G-Quadruplexes influence pri-microRNA processing

RNA G-Quadruplexes (G4) have been shown to possess many biological functions, including the regulation of microRNA (miRNA) biogenesis and function. However, their impact on pri-miRNA processing remains unknown. We identified G4 located near the Drosha cleavage site in three distinct pri-miRNAs: pri-mir200c, pri-mir451a, and pri-mir497. The folding of the potential G4 motifs was determined in solution. Subsequently, mutations disrupting G4 folding led to important changes in the mature miRNAs levels in cells. Moreover, using small antisense oligonucleotides binding to the pri-miRNA, it was possible to modulate, either positively or negatively, the mature miRNA levels. Together, these data demonstrate that G4 motifs could contribute to the regulation of pri-mRNA processing, a novel role for G4. Considering that bio-informatics screening indicates that between 9% and 50% of all pri-miRNAs contain a putative G4, these structures possess interesting potential as future therapeutic targets.

RNA G-四链体（RNA G-Quadruplexes，G4）已被证实具备多种生物学功能，包括调控微小RNA（microRNA，miRNA）的生成与功能。然而，其对初级微小RNA（pri-miRNA）加工过程的影响仍未明确。本研究在三种不同的初级微小RNA——pri-mir200c、pri-mir451a及pri-mir497中，鉴定出了位于Drosha切割位点附近的G4结构。研究人员在溶液中验证了潜在G4基序的折叠特性。随后，破坏G4折叠的突变会导致细胞内成熟miRNA水平发生显著变化。此外，通过结合至pri-miRNA的小型反义寡核苷酸，可正向或负向调节成熟miRNA的表达水平。综上，本研究数据证实G4基序可参与调控pri-miRNA的加工过程，这是G4的一种全新功能。考虑到生物信息学筛选显示，9%至50%的所有pri-miRNA均含有推定的G4结构，这类结构具备成为未来治疗靶点的可观潜力。