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Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
p53 targets identified by protein expression profiling
Rubaiyat Rahman-Roblick1, Uwe Johannes Roblick, Ulf Hellman
1Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
Abstract:
p53 triggers cell cycle arrest and apoptosis through transcriptional regulation of specific target genes. We have investigated the effect of p53 activation on the proteome using 2D gel electrophoresis analysis of mitomycin C-treated HCT116 colon carcinoma cells carrying wild-type p53. Approximately 5,800 protein spots were separated in overlapping narrow-pH-range gel strips, and 115 protein spots showed significant expression changes upon p53 activation. The identity of 55 protein spots was obtained by mass spectrometry. The majority of the identified proteins have no previous connection to p53. The proteins fall into different functional categories, such as mRNA processing, translation, redox regulation, and apoptosis, consistent with the idea that p53 regulates multiple cellular pathways. p53-dependent regulation of five of the up-regulated proteins, eIF5A, hnRNP C1/C2, hnRNP K, lamin A/C, and Nm23-H1, and two of the down-regulated proteins, Prx II and TrpRS, was examined in further detail. Analysis of mRNA expression levels demonstrated both transcription-dependent and transcription-independent regulation among the identified targets. Thus, this study reveals protein targets of p53 and highlights the role of transcription-independent effects for the p53-induced biological response.
Insights
The tumor suppressor p53 (also known as TP53) activates cell cycle arrest and apoptosis. This study identified novel p53 protein targets, revealing transcription-independent roles in cellular responses.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- The p53 protein (TP53) is a crucial tumor suppressor involved in cell cycle arrest and apoptosis.
- p53 exerts its functions primarily through transcriptional regulation of target genes.
Purpose of the Study:
- To investigate the global proteomic changes induced by p53 activation.
- To identify novel protein targets regulated by p53.
- To explore both transcription-dependent and independent mechanisms of p53 action.
Main Methods:
- Proteomic analysis using 2D gel electrophoresis on mitomycin C-treated HCT116 colon carcinoma cells with wild-type p53.
- Mass spectrometry for protein identification.
- mRNA expression analysis to validate regulatory mechanisms.
Main Results:
- Over 5,800 protein spots were analyzed, with 115 showing significant expression changes upon p53 activation.
- Mass spectrometry identified 55 proteins, many with no previously known association with p53.
- Identified proteins span diverse functional categories including mRNA processing, translation, redox regulation, and apoptosis.
- Detailed analysis confirmed p53-dependent regulation of specific up-regulated (e.g., eIF5A, hnRNP K) and down-regulated (e.g., Prx II) proteins.
- Evidence for both transcription-dependent and transcription-independent regulation was found.
Conclusions:
- This study expands the known targets of p53 beyond transcriptional targets.
- p53 influences cellular processes through both direct and indirect mechanisms, including transcription-independent pathways.
- The findings highlight the complexity of p53-mediated cellular responses and its role in multiple biological pathways.
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