title: Constant rate of p53 tetramerization in response to DNA damage controls the p53 response.
abstract: The dynamics of the tumor suppressor protein p53 have been previously investigated in single cells using fluorescently tagged p53. Such approach reports on the total abundance of p53 but does not provide a measure for functional p53. We used fluorescent protein-fragment complementation assay (PCA) to quantify in single cells the dynamics of p53 tetramers, the functional units of p53. We found that while total p53 increases proportionally to the input strength, p53 tetramers are formed in cells at a constant rate. This breaks the linear input-output relation and dampens the p53 response. Disruption of the p53-binding protein ARC led to a dose-dependent rate of tetramers formation, resulting in enhanced tetramerization and induction of p53 target genes. Our work suggests that constraining the p53 response in face of variable inputs may protect cells from committing to terminal outcomes and highlights the importance of quantifying the active form of signaling molecules in single cells.
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA, USA.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Gaglia
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA, USA galit@hms.harvard.edu.
authors.forename: Galit
authors.initials: G
authors.lastname: Lahav
mesh_terms: D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D005786:Gene Expression Regulation; D006801:Humans; D061986:MCF-7 Cells; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization; D013050:Spectrometry, Fluorescence; D059008:Time-Lapse Imaging; D016159:Tumor Suppressor Protein p53 / Q000032:analysis* / Q000737:chemistry / Q000235:genetics
chemical_list: D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C092069:activity regulated cytoskeletal-associated protein
keywords: DNA damage; fluorescence imaging; p53 dynamics; single cells; tetramers