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SAG/ROC2/RBX2 is a HIF-1 target gene that promotes HIF-1α ubiquitination and degradation

Oncogene volume 27, pages 1404–1411 (2008)Cite this article

Abstract

SAG (sensitive to apoptosis gene) or ROC2/RBX2 is the second family member of ROC1/RBX1, a component of SCF (Skp1, Cullin, F-box protein) and VCB (von Hippel–Lindau (VHL), Cullin and Elongin B/C) E3 ubiquitin ligases. SAG protected cells from hypoxia-induced apoptosis when overexpressed. We report here that SAG was subjected to hypoxia induction at the levels of mRNA and protein. Hypoxia induction of SAG was largely HIF-1α dependent. A consensus HIF-1-binding site, GCGTG was identified in the first intron of the SAG gene. In response to hypoxia, HIF-1 bound to this site and transactivated SAG expression. SAG transactivation required both the intact binding site in cis and HIF-1α in trans. On the other hand, like its family member, ROC1, SAG promoted VHL-mediated HIF-1α ubiquitination and degradation, which was significantly inhibited upon small interfering RNA silencing of SAG or ROC1. Furthermore, the endogenous HIF-1α at both basal and hypoxia-induced levels was significantly increased upon SAG silencing. Finally, SAG forms in vivo complex with Cul-5 and VHL under hypoxia condition. These results suggest an HIF-1-SAG feedback loop in response to hypoxia, as follows: hypoxia induces HIF-1 to transactivate SAG. Induced SAG then promotes HIF-1α ubiquitination and degradation. This feedback loop may serve as a cellular defensive mechanism to reduce potential cytotoxic effects of prolonged HIF-1 activation under hypoxia.

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References

  • Chanalaris A, Sun Y, Latchman DS, Stephanou A . (2003). SAG attenuates apoptotic cell death caused by simulated ischaemia/reoxygenation in rat cardiomyocytes. J Mol Cell Cardiol 35: 257–264.

    Article  CAS  Google Scholar 

  • Corn PG, McDonald III ER, Herman JG, El-Deiry WS . (2003). Tat-binding protein-1, a component of the 26S proteasome, contributes to the E3 ubiquitin ligase function of the von Hippel–Lindau protein. Nat Genet 35: 229–237.

    Article  CAS  Google Scholar 

  • Duan H, Wang Y, Aviram M, Swaroop M, Loo JA, Bian J et al. (1999). SAG, a novel zinc RING finger protein that protects cells from apoptosis induced by redox agents. Mol Cell Biol 19: 3145–3155.

    Article  CAS  Google Scholar 

  • Feldser D, Agani F, Iyer NV, Pak B, Ferreira G, Semenza GL . (1999). Reciprocal positive regulation of hypoxia-inducible factor 1alpha and insulin-like growth factor 2. Cancer Res 59: 3915–3918.

    CAS  Google Scholar 

  • Forsythe JA, Jiang BH, Iyer NV, Agani F, Leung SW, Koos RD et al. (1996). Activation of vascular endothelial growth factor gene transcription by hypoxia-inducible factor 1. Mol Cell Biol 16: 4604–4613.

    Article  CAS  Google Scholar 

  • Gu Q, Tan M, Sun Y . (2007). SAG/ROC2/Rbx2 is a novel AP-1 target that promotes c-Jun degradation and inhibits TPA induced neoplastic transformation. Cancer Res 67: 3616–3625.

    Article  CAS  Google Scholar 

  • Harris AL . (2002). Hypoxia—a key regulatory factor in tumour growth. Nat Rev Cancer 2: 38–47.

    Article  CAS  Google Scholar 

  • Ivan M, Kondo K, Yang H, Kim W, Valiando J, Ohh M et al. (2001). HIFalpha targeted for VHL-mediated destruction by proline hydroxylation: implications for O2 sensing. Science 292: 464–468.

    Article  CAS  Google Scholar 

  • Jaakkola P, Mole DR, Tian YM, Wilson MI, Gielbert J, Gaskell SJ et al. (2001). Targeting of HIF-alpha to the von Hippel–Lindau ubiquitylation complex by O2-regulated prolyl hydroxylation. Science 292: 468–472.

    Article  CAS  Google Scholar 

  • Kamura T, Conrad MN, Yan Q, Conaway RC, Conaway JW . (1999a). The Rbx1 subunit of SCF and VHL E3 ubiquitin ligase activates Rub1 modification of cullins Cdc53 and Cul2. Genes Dev 13: 2928–2933.

    Article  CAS  Google Scholar 

  • Kamura T, Koepp DM, Conrad MN, Skowyra D, Moreland RJ, Iliopoulos O et al. (1999b). Rbx1, a component of the VHL tumor suppressor complex and SCF ubiquitin ligase. Science 284: 657–661.

    Article  CAS  Google Scholar 

  • Kamura T, Maenaka K, Kotoshiba S, Matsumoto M, Kohda D, Conaway RC et al. (2004). VHL-box and SOCS-box domains determine binding specificity for Cul2-Rbx1 and Cul5-Rbx2 modules of ubiquitin ligases. Genes Dev 18: 3055–3065.

    Article  CAS  Google Scholar 

  • Kamura T, Sato S, Iwai K, Czyzyk-Krzeska M, Conaway RC, Conaway JW . (2000). Activation of HIF1alpha ubiquitination by a reconstituted von Hippel–Lindau (VHL) tumor suppressor complex. Proc Natl Acad Sci USA 97: 10430–10435.

    Article  CAS  Google Scholar 

  • Kim SY, Lee JH, Yang ES, Kil IS, Bae YS . (2003). Human sensitive to apoptosis gene protein inhibits peroxynitrite-induced DNA damage. Biochem Biophys Res Commun 301: 671–674.

    Article  CAS  Google Scholar 

  • Lando D, Peet DJ, Whelan DA, Gorman JJ, Whitelaw ML . (2002). Asparagine hydroxylation of the HIF transactivation domain a hypoxic switch. Science 295: 858–861.

    Article  CAS  Google Scholar 

  • Maxwell PH, Wiesener MS, Chang GW, Clifford SC, Vaux EC, Cockman ME et al. (1999). The tumour suppressor protein VHL targets hypoxia-inducible factors for oxygen-dependent proteolysis. Nature 399: 271–275.

    Article  CAS  Google Scholar 

  • Ohta T, Michel JJ, Schottelius AJ, Xiong Y . (1999). ROC1, a homolog of APC11, represents a family of cullin partners with an associated ubiquitin ligase activity. Mol Cell 3: 535–541.

    Article  CAS  Google Scholar 

  • Pugh CW, Ratcliffe PJ . (2003). The von Hippel–Lindau tumor suppressor, hypoxia-inducible factor-1 (HIF-1) degradation, and cancer pathogenesis. Semin Cancer Biol 13: 83–89.

    Article  CAS  Google Scholar 

  • Sun Y . (2006). p53 and its downstream proteins as molecular targets of cancer. Mol Carcinog 45: 409–415.

    Article  CAS  Google Scholar 

  • Sun Y, Tan M, Duan H, Swaroop M . (2001). SAG/ROC/Rbx/Hrt, a zinc RING finger gene family: molecular cloning, biochemical properties, and biological functions. Antioxid Redox Signal 3: 635–650.

    Article  CAS  Google Scholar 

  • Swaroop M, Bian J, Aviram M, Duan H, Bisgaier CL, Loo JA et al. (1999). Expression, purification, and biochemical characterization of SAG, a RING finger redox sensitive protein. Free Radicals Biol Med 27: 193–202.

    Article  CAS  Google Scholar 

  • Tazuke SI, Mazure NM, Sugawara J, Carland G, Faessen GH, Suen LF et al. (1998). Hypoxia stimulates insulin-like growth factor binding protein 1 (IGFBP-1) gene expression in HepG2 cells: a possible model for IGFBP-1 expression in fetal hypoxia. Proc Natl Acad Sci USA 95: 10188–10193.

    Article  CAS  Google Scholar 

  • Wang GL, Jiang BH, Rue EA, Semenza GL . (1995). Hypoxia-inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension. Proc Natl Acad Sci USA 92: 5510–5514.

    Article  CAS  Google Scholar 

  • Wu X, Bayle JH, Olson D, Levine AJ . (1993). The p53-mdm-2 autoregulatory feedback loop. Genes Dev 7: 1126–1132.

    Article  CAS  Google Scholar 

  • Yang GY, Pang L, Ge HL, Tan M, Ye W, Liu XH et al. (2001). Attenuation of ischemia-induced mouse brain injury by SAG, a redox-inducible antioxidant protein. J Cereb Blood Flow Metab 21: 722–733.

    Article  CAS  Google Scholar 

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Acknowledgements

We thank Dr Wafik El-Deiry at the University of Pennsylvania for plasmids expressing HIF-1α, VHL and VHL mutant (VHL-Y98L), Dr Bing-Hua Jiang at West Virginia University for VEGF-luciferase reporter construct. This work is supported by the NCI grants (CA111554, CA116982 and CA118762) to YS.

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Authors and Affiliations

  1. Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI, USA

    M Tan, Q Gu, H He, D Pamarthy & Y Sun

  2. Departments of Pediatrics, Vascular Biology Program, Institute for Cell Engineering, Medicine, Oncology, Radiation Oncology, McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA

    G L Semenza

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  1. M Tan
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  2. Q Gu
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Correspondence to Y Sun.

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Tan, M., Gu, Q., He, H. et al. SAG/ROC2/RBX2 is a HIF-1 target gene that promotes HIF-1α ubiquitination and degradation. Oncogene 27, 1404–1411 (2008). https://doi.org/10.1038/sj.onc.1210780

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