Project description:The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of cellular response pathways. The molecular mechanisms that discriminate between the distinct p53-responses towards different stress treatments have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by two chemotherapeutical treatments, Actinomycin D inducing growth arrest and Etoposide resulting in apoptosis. We found that the genome-wide p53-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in genome-wide transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the extent of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46), a modification that has been linked to apoptosis-pathways, and the extent of phosphorylation of Serine 15 (p53-pS15), a general p53-activation mark. Interestingly, the overall extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 of DNA bound p53 remains highly similar upon both treatments. Moreover, our data suggest that, following different chemotherapeutical treatments, the extent of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes, including the BAX and PUMA genes. These data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding, but possibly through post-translational modifications of chromatin bound p53. Microarray analysis (Affymetrix Human Exon array) of the p53 response in U2OS cells treated with either Etoposide or Actinomycin D
Project description:The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of cellular response pathways. The molecular mechanisms that discriminate between the distinct p53-responses towards different stress treatments have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by two chemotherapeutical treatments, Actinomycin D inducing growth arrest and Etoposide resulting in apoptosis. We found that the genome-wide p53-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in genome-wide transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the extent of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46), a modification that has been linked to apoptosis-pathways, and the extent of phosphorylation of Serine 15 (p53-pS15), a general p53-activation mark. Interestingly, the overall extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 of DNA bound p53 remains highly similar upon both treatments. Moreover, our data suggest that, following different chemotherapeutical treatments, the extent of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes, including the BAX and PUMA genes. These data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding, but possibly through post-translational modifications of chromatin bound p53. ChIP-seq profiles of p53, p53phosphorylated at Serine 15 (p53-pS15) and p53 phosphorylated at Serine 46 (p53-pS46) in U2OS cells treated with either Actinomycin D or Etoposide.
Project description:The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of cellular response pathways. The molecular mechanisms that discriminate between the distinct p53-responses towards different stress treatments have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by two chemotherapeutical treatments, Actinomycin D inducing growth arrest and Etoposide resulting in apoptosis. We found that the genome-wide p53-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in genome-wide transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the extent of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46), a modification that has been linked to apoptosis-pathways, and the extent of phosphorylation of Serine 15 (p53-pS15), a general p53-activation mark. Interestingly, the overall extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 of DNA bound p53 remains highly similar upon both treatments. Moreover, our data suggest that, following different chemotherapeutical treatments, the extent of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes, including the BAX and PUMA genes. These data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding, but possibly through post-translational modifications of chromatin bound p53.
Project description:The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of cellular response pathways. The molecular mechanisms that discriminate between the distinct p53-responses towards different stress treatments have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by two chemotherapeutical treatments, Actinomycin D inducing growth arrest and Etoposide resulting in apoptosis. We found that the genome-wide p53-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in genome-wide transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the extent of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46), a modification that has been linked to apoptosis-pathways, and the extent of phosphorylation of Serine 15 (p53-pS15), a general p53-activation mark. Interestingly, the overall extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 of DNA bound p53 remains highly similar upon both treatments. Moreover, our data suggest that, following different chemotherapeutical treatments, the extent of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes, including the BAX and PUMA genes. These data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding, but possibly through post-translational modifications of chromatin bound p53.
Project description:The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of different response pathways. The molecular mechanisms that discriminate between the distinct p53-responses have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by Actinomycin D and Etoposide treatment resulting in more growth arrested versus apoptotic cells respectively. We found that the genome-wide p53 DNA-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in global transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the genome-wide level of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46) and of Serine 15 (p53-pS15). Interestingly, the extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 remains highly similar. Moreover, our data suggest that following different chemotherapeutical treatments, the amount of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes. Our data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding and that post-translationally modified p53 can have distinct DNA-binding characteristics.
Project description:Post-translational modifications (PTMs) play pivotal roles in controlling the stability and activity of the tumor suppressor p53 in response to distinct stressors. Here we report an unexpected finding of a short chain fatty acid modification of p53 in human cells. Crotonic acid (CA) treatment induces p53 crotonylation, but surprisingly reduces its protein, but not mRNA level, leading to inhibition of p53 activity in a dose dependent fashion. Surprisingly this crotonylation targets serine 46, instead of any predicted lysine residues, of p53, as detected in TCEP-probe labeled crotonylation and anti-crotonylated peptide antibody reaction assays. This is further confirmed by substitution of serine 46 with alanine, which abolishes p53 crotonylation in vitro and in cells. CA increases p53-dependent glycolytic activity, and augments cancer cell proliferation in response to metabolic or DNA damage stress. Since serine 46 is only found in human p53, our studies unveil an unconventional PTM unique for human p53, impairing its activity in response to CA. Because CA is likely produced by the gut microbiome, our results also predict that this type of PTM might play a role in early human colorectal neoplasia development by negating p53 activity without mutation of this tumor suppressor gene.