Reconstitution of membranes simulating "glycosignaling domain" and their susceptibility to lyso-GM3

GM3 ganglioside at the surface of mouse melanoma B16 cells is clustered and organized with signal transducer molecules c-Src, Rho A, and focal adhesion kinase (FAK) to form a membrane unit separable from caveolae, which are enriched in cholesterol and caveolin but do not contain GM3 or the above three signal transducers. The GM3-enriched membrane units are involved in GM3-dependent cell adhesion coupled with activation of c-Src, Rho A, and FAK and are termed the "glycosphingolipid signaling domain" or the "glycosignaling domain" (GSD). In order to assess the essential components that display GSD function, membranes with properties similar to those of GSD were reconstituted using GM3, sphingomyelin, and c-Src, with or without other lipid components. The reconstituted membrane thus prepared displayed GM3-dependent adhesion to plates coated with Gg3 or anti-GM3 antibody, resulting in enhanced c-Src phosphorylation (c-Src phosphorylation response). This response in reconstituted membrane depends on GM3 concentration and was not observed when GM3 was absent or replaced with other gangliosides GM1 or GD1a, or with LacCer. The GM3-dependent c-Src phosphorylation response was enhanced when cholesterol and phosphatidylcholine were added. Although GM3, sphingomyelin, and c-Src are essential for GSD function, a small quantity of cholesterol and phosphatidylcholine may act as an auxiliary factor to stabilize membrane. GSD function in terms of GM3-dependent adhesion and signaling was blocked in the presence of lyso-GM3 or its analogue but not psychosine, lactosyl-sphingosine, or lyso-phosphatidylcholine. Such susceptibility of reconstituted GSD to lyso-GM3 and other lyso compounds is the same as GSD of original B16 cells. Thus, functional organization of the reconstituted membrane closely simulates that of GSD in B16 cells, which is based on clustered GM3 organized with c-Src as the essential components.     

Ultraweak sugar-sugar interactions for transient cell adhesion

Carbohydrate-carbohydrate interactions are rarely considered in biologically relevant situations such as cell recognition and adhesion. One Ca(2+)-mediated homotypic interaction between two Lewis(x) determinants (Le(x)) has been proposed to drive cell adhesion in murine embryogenesis. Here, we confirm the existence of this specific interaction by reporting the first direct quantitative measurements in an environment akin to that provided by membranes. The adhesion between giant vesicles functionalized with Le(x) was obtained by micropipette aspiration and contact angle measurements. This interaction is below the thermal energy, and cell-cell adhesion will require a large number of molecules, as illustrated by the Le(x) concentration peak observed at the cell membranes during the morula stage of the embryo. This adhesion is ultralow and therefore difficult to measure. Such small interactions explain why the concept of specific interactions between carbohydrates is often neglected.     

DNA-methylation profiling of fetal tissues reveals marked epigenetic differences between chorionic and amniotic samples

Epigenetic mechanisms including DNA methylation are supposed to play a key role in fetal development. Here we have investigated fetal DNA-methylation levels of 27,578 CpG loci in 47 chorionic villi (CVS) and 16 amniotic cell (AC) samples. Methylation levels differed significantly between karyotypically normal AC and CVS for 2,014 genes. AC showed more extreme DNA-methylation levels of these genes than CVS and the differentially methylated genes are significantly enriched for processes characteristic for the different cell types sampled. Furthermore, we identified 404 genes differentially methylated in CVS with trisomy 21. These genes were significantly enriched for high CG dinucleotid (CpG) content and developmental processes associated with Down syndrome. Our study points to major tissue-specific differences of fetal DNA-methylation and gives rise to the hypothesis that part of the Down syndrome phenotype is epigenetically programmed in the first trimester of pregnancy.     

Conjugation of cyclodextrin with fullerene as a new class of HCV entry inhibitors

An α-cyclodextrin-[60]fullerene conjugate with a flexible linker at the secondary face of α-cyclodextrin has been prepared, which displays significant water solubility and, more importantly, acts as a new class of HCV entry inhibitor with IC(50) at 0.17μM level.     

How to monitor environmental pressures of a circular economy: An assessment of indicators

Understanding how a circular economy (CE) can reduce environmental pressures from economic activities is crucial for policy and practice. Science provides a range of indicators to monitor and assess CE activities. However, common CE activities, such as recycling and eco‐design, are contested in terms of their contribution to environmental sustainability. This article assesses whether and to what extent current approaches to assess CE activities sufficiently capture environmental pressures to monitor progress toward environmental sustainability. Based on a material flow perspective, we show that most indicators do not capture environmental pressures related to the CE activities they address. Many focus on a single CE activity or process, which does not necessarily contribute to increased environmental sustainability overall. Based on these results, we suggest complementing CE management indicators with indicators capturing basic environmental pressures related to the respective CE activity. Given the conceptual linkage between CE activities, resource extraction, and waste flows, we suggest that a resource‐based footprint approach accounting for major environmental inputs and outputs is necessary—while not sufficient—to assess the environmental sustainability of CE activities. As footprint approaches can be used across scales, they could aid the challenging process of developing indicators for monitoring progress toward an environmentally sustainable CE at the European, national, and company levels.     

The conformation of the C-glycosyl analogue of N-acetyl-lactosamine in the free state and bound to a toxic plant agglutinin and human adhesion/growth-regulatory galectin-1

The conformational behavior of the C-glycoside analogue of N-acetyl-lactosamine, beta-C-Gal-(1-->4)-beta-GlcNAc-OMe, 1, has been studied using a combination of molecular mechanics calculations and NMR spectroscopy (J and NOE data). It is shown that the C-disaccharide populates three distinctive conformational families in solution, the major one being the anti-psi conformation. Of note, this conformation is only marginally populated for the O-disaccharide. Due to its conspicuous role in the regulation of adhesion, growth and tissue invasion of tumors and its avid binding to N-acetyl-lactosamine human, galectin-1 was tested as a receptor. This endogenous lectin recognizes a local minimum of 1, the syn-PhiPsi conformer, and thus a conformational selection process is correlated with the molecular recognition event.     

Improvement of cytotoxicity of mitoxantrone and daunorubicin by candidone,tephrosin, and bavachinin

Molecular Biology Reports - Flavonoids have been demonstrated to have the ability of sensitizing cancer cells to chemotherapy and inverse multidrug resistance via various mechanisms, such as...     

Resistance mechanisms to immune checkpoints blockade by monoclonal antibody drugs in cancer immunotherapy: Focus on myeloma

Multiple myeloma (MM) is a clonal B‐cell malignancy characterized by the accumulation of neoplastic proliferation of a plasma cell in the bone marrow that produces a monoclonal immunoglobulin. The immune checkpoint inhibitors against programmed death‐1/programmed death‐1 ligand and cytotoxic T‐lymphocyte antigen 4 axis have demonstrated appropriate anticancer activity in several solid tumors and liquid cancers, and are rapidly transforming the practice of medical oncology. However, in a high percentage of patients, the efficacy of immune checkpoints blockade remains limited due to innate or primary resistance. Moreover, the malignancies progress in many patients due to acquired or secondary resistance, even after the clinical response to immune checkpoints' blockade. The evidence shows that multiple tumor‐intrinsic and tumor‐extrinsic factors and alterations in signaling pathways are involved in primary and secondary resistance to immune checkpoints blockade. Improved identification of intrinsic and extrinsic factors and mechanisms of resistance or response to immune checkpoints blockade may not only provide novel prognostic or predictive biomarkers but also guide the optimal combination/sequencing of immune checkpoint blockade therapy in the clinic. Here, we review the underlying biology and role of immune checkpoints blockade in patients with MM. Furthermore, we review the host and tumor‐related factor effects on immune checkpoints blockade in MM immunotherapy.     

Applicability of Chromatographic Co‐Elution for Antibiotic Target Identification

Identification of the molecular target is a crucial step in evaluating novel antibiotics. To support target identification, a label‐free method based on chromatographic co‐elution has previously been developed. Target identification by chromatographic coelution (TICC) exploits the alteration of the elution profile of target‐bound drug versus free drug in ion exchange (IEX) chromatography to identify potential target proteins from elution fractions. The applicability of TICC for antibiotic research is investigated by evaluating which proteins, that is, putative targets, can be monitored in Bacillus subtilis. Coelution of components of known protein complexes provides a read‐out for how well the native state of proteins is conserved during chromatography. Rifampicin, which targets RNA polymerase, is used in a proof‐of‐concept study.