Fig. 3

A schematic diagram of the interaction between lncRNA, mRNAs and G-quadruplexes in modulating DEAD-box helicases in antiviral innate immunity signaling cascades. DEAD-box helicases have been detected to have a significant role as sensors for nucleic acids, containing dsRNA, cytoplasmic DNA, and viral RNAs, resulting in triggering the induction of interferon and interferon-stimulated genes. Besides, DEAD-box helicases could involve in innate immune cascade downstream of nucleic acid-sensing via modulating protein-protein interactions and elevating the DAMP cascade [48,49,50]. Previous studies have authenticated the interaction between ncRNAs, mRNAs and G-quadruplexes regulating DEAD-box helicases members containing DDX3 and DHX36. As an illustration, accumulating finding has suggested that lncRNA GSEC could play a crucial role in colon cancer cell migration via suppressing the function of DHX36 through its G-quadruplex structure. In fact, GSEC could bind to DHX36 RNA helicase via its G-quadruplex-forming sequence, thereby attenuating DHX36 G-quadruplex unwinding activity [9]. In addition, another research has demonstrated that DHX36 could bind to the p53 RNA G4-forming sequence, whilst a mutation in the p53 G4 sequence could result in suppressing the DHX36 function to process its pre-mRNA 3′-end [34]. All the information regarding the presence and function of G-quadruplexes in ncRNAs and mRNA coding genes can be seen in Tables 1 and 2.