Architectural RNAs: blueprints for functional membraneless organelle assembly.

Among the pervasive transcripts from eukaryotic genomes, a novel subset, referred to as architectural RNAs (arcRNAs), has an essential role in assembling membraneless organelles (MLOs). These arcRNAs sequester specific RNA-binding proteins (RBPs) and promote phase separation through multivalent interactions. NEAT1_2, an archetypal arcRNA, serves as a blueprint for paraspeckle architecture, characterized by a shell-and-core micelle-like configuration and immiscibility with other MLOs, relying on the cooperative contributions of distinct modular RNA domains. arcRNAs regulate gene expression through three of MLO action modes (crucible, sponge, and hub), guided by the functional blueprints embedded in arcRNA sequences. Advanced high-throughput analyses have identified thousands of arcRNA candidates, underscoring their potential in organizing transient intracellular compartments and driving dynamic cellular processes.