Document Detail

Cytosolic heat shock protein 60, apoptosis, and myocardial injury.
MedLine Citation:
PMID:  12070120     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Heat shock proteins (HSPs) are well known for their ability to "protect" the structure and function of native macromolecules, particularly as they traffic across membranes. Considering the role of key mitochondrial proteins in apoptosis and the known antiapoptotic effects of HSP27 and HSP72, we postulated that HSP60, primarily a mitochondrial protein, also exerts an antiapoptotic effect. Methods and Results- To test this hypothesis, we used an antisense phosphorothioate oligonucleotide to effect a 50% reduction in the levels of HSP60 in cardiac myocytes, a cell type that has abundant mitochondria. The induced decrease in HSP60 precipitated apoptosis, as manifested by the release of cytochrome c, activation of caspase 3, and induction of DNA fragmentation. Antisense treatment was associated with an increase in bax and a decrease in bcl-2 secondary to increased synthesis of bax and degradation of bcl-2. A control oligonucleotide had no effect on these measurements. We further demonstrated that cytosolic HSP60 forms a macromolecular complex with bax and bak in vitro suggesting that complex formation with HSP60 may block the ability of bax and bak to effect apoptosis in vivo. Lastly, we show that as cytosolic (nonmitochondrial) HSP60 decreases, a small unbound fraction of bax appears and that the amount of bax associated with the mitochondria and cell membranes increases.
CONCLUSIONS: These results support a key antiapoptotic role for cytosolic HSP60. To our knowledge, this is the first report suggesting that interactions of HSP60 with bax and/or bak regulate apoptosis.
S R Kirchhoff; S Gupta; A A Knowlton
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  105     ISSN:  1524-4539     ISO Abbreviation:  Circulation     Publication Date:  2002 Jun 
Date Detail:
Created Date:  2002-06-18     Completed Date:  2002-06-28     Revised Date:  2014-02-07    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2899-904     Citation Subset:  AIM; IM    
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MeSH Terms
Cells, Cultured
Chaperonin 60 / genetics,  physiology*
Cytosol / metabolism
Membrane Proteins / metabolism
Mitochondrial Proteins / genetics,  physiology
Myocardium / cytology,  metabolism*
Oligonucleotides, Antisense / pharmacology
Proto-Oncogene Proteins / metabolism
Proto-Oncogene Proteins c-bcl-2 / metabolism
Rats, Sprague-Dawley
bcl-2 Homologous Antagonist-Killer Protein
bcl-2-Associated X Protein
Grant Support
Reg. No./Substance:
0/Bak1 protein, rat; 0/Bax protein, rat; 0/Chaperonin 60; 0/Membrane Proteins; 0/Mitochondrial Proteins; 0/Oligonucleotides, Antisense; 0/Proto-Oncogene Proteins; 0/Proto-Oncogene Proteins c-bcl-2; 0/bcl-2 Homologous Antagonist-Killer Protein; 0/bcl-2-Associated X Protein

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