A series of new 2,4-bis[(substituted-aminomethyl)phenyl]quinoline, 1,3-bis[(substituted-aminomethyl)phenyl]isoquinoline, and 2,4-bis[(substituted-aminomethyl)phenyl]quinazoline derivatives was designed, synthesised, and evaluated in vitro against three protozoan parasites (Plasmodium falciparum, Leishmania donovani, and Trypanosoma brucei brucei). Biological results showed antiprotozoal activity with IC50 values in the µM range. In addition, the in vitro cytotoxicity of these original molecules was assessed with human HepG2 cells. The quinoline 1c was identified as the most potent antimalarial candidate with a ratio of cytotoxic to antiparasitic activities of 97 against the P. falciparum CQ-sensitive strain 3D7. The quinazoline 3h was also identified as the most potent trypanosomal candidate with a selectivity index (SI) of 43 on T. brucei brucei strain. Moreover, as the telomeres of the parasites P. falciparum and Trypanosoma are possible targets of this kind of nitrogen heterocyclic compounds, we have also investigated stabilisation of the Plasmodium and Trypanosoma telomeric G-quadruplexes by our best compounds through FRET melting assays.

• Klíčová slova
• Antimalarial activity, G-quadruplex, antileishmanial activity, antitrypanosomal activity, quinoline-like derivatives,
• MeSH
• antiprotozoální látky chemická syntéza   chemie   farmakologie   MeSH
• buňky Hep G2 MeSH
• chinoliny chemická syntéza   chemie   farmakologie   MeSH
• Leishmania donovani účinky léků   MeSH
• lidé MeSH
• Plasmodium falciparum účinky léků   MeSH
• racionální návrh léčiv * MeSH
• Trypanosoma brucei brucei účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antiprotozoální látky MeSH
• chinoliny MeSH

Mechanisms of transcriptional control in malaria parasites are still not fully understood. The positioning patterns of G-quadruplex (G4) DNA motifs in the parasite's AT-rich genome, especially within the var gene family which encodes virulence factors, and in the vicinity of recombination hotspots, points towards a possible regulatory role of G4 in gene expression and genome stability. Here, we carried out the most comprehensive genome-wide survey, to date, of G4s in the Plasmodium falciparum genome using G4Hunter, which identifies G4 forming sequences (G4FS) considering their G-richness and G-skewness. We show an enrichment of G4FS in nucleosome-depleted regions and in the first exon of var genes, a pattern that is conserved within the closely related Laverania Plasmodium parasites. Under G4-stabilizing conditions, i.e., following treatment with pyridostatin (a high affinity G4 ligand), we show that a bona fide G4 found in the non-coding strand of var promoters modulates reporter gene expression. Furthermore, transcriptional profiling of pyridostatin-treated parasites, shows large scale perturbations, with deregulation affecting for instance the ApiAP2 family of transcription factors and genes involved in ribosome biogenesis. Overall, our study highlights G4s as important DNA secondary structures with a role in Plasmodium gene expression regulation, sub-telomeric recombination and var gene biology.

• MeSH
• aminochinoliny farmakologie   MeSH
• G-kvadruplexy * MeSH
• genom účinky léků   MeSH
• kyseliny pikolinové farmakologie   MeSH
• lidé MeSH
• malárie farmakoterapie   genetika   parazitologie   MeSH
• nukleotidové motivy genetika   MeSH
• Plasmodium falciparum genetika   patogenita   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• regulace genové exprese účinky léků   MeSH
• ribozomy účinky léků   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminochinoliny MeSH
• kyseliny pikolinové MeSH
• pyridostatin MeSH Prohlížeč

G-quadruplexes (G4) are non-canonical DNA and/or RNA secondary structures formed in guanine-rich regions. Given their over-representation in specific regions in the genome such as promoters and telomeres, they are likely to play important roles in key processes such as transcription, replication or RNA maturation. Putative G4-forming sequences (G4FS) have been reported in humans, yeast, bacteria, viruses and many organisms. Here we present the first mapping of G-quadruplex sequences in Dictyostelium discoideum, the social amoeba. 'Dicty' is an ameboid protozoan with a small (34 Mb) and extremely AT rich genome (78%). As a consequence, very few G4-prone motifs are expected. An in silico analysis of the Dictyostelium genome with the G4Hunter software detected 249-1055 G4-prone motifs, depending on G4Hunter chosen threshold. Interestingly, despite an even lower GC content (as compared to the whole Dicty genome), the density of G4 motifs in Dictyostelium promoters and introns is significantly higher than in the rest of the genome. Fourteen selected sequences located in important genes were characterized by a combination of biophysical and biochemical techniques. Our data show that these sequences form highly stable G4 structures under physiological conditions. Five Dictyostelium genes containing G4-prone motifs in their promoters were studied for the effect of a new G4-binding porphyrin derivative on their expression. Our results demonstrated that the new ligand significantly decreased their expression. Overall, our results constitute the first step to adopt Dictyostelium discoideum as a 'G4-poor' model for studies on G-quadruplexes.

• MeSH
• Dictyostelium genetika   MeSH
• G-kvadruplexy * MeSH
• genom genetika   MeSH
• konformace nukleové kyseliny MeSH
• počítačová simulace MeSH
• porfyriny genetika   MeSH
• promotorové oblasti (genetika) * MeSH
• telomery genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• porfyriny MeSH

The role of local DNA structures in the regulation of basic cellular processes is an emerging field of research. Amongst local non-B DNA structures, the significance of G-quadruplexes was demonstrated in the last decade, and their presence and functional relevance has been demonstrated in many genomes, including humans. In this study, we analyzed the presence and locations of G-quadruplex-forming sequences by G4Hunter in all complete bacterial genomes available in the NCBI database. G-quadruplex-forming sequences were identified in all species, however the frequency differed significantly across evolutionary groups. The highest frequency of G-quadruplex forming sequences was detected in the subgroup Deinococcus-Thermus, and the lowest frequency in Thermotogae. G-quadruplex forming sequences are non-randomly distributed and are favored in various evolutionary groups. G-quadruplex-forming sequences are enriched in ncRNA segments followed by mRNAs. Analyses of surrounding sequences showed G-quadruplex-forming sequences around tRNA and regulatory sequences. These data point to the unique and non-random localization of G-quadruplex-forming sequences in bacterial genomes.

• Klíčová slova
• G-quadruplex, G4Hunter, bacteria, bioinformatics, deinococcus,
• MeSH
• Bacteria genetika   MeSH
• DNA bakterií chemie   MeSH
• fylogeneze MeSH
• G-kvadruplexy * MeSH
• genom bakteriální MeSH
• konformace nukleové kyseliny MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA bakterií MeSH

Guanine-rich nucleic acid sequences can fold into four-stranded G-quadruplex (G4) structures. Despite growing evidence for their biological significance, considerable work still needs to be done to detail their cellular occurrence and functions. Herein, we describe an optimized core-extended naphthalene diimide (cex-NDI) to be exploited as a G4 light-up sensor. The sensing mechanism relies on the shift of the aggregate-monomer equilibrium towards the bright monomeric state upon G4 binding. In contrast with the majority of other ligands, this novel cex-NDI is able to discriminate among G4s with different topologies, with a remarkable fluorescent response for the parallel ones. We investigate this sensing by means of biophysical methods, comparing the lead compound to a non-selective analogue. We demonstrate that mitigating the affinity of the binding core for G4s results in an increased selectivity and sensitivity of the fluorescent response. This is achieved by replacing positively charged substituents with diethylene glycol (DEG) side chains. Remarkably, the limit of detection values obtained for parallel G4s are more than one order of magnitude lower than those of the parallel-selective ligand N-methyl mesoporphyrin IX (NMM). Interestingly, the classical fluorescent intercalator displacement (FID) assay failed to reveal binding of cex-NDI to G4 because of the presence a ternary complex (G4-TO-cex-NDI) revealed by electrospray-MS. Our study thus provides a rational basis to design or modify existent scaffolds to redirect the binding preference of G4 ligands.

• MeSH
• biosenzitivní techniky metody   MeSH
• fluorescenční barviva chemická syntéza   chemie   farmakologie   MeSH
• G-kvadruplexy * účinky léků   MeSH
• imidy chemická syntéza   chemie   farmakologie   MeSH
• interkalátory chemická syntéza   chemie   farmakologie   MeSH
• ligandy * MeSH
• naftaleny chemická syntéza   chemie   farmakologie   MeSH
• rozpustnost MeSH
• substrátová specifita MeSH
• vazebná místa MeSH
• voda chemie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fluorescenční barviva MeSH
• imidy MeSH
• interkalátory MeSH
• ligandy * MeSH
• naftaleny MeSH
• naphthalenediimide MeSH Prohlížeč
• voda MeSH