LncRNAOIP5-AS1/cyranosponges RNA-binding protein HuR

Abstract

The function of the vast majority of mammalian long noncoding (lnc) RNAs remains unknown. Here, analysis of a highly abundant mammalian lncRNA, OIP5-AS1, known as cyrano in zebrafish, revealed that OIP5-AS1 reduces cell proliferation. In human cervical carcinoma HeLa cells, the RNA-binding protein HuR, which enhances cell proliferation, associated with OIP5-AS1 and stabilized it. Tagging OIP5-AS1 with MS2 hairpins to identify associated microRNAs revealed that miR-424 interacted with OIP5-AS1 and competed with HuR for binding to OIP5-AS1. We further identified a ‘sponge’ function for OIP5-AS1, as high levels of OIP5-AS1 increased HuR-OIP5-AS1 complexes and prevented HuR interaction with target mRNAs, including those that encoded proliferative proteins, while conversely, lowering OIP5-AS1 increased the abundance of HuR complexes with target mRNAs. We propose that OIP5-AS1 serves as a sponge or a competing endogenous (ce)RNA for HuR, restricting its availability to HuR target mRNAs and thereby repressing HuR-elicited proliferative phenotypes.

The Long Noncoding RNA OIP5-AS1 Is Involved in the Regulation of Cell Proliferation

“…These results suggest that OIP5-AS1 positively regulates HeLa cell proliferation. This is in contrast to the findings of a recent study by another group that showed that siRNA-mediated depletion of OIP5-AS1 promoted HeLa cell proliferation, which suggested that OIP5-AS1 functions to reduce cell proliferation (13). The reason for these conflicting results is not clear.…”

“…Recently, another group reported that OIP5-AS1 functions to repress HeLa proliferation by binding to Hu Antigen R (HuR) and preventing it from binding to and stabilizing protein-coding mRNAs such as cyclin A2 (13). This is in contrast to our findings.…”

Identification of HuR target circular RNAs uncovers suppression of PABPN1 translation by CircPABPN1

“…4,29,30 In a recent example, lncRNA OIP5-AS1/cyrano displayed strong affinity for HuR and prevented HuR binding to a subset of mRNAs encoding proliferative proteins, in turn reducing cell growth. 31 However, in other cases, the ncRNA and the RBP may compete for binding to the shared target mRNA; for example, 7SL and HuR competed for binding to TP53 mRNA, and thus 7SL was capable of preventing the HuRmediated promotion of TP53 translation. 30 Given that the main HuR target identified in this study, CircPABPN1, is not very abundant (»12 copies per cell in HeLa cells, Fig.…”

Long noncoding RNA complementarity and target transcripts abundance

“…Because the effect of sequence complementarity may vary in each lncRNA, we examined an additional lncRNA, OIP5-AS1 , a zebrafish homolog in humans [11, 16, 20]. After identifying human OIP5- AS1 target mRNAs by MS2-GST pull down analysis [11], we compared this profile to mRNAs containing sequence complementarity (Figures 5A, 5B, Tables S5, S6) as performed previously [18].…”

“…RNA affinity pull down was performed as described previously [7, 11, 16]. Acidic phenol was used for purification of RNAs from the MST-GST pellets for microarray analysis or small RNA-sequencing [17].…”