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Regulation of p53-mediated apoptosis and cell cycle arrest by Steel factor
J L Abrahamson1, J M Lee, A Bernstein
1Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Abstract:
Activation of the p53 protein can lead to apoptosis and cell cycle arrest. In contrast, activation of the signalling pathway controlled by the Kit receptor tyrosine kinase prevents apoptosis and promotes cell division of a number of different cell types in vivo. We have investigated the consequences of activating the Kit signalling pathway by its ligand Steel factor on these opposing functions of the p53 protein in Friend erythroleukemia cells. A temperature-sensitive p53 allele (Val-135) was introduced into the Friend erythroleukemia cell line (DP-16) which lacks endogenous p53 expression. At 38.5 degrees C, the Val-135 protein maintains a mutant conformation and has no effect on cell growth. At 32 degrees C, the mutant protein assumes wild-type properties and induces these cells to arrest in G1, terminally differentiate, and die by apoptosis. We demonstrate that Steel factor inhibits p53-mediated apoptosis and differentiation but has no effect on p53-mediated G1/S cell cycle arrest. These results demonstrate that Steel factor functions as a cell survival factor in part through the suppression of differentiation and apoptosis induced by p53 and suggest that cell cycle arrest and apoptosis may be separable functions of p53.
Insights
Steel factor, a Kit pathway activator, prevents p53-induced apoptosis and differentiation in erythroleukemia cells. However, it does not affect p53-mediated cell cycle arrest, suggesting separable p53 functions.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- The p53 protein induces apoptosis and cell cycle arrest.
- The Kit receptor tyrosine kinase pathway promotes cell survival and division.
- Opposing roles of p53 and Kit signaling in cell fate determination.
Purpose of the Study:
- Investigate Steel factor's effect on p53 functions in Friend erythroleukemia cells.
- Determine if Kit pathway activation influences p53-mediated apoptosis and differentiation.
- Clarify the interplay between Kit signaling and p53 in cell fate control.
Main Methods:
- Utilized a Friend erythroleukemia cell line (DP-16) with a temperature-sensitive p53 allele (Val-135).
- Manipulated p53 activity by temperature shifts (38.5°C vs. 32°C).
- Administered Steel factor to assess its impact on p53-induced cellular responses.
Main Results:
- Steel factor inhibited p53-mediated apoptosis and terminal differentiation.
- Steel factor did not affect p53-induced G1/S cell cycle arrest.
- p53 activation at 32°C induced G1 arrest, differentiation, and apoptosis in DP-16 cells.
Conclusions:
- Steel factor acts as a cell survival factor by suppressing p53-driven apoptosis and differentiation.
- Cell cycle arrest and apoptosis appear to be distinct functions of the p53 protein.
- Kit signaling pathway modulation offers potential therapeutic strategies for cancers involving p53 dysregulation.