IGF2BP1-Mediated\nRegulation of CCN1 Expression by\nSpecific Binding to G‑Quadruplex Structure in Its 3′UTR

The intricate regulation of gene expression is fundamental\nto the\nbiological complexity of higher organisms, and is primarily governed\nby transcriptional and post-transcriptional mechanisms. The 3′-untranslated\nregion (3′UTR) of mRNA is rich in cis-regulatory elements like\nG-quadruplexes (G4s), and plays a crucial role in post-transcriptional\nregulation. G4s have emerged as significant gene regulators, impacting\nmRNA stability, translation, and localization. In this study, we investigate\nthe role of a robust parallel G4 structure situated within the 3′UTR\nof CCN1 mRNA in post-transcriptional regulation. This G4 structure\nis proximal to the stop codon of human CCN1, and evolutionarily conserved.\nWe elucidated its interaction with the insulin-like growth factor\n2 binding protein 1 (IGF2BP1), a noncanonical RNA N6-methyladenosine\n(m6A) modification reader, revealing a novel interplay between RNA\nmodifications and G-quadruplex structures. Knockdown experiments and\nmutagenesis studies demonstrate that IGF2BP1 binds specifically to\nthe G4 structure, modulating CCN1 mRNA stability. Additionally, we\nunveil the role of IGF2BP1’s RNA recognition motifs in G4 recognition,\nhighlighting this enthalpically driven interaction. Our findings offer\nfresh perspectives on the complex mechanisms of post-transcriptional\ngene regulation mediated by G4 RNA secondary structures.