Abstract
Poly (ADP-ribose) polymerase 1 (PARP1) has emerged as an attractive target for cancer therapy due to its key role in DNA repair processes. Inhibition of PARP1 in BRCA-mutated cancers has ...been observed to be clinically beneficial. Recent genome-mapping experiments have identified a non-canonical G-quadruplex-forming sequence containing bulges within the PARP1 promoter. Structural features, like bulges, provide opportunities for selective chemical targeting of the non-canonical G-quadruplex structure within the PARP1 promoter, which could serve as an alternative therapeutic approach for the regulation of PARP1 expression. Here we report the G-quadruplex structure formed by a 23-nucleotide G-rich sequence in the PARP1 promoter. Our study revealed a three-layered intramolecular (3+1) hybrid G-quadruplex scaffold, in which three strands are oriented in one direction and the fourth in the opposite direction. This structure exhibits unique structural features such as an adenine bulge and a G·G·T base triple capping structure formed between the central edgewise loop, propeller loop and 5′ flanking terminal. Given the highly important role of PARP1 in DNA repair and cancer intervention, this structure presents an attractive opportunity to explore the therapeutic potential of PARP1 inhibition via G-quadruplex DNA targeting.
Lighting up: The systematic design and synthesis of a G‐quartet‐inspired fluorescence probe (APD), which is made of two acetylene‐bridged purines, are reported. The APD lights up in the presence of ...parallel DNA (e.g. c‐MYC) or RNA G‐quadruplexes, while it shows no fluorescence enhancement with double‐stranded DNA, antiparallel or mixed‐type (e.g. h‐Telo) G‐quadruplexes (see picture). The utility of APD in the preferential staining of G‐quadruplexes is also demonstrated.
Reactive oxygen species play an important role in cancer, however, their promiscuous reactivity, low abundance, and short-lived nature limit our ability to study them in real time in living subjects ...with conventional noninvasive imaging methods. Photoacoustic imaging is an emerging modality for
visualization of molecular processes with deep tissue penetration and high spatiotemporal resolution. Here, we describe the design and synthesis of a targeted, activatable probe for photoacoustic imaging, which is responsive to one of the major and abundant reactive oxygen species, hydrogen peroxide (H
O
). This bifunctional probe, which is also detectable with fluorescence imaging, is composed of a heptamethine carbocyanine dye scaffold for signal generation, a 2-deoxyglucose cancer localization moiety, and a boronic ester functionality that specifically detects and reacts to H
O
. The optical properties of the probe were characterized using absorption, fluorescence, and photoacoustic measurements; upon addition of pathophysiologic H
O
concentrations, a clear increase in fluorescence and red-shift of the absorption and photoacoustic spectra were observed. Studies performed
showed no significant toxicity and specific uptake of the probe into the cytosol in breast cancer cell lines. Importantly, intravenous injection of the probe led to targeted uptake and accumulation in solid tumors, which enabled noninvasive photoacoustic and fluorescence imaging of H
O
. In conclusion, the reported probe shows promise for the
visualization of hydrogen peroxide. SIGNIFICANCE: This study presents the first activatable and cancer-targeted hydrogen peroxide probe for photoacoustic molecular imaging, paving the way for visualization of hydrogen peroxide at high spatiotemporal resolution in living subjects.
http://cancerres.aacrjournals.org/content/canres/79/20/5407/F1.large.jpg.
Traditionally viewed as poorly plastic, neutrophils are now recognized as functionally diverse; however, the extent and determinants of neutrophil heterogeneity in humans remain unclear. We performed ...a comprehensive immunophenotypic and transcriptome analysis, at a bulk and single-cell level, of neutrophils from healthy donors and patients undergoing stress myelopoiesis upon exposure to growth factors, transplantation of hematopoietic stem cells (HSC-T), development of pancreatic cancer and viral infection. We uncover an extreme diversity of human neutrophils in vivo, reflecting the rates of cell mobilization, differentiation and exposure to environmental signals. Integrated control of developmental and inducible transcriptional programs linked flexible granulopoietic outputs with elicitation of stimulus-specific functional responses. In this context, we detected an acute interferon (IFN) response in the blood of patients receiving HSC-T that was mirrored by marked upregulation of IFN-stimulated genes in neutrophils but not in monocytes. Systematic characterization of human neutrophil plasticity may uncover clinically relevant biomarkers and support the development of diagnostic and therapeutic tools.
Athletes are not just sports people; they are certainly among the most prominent figures of their present time, playing an important role in shaping opinions with their power to inspire. For this ...very reason, athletes’ freedom of expression is strongly limited by the sport authorities in light of the fundamental principle of sport neutrality. This study analyses and questions the traditional constraints to athletes’ free speech by taking into consideration the role of human rights in sports legal order and in sporting affairs. By assuming an emerging relativization of sport political neutrality, the essay investigates the case-law concerning athletes’ freedom of expression identifying limits and perspectives of the current evolutions on athletes’ public statements, establishing to what extent a reform of the present sporting regulation on freedom of expression is needed.
Control of DNA methylation level is critical for gene regulation, and the factors that govern hypomethylation at CpG islands (CGIs) are still being uncovered. Here, we provide evidence that ...G-quadruplex (G4) DNA secondary structures are genomic features that influence methylation at CGIs. We show that the presence of G4 structure is tightly associated with CGI hypomethylation in the human genome. Surprisingly, we find that these G4 sites are enriched for DNA methyltransferase 1 (DNMT1) occupancy, which is consistent with our biophysical observations that DNMT1 exhibits higher binding affinity for G4s as compared to duplex, hemi-methylated, or single-stranded DNA. The biochemical assays also show that the G4 structure itself, rather than sequence, inhibits DNMT1 enzymatic activity. Based on these data, we propose that G4 formation sequesters DNMT1 thereby protecting certain CGIs from methylation and inhibiting local methylation.
In investigating the binding interactions between the human telomeric RNA (TERRA) G‐quadruplex (GQ) and its ligands, it was found that the small molecule carboxypyridostatin (cPDS) and the ...GQ‐selective antibody BG4 simultaneously bind the TERRA GQ. We previously showed that the overall binding affinity of BG4 for RNA GQs is not significantly affected in the presence of cPDS. However, single‐molecule mechanical unfolding experiments revealed a population (48 %) with substantially increased mechanical and thermodynamic stability. Force‐jump kinetic investigations suggested competitive binding of cPDS and BG4 to the TERRA GQ. Following this, the two bound ligands slowly rearrange, thereby leading to the minor population with increased stability. Given the relevance of G‐quadruplexes in the regulation of biological processes, we anticipate that the unprecedented conformational rearrangement observed in the TERRA‐GQ–ligand complex may inspire new strategies for the selective stabilization of G‐quadruplexes in cells.
Quadruplex complex: Single‐molecule mechanical unfolding experiments revealed that the small molecule carboxypyridostatin (cPDS; red and blue ovals) and the GQ‐selective antibody BG4 simultaneously bind the human telomeric RNA (TERRA) G‐quadruplex (GQ) in a process that involves conformational rearrangement. The resulting increased mechanical and thermodynamic stability could provide new leads for the design of more effective GQ‐binding ligands.
This essay focuses on the relation between amateur sport and Union citizenship, analysing the recent Biffi ruling of the European Court of Justice. It examines the opinion of the Advocate General and ...the Judgment of the ECJ, starting from the established case-law according to which sport is subject to EU law insofar as it constitutes an economic activity. Taking into account the possible application of the Treaty in light of the indirect impact on economic activities of the amateur athlete, the study analyses the legal implications of Article 165 TFUE considering the social function of sport. Finally, the paper illustrates to what extent the Biffi case represents a simple clarification of the existing legal relationship, a coherent case-law development, or another seismic ECJ ruling on sport.
G-quadruplexes (G4s) are non-canonical DNA secondary structures. The identification of selective tools to probe individual G4s over the ∼700 000 found in the human genome is key to unravel the ...biological significance of specific G4s. We took inspiration from a crystal structure of the bovine DHX36 helicase bound to the G4 formed in the promoter region of the oncogene c-MYC to identify a short peptide that preferentially binds MYC G4 with nM affinity over a small panel of parallel and non-parallel G4s tested.
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