Abstract
Loss of p53-dependent apoptosis contributes to the development of hematologic malignancies and failure to respond to treatment. Proapoptotic Bcl-2 family member Puma is essential for apoptosis in HoxB8-immortalized interleukin-3 (IL-3)-dependent myeloid cell lines (FDM cells) provoked by IL-3 deprivation. p53 and FoxO3a can transcriptionally regulate Puma. To investigate which transcriptional regulator is responsible for IL-3 deprivation-induced Puma expression and apoptosis, we generated wild-type (WT), p53(-/-), and FoxO3a(-/-) FDM cells and found that p53(-/-) but not FoxO3a(-/-) cells were protected against IL-3 withdrawal. Loss of p21(cip/waf), which is critical for p53-mediated cell-cycle arrest, afforded no protection against IL-3 deprivation. A survival advantage was also observed in untransformed p53(-/-) hematopoietic progenitor cells cultured in the presence or absence of cytokines. In response to IL-3 deprivation, increased Puma protein levels in p53(-/-) cells were substantially delayed compared with WT cells. Increased p53 transcriptional activity was detected after cytokine deprivation. This was substantially less than that induced by DNA damage and associated not with increased p53 protein levels but with loss of the p53 regulator, MDM2. Thus, we conclude that p53 protein is activated after IL-3 deprivation by loss of MDM2. Activated p53 transcriptionally up-regulates Puma, which initiates apoptosis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Apoptosis Regulatory Proteins / biosynthesis*
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Apoptosis Regulatory Proteins / genetics
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Apoptosis*
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Cell Line, Tumor
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Cell Survival / drug effects
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Cell Survival / genetics
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Cyclin-Dependent Kinase Inhibitor p21 / genetics
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Cyclin-Dependent Kinase Inhibitor p21 / metabolism
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DNA Damage / drug effects
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DNA Damage / genetics
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Forkhead Box Protein O3
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Forkhead Transcription Factors / genetics
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Forkhead Transcription Factors / metabolism
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Gene Deletion
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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Interleukin-3 / metabolism*
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Interleukin-3 / pharmacology
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Mice
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Myeloid Progenitor Cells / cytology
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Myeloid Progenitor Cells / metabolism*
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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Proto-Oncogene Proteins c-mdm2 / genetics
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Proto-Oncogene Proteins c-mdm2 / metabolism
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Time Factors
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Transcription, Genetic / drug effects
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Transcription, Genetic / genetics
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism*
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Tumor Suppressor Proteins / biosynthesis*
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Tumor Suppressor Proteins / genetics
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Up-Regulation*
Substances
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Apoptosis Regulatory Proteins
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Cdkn1a protein, mouse
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Cyclin-Dependent Kinase Inhibitor p21
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Forkhead Box Protein O3
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Forkhead Transcription Factors
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FoxO3 protein, mouse
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Homeodomain Proteins
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Hoxb8 protein, mouse
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Interleukin-3
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PUMA protein, mouse
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Proto-Oncogene Proteins c-bcl-2
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Tumor Suppressor Protein p53
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Tumor Suppressor Proteins
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Mdm2 protein, mouse
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Proto-Oncogene Proteins c-mdm2