Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Galhuber, M.
Complementary omics strategies to dissect p53 signaling networks under nutrient stress
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Medizinische Universität Graz; 2022. pp. 108
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Deutsch Alexander
- Prokesch Andreas
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- Abstract:
- Cellular signal transduction by tumor suppressor protein TP53 (p53) is an important stress response mechanism that protects cells from detrimental changes such as DNA damage, replication stress, telomere erosion, ribosomal stress, hypoxia, reactive oxygen species (ROS) production or epigenetic changes. In addition, p53 is involved in adapting the cell to fluctuations in nutrient availability (e.g., carbohydrates, lipids). The cellular responses to nutrient deprivation are reversible processes such as cell cycle arrest, alternate substrate utilization and distribution or autophagy, which have been associated with the p53 pathway. The functions of p53 are mediated by direct protein-protein interaction ("interactome") with signaling proteins, which mainly leads to activation of p53 as a transcription factor, thereby initiating protective cellular programs. In this study, we show in a p53-proficient human hepatoma cell line (HepG2) that nutrient deprivation leads to robust stabilization of p53 in the nucleus. Using the proximity proteomics method BioID, we determine the cytoplasmic p53 interaction network during the starvation response that occurs immediately after nutrient deprivation and show that p53 dissociates from several metabolic enzymes as well as the protein kinase PAK2. Direct binding of PAK2 to the DNA-binding domain of p53 has been confirmed using nuclear magnetic resonance (NMR) interaction studies. After translocation of p53 into the nucleus, we analyzed the nuclear interactome using a chromatin immunoprecipitation-based proteomics method, which interrogates protein interaction of p53 with other DNA-binding proteins. From these analyses, we were able to confirm new p53 interactors SORBS1 (insulin receptor signaling) and UGP2 (glycogen synthesis) with co-immunoprecipitation experiments. Finally, we demonstrated that binding of p53 to DNA after prolonged nutrient deprivation coordinates starvation-specific transcriptional programs, which included nutrient-dependent p53 target genes that were previously unknown. In summary, we have established the role of p53 in protein interaction networks, as well as in its function as a transcription factor in sensing cellular nutrient availability. Considering the diverse roles of p53 in cellular metabolism and its important role in the suppression of carcinogenesis, we have attempted to identify cellular targets that may be exploited in the future for either cancer prevention or pharmacological cancer intervention.