Influence of the RNA-binding protein HuR in pVHL-regulated p53 expression in renal carcinoma cells

Stefanie Galbán, Jennifer L. Martindale, Krystyna Mazan-Mamczarz, Isabel López de Silanes, Jinshui Fan, Wengong Wang, Jochen Decker, Myriam Gorospe

Research output: Contribution to journalArticlepeer-review

Abstract

A recent analysis of gene expression in renal cell carcinoma cells led to the identification of mRNAs whose translation was dependent on the presence of the von Hippel-Lindau (VHL) tumor suppressor gene product, pVHL. Here, we investigate the finding that pVHL-expressing RCC cells (VHL+) exhibited elevated levels of polysome-associated p53 mRNA and increased p53 protein levels compared with VHL-defective (VHL-) cells. Our findings indicate that p53 translation is specifically heightened in VHL + cells, given that (i) p53 mRNA abundance in VHL+ and VHL- cells was comparable, (ii) p53 degradation did not significantly influence p53 expression, and (iii) p53 synthesis was markedly induced in VHL+ cells. Electrophoretic mobility shift and immunoprecipitation assays to detect endogenous and radiolabeled p53 transcripts revealed that the RNA-binding protein HuR, previously shown to regulate mRNA turnover and translation, was capable of binding to the 3′ untranslated region of the p53 mRNA in a VHL-dependent fashion. Interestingly, while whole-cell levels of HuR in VHL+ and VHL- cells were comparable, HuR was markedly more abundant in the cytoplasmic and polysome-associated fractions of VHL+ cells. In keeping with earlier reports, the elevated cytoplasmic HuR in VHL+ cells was likely due to the reduced AMP-activated kinase activity in these cells. Demonstration that HuR indeed contributed to the increased expression of p53 in VHL+ cells was obtained through use of RNA interference, which effectively reduced HuR expression and in turn caused marked decreases in p53 translation and p53 abundance. Taken together, our findings support a role for pVHL in elevating p53 expression, implicate HuR in enhancing VHL-mediated p53 translation, and suggest that VHL-mediated p53 upregulation may contribute to pVHL's tumor suppressive functions in renal cell carcinoma.

Original languageEnglish (US)
Pages (from-to)7083-7095
Number of pages13
JournalMolecular and cellular biology
Volume23
Issue number20
DOIs
StatePublished - Oct 2003

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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