Direct and Catalytic C-Glycosylation of Arenes: Expeditious Synthesis of the Remdesivir Nucleoside

Since early 2020, scientists have strived to find an effective solution to fight SARS-CoV-2, especially by developing reliable vaccines that inhibit the spread of the disease and repurposing drugs for combatting its effects on the human body. The antiviral prodrug Remdesivir is still the most widely used therapeutic during the early stage of the infection. However, the current synthetic routes rely on the use of protecting groups, air-sensitive reagents, and cryogenic conditions, impeding the cost-efficient supply to patients. We therefore focused on the development of a straightforward, direct addition of (hetero)arenes to unprotected sugars. Here we report a silylium-catalyzed and completely stereoselective C -glycosylation that initially yields the open-chain polyols, which can be selectively cyclized to provide either the kinetic α-furanose or the thermodynamically favored β-anomer. The method significantly expedites the synthesis of Remdesivir precursor GS-441524 after subsequent Mn-catalyzed C–H oxidation and deoxycyanation

Intrinsic resistance to PIM kinase inhibition in AML through p38α-mediated feedback activation of mTOR signaling

Although conventional therapies for acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) are effective in inducing remission, many patients relapse upon treatment. Hence, there is an urgent need for novel therapies. PIM kinases are often overexpressed in AML and DLBCL and are therefore an attractive therapeutic target. However, in vitro experiments have demonstrated that intrinsic resistance to PIM inhibition is common. It is therefore likely that only a minority of patients will benefit from single agent PIM inhibitor treatment. In this study, we performed an shRNA-based genetic screen to identify kinases whose suppression is synergistic with PIM inhibition. Here, we report that suppression of p38α (MAPK14) is synthetic lethal with the PIM kinase inhibitor AZD1208. PIM inhibition elevates reactive oxygen species (ROS) levels, which subsequently activates p38α and downstream AKT/mTOR signaling. We found that p38α inhibitors sensitize hematological tumor cell lines to AZD1208 treatment in vitro and in vivo. These results were validated in ex vivo patient-derived AML cells. Our findings provide mechanistic and translational evidence supporting the rationale to test a combination of p38α and PIM inhibitors in clinical trials for AML and DLBCL

Modulation of the <i>Neisseria gonorrhoeae </i>drug efflux conduit MtrE

We acknowledge funding through the Wellcome Trust Interdisciplinary Research Funds (grant WT097818MF), the Scottish Universities’ Physics Alliance (SUPA), Tenovus Tayside (grant T16/30) and the Tayside Charitable Trust. O.N.V. has been funded through a BBSRC CASE award (BB/J013072/1).Widespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques. Our in vitro results show that MtrE can be regulated by periplasmic binding events and that the interaction between MtrE and MtrC is sufficient to stabilize this complex in an open state. In contrast to other efflux conduits, the open complex only displays a slight preference for cations. The maximum conductance we obtain in the in vitro recordings is comparable to that seen in our computational electrophysiology simulations conducted on the MtrE crystal structure, indicating that this state may reflect a physiologically relevant open conformation of MtrE. Our results suggest that the MtrC/E binding interface is an important modulator of MtrE function, which could potentially be targeted by new efflux inhibitors.Publisher PDFPeer reviewe

A83-01 inhibits TGF-β-induced upregulation of Wnt3 and epithelial to mesenchymal transition in HER2-overexpressing breast cancer cells

PurposeThe aim of this study is to investigate the mechanisms of interactions between TGF-β and Wnt/β-catenin pathways that induce and regulate EMT and promote breast cancer cells to become resistant to treatment.MethodsThe effect of TGF-β on Wnt/β-catenin signaling pathway was examined by using a human Wnt/β-catenin-regulated cDNA plate array and western blot analysis. The interaction of Twist at promoter of Wnt3 was examined by chromatin immunoprecipitation (ChIP) assay. Secreted Wnt3 level was determined by ELISA assay.ResultsHER2-overexpressing breast cancer cells treated with TGF-β have a reduced response to trastuzumab and exhibited EMT-like phenotype. The TGF-β-induced EMT in HER2-cells was concordant with upregulation of Wnt3 and β-catenin pathways. The TGF-β-induced induction of Wnt3 during EMT was found to be Smad3-dependent. ChIP analysis identified occupancy of Twist at promoter region of Wnt3. Knock-down of Twist by shRNA confirmed the significance of Twist in response to TGF-β regulating Wnt3 during EMT. Subsequently, TGF-β-induced matrix metalloproteinases, MMP1, MMP7, MMP9, MMP26, Vascular endothelial growth factors (VEGF), and activation of Wnt/β-catenin signaling were repressed by the shRNA treatment. TGF-βR1 ALK5 kinase inhibitor, A83-01 can effectively prevent the TGF-β-induced Twist and Wnt3. Co-treating A83-01 and trastuzumab inhibited TGF-β-induced cell invasion significantly in both trastuzumab responsive and resistant cells.ConclusionsOur data demonstrated an important interdependence between TGF-β and Wnt/β-catenin pathways inducing EMT in HER2-overexpressing breast cancer cells. Twist served as a linkage between the two pathways during TGF-β-induced EMT. A83-01 could inhibit the TGF-β-initiated pathway interactions and enhance HER2-cells response to trastuzumab treatment

Thermal conductivity, electrical resistivity and Lorenz function data for metallic elements in the range 273 to 1500 K

The report contains measured values of the thermal conductivity and the electrical resistivity, as well as the (total) Lorenz functions L(T) calculated from them in the temperature range 273-1500 K by two precision methods on 43 pure metals. Two precision measuring methods were brought into operation. Except for the data for six alkali and alkaline-earth metals determined by Cook et al. according to the NRCC method, all other data were determined according to the direct heating method developed from 1982 at KFA Jülich. Apart from closing various gaps in knowledge concerning thermal conductivity, for example with the noble metals, lanthanides and some other metals, including Y, Hf, Re, V, Zr and Ti, the special feature of the present report is a regular behavior found for the Lorenz functions L(T) not previously known for high temperatures. On the basis of previous conceptions, an approximation to the Sommerfeld value of L$_{0}$=2.44$\cdot$10$^{-8}$ V2/K2 was generally expected. However, a grouping within five approximately equidistant bands was found, covering the range from 2.15 to 3.15$\cdot$10$^{-8}$ V2/K2

Thermal conductivity, electric resistivity and Lorenz function data for metallic elements in the range 273 to 1500 K

The report contains measured values of the thermal conductivity and the electrical resistivity, as well as the (total) Lorenz functions L(T) calculated from them in the temperature range 273-1500 K by two precision methods on 43 pure metals. Two precision measuring methods were brought into operation. Except for the data for six alkali and alkaline-earth metals determined by Cook et al. according to the NRCC method, all other data were determined according to the direct heating method developed from 1982 at KFA Jülich. Apart from closing various gaps in knowledge concerning thermal conductivity, for example with the noble metals, lanthanides and some other metals, including Y, Hf, Re, V, Zr and Ti, the special feature of the present report is a regular behavior found for the Lorenz functions L(T) not previously known for high temperatures. On the basis of previous conceptions, an approximation to the Sommerfeld value of L$_{0}$=2.44$\cdot$10$^{-8}$ V2/K2 was generally expected. However, a grouping within five approximately equidistant bands was found, covering the range from 2.15 to 3.15$\cdot$10$^{-8}$ V2/K2

Significance of positively charged amino acids for the function of the acidovorax delafieldii porin omp34

The functional significance of charged amino acids of the anion-selective porin Omp34 from Acidovorax delafieldii was investigated by means of conductance measurements. Chemical modification of Lys end Arg as well as titration of charges by adjusting the pH value revealed that positively charged amino acid residues determine the major functional properties of the porin. Positive charges are involved in creating the protein surface potential, the selectivity filter inside the channels, and the voltage-sensing and/or gating mechanisms. [References: 19

The Functional Properties of Ompb, the Regularly Arrayed Porin of the Hyperthermophilic Bacterium Thermotoga maritima

The regularly arrayed outer membrane protein, Ompɿ, of Thermotoga maritima was purified to homogeneity and was characterized functionally by incorporation into artificial lipid bilayers. The polypeptide has an apparent molecular mass (Mr) of approx. 40 000 and forms stable trimers in the presence of 1% octyl-polyoxyethylene or 2% SDS which dissociate when boiling the sample. The protein has a secondary structure (predominantly ɿ-sheet) and an amino acid composition characteristic for porins. Pore-forming activity was demonstrated by porin incorporation into artificial bilayers proving that Ompɿ is a true porin: selectivity measurements showed a 4.4-fold selectivity for cations over anions. Conductivity of the porin is influenced by surface charges and also depends on the applied voltage