title: Teratogen-induced activation of p53 in early postimplantation mouse embryos.
abstract: Hyperthermia (HS) and 4-hydroperoxycyclophosphamide (4CP) activate the mitochondrial apoptotic pathway in day 9 mouse embryos. Previous microarray analyses Microarray analyses revealed that several p53 target genes are upregulated after exposure to HS or 4CP, suggesting a role for p53 in teratogen-induced apoptosis. To explore the role of p53, we assessed the activation of p53 in day 9 mouse embryos exposed to HS or 4CP in vitro. Both teratogens induced the accumulation of p53 and phosphorylation of p53 at ser-15, two hallmarks of p53 activation. HS and 4CP also induced an increase in Noxa and Puma mRNAs, transcripts of two known proapoptotic p53 target genes; however, these two teratogens did not induce significant increases in NOXA and PUMA proteins, suggesting that p53 does not activate the mitochondrial apoptotic pathway by transcriptionally upregulating the expression of NOXA and PUMA proteins. HS and 4CP also induced the expression of p21 mRNA and protein, suggesting a role for p53 in teratogen-induced cell cycle arrest. Previously, we also showed that HS and 4CP activate the apoptotic pathway in the embryo proper (head and trunk) but not in the heart. We now show that HS and 4CP induce a robust activation of p53 in the embryo proper but an attenuated induction in the heart. HS and 4CP induce the expression of p21 protein in majority of the cells in the embryo; however, expression of NOXA and PUMA proteins were not significantly induced in heads, hearts, or trunks of day 9 embryos. Overall, our results suggest that p53 may play a transcription-dependent role in teratogen-induced cell cycle arrest but a transcription-independent role in teratogen-induced apoptosis in day 9 mouse embryos exposed to HS or 4CP.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, MS4466 435 VMR Building, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Hosako
authors.forename: Sally A
authors.initials: SA
authors.lastname: Little
authors.forename: Marianne
authors.initials: M
authors.lastname: Barrier
authors.forename: Philip E
authors.initials: PE
authors.lastname: Mirkes
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D003520:Cyclophosphamide / Q000031:analogs & derivatives / Q000633:toxicity; D046149:Embryo Culture Techniques; D004622:Embryo, Mammalian / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D047108:Embryonic Development / Q000187:drug effects*; D006358:Hot Temperature / Q000009:adverse effects; D007700:Kinetics; D051379:Mice; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013723:Teratogens / Q000633:toxicity*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; C488588:PUMA protein, mouse; C408009:Pmaip1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D013723:Teratogens; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D003520:Cyclophosphamide; C011272:perfosfamide