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Programmed cell death and Bcl-2 protection in the absence of a nucleus
M D Jacobson1, J F Burne, M C Raff
1Developmental Neurobiology Programme, MRC Laboratory for Molecular Cell Biology, London, UK.
Abstract:
The molecular basis of programmed cell death (PCD) is unknown. An important clue is provided by the Bcl-2 protein, which can protect many cell types from PCD, although it is not known where or how it acts. Nuclear condensation, DNA fragmentation and a requirement for new RNA and protein synthesis are often considered hallmarks of PCD. We show here, however, that anucleate cytoplasts can undergo PCD and that Bcl-2 and extracellular survival signals can protect them, indicating that, in some cases at least, the nucleus is not required for PCD or for Bcl-2 or survival factor protection. We propose that PCD, like the cell cycle, is orchestrated by a cytoplasmic regulator that has multiple intracellular targets.
Insights
Programmed cell death (PCD) can occur without a nucleus, challenging previous assumptions. The Bcl-2 protein and survival signals protect these anucleate cells, suggesting a cytoplasmic basis for cell death regulation.
Area of Science:
- Cell Biology
- Molecular Biology
- Apoptosis Research
Background:
- The molecular mechanisms governing programmed cell death (PCD) remain largely unknown.
- The Bcl-2 protein is known to inhibit PCD across various cell types, but its site and mode of action are unclear.
- Traditional hallmarks of PCD include nuclear condensation, DNA fragmentation, and the necessity of new RNA and protein synthesis.
Purpose of the Study:
- To investigate whether the nucleus is essential for programmed cell death (PCD).
- To determine if Bcl-2 and extracellular survival signals can prevent PCD in the absence of a nucleus.
- To explore the potential role of cytoplasmic factors in regulating PCD.
Main Methods:
- Utilizing anucleate cytoplasts (cell fragments without a nucleus) to study PCD.
- Treating cytoplasts with agents that induce PCD.
- Assessing the protective effects of Bcl-2 and extracellular survival signals on cytoplasts undergoing PCD.
Main Results:
- Anucleate cytoplasts were demonstrated to undergo programmed cell death (PCD).
- Bcl-2 and extracellular survival signals were shown to protect these anucleate cytoplasts from PCD.
- These findings indicate that the nucleus is not always required for PCD or for the protective actions of Bcl-2 and survival factors.
Conclusions:
- Programmed cell death (PCD) can be regulated independently of the nucleus.
- Bcl-2 and survival signals can exert protective effects in a cell compartment lacking a nucleus.
- A cytoplasmic regulator, analogous to cell cycle control, may orchestrate PCD through multiple intracellular targets.