Selective RNA versus DNA G-quadruplex targeting by in situ click chemistry

Abstract

It all clicks into place: A potent telomere-targeting small molecule has been identified by using the copper-free 1,3-dipolar cycloaddition of a series of alkyne and azide building blocks catalyzed by a non-Watson-Crick DNA secondary structure (see picture). This method rapidly identifies, otherwise unanticipated, potent small-molecule probes to selectively target a given RNA or DNA.

Figure 1

A) Molecular structure of alkyne and azide building blocks; B) adducts generated by treating 1 and 2 with 3–8; C) in situ synthesis of triazoles catalyzed by H-Telo.

Figure 2

Chromatogram tuned on 14 mass channels of alkynes 1 and 2 and adducts 9–20 obtained from the reaction carried out in the presence of H-Telo.

Figure 3

Chromatogram tuned on the 14 mass channels of alkynes 1 and 2 and adducts 9–20 obtained from the reaction carried out in the presence of A) a Cu catalyst and B) a Cu/H-Telo catalyst. C) Histogram showing the relative abundance of each product obtained in copper- (control), Cu/H-Telo-, and Cu/ds-DNA-catalyzed reactions. Data were plotted as the surface area measured under each individual chromatogram signal.

Figure 4

A) Fluorescent microscopy images of untreated MRC5-SV40 cells or treated with 2 μm compound for 24 h. Cells were stained with 4,6-diamidino-2-phenylindole (DAPI) and anti-TRF1 antibody; scale bar: 20 μm, zoom images are 25X magnified. B) Dose-response readout based on the number of TRF1 foci per cell upon treatment with 10 for 24 h. C) Number of TRF1 foci per cell upon treatment with various adducts and PDS (2 μm, 24 h).

Figure 5

A) Chromatogram tuned on the 14 mass channels of alkynes 1 and 2 and adducts 9–20 obtained from the reaction carried out in the presence of Cu/TERRA catalysts. B) Histogram showing the relative abundance of 13 obtained from Cu- (control), Cu/H-Telo-, Cu-TERRA-, and Cu/ds-DNA-catalyzed reactions. C) Histogram showing the shift in the melting temperature of doubly labeled TERRA in the presence of 13 or PDS (2 μm) and increasing amounts of unlabeled H-Telo competitor.