Overexpression of bcl-2 Results in Reduction of Cytochrome c Content and Inhibition of Complex I Activity

Bcl-2 has been shown to exert its antiapoptotic activity predominantly at the level of mitochondria by preventing cytochrome c release. Whether Bcl-2 is involved in the regulation of mitochondrial function prior to an apoptotic stimulus remains elusive. Using functional and spectrophotometric measur...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2001-02, Vol.280 (4), p.1021-1027
Main Authors: Schwarz, C.S., Evert, B.O., Seyfried, J., Schaupp, M., Kunz, W.S., Vielhaber, S., Klockgether, T., Wüllner, U.
Format: Article
Language:English
Subjects:
Animals
Apoptosis
Bcl-2
Blotting, Northern
Blotting, Western
Cell Line
Citrate (si)-Synthase - metabolism
complex I
cytochrome b
Cytochrome b Group - metabolism
cytochrome c
Cytochrome c Group - metabolism
Dose-Response Relationship, Drug
Electron Transport Complex I
mitochondria
NADH Dehydrogenase - metabolism
NADH, NADPH Oxidoreductases - metabolism
Oligonucleotides, Antisense - metabolism
PC12 Cells
Plasmids - metabolism
Promoter Regions, Genetic
Proto-Oncogene Proteins c-bcl-2 - biosynthesis
Rats
RNA, Messenger - metabolism
Spectrophotometry
Subcellular Fractions - metabolism
Tetracycline - metabolism
Time Factors
Transfection
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Summary:Bcl-2 has been shown to exert its antiapoptotic activity predominantly at the level of mitochondria by preventing cytochrome c release. Whether Bcl-2 is involved in the regulation of mitochondrial function prior to an apoptotic stimulus remains elusive. Using functional and spectrophotometric measurements in an inducible PC12-Tet-on-bcl-2 cell line we demonstrate that induction of Bcl-2 overexpression rapidly reduced cytochrome b and c levels as well as complex I activity. To confirm that these changes were specific for Bcl-2 we generated a bcl-2 antisense construct under the control of the tetracycline responsive promotor. Transient transfection with this antisense plasmid prevented both the decrease of cytochrome b and c levels and the loss of complex I activity. The decrease of cytochrome b levels was paralleled by a decrease of cytochrome b mRNA levels while Northern blot analysis of cytochrome c mRNA expression did not reveal any overt changes in Bcl-2 cells. We propose that the antiapoptotic properties of Bcl-2 are related to the reduction of mitochondrial complex I activity and lowered mitochondrial cytochrome b and c levels.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.2001.4242