RNA stem-loop to G-quadruplex equilibrium controls mature miRNA production inside the cell

Biological role for existence of overlapping structures in RNA is possible yet remains very less explored. G-rich tracts of RNA form G-quadruplexes while GC-rich sequences prefer stem-loop structures. Equilibrium between alternate structures within RNA may occur and influence its functionality. We t...

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Bibliographic Details
Published inBiochemistry (Easton)
Main Authors Pandey, Satyaprakash, Agarwala, Prachi, Jayaraj, Gopal G, Gargallo Gómez, Raimundo, Maiti, Souvik
Format Journal Article
LanguageEnglish
Published American Chemical Society 10.11.2015
Subjects
Porfirines
Porphyrins
RNA
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Summary:Biological role for existence of overlapping structures in RNA is possible yet remains very less explored. G-rich tracts of RNA form G-quadruplexes while GC-rich sequences prefer stem-loop structures. Equilibrium between alternate structures within RNA may occur and influence its functionality. We tested equilibrium between G-quadruplex and stem-loop structure in RNA and its effect on biological processes using pre-miRNA as a model system. Dicer enzyme recognizes canonical stem-loop structures in pre-miRNA to produce mature miRNAs. Deviation from stem-loop leads to deregulated mature miRNA levels, providing readout of existence of alternate structure per se G-quadruplex mediated structural interference in miRNA maturation. In vitro analysis using beacon and Dicer cleavage assays indicated that mature miRNA levels depend on relative amounts of K+ and Mg2+ ions suggesting an ion-dependent structural shift. Further in cellulo studies with and without TmPyP4 (RNA G-quadruplex destabilizer) demonstrated that miRNA biogenesis is modulated by G-quadruplex-stem-loop equilibrium in a subset of pre-miRNAs. Our combined analysis thus provides evidence for formation of non-canonical G-quadruplexes in competition with canonical stem-loop structure inside the cell and its effect on miRNA maturation in a comprehensive manner.
ISSN:0006-2960