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HSP60, Bax, and cardiac apoptosis
1Cardiovascular Division, Department of Medicine, University of California, Davis 95616, USA. aaknowlton@ucdavis.edu
Cardiovascular Toxicology
|October 14, 2003
Summary
Heat shock protein 60 (HSP60) has crucial anti-apoptotic roles outside the mitochondria. Its reduction and redistribution during hypoxia trigger programmed cell death, impacting heart function.
Area of Science:
- Cellular Biology
- Molecular Biology
- Cardiovascular Science
Background:
- Heat shock protein 60 (HSP60) is traditionally recognized for its chaperonin and protein folding roles within mitochondria.
- Emerging evidence indicates substantial HSP60 presence in extra-mitochondrial compartments.
Purpose of the Study:
- To investigate the extra-mitochondrial functions of HSP60, particularly its role in apoptosis within the heart.
- To elucidate the interaction of extra-mitochondrial HSP60 with key apoptotic regulatory proteins.
Main Methods:
- Analysis of HSP60 localization and expression in cardiac tissue.
- Investigation of HSP60 interactions with BAX, BAK, and BCL-2 proteins.
- Assessment of HSP60 levels and cellular localization during hypoxia and reoxygenation.
Main Results:
- Extra-mitochondrial HSP60 in the heart exhibits significant anti-apoptotic functions.
- HSP60 forms complexes with BAX and BAK, but not BCL-2, influencing the apoptotic pathway.
- A reduction in HSP60 levels is sufficient to induce apoptosis.
- Hypoxia and reoxygenation lead to decreased HSP60 levels, with cytosolic HSP60 redistribution to the plasma membrane during hypoxia preceding apoptosis initiation.
Conclusions:
- Extra-mitochondrial HSP60 plays a critical role in preventing cardiac apoptosis.
- The interaction of HSP60 with BAX and BAK is central to its anti-apoptotic mechanism.
- Altered HSP60 levels and localization during hypoxic stress contribute to the initiation of the apoptotic cascade in the heart.
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