title: Anaphase-promoting complex/cyclosome-cdh1 mediates the ubiquitination and degradation of TRB3.
abstract: We have recently demonstrated that TRB3, a novel endoplasmic reticulum (ER) stress-inducible protein, is induced by CHOP and ATF4 to regulate their function and ER stress-induced cell death; however, the regulation of TRB3 function has not been well characterized. Here we demonstrate that TRB3 is an unstable protein regulated by the ubiquitin-proteasome system. The carboxyl-terminal domain of TRB3 is necessary for protein degradation, and in this region, we found the typical D-box motif, which is a critical sequence for the anaphase-promoting complex/cyclosome (APC/C) dependent proteolysis. TRB3 proteins were stabilized by deletion of its D-box motif and interacted with APC/C coactivator proteins, Cdc20 and Cdh1. The expression level of TRB3 protein is down-regulated by over-expression of Cdh1 but not by that of Cdc20. In addition, knockdown of Cdh1 enhanced the endogenous TRB3 expression level and suppressed its ubiquitination level. These results suggest that APC/C(Cdh1) is involved in ubiquitination and down-regulating the stability of TRB3 protein.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
authors.forename: Nobumichi
authors.initials: N
authors.lastname: Ohoka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sakai
authors.forename: Kikuo
authors.initials: K
authors.lastname: Onozaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D004795:Enzyme Stability / Q000235:genetics; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism* / Q000037:antagonists & inhibitors; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D018797:Cell Cycle Proteins; D012097:Repressor Proteins; C474831:TRIB3 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D017346:Protein Serine-Threonine Kinases