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Actin has participated various kinds of functions extensively, such as amoeboid motion, cytokinesis, to maintain the morphous and so on, in eukaryotic cells by microfilament in cytoplasm. It has been comprehended deeply in nucleolus. It is known that nuclear actin can execution various kinds of function, such as chromatin remodeling,gene transcriptional regulation, mRNA processing and export, DNA damage and repair and mitosis, and so far. There are usually three states, which are F-Actin, oligomer, G-Actin. F-Actin usually exists in cytoplasm, and G-Actin principal in nucleolus, and it is reported that F-Actin can interchange with G-Actin.As a tumor suppressor gene, p53 is also a high-performance transcription factor. They can be epigenetic modification, like phosphorylation, acetylation, and others. Of these sites, 15 serine, 18 threonine and 20 serine are very important, as they can play a significance role when p53 interaction with targeting protein,regulating the expression of the downstream genic. P53 is low expression in normal cells. But it will be activated, then enter into nucleolus to participate in many physiological Processes, such as mitotic cycle restraining, genetic transcription regulation, programmed cell death and over expression, etc in tumor cells or DNA damage cells. Most p53 is mutated in tumor cells, but it is unknown that the interaction between different formation actin and mutational p53.We mainly discussed whether actin interaction with p53 to complete determinate physiological processes in p53 defect cells in unstressed condition. Experimental result shows that actin can mutual effect with p53 in its defect cells, and it is interesting that this mutual effect will be abolition when the three amine acid of p53 are all changed into alanine. In order to further investigate the effect between its series mutant protein and actin, we use actin depolymerization restrain drug jasplakinolide and actin polymerization restrain drug cytochalasinD to stimulation PC3(P53-/-) cells, which have been transfected with p53 or its series mutant plasmids, then co-immunoprecipitation, the result shows that it is co-immunoprecipitation with wtp53 or unit point plasmids S15A,T18A,S20A and actin, but the p53 which the transcriptional activation domain ahead 1-41 amine acid missing or 15,18,20 are all changed into alanine can co-immunoprecipitation with F-Actin. The result also shows that G-Actin co-immunoprecipitate with wtp53 or unit point plasmids which are S15A,T18A,S20A, in background level, and the p53 which the ahead 1-41 amine acid missing or 15,18,20 are all changed into alanine can’t interact with G-Actin. These results display all the three points are changed into alanine of p53 will influence the interaction between p53 and actin.
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