The F-box protein Fbxo7 interacts with human inhibitor of apoptosis protein cIAP1 and promotes cIAP1 ubiquitination.
Human cIAP1 protein is a member of the inhibitor of apoptosis proteins (IAPs) that are involved in apoptosis regulation and an increasing number of other functions, including cell cycle and intracellular signal transduction. In order to identify novel proteins involved in cIAP1 regulation, we performed a yeast two-hybrid screen and identified an F-box protein Fbxo7 as a cIAP1 interacting protein. Co-immunoprecipitation assay showed that cIAP1 can interact with Fbxo7 in human cells. When co-expressed in cells, cIAP1 and Fbxo7 co-localized remarkably both in the cytoplasm and nucleus, and considerable amounts of these often co-localized at one or few distinct Golgi-like structures close to the nucleus. Furthermore, we showed that overexpression of Fbxo7 promotes the ubiquitination of cIAP1. Since F-box proteins are specificity determining subunits of SCF ubiquitin protein ligases, our results suggest that Fbxo7 can mediate the ubiquitination of cIAP1 by SCF ubiquitin protein ligase and thus have important implication in the regulation of cIAP1 function.
Chang
Yung-Fu
YF
Faculty of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC.
Cheng
Chih-Mei
CM
Chang
Li-Kwan
LK
Jong
Yuh-Jyh
YJ
Yuo
Chung-Yee
CY
D002478:Cells, Cultured; D044783:F-Box Proteins / Q000378:metabolism*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D025941:Protein Interaction Mapping; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism*
D044783:F-Box Proteins; C489149:FBXO7 protein, human; D051034:Inhibitor of Apoptosis Proteins; D025801:Ubiquitin