Fig. 2

Five functional archetypes involved in the lncRNAs molecular mechanisms. I. Decoy: LncRNAs are transcribed and subsequently bound to the transcription factors, chromatin modifiers, or other regulatory factors outside from the chromatin structure, as well as moved in other nuclear subdomains preventing them from performing their biological effector function, free to perform any additional function, probably acting as a negative transcriptional regulator functionality. II. Signaling: LncRNAs are employed as molecular signals conducing to combinatorial actions of transcription factors and/or cell signaling pathways by regulating the space and time, on the stage of development and/or genetic expression patterns under certain cellular conditions by external stimuli. This archetype may act as biologically and functionally significant event markers at the cellular and/or tissue level of diseases events. III. Scaffolds: LncRNAs act as molecular platforms on which multiple proteins are assembled to form ribonucleoprotein complexes (RNPs). Each lncRNA-RNP complex may function in a structural manner by stabilizing complexes and controlling effector functions with an activating or repressive transcriptional activity or by altering post-translational modifications of the histone marks. IV. Guides: LncRNAs may recruit chromatin modifying proteins or remodeling enzymes to target specific genes, either in Cis position (near the site where lncRNA was transcribed or in neighboring regions) or in Trans position to target-distant genes into the chromatin specific sites. V. Sponge: LncRNAs that by complementarity of bases succeed in matching or sequestering sequences of small non-coding RNAs, such as miRNAs, are controlling the bioavailability of miRNAs versus lncRNAs themselves, with the functional biological repercussions at cellular level