification of I/R-induced cell death. A better understanding of specific caspase activity and the physiological interplay between caspases, mitochondrial ROS, and the endogenous regulators which act on or are released from the mitochondria will be critical in assessing the therapeutic potential of these targets.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL079641-02
Application #
7006058
Study Section
Special Emphasis Panel (ZRG1-MIM (01))
Program Officer
Schwartz, Lisa
Project Start
2005-01-15
Project End
2009-12-31
Budget Start
2006-01-01
Budget End
2006-12-31
Support Year
2
Fiscal Year
2006
Total Cost
$372,291
Indirect Cost
Name
University of Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
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