title: p53 activation in response to microtubule disruption is mediated by integrin-Erk signaling.
abstract: The p53 tumor suppressor is activated in response to various stresses driving the cells into growth arrest or apoptosis. We have addressed the question of how disintegration of microtubule system induces activation of p53. Depolymerization of microtubules by colcemid in rat and human quiescent fibroblasts resulted in accumulation of transcriptionally active p53 that caused cell-cycle arrest at the G1/S boundary. The p53 activation correlated with prominent activation of Erk1/2 MAP kinases that resulted from colcemid-stimulated development of focal adhesions. Inhibition of focal contacts development by plating of cells onto poly-L-lysine abrogated both Erk1/2 and p53 activations in colcemid-treated cells, while plating of cells onto fibronectin caused transient up-regulation of p53 even in the absence of colcemid. Pre-treatment of cells with the specific MEK1 inhibitor PD098059 also attenuated colcemid-induced p53 activation and G1 cell cycle arrest. Cell types which either failed to develop focal adhesions in response to colcemid treatment (human MCF-7 epithelial cells), or lacked colcemid-induced sustained Erk activation (primary mouse embryo fibroblasts and 12(1) cells) showed virtually no p53 up-regulation in response to disruption of microtubules during G0/G1. Our results indicate that p53 activation is not triggered by disintegration of microtubule system by itself, but rather originates from some of the consequences of such disintegration, in particular, from the development of focal adhesions leading to activation of Erk signaling pathway.
authors: Institute of Cancerogenesis, Russian Cancer Research Center, Moscow, Russia.
authors: A A
authors: AA
authors: Sablina
authors: P M
authors: PM
authors: Chumakov
authors: A J
authors: AJ
authors: Levine
authors: B P
authors: BP
authors: Kopnin
mesh_terms: D000818:Animals; D003703:Demecolcine / Q000494:pharmacology; D005353:Fibronectins / Q000494:pharmacology; D022001:Focal Adhesions; D016193:G1 Phase; D006801:Humans; D048369:MAP Kinase Kinase 1; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D016196:S Phase; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D015854:Up-Regulation
chemical_list: D005353:Fibronectins; D016159:Tumor Suppressor Protein p53; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D003703:Demecolcine