Identification of long non-coding RNAs as substrates for cytoplasmic capping enzyme

Cytoplasmic capping returns a cap to specific mRNAs thus protecting uncapped RNAs from decay. Prior to the identification of cytoplasmic capping, uncapped mRNAs were thought to be degraded. Here, we test whether long non-coding RNAs (lncRNAs) are cytoplasmic capping enzyme (cCE) substrates. The subcellular localization of fourteen lncRNAs associated with sarcomas were examined in U2OS osteosarcoma cells. We used 5 rapid amplification of cDNA ends (RACE) to assay uncapped forms of these lncRNAs. Inhibiting cytoplasmic capping elevated uncapped forms of selected lncRNAs indicating a plausible role of cCE in targeting them. Analysis of published cap analysis of gene expression (CAGE) data shows increased prevalence of certain 5-RACE cloned sequences suggesting that these uncapped lncRNAs are cytoplasmic capping targets.