• Authors: Mamouni, K., Cristini, A., Guirouilh-Barbat, J., Monferran, S., Lemarie, A., Faye, J. C., Lopez, B. S., Favre, G., Sordet, O.
  • Year: 2014
  • Journal: Mol Cell Biol 34 3144-55
  • Applications: in vitro / DNA / jetPEI
  • Cell types:
    1. Name: GC.92
      Known as: lambda92
    2. Name: RG37
      Description: Human SV-40 immortalized fibroblast cells


Unlike other Rho GTPases, RhoB is rapidly induced by DNA damage, and its expression level decreases during cancer progression. Because inefficient repair of DNA double-strand breaks (DSBs) can lead to cancer, we investigated whether camptothecin, an anticancer drug that produces DSBs, induces RhoB expression and examined its role in the camptothecin-induced DNA damage response. We show that in camptothecin-treated cells, DSBs induce RhoB expression by a mechanism that depends notably on Chk2 and its substrate HuR, which binds to RhoB mRNA and protects it against degradation. RhoB-deficient cells fail to dephosphorylate gammaH2AX following camptothecin removal and show reduced efficiency of DSB repair by homologous recombination. These cells also show decreased activity of protein phosphatase 2A (PP2A), a phosphatase for gammaH2AX and other DNA damage and repair proteins. Thus, we propose that DSBs activate a Chk2-HuR-RhoB pathway that promotes PP2A-mediated dephosphorylation of gammaH2AX and DSB repair. Finally, we show that RhoB-deficient cells accumulate endogenous gammaH2AX and chromosomal abnormalities, suggesting that RhoB loss increases DSB-mediated genomic instability and tumor progression.

Go to