Biophysical characterisation of the Bcl-x pre-mRNA and binding specificity of the ellipticine derivative GQC-05 : implication for alternative splicing regulation

The BCL2L1 gene expresses two isoforms of Bcl-x protein via the use of either of two alternative 5′ splice sites (5′ss) in exon 2. These proteins have antagonistic actions, Bcl-XL being anti-apoptotic and Bcl-XS pro-apoptotic. In a number of cancers the Bcl-XL isoform is over-expressed, resulting in cancer cell survival and growth, so switching splicing to the Xs isoform could have therapeutic benefits. We have previously proposed that a putative G-quadruplex (G4) exists downstream of the XS 5′ss and shown that the ellipticine derivative GQC-05, a previously identified DNA G4-specific ligand, induces an increase in the XS/XL ratio both in vitro and in cells. Here, we demonstrate that this G4 forms in vitro and that the structure is stabilised in the presence of GQC-05. We also show that GQC-05 binds RNA non-specifically in buffer conditions, but selectively to the Bcl-x G4 in the presence of nuclear extract, highlighting the limitations of biophysical measurements taken outside of a functional environment. We also demonstrate that GQC-05 is able to shift the equilibrium between competing G4 and duplex structures towards the G4 conformation, leading to an increase in accessibility of the XS 5′ss, supporting our previous model on the mechanism of action of GQC-05

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Miméticos de factores de transcripción: herramientas químicas para el estudio de modificaciones post-traduccionales de proteínas nucleares que interaccionan con ADN

La investigación que se presenta en esta memoria se enmarca dentro de un proyecto más general encaminado al diseño y síntesis de herramientas químicas que aporten luz sobre el papel que juegan las modificaciones post-traduccionales, ß-O-GlcNAc glicosilación y fosforilación, en los procesos de interacción en los cuales los factores de transcripción participan. En concreto, el objetivo de esta Tesis Doctoral es aportar nuevos datos sobre el papel que juega la modificación post-traduccional por O-ß-GlcNAc de los residuos serina y treonina en las proteínas nucleares que actúan como factores de trascripción del ADN. Por eso, la aproximación que se va a realizar en esta Tesis Doctoral, va a consistir en el diseño, síntesis y estudio de miméticos de factores de transcripción, tanto no glicosilados como glicosilados, para estudiar en detalle la influencia que tiene la modificación post-traduccional por ß-O-GlcNAc en la interacción con el ADNDepartamento de Química Orgánic

Supramolecular DNA-based catalysis in organic solvents

The distinct folding accompanied by its polymorphic character renders DNA G-quadruplexes promising biomolecular building blocks to construct novel DNA-based and supramolecular assemblies. However, the highly polar nature of DNA limits the use of G-quadruplexes to water as a solvent. In addition, the archetypical G-quadruplex fold needs to be stabilized by metal-cations, which is usually a potassium ion. Here, we show that a noncovalent PEGylation process enabled by electrostatic interactions allows the first metal-free G-quadruplexes in organic solvents. Strikingly, incorporation of an iron-containing porphyrin renders the self-assembled metal-free G-quadruplex catalytically active in organic solvents. Hence, these “supraG4zymes” enable DNA-based catalysis in organic media. The results will allow the broad utilization of DNA G-quadruplexes in nonaqueous environments.</p

Sugar-Oligoamides: Bound-State Conformation and DNA Minor-Groove-Binding Description by TR-NOESY and Differential-Frequency Saturation-Transfer-Difference Experiments

8 páginas, 4 figuras, 1 esquema -- PAGS nros. 2435-2442Selective-frequency saturation-transfer-difference (STD) spectra allow the description of complexes established between minor-groove binders and long tracts of calf thymus DNA (ct-DNA). Two sets of experiments with selective saturation of either the H1' or H4'/H5'/H5'' proton NMR regions of deoxyribose allow the description of the ligand residues close to the inner (H1') and outer regions (H4'/H5'/H5'') of the minor groove of double-helical DNA. A series of complexes of sugar-oligoamides (2-6) with ct-DNA have been studied by both TR-NOESY and STD experiments. The binding mode of the complexes is similar to that of netropsin (1) and allows us to define a general binding mode for this family of ligands, in which an NH rim points towards the internal area (inner region) and a CH3 rim points towards the external part (outer region) of the minor groove of DNA. Also by means of both TR-NOESY and STD experiments, a description of the asymmetric centers of the sugar residue close to the inner and outer regions of the groove has been achieved. These results confirm that the sugar is responsible for the differences previously found in binding energeticsFinancial support for this work was provided by the MEC (BQU2003-03550-C03-01 and -02 and CTQ2006-10874-C02-01 and -02) and a European RTN project (HPRN-CT-2002-00190). P.P. is grateful to the Consejo superior de Investigaciones Científicas for an I3P predoctoral fellowship. C.B. and R.V.-G. thank the MEC for FPI and FPU predoctoral fellowships, respectively, while F.S. thanks RTN for a postdoctoral positionPeer reviewe

D - And L -Mannose-Containing glyco-Oligoamides Show Distinct Recognition Properties When Interacting with DNA

Mannose glyco-oligoamide β-D-Man-Py-γ-Py-Ind (β-D-Man, 1) and two new glyco-oligoamides, β-L-Man-Py-γ-Py-Ind (β-L-Man, 2) and 6-deoxy-β-D-Man-Py-γ-Py-Ind (6-deoxy-β-D-Man, 3), have been designed and synthesized to investigate the role of hydrogen-bonding cooperative donor centres of carbohydrates in their recognition by DNA. The free- and bound-state geometries were studied, as were the affinities of the D and L enantiomers of the mannose glyco-oligoamides (1 and 2) for DNA polymers [ct-DNA and poly(dA-dT)2]. TR-NOESY and DF-STD experiments for the diastereomeric complexes formed with DNA allow the asymmetric centres of the sugar residue that are close to the inner and outer regions of the DNA minor grooves to be distinguished. A C→N hairpin folding in β-L-Man derivative 2 was observed, with the α face of the sugar close to the indole ring. The C-2 and C-3 centres are orientated towards the inner region of the DNA minor groove. The affinity data for poly(dA-dT)2 indicate that there is a chiral discrimination process, with β-L-Man derivative 2 being the best ligand. 6-Deoxy-β-D-Man derivative 3 forms the least stable complexes with DNA. Molecular dynamics simulations of β-L-Man derivative 2 in complex with a double-strand dodecamer d(AT)12 are in agreement with the experimental NMR spectroscopic data. Thus, the cooperative donor centre 2-OH in the L-mannose enantiomer is a key contributor to the stability of the 2·poly(dA-dT)2 complex. Structural and affinity data have been obtained for different mannose oligoamides when binding to DNA polymers. A β-L-Man ligand (2) binds to poly(dA-dT)2 with a more well-defined structure, consistent with a better affinity. Thus, the placement of cooperative hydrogen-bond donor centres towards the inner region of the minor groove increases the binding affinity for polyAT(dA-dT)2.This work was supported by the Spanish Ministry of Economy and Competitiviness (MEC) (projects CTQ-10847-C02-01, CTQ-10847- C02-02, CTQ2009-10547, and CTQ2012-32025), and the European Cooperation in Science and Technology, COST Action CM1102. M. C. F. A. thanks the Consejo Superior de Investigaciones Científicas (JAE-Doc CSIC program) for financial support. F. M. thanks the Portuguese Fundo Europeu de Desenvolvimento Regional (FCT) for a post-doctoral research grant (SFRH/BPD/65462/2009). R. V. G. thanks the Ministerio of Education for FPU predoctoral fellowships.Peer Reviewe