Recently, the 1H-detected in-cell NMR spectroscopy has emerged as a unique tool allowing the characterization of interactions between nucleic acid-based targets and drug-like molecules in living human cells. Here, we assess the application potential of 1H and 19F-detected in-cell NMR spectroscopy to profile drugs/ligands targeting DNA G-quadruplexes, arguably the most studied class of anti-cancer drugs targeting nucleic acids. We show that the extension of the original in-cell NMR approach is not straightforward. The severe signal broadening and overlap of 1H in-cell NMR spectra of polymorphic G-quadruplexes and their complexes complicate their quantitative interpretation. Nevertheless, the 1H in-cell NMR can be used to identify drugs that, despite strong interaction in vitro, lose their ability to bind G-quadruplexes in the native environment. The in-cell NMR approach is adjusted to a recently developed 3,5-bis(trifluoromethyl)phenyl probe to monitor the intracellular interaction with ligands using 19F-detected in-cell NMR. The probe allows dissecting polymorphic mixture in terms of number and relative populations of individual G-quadruplex species, including ligand-bound and unbound forms in vitro and in cellulo. Despite the probe's discussed limitations, the 19F-detected in-cell NMR appears to be a promising strategy to profile G-quadruplex-ligand interactions in the complex environment of living cells.

• Klíčová slova
• BRACO19, Bcl2, G-quadruplex, KRAS, NMM, PhenDC3, drug, in-cell NMR, ligand, telomeric DNA,
• MeSH
• DNA chemie   účinky léků   MeSH
• G-kvadruplexy účinky léků   MeSH
• konformace nukleové kyseliny účinky léků   MeSH
• léčivé přípravky chemie   MeSH
• lidé MeSH
• ligandy MeSH
• magnetická rezonanční spektroskopie MeSH
• molekulární modely MeSH
• protony MeSH
• vazebná místa účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• léčivé přípravky MeSH
• ligandy MeSH
• protony MeSH

We report here the in-cell NMR-spectroscopic observation of the binding of the cognate ligand 2'-deoxyguanosine to the aptamer domain of the bacterial 2'-deoxyguanosine-sensing riboswitch in eukaryotic cells, namely Xenopus laevis oocytes and in human HeLa cells. The riboswitch is sufficiently stable in both cell types to allow for detection of binding of the ligand to the riboswitch. Most importantly, we show that the binding mode established by in vitro characterization of this prokaryotic riboswitch is maintained in eukaryotic cellular environment. Our data also bring important methodological insights: Thus far, in-cell NMR studies on RNA in mammalian cells have been limited to investigations of short (<15 nt) RNA fragments that were extensively modified by protecting groups to limit their degradation in the intracellular space. Here, we show that the in-cell NMR setup can be adjusted for characterization of much larger (≈70 nt) functional and chemically non-modified RNA.

• Klíčová slova
• 2′-deoxyguanosine riboswitch, HeLa cells, RNA structures, aptamers, structural biology,
• MeSH
• aptamery nukleotidové chemie   metabolismus   MeSH
• HeLa buňky MeSH
• konfokální mikroskopie MeSH
• konformace nukleové kyseliny MeSH
• lidé MeSH
• ligandy MeSH
• nukleární magnetická rezonance biomolekulární * MeSH
• riboswitch MeSH
• RNA chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aptamery nukleotidové MeSH
• ligandy MeSH
• riboswitch MeSH
• RNA MeSH

Protein-RNA interactions (PRIs) control pivotal steps in RNA biogenesis, regulate multiple physiological and pathological cellular networks, and are emerging as important drug targets. However, targeting of specific protein-RNA interactions for therapeutic developments is still poorly advanced. Studies and manipulation of these interactions are technically challenging and in vitro drug screening assays are often hampered due to the complexity of RNA structures. The binding of nucleolin (NCL) to a G-quadruplex (G4) structure in the messenger RNA (mRNA) of the Epstein-Barr virus (EBV)-encoded EBNA1 has emerged as an interesting therapeutic target to interfere with immune evasion of EBV-associated cancers. Using the NCL-EBNA1 mRNA interaction as a model, we describe a quantitative proximity ligation assay (PLA)-based in cellulo approach to determine the structure activity relationship of small chemical G4 ligands. Our results show how different G4 ligands have different effects on NCL binding to G4 of the EBNA1 mRNA and highlight the importance of in-cellulo screening assays for targeting RNA structure-dependent interactions.

• Klíčová slova
• EBNA1, Epstein-Barr virus (EBV), G-quadruplexes, PhenDC3, protein-mRNA interactions, pyridostatin, structure-activity relationship,
• MeSH
• aminochinoliny chemie   MeSH
• biotest metody   MeSH
• fosfoproteiny metabolismus   MeSH
• G-kvadruplexy * MeSH
• kyseliny pikolinové chemie   MeSH
• lidé MeSH
• messenger RNA metabolismus   MeSH
• nádorové buněčné linie MeSH
• nukleolin MeSH
• proteiny vázající RNA metabolismus   MeSH
• virus Epsteinův-Barrové - jaderné antigeny genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aminochinoliny MeSH
• EBV-encoded nuclear antigen 1 MeSH Prohlížeč
• fosfoproteiny MeSH
• kyseliny pikolinové MeSH
• messenger RNA MeSH
• proteiny vázající RNA MeSH
• pyridostatin MeSH Prohlížeč
• virus Epsteinův-Barrové - jaderné antigeny MeSH