Application of bioanalytical and computational methods in decoding the roles of glycans in host-pathogen interactions

Host-pathogen interactions (HPIs) are complex processes that require tight regulation. A common regulatory mechanism of HPIs is through glycans of either host cells or pathogens. Due to their diverse sequences, complex structures, and conformations, studies of glycans require highly sensitive and powerful tools. Recent improvements in technology have enabled the application of many bioanalytical techniques and modeling methods to investigate glycans and their mechanisms in HPIs. This mini-review highlights how these advances have been used to understand the role glycans play in HPIs in the past 2 years.

Discovery of a cryptic site at the interface 2 of TEAD - Towards a new family of YAP/TAZ-TEAD inhibitors

The Hippo pathway is involved in organ size control and tissue homeostasis by regulating cell growth, proliferation and apoptosis. It controls the phosphorylation of the transcription co-activator YAP (Yes associated protein) and TAZ (Transcriptional coactivator with PDZ-binding motif) in order to control their nuclear import and their interaction with TEAD (Transcriptional Enhanced Associated Domain). YAP, TAZ and TEADs are dysregulated in several cancers making YAP/TAZ-TEAD interaction a new emerging anti-cancer target. We report the synthesis of a set of trisubstituted pyrazoles which bind to hTEAD2 at the interface 2 revealing for the first time a cryptic pocket created by the movement of the phenol ring of Y382. Compound 6 disrupts YAP/TAZ-TEAD interaction in HEK293T cells and inhibits TEAD target genes and cell proliferation in MDA-MB-231 cells. Compound 6 is therefore the first inhibitor of YAP/TAZ-TEAD targeting interface 2. This molecule could serve with other pan-TEAD inhibitors such as interface 3 ligands, for the delineation of the relative importance of VGLL vs YAP/TAZ in a given cellular model.

History of the dopamine hypothesis of antipsychotic action

The dopamine hypothesis of how antipsychotic drugs exert their beneficial effect in psychotic illness has an interesting history that dates back to 1950. This hypothesis is not to be confused with the dopamine hypothesis of schizophrenia; the aim of the latter is to explain the etiology of schizophrenia. The present review does not deal with schizophrenia but, rather, with the historical development of our current understanding of the dopamine-associated actions of the drugs that reduce the symptoms of psychosis. This historical review begins with the serendipitous discovery of chlorpromazine, a drug synthesized around a chemical core that initially served to produce man-made dyes. This molecular core subsequently contributed to the chemistry of antihistamines. It was with the aim of producing a superior antihistamine that chlorpromazine was synthesized; instead, it revolutionized the treatment of psychosis. The first hypothesis of how this drug worked was that it induced hypothermia, a cooling of the body that led to a tranquilization of the mind. The new, at the time, discoveries of the presence of chemical transmitters in the brain soon steered investigations away from a temperature-related hypothesis toward questioning how this drug, and other drugs with similar properties and effects, modulated endogenous neurotransmission. As a result, over the years, researchers from around the world have begun to progressively learn what antipsychotic drugs do in the brain.

Transgenic insect-resistant Bt cotton expressing Cry1Ac/CpTI does not affect the mirid bug Apolygus lucorum

Common varieties of genetically modified (GM) cotton increasingly display insect-resistant properties via expression of bacterial-derived toxins from Bacillus thuringiensis (Bt). This necessitates a deeper understanding of the possible effects of these crops on non-target insects. The mirid bug Apolygus lucorum is a major pest in cotton production in China, however, the effect of GM cotton on this non-target species is currently virtually unknown. This insect is exposed to these transgenic plants by consuming genetically modified (GM) leaves. In this study, laboratory experiments were conducted to assess the toxicity of CCRI41 and CCRI45, (genetically modified cotton varieties which express the toxins Cry1Ac and CpTI (Cowpea Trypsin Inhibitor)) on nymphs and adults of A. lucorum. There was no detectable increase in mortality after A. lucorum fed on GM cotton leaves for 20 days. While we detected trace amounts of Cry1Ac proteins in both A. lucorum nymphs and adults (<10 ng/g fresh weight), the expression of genes related to detoxification did not detectably differ from those feeding on non-GM cotton. Our binding assays did not show Cry1Ac binding to receptors on the midgut brush border membrane from either A. lucorum nymphs or adults. Our findings collectively indicate that feeding on leaves of the GM cotton varieties CCRI41 and CCRI45 have few toxic effects on A. lucorum.

Pioneer factors and their in vitro identification methods

Pioneer transcription factors are a special group of transcription factors that can interact with nucleosomal DNA and initiate regulatory events. Their binding to regulatory regions is the first event in gene activation and can occur in silent or heterochromatin regions. Several research groups have endeavored to define pioneer factors and study their binding characteristics using various techniques. In this review, we describe the in vitro methods used to define and characterize pioneer factors, paying particular attention to differences in methodologies and how these differences can affect results.

Screening oxime libraries by means of mass spectrometry (MS) binding assays: Identification of new highly potent inhibitors to optimized inhibitors γ-aminobutyric acid transporter 1

Generation and screening of oxime libraries by competitive MS Binding Assays represents a powerful tool for the identification of new compounds, with affinity to mGAT1, the most abundant plasma membrane bound GABA transporter in the CNS. By screening a guvacine derived oxime library, new potent inhibitors of mGAT1 had been revealed. In the present study, oxime libraries generated by reaction of a large excess of a rac-nipecotic acid derivative displaying a hydroxylamine functionality in which various aldehydes under suitable conditions, were examined for new potent inhibitors of mGAT1. The pK_i values obtained of the best hits were compared with those of related compounds displaying a guvacine instead of a nipecotic acid subunit as hydrophilic moiety. Amongst the new compounds one of the most affine ligands of mGAT1 known so far (pK_i = 8.55 ± 0.04) was found.

Transgenic Bt cotton expressing Cry1Ac/Cry2Ab or Cry1Ac/EPSPS does not affect the plant bug Adelphocoris suturalis or the pollinating beetle Haptoncus luteolus

The widespread cultivation of transgenic Bt cotton makes assessing the potential effects of this recombinant crop on non-target organisms a priority. However, the effect of Bt cotton on many insects is currently virtually unknown. The plant bug Adelphocoris suturalis is now a major pest of cotton in southern China and the beetle Haptoncus luteolus is one of the most ancient cotton pollinators. We conducted laboratory experiments to evaluate the toxicity of the Bt cotton varieties ZMSJ, which expresses the toxins Cry1Ac and Cry2Ab, and ZMKCKC, which expresses Cry1Ac and EPSPS, on adult A. suturalis and H. luteolus. No significant increase in the mortality of either species was detected after feeding on Bt cotton leaves or pollen for 7 days. Trace amounts of Cry1Ac and Cry2Ab proteins could be detected in both species but in vitro binding experiments found no evidence of Cry1Ac and Cry2Ab binding proteins. These results demonstrate that feeding on the leaves or pollen of these two Bt cotton varieties has no toxic effects on adult A. suturalis or H. luteolus.

Performance and Specificity of 6 Immunoassays for TSH Receptor Antibodies: A Multicenter Study

BACKGROUND

The measurement of TSH receptor (TSHR) antibodies is warranted for diagnosis of Graves' disease (GD).

OBJECTIVE

The performance, detection sensitivity, and specificity of 6 TSHR immunoassays were compared.

METHODS

Two bioassays and 4 binding assays (Kronus, Immulite, Kryptor, Dynex) were compared in a dilution study performed in patients with autoimmune thyroid disease. Both bioassays were compared to 2 binding assays using stimulatory (M22) and blocking (K1-70) monoclonal antibody (MAb) mixtures.

RESULTS

Thirty samples from stimulatory (TSAb)-positive/blocking (TBAb)-negative patients with GD were diluted serially and measured in all assays. Samples were positive until dilution 1:2,187 in the TSAb bioassay, 1:81 in the Immulite (p < 0.002 vs. bioassay) and Kronus ELISA (p = 0.039) assays, and 1:27 in the Kryptor and Dynex ELISA (p < 0.001 vs. bioassay). Ten samples from TBAb-positive/TSAb-negative patients with GD or Hashimoto's thyroiditis were positive in all binding assays. None of the binding assays differentiated between TSAb and TBAb. Mixtures of 100% K1-70 (200 ng/mL), 80% K1-70 + 20% M22, 60% K1-70 + 40% M22, 40% K1-70 + 60% M22, 20% K1-70 + 80% M22, and 100% M22 (20 ng/mL) tested positive in both Immulite (26.4, 20.2, 15.2, 10.5, 6.3, 2.00 IU/L) and Kronus assays (27.1, 23.3, 19.3, 12.0, 5.7, 2.2 IU/L). These MAb mixtures were tested in the TBAb bioassay and showed 82, 61, 24 (negative), -26 (negative), -77 (negative), and -95% (negative) inhibition, respectively.

CONCLUSIONS

The sample dilution study showed higher detection sensitivity for the TSAb bioassay, and the antibody mixture study demonstrated exclusive specificity of the bioassays over all automated and ELISA binding assays.

Highly variable sensitivity of five binding and two bio-assays for TSH-receptor antibodies

PURPOSE

TSH-receptor (TSHR) antibodies (Ab) can be measured with binding or bio-assays. Sensitivity and specificity of five binding and two bio-assays were compared.

METHODS

TSHR-blocking (TBAb) and TSHR-stimulating (TSAb) Ab were measured with reporter bio-assays. Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bTSH alone. TSAb was reported as percentage of specimen-to-reference ratio (SRR%). TSHR-binding inhibitory immunoglobulins (TBII) were measured with Kronus, Dynex, Kryptor, Cobas, and Immulite.

RESULTS

Sixty patients with Graves' disease (GD), 20 with Hashimoto's thyroiditis (HT), and 20 healthy controls (C) were included. C tested negative in all assays (specificity 100 %) while all 60 hyperthyroid GD patients tested positive in the TSAb bio-assay (sensitivity 100 %). Among these 60 GD patients, 20 had low TSAb positivity (SRR% 140-279), but were TBII positive in only 20 (100 %), 7 (35 %), 9 (45 %), 11 (55 %), and 18 (90 %) using the Kronus, Dynex, Kryptor, Cobas, and Immulite, respectively. In 20 moderate TSAb-positive (SRR% 280-420) patients, TBII tested positive in 20 (100 %), 14 (70 %), 13 (65 %), 16 (80 %), and 19 (95 %), respectively. The high (SRR% > 420) TSAb-positive patients were all TBII positive. All 20 hypothyroid HT patients tested TBAb positive (sensitivity 100 %) in the bio-assay while they tested TBII positive in 20 (100 %), 18 (90 %), 20, 20, and 18, respectively. Results obtained with two luminometers correlated for TSAb positive (r = 0.99, p < 0.001), TBAb positive (r = 0.88, p < 0.001), and C (r = 0.86, p < 0.001). None of the binding assays differentiated between TSAb and TBAb.

CONCLUSIONS

Sensitivity is highly variable between binding and bio-assays for TSHR-Abs.

Synthesis, in vitro and in vivo pharmacological evaluation of serotoninergic ligands containing an isonicotinic nucleus

Isonicotinamide derivatives, linked to an arylpiperazine moiety, were prepared and their affinity to 5-HT1A, 5-HT2A and 5-HT2C receptors were evaluated. The combination of structural elements (heterocyclic nucleus, alkyl chain and 4-substituted piperazine) known to play critical roles in affinity for serotoninergic receptors and the proper selection of substituents led to compounds with high specificity and affinity towards serotoninergic receptors. In binding studies, several molecules showed high affinity in nanomolar and subnanomolar range at 5-HT1A, 5-HT2A and 5-HT2C receptors and moderate or no affinity for other relevant receptors (D1, D2, α1 and α2). N-(3-(4-(bis(4-fluorophenyl)methyl)piperazin-1-yl)propyl)isonicotinamide (4s) with Ki = 0.130 nM, was the most active and selective derivative for the 5-HT1A receptor compared to other serotoninergic, dopaminergic and adrenergic receptors. Compound 4o, instead, showed 5-HT2A affinity values in subnamolar range. Moreover, the compounds having better affinity and selectivity binding profile towards 5-HT1A and 5-HT2A receptors were selected in order to be tested by in vitro and in vivo assays to determine their functional activity.

Inhibition of Infected Red Blood Cell Binding to the Vascular Endothelium

Plasmodium falciparum-infected red blood cells (IRBC) adhere to the endothelium via receptors expressed on the surface of vascular endothelial cells (EC) and sequester in the microvasculature of several organs. Sequestration is the primary step leading to complications related to the severity of malaria. In order to study this cytoadhesion phenomenon, IRBC in vitro binding assays have been developed using a monolayer of primary or transformed endothelial cells. Here we describe the methodology of an assay to inhibit the binding of IRBC on vascular endothelial cells under static adhesion conditions. Similar techniques could be used for conducting a binding inhibition assay under flow assay conditions using an appropriate device.

Synthesis and biological evaluation of novel delta (δ) opioid receptor ligands with diazatricyclodecane skeletons

Considering the interesting pharmacological profile of the delta (δ) selective opioid agonist compound SNC-80, conformationally constrained analogs containing two diazatricyclodecane ring systems in place of dimethylpiperazine core motif were synthesized. The compounds showed subnanomolar or low nanomolar δ opioid receptor binding affinity. Depending upon the substituents on the diazatricyclodecane ring, these compounds displayed varying selectivity for δ opioid receptor over μ and κ receptors. Amongst the novel compounds, 1Aa showed the more interesting biological profile, with higher δ affinity and selectivity compared to SNC-80. The δ receptor agonist profile and antinociceptive activity of 1Aa were confirmed using ex-vivo (isolated mouse vas deferens) and in vivo (tail flick) assays.

Resistance to Bt maize in Mythimna unipuncta (Lepidoptera: Noctuidae) is mediated by alteration in Cry1Ab protein activation

Bt maize cultivars based on the event MON810 (expressing Cry1Ab) have shown high efficacy for controlling corn borers. However, their efficiency for controlling some secondary lepidopteran pests such as Mythimna unipuncta has been questioned, raising concerns about potential outbreaks and its economic consequences. We have selected a resistant strain (MR) of M. unipuncta, which is capable of completing its life cycle on Bt maize and displays a similar performance when feeding on both Bt and non-Bt maize. The proteolytic activation of the protoxin and the binding of active toxin to brush border membrane vesicles were investigated in the resistant and a control strain. A reduction in the activity of proteolytic enzymes, which correlates with impaired capacity of midgut extracts to activate the Cry1Ab protoxin has been observed in the resistant strain. Moreover, resistance in larvae of the MR strain was reverted when treated with Cry1Ab toxin activated with midgut juice from the control strain. All these data indicate that resistance in the MR strain is mediated by alteration of toxin activation rather than to an increase in the proteolytic degradation of the protein. By contrast, binding assays performed with biotin labelled Cry1Ab suggest that binding to midgut receptors does not play a major role in the resistance to Bt maize. Our results emphasize the risk of development of resistance in field populations of M. unipuncta and the need to consider this secondary pest in ongoing resistance management programs to avoid the likely negative agronomic and environmental consequences.