title: Different impact of p53 and p21 on the radiation response of mouse tissues.
abstract: Mammalian tissues differ dramatically in their sensitivity to genotoxic stress, although the mechanisms determining these differences remain largely unknown. To analyse the role of p53 and p21 in determination of tissue specificity to DNA damage in vivo, we compared the effects of gamma radiation on DNA synthesis on whole-body sections of wild type, p53-deficient and p21-deficient mice. A dramatic reduction in 14C-thymidine incorporation after gamma irradiation was observed in the majority of rapidly proliferating tissues of wild type and p21-/- but not in p53-/- mice, confirming the key role of p53 in determination of tissue response to genotoxic stress in vivo and suggesting that p53-mediated inhibition of DNA synthesis does not depend on p21. Rapid radiation induced p53-dependent apoptosis was mapped to the areas of high levels of p53 mRNA in radiation sensitive tissues analysed (white pulp in the spleen and bases of crypts in small intestine), indicating that p53 regulation at the mRNA level is a determinant of cellular sensitivity to genotoxic stress. High p53 mRNA expression is inherited as a recessive trait in cell-cell hybrids suggesting the involvement of a negative control mechanism in the regulation of p53 gene expression.
authors.affiliation: Department of Molecular Genetics, University of Illinois at Chicago, 60607, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Komarova
authors.forename: K
authors.initials: K
authors.lastname: Christov
authors.forename: A I
authors.initials: AI
authors.lastname: Faerman
authors.forename: A V
authors.initials: AV
authors.lastname: Gudkov
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000502:physiology*; D005720:Gamma Rays; D015870:Gene Expression / Q000528:radiation effects; D005799:Genes, Dominant; D005808:Genes, Recessive; D007421:Intestine, Small / Q000166:cytology / Q000473:pathology / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D012333:RNA, Messenger; D013154:Spleen / Q000166:cytology / Q000473:pathology / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*; D014916:Whole-Body Irradiation
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53