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Wild-type human p53 and a temperature-sensitive mutant induce Fas/APO-1 expression
L B Owen-Schaub1, W Zhang, J C Cusack
1Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Molecular and Cellular Biology
|June 1, 1995
Summary
The tumor suppressor protein p53 directly upregulates the expression of Fas/APO-1, a key protein in apoptosis. This finding identifies Fas/APO-1 as a transcriptional target of p53.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Fas/APO-1 is a cell surface receptor that mediates apoptosis.
- The tumor suppressor protein p53 is known to induce apoptosis and regulate gene transcription.
- The relationship between p53 and Fas/APO-1 expression was not fully understood.
Purpose of the Study:
- To investigate whether wild-type p53 can upregulate Fas/APO-1 expression.
- To determine if Fas/APO-1 is a transcriptional target of p53.
Main Methods:
- Utilized human cell lines with wild-type p53, p53-null status, or temperature-sensitive p53 mutants.
- Employed adenovirus-mediated gene transfer and stable transfection for p53 expression.
- Assessed Fas/APO-1 upregulation using flow cytometry, immunoprecipitation, nuclear run-on, and Northern blot analyses.
Main Results:
- Wild-type p53 expression led to a 3-4 fold increase in cell surface Fas/APO-1 in H358 and H460 cells.
- Temperature-sensitive p53 mutants induced a 4-6 fold upregulation of Fas/APO-1 in K562 cells at permissive temperatures.
- Fas/APO-1 upregulation resulted from increased mRNA production and was independent of de novo protein synthesis.
Conclusions:
- Fas/APO-1 is a direct transcriptional target of wild-type p53.
- p53-mediated upregulation of Fas/APO-1 plays a role in p53-induced apoptosis.
- This study elucidates a novel mechanism in p53-regulated apoptosis.