title: Stress-dependent Daxx-CHIP interaction suppresses the p53 apoptotic program.
abstract: Our previous studies have implicated CHIP (carboxyl terminus of Hsp70-interacting protein) as a co-chaperone/ubiquitin ligase whose activities yield protection against stress-induced apoptotic events. In this report, we demonstrate a stress-dependent interaction between CHIP and Daxx (death domain-associated protein). This interaction interferes with the stress-dependent association of HIPK2 with Daxx, blocking phosphorylation of serine 46 in p53 and inhibiting the p53-dependent apoptotic program. Microarray analysis confirmed suppression of the p53-dependent transcriptional portrait in CHIP(+/+) but not in CHIP(-/-) heat shocked mouse embryonic fibroblasts. The interaction between CHIP and Daxx results in ubiquitination of Daxx, which is then partitioned to an insoluble compartment of the cell. In vitro ubiquitination of Daxx by CHIP revealed that ubiquitin chain formation utilizes non-canonical lysine linkages associated with resistance to proteasomal degradation. The ubiquitination of Daxx by CHIP utilizes lysines 630 and 631 and competes with the sumoylation machinery of the cell at these residues. These studies implicate CHIP as a stress-dependent regulator of Daxx that counters the pro-apoptotic influence of Daxx in the cell. By abrogating p53-dependent apoptotic pathways and by ubiquitination competitive with Daxx sumoylation, CHIP integrates the proteotoxic stress response of the cell with cell cycle pathways that influence cell survival.
authors.affiliation: Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, North Carolina 27599-7126, USA.
authors.forename: Holly
authors.initials: H
authors.lastname: McDonough
authors.forename: Peter C
authors.initials: PC
authors.lastname: Charles
authors.forename: Eleanor G
authors.initials: EG
authors.lastname: Hilliard
authors.forename: Shu-Bing
authors.initials: SB
authors.lastname: Qian
authors.forename: Jin-Na
authors.initials: JN
authors.lastname: Min
authors.forename: Andrea
authors.initials: A
authors.lastname: Portbury
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Cyr
authors.forename: Cam
authors.initials: C
authors.lastname: Patterson
mesh_terms: D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D056970:Co-Repressor Proteins; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D020869:Gene Expression Profiling; D018869:Heat-Shock Response; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D051379:Mice; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism; D012995:Solubility; D013312:Stress, Physiological; D013379:Substrate Specificity; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D056970:Co-Repressor Proteins; C491473:Daxx protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D016159:Tumor Suppressor Protein p53; C492951:Stub1 protein, mouse; D044767:Ubiquitin-Protein Ligases; C492003:Hipk2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D008239:Lysine