HuR Uses AUF1 as a Cofactor To Promote p16^INK4 mRNA Decay

Abstract

In this study, we show that HuR destabilizes p16 INK4 mRNA. Although the knockdown of HuR or AUF1 increased p16 expression, concomitant AUF1 and HuR knockdown had a much weaker effect. The knockdown of Ago2, a component of the RNA-induced silencing complex (RISC), stabilized p16 mRNA. The knockdown of HuR diminished the association of the p16 3 untranslated region (3UTR) with AUF1 and vice versa. While the knockdown of HuR or AUF1 reduced the association of Ago2 with the p16 3UTR, Ago2 knockdown had no influence on HuR or AUF1 binding to the p16 3UTR. The use of EGFP-p16 chimeric reporter transcripts revealed that p16 mRNA decay depended on a stem-loop structure present in the p16 3UTR, as HuR and AUF1 destabilized EGFP-derived chimeric transcripts bearing wild-type sequences but not transcripts with mutations in the stem-loop structure. In senescent and HuR-silenced IDH4 human diploid fibroblasts, the EGFPp16 3UTR transcript was more stable. Our results suggest that HuR destabilizes p16 mRNA by recruiting the RISC, an effect that depends on the secondary structure of the p16 3UTR and requires AUF1 as a cofactor.

The role of the 3' untranslated region in post-transcriptional regulation of protein expression in mammalian cells.

“…74 In contrast, antagonism is seen in regulation of cyclin D1 expression or ATF3, where HuR and AUF1 compete for binding to the specific mRNA sequence. 75,76 Opposite effects on translation efficiency has also been reported during regulation of COX-2 expression.…”

Enhanced NOLC1 promotes cell senescence and represses hepatocellular carcinoma cell proliferation by disturbing the organization of nucleolus

“…Whole 293 cells lysate or purified flag‐CSG (Fig. 2I) were prepared and used for the pulldown analysis as previously described (Chang et al ., 2010). As shown in Fig.…”

RNA-binding proteins regulate cell respiration and coenzyme Q biosynthesis by post-transcriptional regulation ofCOQ7

“…Similarly, primary deficiency of CoQ 10 led to a decrease of mitochondrial respiratory chain activities affecting oxidative phosphorylation and forcing cells toward enhanced glycolysis. 52 The functional association between HuR and other RBPs, such as AUF1, has been widely described, 30,33,53,54 and the interactions between different RPBs may be cooperative or competitive depending on cell type, growth conditions, RBP concentration, cellular compartment and target mRNA. 31,55,56 Cooperative hnRNP C1 and HuR interaction to modulate alternative Fas splicing has been also described.…”

“…24 HuR is a ubiquitously expressed RNA-binding protein (RBP) member of ELAVL protein family 25 that can regulate the stability and translation of hundreds mRNA involved in cell division, carcinogenesis, muscle cell differentiation, replicative senescence, immune cell activation, and stress response. [26][27][28][29][30] HuR and several members of the hnRNP family as hnRNP D (also known as AUF1) are able to bind specifically to AU-rich elements (AREs) in the 3 0 UTR of target mRNAs, [30][31][32] in cooperative or competitive manners to regulate the translation of shared target mRNAs. 31,33 We show here that HuR and hnRNP C1/C2 proteins, both of which bind to the COQ7 3 0 UTR, determine the rates of CoQ 10 biosynthesis.…”