TY - JOUR T1 - Influence of the RNA-Binding Protein HuR in pVHL-Regulated p53 Expression in Renal Carcinoma Cells JF - Molecular and Cellular Biology JO - Mol. Cell. Biol. SP - 7083 LP - 7095 DO - 10.1128/MCB.23.20.7083-7095.2003 VL - 23 IS - 20 AU - Galbán, Stefanie AU - Martindale, Jennifer L. AU - Mazan-Mamczarz, Krystyna AU - López de Silanes, Isabel AU - Fan, Jinshui AU - Wang, Wengong AU - Decker, Jochen AU - Gorospe, Myriam Y1 - 2003/10/15 UR - http://mcb.asm.org/content/23/20/7083.abstract N2 - 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. ER -