Age associated high level of major vault protein is p53 dependent

Major vault protein (MVP) represents the main component of vaults and has been linked to multi-drug resistance (MDR) in cancer cells. We previously reported that MVP plays an important role in the resistance of senescent human diploid fibroblasts (HDFs) to apoptosis and also that MVP expression is markedly reduced in young HDFs but not in senescent HDFs. In this study, designed to elucidate the regulation of MVP in young and senescent HDFs, we examined the levels of transcriptional factors for the MVP gene, which revealed that among the putative transcriptional factors, p53 decreased only in young HDFs, but not in senescent HDFs in response to H2O2 treatment in the same mode as the expression of MVP. Moreover, the phosphorylation status of p53 increased only in senescent HDFs but not in young HDFs in response to H2O2 treatment. Therefore, we tested the possibility of MVP regulation by p53 status. MVP is upregulated in p53 over-expressing young HDFs, while MVP is downregulated in p53-spccific small interfering RNA (siRNA)-transfected senescent HDFs, which suggests that the expression of MVP would be p53 dependent. Furthermore, using chromatin immunoprecipitation (ChIP) assay, we observed that p53 binds directly to the MVP promoter. Taken together, these results suggest that p53 would be a major transcriptional factor for MVP gene expression. Copyright (C) 2009 John Wiley & Sons, Ltd.