Transcriptional Repression of High-Mobility Group Box 2 by p21 in Radiation-Induced Senescence

  • Kim, Hyun-Kyung (Division of Applied Radiation Bioscience, Korea Institute of Radiological and Medical Sciences) ;
  • Kang, Mi Ae (Division of Applied Radiation Bioscience, Korea Institute of Radiological and Medical Sciences) ;
  • Kim, Mi-Sook (Department of Radiation Oncology, Korea Institute of Radiological and Medical Sciences) ;
  • Shin, Young-Joo (Department of Radiation Oncology, Inje University Sanggye Paik Hospital) ;
  • Chi, Sung-Gil (Department of Life Sciences, Korea University) ;
  • Jeong, Jae-Hoon (Division of Applied Radiation Bioscience, Korea Institute of Radiological and Medical Sciences)
  • Received : 2017.11.06
  • Accepted : 2018.01.28
  • Published : 2018.04.30


High mobility group box 2 (HMGB2) is an abundant, chromatin-associated, non-histone protein involved in transcription, chromatin remodeling, and recombination. Recently, the HMGB2 gene was found to be significantly downregulated during senescence and shown to regulate the expression of senescent-associated secretory proteins. Here, we demonstrate that HMGB2 transcription is repressed by p21 during radiation-induced senescence through the ATM-p53-p21 DNA damage signaling cascade. The loss of p21 abolished the downregulation of HMGB2 caused by ionizing radiation, and the conditional induction of p21 was sufficient to repress the transcription of HMGB2. We also showed that the p21 protein binds to the HMGB2 promoter region, leading to sequestration of RNA polymerase and transcription factors E2F1, Sp1, and p300. In contrast, NF-Y, a CCAAT box-binding protein complex, is required for the expression of HMGB2, but NF-Y binding to the HMGB2 promoter was unaffected by either radiation or p21 induction. A proximity ligation assay results confirmed that the chromosome binding of E2F1 and Sp1 was inhibited by p21 induction. As HMGB2 have been shown to regulate premature senescence by IR, targeting the p21-mediated repression of HMGB2 could be a strategy to overcome the detrimental effects of radiation-induced senescence.


HMGB2;p21;radiation;senescence;transcription repression


Supported by : Korea Institute of Radiological and Medical Sciences (KIRAMS), National Research Foundation of Korea (NRF)


  1. Aird, K.M., Iwasaki, O., Kossenkov, A.V., Tanizawa, H., Fatkhutdinov, N., Bitler, B.G., Le, L., Alicea, G., Yang, T.L., Johnson, F.B., et al. (2016). HMGB2 orchestrates the chromatin landscape of senescence-associated secretory phenotype gene loci. J. Cell Biol. 215, 325-334.
  2. Bianchi, M.E., and Agresti, A. (2005). HMG proteins: dynamic players in gene regulation and differentiation. Curr. Opin. Genet. Dev. 15, 496-506.
  3. Davalos, A.R., Coppe, J.P., Campisi, J., and Desprez, P.Y. (2010). Senescent cells as a source of inflammatory factors for tumor progression. Cancer Metastasis Rev. 29, 273-283.
  4. Devgan, V., Mammucari, C., Millar, S.E., Brisken, C., and Dotto, G.P. (2005). p21WAF1/Cip1 is a negative transcriptional regulator of Wnt4 expression downstream of Notch1 activation. Genes Dev.19, 1485-1495.
  5. Dimri, G.P., Lee, X., Basile, G., Acosta, M., Scott, G., Roskelley, C., Medrano, E.E., Linskens, M., Rubelj, I., Pereira-Smith, O., et al. (1995). A biomarker that identifies senescent human cells in culture and in aging skin in vivo. Proc. Natl. Acad. Sci. USA 92, 9363-9367.
  6. Fagan, R., Flint, K.J., and Jones, N. (1994). Phosphorylation of E2F-1 modulates its interaction with the retinoblastoma gene product and the adenoviral E4 19 kDa protein. Cell 78, 799-811.
  7. Ferrandiz, N., Caraballo, J.M., Garcia-Gutierrez, L., Devgan, V., Rodriguez-Paredes, M., Lafita, M.C., Bretones, G., Quintanilla, A., Munoz-Alonso, M.J., Blanco, R., et al. (2012). p21 as a transcriptional co-repressor of S-phase and mitotic control genes. PloS One 7, e37759.
  8. Fischer, M., Quaas, M., Steiner, L., and Engeland, K. (2016). The p53-p21-DREAM-CDE/CHR pathway regulates G2/M cell cycle genes. Nucleic Acids Res. 44, 164-174.
  9. Harper, J.W., Adami, G.R., Wei, N., Keyomarsi, K., and Elledge, S.J. (1993). The p21 Cdk-interacting protein Cip1 is a potent inhibitor of G1 cyclin-dependent kinases. Cell 75, 805-816.
  10. Hayflick, L., and Moorhead, P.S. (1961). The serial cultivation of human diploid cell strains. Exp. Cell Res. 25, 585-621.
  11. Kuilman, T., Michaloglou, C., Mooi, W.J., and Peeper, D.S. (2010). The essence of senescence. Genes Dev. 24, 2463-2479.
  12. Lagger, G., Doetzlhofer, A., Schuettengruber, B., Haidweger, E., Simboeck, E., Tischler, J., Chiocca, S., Suske, G., Rotheneder, H., Wintersberger, E., et al. (2003). The tumor suppressor p53 and histone deacetylase 1 are antagonistic regulators of the cyclindependent kinase inhibitor p21/WAF1/CIP1 gene. Mol. Cell. Biol. 23, 2669-2679.
  13. Li, Y., Jenkins, C.W., Nichols, M.A., and Xiong, Y. (1994). Cell cycle expression and p53 regulation of the cyclin-dependent kinase inhibitor p21. Oncogene 9, 2261-2268.
  14. Livak, K.J., and Schmittgen, T.D.(2001). Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) method. Methods 25, 402-408.
  15. Lopez-Otin, C., Blasco, M.A., Partridge, L., Serrano, M., and Kroemer, G. (2013). The hallmarks of aging. Cell 153, 1194-1217.
  16. Malarkey, C.S., and Churchill, M.E. (2012). The high mobility group box: the ultimate utility player of a cell. Trend. Biochem. Sci. 37, 553-562.
  17. Quaas, M., Muller, G.A., and Engeland, K. (2012). p53 can repress transcription of cell cycle genes through a p21(WAF1/CIP1)-dependent switch from MMB to DREAM protein complex binding at CHR promoter elements. Cell Cycle 11, 4661-4672.
  18. Shin, Y.J., Kim, M.S., Kim, M.S., Lee, J., Kang, M., and Jeong, J.H. (2013). High-mobility group box 2 (HMGB2) modulates radioresponse and is downregulated by p53 in colorectal cancer cell. Cancer Biol. Ther. 14, 213-221.
  19. Taniguchi, N., Carames, B., Ronfani, L., Ulmer, U., Komiya, S., Bianchi, M.E., and Lotz, M., (2009). Aging-related loss of the chromatin protein HMGB2 in articular cartilage is linked to reduced cellularity and osteoarthritis. Proc. Natl. Acad. Sci. USA 106, 1181-1186.
  20. Taniguchi, N., Kawakami, Y., Maruyama, I., and Lotz, M. (2017). HMGB proteins and arthritis. Hum. Cell 31, 1-9.
  21. Thomas, J.O. (2001). HMG1 and 2: architectural DNA-binding proteins. Biochem. Soc. Trans. 29(Pt 4), 395-401.
  22. van Deursen, J.M. (2014). The role of senescent cells in ageing. Nature 509, 439-446.
  23. Xiong, Y., Hannon, G.J., Zhang, H., Casso, D., Kobayashi, R., and Beach, D. (1993). p21 is a universal inhibitor of cyclin kinases. Nature 366, 701-704.