Critical and functional regulation of CHOP (C/EBP homologous protein) through the N-terminal portion.
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Ohoka N, Hattori T, Kitagawa M, Onozaki K, Hayashi H
Critical and functional regulation of CHOP (C/EBP homologous protein) through the N-terminal portion.
J Biol Chem. 2007 Dec 7;282(49):35687-94. Epub 2007 Sep 14.
- PubMed ID
- 17872950 [ View in PubMed]
- Abstract
C/EBP homologous protein (CHOP) is an endoplasmic reticulum stress-inducible protein that plays a critical role in the regulation of programmed cell death; however, the regulation of its function has not been well characterized. We have previously demonstrated that CHOP is regulated by the ubiquitin-proteasome system. In this study, during the process of clarifying the mechanism of the degradation of CHOP, we identified a novel regulation domain of CHOP in its N-terminal portion that is involved in various regulations and functions. The CHOP N-terminal domain is necessary not only for protein degradation but also for its transactivity and interaction with p300. In addition, trichostatin A, a histone deacetylase inhibitor, repressed the degradation of CHOP protein via the N-terminal domain. TRB3, a mammalian tribbles homolog that functions as a repressor of CHOP, also interacted with CHOP via the N-terminal portion and significantly blocked the association of p300 with CHOP. These results suggest that the N-terminal portion of CHOP plays a crucial role in its functional regulation and enable us to identify a novel function of TRB3 as an intracellular antagonist of the p300-binding domain of CHOP.