The relationship of p53 and stress proteins in response to bleomycin and retinoic acid in the p53 heterozygous mouse

A single, i.p. dose of bleomycin was administered simultaneously with [S-35 ]methionine to 4-month-old p53 wild type (+/+) and p53 heterozygous (+/-) C 57BL/6 mice. Following a period of 3.5 h from dosing, the bone marrow nucle i were examined by two-dimensional PAGE and fluorography for induction of s tress proteins (sps). Eight sps ranging from 22 000 to 100 000 M-r were syn thesized in p53+/- and p53+/+ mice following elicitation by bleomycin. No q uantitative or qualitative differences were observed in sp expression in th ese two groups of animals. In a second experiment, three doses of retinoic acid were given i.p. to p53+/- and p53+/+ mice over a 36 h period. The p53 isoforms in bone marrow nuclei from these mice were analyzed by PAGE for in corporation of [S-35]methionine following retinoic acid injections. Quantit ative and qualitative alterations in p53 isotypes were substantially increa sed in p53+/+ as compared with p53+/- mice. The increased complexity in the synthesis patterns in both groups of dosed mice consisted of additional is oforms possessing more acidic isoelectric values. In an in vitro binding as say, individual p53 isoforms demonstrated varying degrees of association wi th sps 25a, 70i, 72c and 90 which was consistently greater in p53+/+ mice. Both the synthesis and binding of isoforms were greater in G(1) than in S+G (2) phase, in both groups of animals, reflecting a cell cycle regulated mec hanism for these events. Collectively, these data implied that the synthesi s and the binding characteristics of p53 isoforms with sps were enhanced in the p53+/+ mice relative to the p53+/- mouse; however, sp labeling was not affected by p53 genotype. (C) 1999 Elsevier Science B.V. All rights reserv ed.