Yoon J H et al., 2012 uncovered new role of lincRNA as a post-transcriptional inhibitor of translation. They propose that HuR controls translation of a subset of target mRNAs by influencing lincRNA-p21 levels.

  • HuR (human antigen R) or ELAV-like protein 1 is a protein that in humans is encoded by the ELAVL1 gene. The protein encoded by this gene is a member of the ELAVL protein family. This encoded protein contains 3 RNA-binding domains and binds cis-acting AU-rich elements. It stabilizes mRNAs and thereby regulates gene expression

An association between HuR with lincRNA-p21 was detected using the RNP immunoprecipitation (RIP) assay. RIP is an antibody-based technique used to map RNA–protein interactions in vivo by immunoprecipitating the RNA binding protein of interest together with its associated RNA and allows identification of bound transcripts. RIP precipitates a specific RNA binding protein (RBP) and associated RNA (mRNAs, non coding RNAs, viral RNAs) that can be detected by real- time PCR, microarrays or e.g. sequencing. (in this case IP reactions were carried out using HeLa cell lysates and anti-HuR antibody)

The group propose that in the presence of HuR, lincRNA-p21 is unstable through the recruitment of let-7/Ago2. HuR then promotes the translation of targets CTNNB1 and JUNB mRNAs by favoring their association with polysomes and in the absence of HuR, lincRNA-p21 is stable and accumulates, and Rck promotes the association of lincRNA-p21 with CTNNB1 and JUNB mRNAs, repressing their translation through a mechanism that includes reduced polysome sizes and in addition, base-pair interactions of lincRNA-p21 with target mRNAs may result in ribosome ‘drop-off’. In sum, HuR-dependent translation activation requires rapid degradation of lincRNA-p21 in order to prevent the recruitment of translation repressors onto target mRNAs.

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