Novel 3' ends that support translation

Abstract

The 3' ends of two large noncoding RNAs, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) and MEN β, are formed by cleavage by RNase P and are capped but not polyadenylated. In the November 1, 2012, issue of Genes & Development, Wilusz and colleagues (pp. 2392-2407) show that when these 3' ends are formed on a GFP reporter, the resulting mRNA is exported to the cytoplasm and translated. The 3' end forms a novel triple-helical structure that supports export and translation as well as a poly(A) tail does.

Figure 1.

Structure at the 3′ end of MALAT1 RNA. The triple-helix structure formed by the two U-rich motifs (shaded in pink and green) and the A-rich 3′ end of the RNA (shaded in cyan) is indicated. Mutation of the nucleotides shaded in purple blocked translation of the RNA, and mutation of the nucleotides shaded in orange destabilized the RNA. (Adapted from Fig. 4A in Wilusz et al. 2012.)