title: Death effector domain DEDa, a self-cleaved product of caspase-8/Mch5, translocates to the nucleus by binding to ERK1/2 and upregulates procaspase-8 expression via a p53-dependent mechanism.
abstract: Activation of the apical caspase-8 is crucial to the extrinsic apoptotic pathway. Although the death effector domain (DED) of caspase-8 has been reported to be involved in death-inducing signaling complex formation, the detailed mechanism of how DED functions in regulating apoptosis remains largely unknown. Here, we demonstrate that the prodomain of the caspase-8/Mch5 can be further cleaved between two tandemly repeated DEDs (DEDa-DEDb) at the amino-acid residue Asp129 by caspase-8 itself. The DEDa fragment generated from the endogenous caspase-8 was detected in isolated nucleoli upon treatment with TRAIL (tumor necrosis factor-related apoptosis-inducing ligand). Cleaved DEDa appears to translocate into the nucleus by association with extracellular signal-regulated protein kinases-1/2 (ERK1/2). Elimination of ERK1/2 expression by RNA interference resulted in a significant attenuation of nuclear entry of DEDa and reduced caspase-8-dependent apoptosis. In the nucleus, DEDa interacts with TOPORS, a p53 and topoisomerase I binding protein, and possibly displaces p53 from TOPORS, allowing p53 to stimulate caspase-8 gene expression. In summary, we postulate a positive feedback loop involving DEDa, which enables the continual replenishment of procaspase-8 during apoptosis.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Yao
authors.forename: Shanshan
authors.initials: S
authors.lastname: Duan
authors.forename: Dezhi
authors.initials: D
authors.lastname: Hou
authors.forename: Klaus
authors.initials: K
authors.lastname: Heese
authors.forename: Mian
authors.initials: M
authors.lastname: Wu
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics* / Q000502:physiology; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8 / Q000235:genetics* / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D053837:DNA Cleavage; D004268:DNA-Binding Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D014157:Transcription Factors / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C120157:TOPORS protein, human; D044767:Ubiquitin-Protein Ligases; D048052:Mitogen-Activated Protein Kinase 3; D053181:Caspase 8