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- Title
CITED2 mediates the paradoxical responses of HIF-1α to proteasome inhibition.
- Authors
Shin, D. H.; Li, S. H.; Chun, Y.-S.; Huang, L. E.; Kim, M.-S.; Park, J.-W.
- Abstract
Hypoxia-inducible factor-1α (HIF-1α) is destabilized via the ubiquitin–proteasome system. Thus HIF-1α expression is robustly upregulated by proteasome inhibition, but paradoxically its activity is reduced. In the present study, we investigated the mechanism underlying the paradoxical response of HIF-1α to proteasome inhibition. In both Hep3B and HEK293 cells, a proteasome inhibitor MG132 noticeably attenuated hypoxic induction of erythropoietin and VEGF mRNAs. MG132 inactivated HIF-1α C-terminal transactivation domain (CAD), independently of factor inhibiting HIF-1 (FIH) and inhibited p300 recruitment by HIF-1α. We next tested the possibility that CITED2 is involved in the HIF-1 inactivation. CITED2 was found to be degraded via the ubiquitin–proteasome system and thus was stabilized by proteasome inhibition. Both the activity and the p300 binding of HIF-1α were inhibited by CITED2 expression and recovered by CITED2 siRNA in the presence of MG132. These results suggest that CITED2 is stabilized by proteasome inhibition and inactivates HIF-1 by interfering with the HIF-1α–p300 interaction. This may be an important mode-of-action for proteasome inhibition-based cancer therapy.Oncogene (2008) 27, 1939–1944; doi:10.1038/sj.onc.1210826; published online 1 October 2007
- Subjects
CANCER treatment; CELL communication; GENE expression; RNA polymerases; HEMATOPOIETIC growth factors; PROTEIN binding
- Publication
Oncogene, 2008, Vol 27, Issue 13, p1939
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/sj.onc.1210826