Abstract
The protein Puma (p53-upregulated modulator of apoptosis) belongs to the BH3-only group of the Bcl-2 family and is a major regulator of apoptosis. Although the transcriptional regulation of Puma is clearly established, little is known about the regulation of its expression at the protein levels. We show here that various signals--including the cytokine TGFβ, the death effector TRAIL or chemical drugs such as anisomycin--downregulate Puma protein levels via a novel pathway based on the sequential activation of caspase-3 and a protease inhibited by the serpase inhibitor N-tosyl-L-phenylalanine chloromethyl ketone. This pathway is specific for Puma because (1) the levels of other BH3-only proteins, such as Bim and Noxa were not modified by these stimuli and (2) this caspase-mediated degradation was dependent on both the BH3 and C-terminal domains of Puma. Our data also show that Puma is regulated during the caspase-3-dependent differentiation of murine embryonic stem cells and suggest that this pathway may be relevant and important during caspase-mediated cell differentiation not associated with 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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Anisomycin / pharmacology
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Apoptosis Regulatory Proteins* / genetics
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Apoptosis Regulatory Proteins* / metabolism
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Caspase 3* / metabolism
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Cell Differentiation / drug effects*
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Cell Differentiation / physiology*
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Cell Line, Tumor
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Embryonic Stem Cells / drug effects*
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Embryonic Stem Cells / metabolism*
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Enzyme Inhibitors / pharmacology
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Gene Silencing / physiology
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Humans
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Mice
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Peptide Fragments / physiology*
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Protein Structure, Tertiary
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins / physiology*
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Serine Proteases* / metabolism
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Signal Transduction / drug effects*
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Signal Transduction / physiology*
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TNF-Related Apoptosis-Inducing Ligand / genetics
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TNF-Related Apoptosis-Inducing Ligand / pharmacology*
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Tosylphenylalanyl Chloromethyl Ketone* / pharmacology
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Transforming Growth Factor beta / genetics
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Transforming Growth Factor beta / pharmacology*
Substances
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Apoptosis Regulatory Proteins
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BBC3 protein, human
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Bax protein (53-86)
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Enzyme Inhibitors
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Peptide Fragments
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Proto-Oncogene Proteins
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TNF-Related Apoptosis-Inducing Ligand
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Transforming Growth Factor beta
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Tosylphenylalanyl Chloromethyl Ketone
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Anisomycin
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Serine Proteases
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Caspase 3