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The shape of cell death
1Faculty of Biology, University of Konstanz, Germany.
Abstract:
Cell death, a scheduled event during development and tissue turnover, or the ultimate consequence of toxic or pathologic insults seems to involve a relatively limited number of execution pathways. This reflects the evolution of an organized sequence of events perhaps converging onto final common pathways that are used to dispose of unwanted or injured cells. In many cases, the ordered execution of this internal death program leads to typical morphological and biochemical changes that have been termed apoptosis. Apoptosis, often equated with developmental or programmed cell death, has been opposed to unscheduled or accidental cell lysis/necrosis. However, increasing evidence suggests that the two forms of cell demise share similar characteristics, at least in the signaling and early progression phase. Recent studies have shown that, when the intensity of the insult is very high and/or when ATP generation is deficient, cells fail to execute the ordered changes ensuing in apoptosis. Then cell lysis/necrosis supervenes before the processes leading to nuclear condensation and exposure of surface molecules can be completed. Thus, apoptosis and necrosis seem to represent only different shapes of cell demise, resulting from a more or less complete execution of the internal death program.
Insights
Cell death pathways, including apoptosis and necrosis, share common signaling mechanisms. The execution of the cell death program determines whether cells undergo apoptosis or necrosis.
Area of Science:
- Cell Biology
- Biochemistry
Background:
- Cell death is a fundamental biological process essential for development and tissue homeostasis.
- It can be triggered by physiological signals or pathological insults.
- Distinct pathways like apoptosis and necrosis have been traditionally described.
Purpose of the Study:
- To investigate the relationship between apoptosis and necrosis.
- To determine if these cell death forms share common execution pathways.
Main Methods:
- Comparative analysis of morphological and biochemical changes in cell death.
- Examination of signaling and progression phases in response to varying insult intensities and ATP levels.
Main Results:
- Cell death involves a limited number of execution pathways.
- Apoptosis and necrosis share signaling and early progression characteristics.
- High insult intensity or ATP deficiency prevents complete apoptosis execution, leading to necrosis.
Conclusions:
- Apoptosis and necrosis are not entirely distinct but represent different outcomes of a shared internal cell death program.
- The extent of the program's execution dictates the observed cell demise morphology.