Related Experiment Videos
The MDR1 downstream promoter contains sequence-specific binding sites for wild-type p53
B E Strauss1, C Shivakumar, S P Deb
1Department of Pathology, University of California, San Diego, La Jolla 92093-0063, USA.
Abstract:
We have examined the interaction of the wild-type p53 protein with the downstream promoter of the human multidrug resistance gene-1 (MDR1). Our findings indicate that wild-type p53 inhibits reporter activity driven by the MDR1 downstream promoter (base pairs -189 to +133 relative to the major transcriptional initiation site) in a dose-dependent manner in cotransfection assays in the BHK and the Saos-2 cell lines. A 123 base-pair segment of DNA (-119 to +4 relative to the major transcriptional initiation site), a 193 base-pair segment (-189 to +4), and a 135 base-pair segment (-2 to +133) have been isolated from the MDR1 downstream promoter which, like the full promoter, are negatively controlled by wild-type p53. In addition, we show sequence-specific binding of wild-type p53 protein to the MDR1 downstream promoter. These in vitro results suggest that the presence of wild-type p53 negatively affects expression of the MDR1 gene product, p-glycoprotein, at the transcriptional level.
Insights
Wild-type p53 protein suppresses the human multidrug resistance gene-1 (MDR1) promoter activity. This interaction occurs at the transcriptional level, impacting p-glycoprotein expression.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- The p53 protein is a critical tumor suppressor involved in regulating cellular responses to stress.
- The multidrug resistance gene-1 (MDR1) encodes P-glycoprotein, a transporter protein associated with multidrug resistance in cancer.
Purpose of the Study:
- To investigate the interaction between wild-type p53 and the promoter region of the human MDR1 gene.
- To determine if p53 influences MDR1 gene expression.
Main Methods:
- Reporter gene assays were performed using constructs containing segments of the MDR1 promoter (-189 to +133, -119 to +4, -189 to +4, -2 to +133).
- Cotransfection assays were conducted in BHK and Saos-2 cell lines with varying amounts of wild-type p53 expression vectors.
- DNA binding assays were used to demonstrate sequence-specific binding of p53 to the MDR1 promoter.
Main Results:
- Wild-type p53 demonstrated dose-dependent inhibition of reporter activity driven by the full MDR1 promoter and its isolated segments.
- Specific DNA segments of the MDR1 promoter were identified as being negatively regulated by wild-type p53.
- Sequence-specific binding of wild-type p53 protein to the MDR1 promoter was confirmed in vitro.
Conclusions:
- Wild-type p53 negatively regulates the expression of the MDR1 gene at the transcriptional level.
- The findings suggest a potential role for p53 in modulating the expression of P-glycoprotein, impacting multidrug resistance.