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Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c
Published on: June 29, 2011
Cytochrome c is released in a single step during apoptosis.
J C Goldstein1, C Muñoz-Pinedo, J-E Ricci
1La Jolla Institute for Allergy and Immunology, 10355 Science Center Dr., San Diego, CA 92121, USA.
Cell Death and Differentiation
|June 4, 2005
Summary
Cytochrome c release from mitochondria during apoptosis occurs in a single, rapid step. This process is independent of mitochondrial membrane potential changes and caspase activity.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cytochrome c release from mitochondria is a critical event in initiating apoptosis.
- Understanding the precise kinetics and regulation of this release is crucial for studying cell death pathways.
Purpose of the Study:
- To quantitatively measure the kinetics of cytochrome c release during apoptosis using fluorescent reporters.
- To investigate the relationship between cytochrome c release, mitochondrial membrane potential, and caspase activity.
Main Methods:
- Utilized fluorescent fusion proteins: cytochrome c-4CYS and cytochrome c-green fluorescent protein (cyt. c-GFP).
- Measured cytochrome c release kinetics in single cells across various cell types and apoptotic inducers.
- Assessed mitochondrial membrane potential (ΔΨm) and caspase activity in conjunction with cytochrome c release.
Main Results:
- Cytochrome c release kinetics were consistent between cyt. c-4CYS and cyt. c-GFP reporters.
- Cytochrome c release occurred rapidly (approx. 5 min) and was independent of significant changes in ΔΨm.
- No evidence of caspase-dependent amplification or preceding ΔΨm changes was observed for cytochrome c release.
Conclusions:
- A general, single-step mechanism governs cytochrome c release during apoptosis.
- This release mechanism is independent of mitochondrial membrane potential fluctuations.
- Cytochrome c release is not amplified by caspase activity in the studied models.
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