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Bcl-2 and Ca(2+)-mediated mitochondrial dysfunction in neural cell death
1MitoKor, San Diego, CA 92121, USA.
Abstract:
Although altered Ca2+ homoeostasis is believed to be a primary cause of death for many cell types in response to toxic insults, the specific Ca(2+)-stimulated event responsible for directing cells down the death pathway has remained elusive. Recent publications support the hypothesis that mitochondrial Ca2+ sequestration is the critical event in induction of excitotoxic neuronal death. If similar pathways are involved in the induction of Ca(2+)-induced necrotic and apoptotic death, then agents that mimic the action of the anti-apoptotic protein Bcl-2 should be particularly useful. Our previous results provide evidence that Bcl-2 increases the maximal capacity of mitochondria to accumulate Ca2+ while providing resistance to Ca(2+)-induced respiratory damage. In addition, we have found that Bcl-2 can block Ca(2+)-ionophore-induced delayed cell death. These data predict that in response to a challenging mitochondrial Ca2+ load, Bcl-2-containing mitochondria would be capable of continuing bioenergetic function, potentially avoiding a catastrophic death signalling event.
Insights
Altered calcium (Ca2+) regulation is key in cell death. The anti-apoptotic protein Bcl-2 enhances mitochondrial calcium uptake, preventing cell death signaling and maintaining function under toxic stress.
Area of Science:
- Cell Biology
- Neuroscience
- Biochemistry
Background:
- Altered calcium (Ca2+) homeostasis is a primary cause of cell death from toxic insults.
- Mitochondrial Ca2+ sequestration is hypothesized as critical in excitotoxic neuronal death.
- The specific Ca2+-stimulated event driving cell death remains elusive.
Purpose of the Study:
- To investigate the role of mitochondrial Ca2+ sequestration in Ca2+-induced cell death.
- To determine if agents mimicking the anti-apoptotic protein Bcl-2 can prevent cell death.
- To explore Bcl-2's effect on mitochondrial Ca2+ accumulation and resistance to damage.
Main Methods:
- Previous experimental results on Bcl-2's effects on mitochondria.
- Analysis of Ca2+ ionophore-induced cell death.
- Assessment of mitochondrial bioenergetic function under Ca2+ load.
Main Results:
- Bcl-2 increases the maximal capacity of mitochondria to accumulate Ca2+.
- Bcl-2 confers resistance to Ca2+-induced mitochondrial respiratory damage.
- Bcl-2 blocks Ca2+-ionophore-induced delayed cell death.
Conclusions:
- Mitochondrial Ca2+ sequestration is a critical event in Ca2+-induced cell death pathways.
- The anti-apoptotic protein Bcl-2 protects cells by enhancing mitochondrial Ca2+ buffering capacity.
- Bcl-2-mediated mitochondrial function may prevent catastrophic cell death signaling events.