Figure 1.
Schematic diagram of the four archetypes of lncRNA mechanism. Archetype I: As Signals, lncRNA expression can faithfully reflect the combinatorial actions of transcription factors (colored ovals) or signaling pathways to indicate gene regulation in space and time. Archetype II: As Decoys, lncRNAs can titrate away transcription factors and other proteins away from chromatin, or titrate the protein factors into nuclear subdomains. A further example of decoys is lncRNA decoy for miRNA target sites (not shown on schematic). Archetype III: As Guides, lncRNAs can recruit chromatin modifying enzymes to target genes, either in cis (near the site of lncRNA production) or in trans to distant target genes. Archetype IV: As scaffolds, lncRNAs can bring together multiple proteins to form ribonucleoprotein complexes. The lncRNA-RNP may act on chromatin as illustrated to affect histone modifications. In other instances, the lncRNA scaffold is structural and stabilizes nuclear structures or signaling complexes