Recent studies have revealed the regulatory potential of many long noncoding RNAs (lncRNAs). Most lncRNAs, like mRNAs, are transcribed by RNA polymerase II and are capped, polyadenylated, and spliced. However, the subcellular fates of lncRNAs are distinct and the mechanisms of action are diverse. Investigating the mechanisms that determine the subcellular fate of lncRNAs has the potential to provide new insights into their biogenesis and specialized functions.
Functions of Long Noncoding RNAs (lncRNAs) Are Associated with Their Subcellular Fates
lncRNAs have distinct subcellular localization patterns, allowing lncRNAs to execute their specified functions. (A) lncRNAs can accumulate and act in cis once they are transcribed. (B) lncRNAs can accumulate in cis once they are transcribed, but act in trans that affects genes located in the same chromosome at a distance or in different chromosomes. (A and B) Mechanisms of lncRNA in cis localization are largely unknown. (C) lncRNAs can localize to elsewhere in the nucleoplasm in trans and act in trans. (D) lncRNAs can accumulate to specific nuclear bodies (orange circles) and act in trans. The mechanisms of lncRNA nuclear retention remain largely unknown, as does whether such lncRNAs are required to be translocated in the nucleus to regulate gene expression. (E) lncRNAs can be exported to the cytoplasm to execute their functions. For example, a cytoplasmic lncRNA can sequester protein (pink circle) or interfere with protein post-translational modification (PTM). Whether the nucleocytoplasmic export of cytoplasmic lncRNAs is distinct from that of mRNA has not yet been examined. The color of shaded oval indicates differences in protein composition of long noncoding ribonucleoproteins. Pink arrows, the unknown mechanisms for lncRNAs to gain specific subcellular localization patterns; black arrows, lncRNAs execute functions in distinct subcellular compartments.