Structure-activity relationship of leucyladenylate sulfamate analogues as leucyl-tRNA synthetase (LRS)-targeting inhibitors of Mammalian target of rapamycin complex 1 (mTORC1)

Leucyl-tRNA synthetase (LRS) plays an important role in amino acid-dependent mTORC1 signaling, which is known to be associated with cellular metabolism and proliferation. Therefore, LRS-targeting small molecules that can suppress mTORC1 activation may provide an alternative strategy to current anticancer therapy. In this work, we developed a library of leucyladenylate sulfate analogues by extensively modifying three different pharmacophoric regions comprising adenine, ribose and leucine. Several effective compounds were identified by cell-based mTORC1 activation assays and further tested for anticancer activity. The selected compounds mostly exhibited selective cytotoxicity toward five different cancer cell lines, supporting the hypothesis that the LRS-mediated mTORC1 pathway is a promising alternative target to current therapeutic approaches.     

Virulence‐associated protein A from Rhodococcus equi is an intercompartmental pH‐neutralising virulence factor

Professional phagocytic cells such as macrophages are a central part of innate immune defence. They ingest microorganisms into membrane‐bound compartments (phagosomes), which acidify and eventually fuse with lysosomes, exposing their contents to a microbicidal environment. Gram‐positive Rhodococcus equi can cause pneumonia in young foals and in immunocompromised humans. The possession of a virulence plasmid allows them to subvert host defence mechanisms and to multiply in macrophages. Here, we show that the plasmid‐encoded and secreted virulence‐associated protein A (VapA) participates in exclusion of the proton‐pumping vacuolar‐ATPase complex from phagosomes and causes membrane permeabilisation, thus contributing to a pH‐neutral phagosome lumen. Using fluorescence and electron microscopy, we show that VapA is also transferred from phagosomes to lysosomes where it permeabilises the limiting membranes for small ions such as protons. This permeabilisation process is different from that of known membrane pore formers as revealed by experiments with artificial lipid bilayers. We demonstrate that, at 24 hr of infection, virulent R. equi is contained in a vacuole, which is enriched in lysosome material, yet possesses a pH of 7.2 whereas phagosomes containing a vapA deletion mutant have a pH of 5.8 and those with virulence plasmid‐less sister strains have a pH of 5.2. Experimentally neutralising the macrophage endocytic system allows avirulent R. equi to multiply. This observation is mirrored in the fact that virulent and avirulent R. equi multiply well in extracts of purified lysosomes at pH 7.2 but not at pH 5.1. Together these data indicate that the major function of VapA is to generate a pH‐neutral and hence growth‐promoting intracellular niche. VapA represents a new type of Gram‐positive virulence factor by trafficking from one subcellular compartment to another, affecting membrane permeability, excluding proton‐pumping ATPase, and consequently disarming host defences.     

X-ray sterilization of biopharmaceutical manufacturing equipment—Extractables profile of a film material and copolyester Tritan™ compared to gamma irradiation

The biopharmaceutical industry gains enormous flexibility in production processes by using sterilized preassembled single-use devices. Gamma irradiation is an established sterilization technology that may be restricted in the future by the availability of ⁶⁰Co as irradiation source and irradiation capacities. X-ray technology is considered an alternative type of radiation for sterilizing SU equipment. In the context of extractables and leachables—one concern connected with the use of single-use process equipment—the effect of X-ray irradiation on the extractables profile of the materials needs to be compared to established gamma irradiation to qualify this alternative technology. An approach is presented to obtain robust and comprehensive extractables data for materials used in SU devices after sterilization either using X-ray or gamma irradiation. A careful selection of the test items and the test design allows a one-to-one comparison of data obtained from a combination of orthogonal analytical techniques. The extractables of a modern SU film material and the copolyester Tritan™ are evaluated. The data presented allow a risk evaluation on the safety of this new sterilization modality for biopharmaceutical applications. It is demonstrated that the extractables profile of a polymer is not affected by the type of irradiation used for sterilization.     

Tandem affinity purification of functional TAP-tagged proteins from human cells

Tandem affinity purification (TAP) is a generic two-step affinity purification protocol for isolation of TAP-tagged proteins together with associated proteins. We used bacterial artificial chromosome to heterologously express TAP-tagged murine Sgo1 protein in human HeLa cells. This allowed us to test the functionality of the Sgo1-TAP protein by RNA interference-mediated depletion of the endogenous human Sgo1. Here, we present an optimized protocol for purification of TAP-tagged Sgo1 protein as well as KIAA1387 from HeLa cells with detailed instructions. The purification protocol can be completed in 1 day and it should be applicable to other proteins.     

Determination of drug permeability and prediction of drug absorption in Caco-2 monolayers

Permeability coefficients across monolayers of the human colon carcinoma cell line Caco-2, cultured on permeable supports, are commonly used to predict the absorption of orally administered drugs and other xenobiotics. This protocol describes our method for the cultivation, characterization and determination of permeability coefficients of xenobiotics (which are, typically, drug-like compounds) in the Caco-2 model. A few modifications that have been introduced over the years are incorporated in the protocol. The method can be used to trace the permeability of a test compound in two directions, from the apical to the basolateral side or vice versa, and both passive and active transport processes can be studied. The permeability assay can be completed within one working day, provided that the Caco-2 monolayers have been cultured and differentiated on the permeable supports 3 weeks in advance.     

Towards development of an efficient somatic embryogenesis protocol for the palm tree Euterpe precatoria (Mart.) from leaf tissues of adult plants

In Vitro Cellular & Developmental Biology - Plant - An efficient, reproducible, and unprecedented protocol of somatic embryogenesis (SE) was developed from leaf tissues of adult plants of...     

Low sodium isocyanurate concentrations as a substitute to medium autoclaving in plant tissue culture

Plant Cell, Tissue and Organ Culture (PCTOC) - An optimization for a medium sterilization method, capable of substituting autoclaving, was developed using low concentrations of sodium isocyanurate...     

Simulation of the entanglement of a North Atlantic right whale (Eubalaena glacialis) with fixed fishing gear

Population estimates of the critically endangered North Atlantic right whale (Eubalaena glacialis) put the number of individuals at 458 with the actual number likely being lower due to a recent unusual mortality event. Entanglement with fixed fishing gear is the most significant cause of mortality of North Atlantic right whales. There remains little documentation of how North Atlantic right whales become enwrapped during an encounter with fixed fishing gear. In order to gain a better understanding of how entanglements might occur, an interactive simulator was developed that allows the user to swim a virtual whale model using a standard game controller through a gear field in an attempt to re‐create an entanglement. The morphologically accurate right whale model produces realistic swimming motions and is capable of pectoral fin motions in response to user input. Using the simulator, gear entanglements involving the pectoral flippers including ropes wrapping around the body and entanglements involving the tailstock were re‐created. Entanglements involving the pectoral flippers with body wraps were more easily generated than entanglements involving the tailstock only. The simulator should aid scientists, fisheries experts, fishing gear designers, and bycatch reduction scientists in understanding entanglement dynamics and testing potential new gear configurations.     

Disassembly of microtubules and inhibition of neurite outgrowth, neuroblastoma cell proliferation, and MAP kinase tyrosine dephosphorylation by dibenzyl trisulphide

Dibenzyl trisulphide (DTS), a main lipophilic compound in Petiveria alliacea L. (Phytolaccaceae), was identified as one of the active immunomodulatory compounds in extracts of the plant. To learn more about its biological activities and molecular mechanisms, we conducted one-dimensional NMR interaction studies with bovine serum albumin (BSA) and tested DTS and related compounds in two well-established neuronal cell-and-tissue culture systems. We found that DTS preferentially binds to an aromatic region of BSA which is rich in tyrosyl residues. In SH-SY5Y neuroblastoma cells, DTS attenuates the dephosphorylation of tyrosyl residues of MAP kinase (erk1/erk2). In the same neuroblastoma cell line and in Wistar 38 human lung fibroblasts, DTS causes a reversible disassembly of microtubules, but it did not affect actin dynamics. Probably due to the disruption of the microtubule dynamics, DTS also inhibits neuroblastoma cell proliferation and neurite outgrowth from spinal cord explants. Related dibenzyl compounds with none, one, or two sulphur atoms were found to be significantly less effective. These data confirmed that the natural compound DTS has a diverse spectrum of biological properties, including cytostatic and neurotoxic actions in addition to immunomodulatory activities.