Human and Mouse Fas (APO-1/CD95) Death Receptor Genes Each Contain a p53-responsive Element That Is Activated by p53 Mutants Unable to Induce Apoptosis

Abstract

p53 is a tumor suppressor protein that induces apoptosis at least in part through its ability to act as a sequence-specific transactivator. This work reports that intron 1 of the mouse Fas death receptor gene contains a p53-responsive element (p53RE) that matches the p53 consensus sequence and that is located between nucleotides ؉1704 and ؉1723 from the transcription initiation site. This element is specifically bound by p53 and functions as a p53-dependent enhancer in mammalian or in yeast reporter gene assays. Contrary to bax, another known pro-apoptotic p53-target gene, both mouse and human FAS p53REs are still activated by the discriminatory p53 mutants Pro-175 and Ala-143, a class of mutants unable to induce apoptosis. We propose that p53-dependent up-regulation of Fas does not induce apoptosis per se but sensitizes the cell to other proapoptotic signal(s). The functional conservation of p53-dependent Fas up-regulation argues strongly in favor of its biological importance and suggests that murine models may be used to study further the in vivo role of Fas in the p53 response.

Single-stranded RNA viruses inactivate the transcriptional activity of p53 but induce NOXA-dependent apoptosis via post-translational modifications of IRF-1, IRF-3 and CREB

“…It encodes the mouse p53DD truncated protein, a p53 dominant-negative mutant. The p21p53RE and the p21p53REm were described previously (Munsch et al, 2000). The 2.1 kb human p21 promoter was obtained by PCR using human genomic DNA as a template and the following oligonucleotide primers: forward (5 0 -gtctcgagccatccctatgct gcctgct-3 0 ) and reverse 5 0 -ctaagcttcctctgagtgcctcggtgcc-3 0 , and inserted at the XhoI/HindIII sites of the pGL3basic (Promega).…”

Hypermethylation of the gene promoter and enhancer region can regulate Fas expression and sensitivity in colon carcinoma

“…15 We therefore examined whether hypermethylation of the Fas gene would affect the p53-dependent transcriptional activation of Fas expression. A putative p53 enhancer region exists in the first intron of the Fas gene, 14 and contains 23 CpG sites. We therefore determined the methylation status of the p53 enhancer region by methylation-sensitive PCR (Figure 4a).…”

“…13 The first intron, which contains a p53 responsive element, is also a region demonstrating high density of CpG sites. 14 This study determined that DNA methylation contributes to the downregulation of Fas expression in 50% of colon carcinoma cell lines examined. Inhibition of methylation by 5-azadC increased Fas expression, restoring sensitivity to Fas-mediated apoptosis and potentiated p53-induced upregulation of Fas expression.…”

Accumulation of an inactive form of p53 protein in cells treated with TNFα

“…59 Real-time quantitation mRNA p53 mRNA was quantified using the TaqMan apparatus (Perkin Elmer Biosystems), while p21/Waf1 and Ddb2 mRNAs were quantified using Lightcycler apparatus (Roche Molecular Biochemicals).…”