Abstract
Prion diseases comprise a fatal neuropathy caused by the conversion of prion protein from a cellular (PrPC) to a pathological (PrPSc) isoform. Previously, we obtained an RNA aptamer, r(GGAGGAGGAGGA) (R12), that folds into a unique G-quadruplex. The R12 homodimer binds to a PrPC molecule, inhibiting PrPC-to-PrPSc conversion. Here, we developed a new RNA aptamer, r(GGAGGAGGAGGAGGAGGAGGAGGA) (R24), where two R12s are tandemly connected. The 50% inhibitory concentration for the formation of PrPSc (IC50) of R24 in scrapie-infected cell lines was ca. 100 nM, i.e., much lower than that of R12 by two orders. Except for some antibodies, R24 exhibited the lowest recorded IC50 and the highest anti-prion activity. We also developed a related aptamer, r(GGAGGAGGAGGA-A-GGAGGAGGAGGA) (R12-A-R12), IC50 being ca. 500 nM. The structure of a single R12-A-R12 molecule determined by NMR resembled that of the R12 homodimer. The quadruplex structure of either R24 or R12-A-R12 is unimolecular, and therefore the structure could be stably formed when they are administered to a prion-infected cell culture. This may be the reason they can exert high anti-prion activity.
Highlights
It was found that the R12 homodimer simultaneously binds to two portions of one prion protein from a cellular (PrPC) molecule (Fig. 1A), resulting in tight binding and stabilization of PrPC20,21
The unique quadruplex structure of a R12 monomer and its dimeric architecture are essential for tight binding to PrPC20
When R12 is dissolved in the cell culture for the assay, the R12 homodimer architecture may be destabilized, resulting in a decrease in the activity
Summary
R24 was supposed to unimolecularly form a similar structure made of two R12 molecules. R24 showed much higher anti-prion activity than R12. Another related aptamer, r(G1G2A3G4G5A6G7G8A9G10G11A12-A13-G14G15A16G17G18A19G20G21A22G23G24A25) (R12-A-R12), was supposed to unimolecularly form a similar structure composed of two R12 molecules. We determined the structure of R12-A-R12 by NMR and deduced the mode of interaction of R12-A-R12 with PrP. These studies confirmed the origin of the high anti-prion activity of R12-A-R12 and R24, and provided further insight. The information on the sequences of potent aptamers and the structural bases of their anti-prion activity revealed in this study may be used to develop aptamer-based drugs against prion diseases
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
