On-DNA Synthesis of Multisubstituted Indoles

The increasing role of the DNA-encoded library technology in early phase drug discovery represents a significant demand for DNA-compatible synthetic methods for therapeutically relevant heterocycles. Herein, we report the first on-DNA synthesis of multisubstituted indoles via a cascade reaction of Sonogashira coupling and intramolecular ring closure. Further functionalization by Suzuki coupling at the third position exploits a diverse chemical space. The high fidelity of the method also enabled the construction of an indole-based mock library.

Anti-CGRP antibody galcanezumab modifies the function of the trigeminovascular nocisensor complex in the rat

BACKGROUND

Monoclonal antibodies directed against the neuropeptide calcitonin gene-related peptide (CGRP) are effective in the prevention of chronic and frequent episodic migraine. Since the antibodies do not cross the blood brain barrier, their antinociceptive effect is attributed to effects in meningeal tissues. We aimed to probe if such an antibody can be visualized within the dura mater and the trigeminal ganglia following its administration to rats and to examine if the activity of the trigeminovascular nocisensor complex is influenced by this treatment.

METHODS

Effects of the anti-CGRP antibody galcanezumab on the trigeminovascular nocisensor complex was examined by measuring release of sensory neuropeptides and histamine from the rat dura mater. Deposits of galcanezumab were visualized by fluorescence microscopy in the trigeminal ganglion and the dura mater.

RESULTS

Fluorophore-labelled galcanezumab was detected in the dura mater and the trigeminal ganglion up to 30 days after treatment affirming the long-lasting modulatory effect of this antibody. In female rats, seven days after systemic treatment with galcanezumab the capsaicin-induced release of CGRP was decreased, while that of substance P (SP) was increased in the dura mater. In control rats, release of the inhibitory neuropeptide somatostatin (SOM) was higher in females than in males. Stimulation with high concentration of KCl did not significantly change the release of SOM in control animals, while in rats treated with galcanezumab SOM release was slightly reduced. Galcanezumab treatment also reduced the amount of histamine released from dural mast cells upon stimulation with CGRP, while the effect of compound 48/80 on histamine release was not changed.

CONCLUSIONS

Galcanezumab treatment is followed by multiple changes in the release of neuropeptides and histamine in the trigeminal nocisensor complex, which may contribute to the migraine preventing effect of anti-CGRP antibodies. These changes affecting the communication between the components of the trigeminal nocisensor complex may reduce pain susceptibility in migraine patients treated with CGRP targeting monoclonal antibodies.

Nanoinjection of extracellular vesicles to single live cells by robotic fluidic force microscopy

In the past decade, extracellular vesicles (EVs) have attracted substantial interest in biomedicine. With progress in the field, we have an increasing understanding of cellular responses to EVs. In this Technical Report, we describe the direct nanoinjection of EVs into the cytoplasm of single cells of different cell lines. By using robotic fluidic force microscopy (robotic FluidFM), nanoinjection of GFP positive EVs and EV-like particles into single live HeLa, H9c2, MDA-MB-231 and LCLC-103H cells proved to be feasible. This injection platform offered the advantage of high cell selectivity and efficiency. The nanoinjected EVs were initially localized in concentrated spot-like regions within the cytoplasm. Later, they were transported towards the periphery of the cells. Based on our proof-of-principle data, robotic FluidFM is suitable for targeting single living cells by EVs and may lead to information about intracellular EV cargo delivery at a single-cell level.

Application of Normal-Phase Silica Column in Hydrophilic Interaction Liquid Chromatography Mode for Simultaneous Determination of Underivatized Amino Acids from Human Serum Samples via Liquid Chromatography-Tandem Mass Spectrometry

In neonatal screening, amino acids have a significant diagnostic role. Determination of their values may identify abnormal conditions. Early diagnosis and continuous monitoring of amino acid disorders results in a better disease outcome. An easy and simple LC-MS/MS method was developed for the quantitation of underivatized amino acids. Amino acids were separated using a normal-phase HPLC column having a totally porous silica stationary phase and using classical reversed-phase eluents. Mass spectrometry in multiple reaction monitoring mode was used for the analysis, providing high selectivity and sensitivity. A standard addition calibration model was applied for quantitation using only one isotope-labeled internal standard for all amino acids. Five calibration points were used for quantitation, and the method was successfully validated. The slopes of the calibration curves of the individual amino acids in parallel measurements were found to be similar. Since the measured slopes were reproducible, one serum sample could represent every series of serum samples of a given day. The method was tested on human serum samples and adequate results were obtained. This new method can be easily applied in clinical laboratories.

Evaluation of bioorthogonally applicable tetrazine-Cy3 probes for fluorogenic labeling schemes

The fluorogenic features of three sets of tetrazine-Cy3 probes were evaluated in bioorthogonal tetrazine-cyclooctyne ligation schemes. These studies revealed that the more efficient, internal conversion-based quenching of fluorescence by the tetrazine modul is translated to improved fluorogenicity compared to the more conventional, energy transfer-enabled design. Furthermore, a comparison of directly conjugated probes and vinylene-linked tetrazine-Cy3 probes revealed that more intimate conjugation of the tetrazine and the chromophore results in more efficient IC-based quenching even in spectral ranges where tetrazine exhibits diminished modulation efficiency. The applicability of these tetrazine-quenched fluorogenic Cy3 probes was demonstrated in the fluorogenic labeling schemes of the extra- and intracellular proteins of live cells.

Identification of an NF1 Microdeletion with Optical Genome Mapping

Neurofibromatosis type 1 (NF1) is a clinically heterogeneous neurocutaneous disorder inherited in autosomal dominant manner. Approximately 5-10% of the cases are caused by NF1 microdeletions involving the NF1 gene and its flanking regions. Microdeletions, which lead to more severe clinical manifestations, can be subclassified into four different types (type 1, 2, 3 and atypical) according to their size, the genomic location of the breakpoints and the number of genes included within the deletion. Besides the prominent hallmarks of NF1, patients with NF1 microdeletions frequently exhibit specific additional clinical manifestations like dysmorphic facial features, macrocephaly, overgrowth, global developmental delay, cognitive disability and an increased risk of malignancies. It is important to identify the genes co-deleted with NF1, because they are likely to have an effect on the clinical manifestation. Multiplex ligation-dependent probe amplification (MLPA) and microarray analysis are the primary techniques for the investigation of NF1 microdeletions. However, based on previous research, optical genome mapping (OGM) could also serve as an alternative method to identify copy number variations (CNVs). Here, we present a case with NF1 microdeletion identified by means of OGM and demonstrate that this novel technology is a suitable tool for the identification and classification of the NF1 microdeletions.

Dual-Role Peptide with Capping and Cleavage Site Motifs in Nanoparticle-Based One-Pot Colorimetric and Electrochemical Protease Assay

A new method for enzyme substrate assembly and its use in proteolytic enzyme assays with colorimetric and electrochemical detection is presented. The novelty of the method is the use of dual-function synthetic peptide containing both gold clustering and protease-sensitive moieties, which not only induces the simple formation of the peptide-decorated gold nanoparticle test substrates but also allows for the detection of proteolysis in the same batch. Protease-treated nanoparticles with a destabilized peptide shell became more prone to electroactivity, and thus, the model enzyme plasmin activity could be quantified with stripping square wave voltammetry analysis as well, giving an alternative method to conduct aggregation-based assays. Spectrophotometric and electrochemical calibration data proved to be linear within the 40-100 nM active enzyme concentration range, with possible extensions of the dynamic range by varying substrate concentration. The simple initial components and the ease of synthesis make the assay substrate preparation economic and easy to implement. The possibility of cross-check analytical results with two independent measurement techniques in the same batch greatly increases the applicability of the proposed system.

Role of Extracellular Vesicles in Liver Diseases

Extracellular vesicles (EVs) are cell-derived membrane structures that are formed by budding from the plasma membrane or originate from the endosomal system. These microparticles (100 nm-100 µm) or nanoparticles (>100 nm) can transport complex cargos to other cells and, thus, provide communication and intercellular regulation. Various cells, such as hepatocytes, liver sinusoidal endothelial cells (LSECs) or hepatic stellate cells (HSCs), secrete and take up EVs in the healthy liver, and the amount, size and content of these vesicles are markedly altered under pathophysiological conditions. A comprehensive knowledge of the modified EV-related processes is very important, as they are of great value as biomarkers or therapeutic targets. In this review, we summarize the latest knowledge on hepatic EVs and the role they play in the homeostatic processes in the healthy liver. In addition, we discuss the characteristic changes of EVs and their potential exacerbating or ameliorating effects in certain liver diseases, such as non-alcoholic fatty liver disease (NAFLD), alcoholic fatty liver disease (AFLD), drug induced liver injury (DILI), autoimmune hepatitis (AIH), hepatocarcinoma (HCC) and viral hepatitis.

Endoplasmin Is a Hypoxia-Inducible Endoplasmic Reticulum-Derived Cargo of Extracellular Vesicles Released by Cardiac Cell Lines

Cardiomyopathies are leading causes of human mortality. Recent data indicate that the cardiomyocyte-derived extracellular vesicles (EVs) released upon cardiac injury are present in circulation. This paper aimed to analyze EVs released under normal and hypoxic conditions by H9c2 (rat), AC16 (human) and HL1 (mouse) cardiac cell lines. Small (sEVs), medium (mEVs) and large EVs (lEVs) were separated from a conditioned medium by a combination of gravity filtration, differential centrifugation and tangential flow filtration. The EVs were characterized by microBCA, SPV lipid assay, nanoparticle tracking analysis, transmission and immunogold electron microscopy, flow cytometry and Western blotting. Proteomic profiles of the EVs were determined. Surprisingly, an endoplasmic reticulum chaperone, endoplasmin (ENPL, grp94 or gp96), was identified in the EV samples, and its association with EVs was validated. The secretion and uptake of ENPL was followed by confocal microscopy using GFP-ENPL fusion protein expressing HL1 cells. We identified ENPL as an internal cargo of cardiomyocyte-derived mEVs and sEVs. Based on our proteomic analysis, its presence in EVs was linked to hypoxia in HL1 and H9c2 cells, and we hypothesize that EV-associated ENPL may have a cardioprotective role by reducing cardiomyocyte ER stress.

High fat diet and PCSK9 knockout modulates lipid profile of the liver and changes the expression of lipid homeostasis related genes

BACKGROUND

High fat diet (HFD) increases the likelihood of dyslipidemia, which can be a serious risk factor for atherosclerosis, diabetes or hepatosteatosis. Although changes in different blood lipid levels were broadly investigated, such alterations in the liver tissue have not been studied before. The aim of the current study was to investigate the effect of HFD on hepatic triglyceride (TG), diglyceride (DG) and ceramide (CER) levels and on the expression of four key genes involved in lipid homeostasis (Pcsk9, Ldlr, Cd36 and Anxa2) in the liver. In addition, the potential role of PCSK9 in the observed changes was further investigated by using PCSK9 deficient mice.

METHODS

We used two in vivo models: mice kept on HFD for 20 weeks and PCSK9^-/- mice. The amount of the major TGs, DGs and CERs was measured by using HPLC-MS/MS analysis. The expression profiles of four lipid related genes, namely Pcsk9, Ldlr, Cd36 and Anxa2 were assessed. Co-localization studies were performed by confocal microscopy.

RESULTS

In HFD mice, hepatic PCSK9 expression was decreased and ANXA2 expression was increased both on mRNA and protein levels, and the amount of LDLR and CD36 receptor proteins was increased. While LDLR protein level was also elevated in the livers of PCSK9^-/- mice, there was no significant change in the expression of ANXA2 and CD36 in these animals. HFD induced a significant elevation in the hepatic levels of all measured TG and DG but not of CER types, and increased the proportion of monounsaturated vs. saturated TGs and DGs. Similar changes were detected in the hepatic lipid profiles of HFD and PCSK9^-/- mice. Co-localization of PCSK9 with LDLR, CD36 and ANXA2 was verified in HepG2 cells.

CONCLUSIONS

Our results show that obesogenic HFD downregulates PCSK9 expression in the liver and causes alterations in the hepatic lipid accumulation, which resemble those observed in PCSK9 deficiency. These findings suggest that PCSK9-mediated modulation of LDLR and CD36 expression might contribute to the HFD-induced changes in lipid homeostasis.

Organic Anion Transporting Polypeptide 3A1 (OATP3A1)-Gated Bio-Orthogonal Labeling of Intracellular Proteins

Organic anion transporting polypeptides (OATPs) were found to readily deliver membrane impermeable, tetrazine bearing fluorescent probes into cells. This feature was explored in OATP3A1 conditioned bio-orthogonal labeling schemes of various intracellular proteins in live cells. Confocal microscopy and super-resolution microscopy (STED) studies have shown that highly specific and efficient staining of the selected intracellular proteins can be achieved with the otherwise non-permeable probes when OATP3A1 is present in the cell membrane of cells. Such a transport protein linked bio-orthogonal labeling scheme is believed to be useful in OATP3A1 activity-controlled protein expression studies in the future.

Novel Erlotinib-Chalcone Hybrids Diminish Resistance in Head and Neck Cancer by Inducing Multiple Cell Death Mechanisms

In a search for novel therapeutic options for head and neck squamous cell carcinomas (HNSCCs) generally treated with limited therapeutic success, we synthesized a series of novel erlotinib-chalcone molecular hybrids with 1,2,3-triazole and alkyne linkers and evaluated them for their anticancer activity on Fadu, Detroit 562 and SCC-25 HNSCC cell lines. Time- and dose-dependent cell viability measurements disclosed a significantly increased efficiency of the hybrids compared to the 1:1 combination of erlotinib and a reference chalcone. The clonogenic assay demonstrated that hybrids eradicate HNSCC cells in low micromolar concentrations. Experiments focusing on potential molecular targets indicate that the hybrids trigger the anticancer effect by a complementary mechanism of action that is independent of the canonical targets of their molecular fragments. Confocal microscopic imaging and real-time apoptosis/necrosis detection assay pointed to slightly different cell death mechanisms induced by the most prominent triazole- and alkyne-tethered hybrids (6a and 13, respectively). While 6a featured the lowest IC₅₀ values on each of the three HNSCC cell lines, in Detroit 562 cells, this hybrid induced necrosis more markedly compared to 13. The therapeutic potential indicated by the observed anticancer efficacy of our selected hybrid molecules validates the concept of development and justifies further investigation to reveal the underlying mechanism of action.

Turning Red without Feeling Embarrassed─Xanthenium-Based Photocages for Red-Light-Activated Phototherapeutics

Herein, we present high-yielding, concise access to a set of xanthenium-derived, water-soluble, low-molecular-weight photocages allowing light-controlled cargo release in the green to red region. Very importantly, these new photocages allow installation of various payloads through ester, carbamate, or carbonate linkages even at the last stage of the synthesis. Payloads were uncaged with high efficiency upon green, orange, or red light irradiation, leading to the release of carboxylic acids, phenols, and amines. The near-ideal properties of a carboxanthenium derivative were further evaluated in the context of light-controlled drug release using a camptothecin-derived chemotherapeutic drug, SN38. Notably, the caged drug showed orders of magnitude lower efficiency in cellulo, which was reinstated after red light irradiation. The presented photocages offer properties that facilitate the translation of photoactivated chemotherapy toward clinical applications.

Nanofiber formation as a promising technology for preservation and easy storage of extracellular vesicles

Extracellular vesicles (EVs) are cell-derived, membrane-enclosed particles with the potential for a wide range of future therapeutic applications. However, EVs have almost always been administered by direct injection, likely hindering their efficacy because of rapid clearance from the injection site. The present study aimed to incorporate medium-sized extracellular vesicles (mEVs) into fast-dissolving electrospun polyvinylpyrrolidone-based nanofibers to explore the storage-dependent structure-activity relationship of the resulting nanofibrous formulations. Aqueous polyvinylpyrrolidone-based precursor solutions were selected for the electrospinning process. The presence of EVs in the electrospun samples was confirmed by transmission electron microscopy, flow cytometry, and confocal laser scanning microscope. The results indicate that the fibrous structure of the samples was preserved until the end of the 12-week storage period. Furthermore, regardless of the storage temperature (4 °C or room temperature), nanofibers and nanofiber-associated EVs were present throughout the experimental period. Incorporating EVs into a stable solid polymeric delivery base could preserve their stability; meanwhile, according to the characteristics of the polymer, their targeted and controlled release can be achieved.

Aspirin Mediates Its Antitumoral Effect Through Inhibiting PTTG1 in Pituitary Adenoma

CONTEXT

DNA demethylation and inhibitory effects of aspirin on pituitary cell proliferation have been demonstrated.

OBJECTIVE

Our aim was to clarify the molecular mechanisms behind the aspirin-related effects in pituitary cells.

METHODS

DNA methylome and whole transcriptome profile were investigated in RC-4B/C and GH3 pituitary cell lines upon aspirin treatment. Effects of aspirin and a demethylation agent, decitabine, were further tested in vitro. PTTG1 expression in 41 human PitNET samples and whole genome gene and protein expression data of 76 PitNET and 34 control samples (available in Gene Expression Omnibus) were evaluated.

RESULTS

Aspirin induced global DNA demethylation and consequential transcriptome changes. Overexpression of Tet enzymes and their cofactor Uhrf2 were identified behind the increase of 5-hydroxymethylcytosine (5hmC). Besides cell cycle, proliferation, and migration effects that were validated by functional experiments, aspirin increased Tp53 activity through p53 acetylation and decreased E2f1 activity. Among the p53 controlled genes, Pttg1 and its interacting partners were downregulated upon aspirin treatment by inhibiting Pttg1 promoter activity. 5hmC positively correlated with Tet1-3 and Tp53 expression, and negatively correlated with Pttg1 expression, which was reinforced by the effect of decitabine. Additionally, high overlap (20.15%) was found between aspirin-regulated genes and dysregulated genes in PitNET tissue samples.

CONCLUSION

A novel regulatory network has been revealed, in which aspirin regulated global demethylation, Tp53 activity, and Pttg1 expression along with decreased cell proliferation and migration. 5hmC, a novel tissue biomarker in PitNET, indicated aspirin antitumoral effect in vitro as well. Our findings suggest the potential beneficial effect of aspirin in PitNET.

In the pitfall of expectations: An exploratory analysis of stressors in elite rhythmic gymnastics

The present study explored the types of stressors faced by rhythmic gymnastics athletes, their parents, and coaches. Semi-structured interviews with 12 participants—four gymnasts, five coaches, and three parents—were analyzed using reflexive thematic analysis in a theory-driven framework. The categorizations of sport-related stressors for the parents, coaches, and gymnasts were based on existing theories. The results showed that both the gymnasts and the coaches predominantly noted mastery-avoidance goals in terms of performance, while the interviews with parents mostly indicated performance-avoidance goals. All three groups of participants consistently reported a detrimental atmosphere in rhythmic gymnastics. For instance, they emphasized the stress related to inadequate communication between the concerned parties. Moreover, all parties believed that having a lean body was linked to success in the competitive world of rhythmic gymnastics. The present study provides insight into some of the potential major stressors and the related subjective experiences affecting athletes socializing in the same sporting environment.

A stepwise one-pot synthesis of aliphatic thiols and their derivatives from acrylamides and sulfur

Elemental sulfur enables the convenient formation of C-S bonds and the direct incoporation of S-S bonds. The reactivity of easily accessible electron deficient alkenes towards sulfur, however, is barely disclosed. Herein, we investigated the reactivity of acrylamides with sulfur and eventually developed a new pseudo-multicomponent reaction for the preparation of polysulfides. Sequential one-pot reduction led to diversely substituted thiols. Additional third stage one-pot modifications provided thioethers, unsymmetric disulfide and thioester.

The relationship between cognitive control and lexical conflict resolution in developmental dyslexia

Previous studies have revealed that cognitive control functions contribute to the resolution of lexical interference. Both cognitive control (CC) deficits and reduced speed of lexical retrieval in Rapid Automatized Naming (RAN) tasks are characteristics of Developmental Dyslexia (DD), but it is still not fully understood how these deficits relate to each other and to reading problems. To examine this question, we tested adolescents with DD (n = 38), poor readers (PR; n = 25) and typical readers (TR; n = 33) matched on age and IQ, on CC functions with Stroop, Stop Signal, Simon, Backward Digit Span and n-back tasks and on lexical retrieval and lexical conflict resolution with RAN of pictures in semantically homogeneous vs. mixed trials. As expected, in the blocked RAN Task DD individuals showed longer naming times and a greater effect of lexical conflict resolution (indexed by difference scores of naming times in the homogeneous and mixed conditions) than TR participants. We also found significant group differences (TR = PR > DD) in CC measures. Naming time was associated with CC, while the lexical interference effect did not show any association with this set of abilities. These findings suggest that DD individuals show impairments in multiple cognitive functions, such as cognitive control, lexical retrieval and lexical conflict resolution. Our results also suggest that CC functions are involved in lexical retrieval, but we have not found evidence for their involvement in lexical conflict resolution processes.

Beyond the Bioorthogonal Inverse-Electron-Demand Diels–Alder Reactions of Tetrazines: 2-Pyrone-Functionalized Fluorogenic Probes

The applicability of pyrones as a bioorthogonal platform was explored in inverse-electron-demand Diels–Alder (IEDDA) reactions with a strained cyclooctyne. Studies showed that the pyrones are indeed suitable for IEDDA reactions under physiological conditions. Furthermore, the stable pyrone moiety could be utilized to construct easily accessible fluorogenic probes. Mutual orthogonality of the IEDDA reaction of 2-pyrones with SPAAC reactions of azides was also explored.

Critical Role of Astrocytic Polyamine and GABA Metabolism in Epileptogenesis

Accumulating evidence indicate that astrocytes are essential players of the excitatory and inhibitory signaling during normal and epileptiform activity via uptake and release of gliotransmitters, ions, and other substances. Polyamines can be regarded as gliotransmitters since they are almost exclusively stored in astrocytes and can be released by various mechanisms. The polyamine putrescine (PUT) is utilized to synthesize GABA, which can also be released from astrocytes and provide tonic inhibition on neurons. The polyamine spermine (SPM), synthesized form PUT through spermidine (SPD), is known to unblock astrocytic Cx43 gap junction channels and therefore facilitate astrocytic synchronization. In addition, SPM released from astrocytes may also modulate neuronal NMDA, AMPA, and kainate receptors. As a consequence, astrocytic polyamines possess the capability to significantly modulate epileptiform activity. In this study, we investigated different steps in polyamine metabolism and coupled GABA release to assess their potential to control seizure generation and maintenance in two different epilepsy models: the low-[Mg2+] model of temporal lobe epilepsy in vitro and in the WAG/Rij rat model of absence epilepsy in vivo. We show that SPM is a gliotransmitter that is released from astrocytes and significantly contributes to network excitation. Importantly, we found that inhibition of SPD synthesis completely prevented seizure generation in WAG/Rij rats. We hypothesize that this antiepileptic effect is attributed to the subsequent enhancement of PUT to GABA conversion in astrocytes, leading to GABA release through GAT-2/3 transporters. This interpretation is supported by the observation that antiepileptic potential of the Food and Drug Administration (FDA)-approved drug levetiracetam can be diminished by specifically blocking astrocytic GAT-2/3 with SNAP-5114, suggesting that levetiracetam exerts its effect by increasing surface expression of GAT-2/3. Our findings conclusively suggest that the major pathway through which astrocytic polyamines contribute to epileptiform activity is the production of GABA. Modulation of astrocytic polyamine levels, therefore, may serve for a more effective antiepileptic drug development in the future.

Bioorthogonal Ligation-Activated Fluorogenic FRET Dyads

An energy transfer‐based signal amplification relay concept enabling transmission of bioorthogonally activatable fluorogenicity of blue‐excitable coumarins to yellow/red emitting cyanine frames is presented. Such relay mechanism resulted in improved cyanine fluorogenicities together with increased photostabilities and large apparent Stokes‐shifts allowing lower background fluorescence even in no‐wash bioorthogonal fluorogenic labeling schemes of intracellular structures in live cells. These energy transfer dyads sharing the same donor moiety together with their parent donor molecule allowed three‐color imaging of intracellular targets using one single excitation source with separate emission windows. Sub‐diffraction imaging of intracellular structures using the bioorthogonally activatable FRET dyads by STED microscopy is also presented.

A relative quantitation method for measuring DNA methylation and hydroxymethylation using guanine as an internal standard

Global DNA methylation and hydroxymethylation play an important role in gene expression. They can be connected with several diseases. The modification status could be a biomarker to determine the status of disease. A fast, easy and accurate liquid chromatography - tandem mass spectrometry method has been developed for the precise quantitation of 5-methylcytosine and 5-hydroxymethylcytosine. Formic acid was used for the hydrolysis of the DNA strand resulting in nucleobases. These polar hydrolysis products were separated on a normal phase column using reversed phase eluents in inverse gradient mode. Multiple reaction monitoring was applied to achieve high selectivity and sensitivity for the quantitation. A new relative quantitation model was developed by using guanine, as an internal standard, present in samples. The new method was successfully validated with excellent accuracy and precision values in the range of 0.005-0.5% for 5hmC and 1-15% for 5mC. The main advantages of this quantitation method are that, due to relative quantitation, calibration curves can be used without reacquiring the calibration points and no additional isotope labeled internal standards are required. The method was tested to identify the concentrations of 5mC and 5hmC in various sample types. The lowest level of DNA sample required in the case of 0.005% 5hmC is 0.5 μg.

A Genetically Encoded Isonitrile Lysine for Orthogonal Bioorthogonal Labeling Schemes

Bioorthogonal click-reactions represent ideal means for labeling biomolecules selectively and specifically with suitable small synthetic dyes. Genetic code expansion (GCE) technology enables efficient site-selective installation of bioorthogonal handles onto proteins of interest (POIs). Incorporation of bioorthogonalized non-canonical amino acids is a minimally perturbing means of enabling the study of proteins in their native environment. The growing demand for the multiple modification of POIs has triggered the quest for developing orthogonal bioorthogonal reactions that allow simultaneous modification of biomolecules. The recently reported bioorthogonal [4 + 1] cycloaddition reaction of bulky tetrazines and sterically demanding isonitriles has prompted us to develop a non-canonical amino acid (ncAA) bearing a suitable isonitrile function. Herein we disclose the synthesis and genetic incorporation of this ncAA together with studies aiming at assessing the mutual orthogonality between its reaction with bulky tetrazines and the inverse electron demand Diels–Alder (IEDDA) reaction of bicyclononyne (BCN) and tetrazine. Results showed that the new ncAA, bulky-isonitrile-carbamate-lysine (BICK) is efficiently and specifically incorporated into proteins by genetic code expansion, and despite the slow [4 + 1] cycloaddition, enables the labeling of outer membrane receptors such as insulin receptor (IR) with a membrane-impermeable dye. Furthermore, double labeling of protein structures in live and fixed mammalian cells was achieved using the mutually orthogonal bioorthogonal IEDDA and [4 + 1] cycloaddition reaction pair, by introducing BICK through GCE and BCN through a HaloTag technique.

A photoresponsive palladium complex of an azopyridyl-triazole ligand: light-controlled solubility drives catalytic activity in the Suzuki coupling reaction

Herein, the design and synthesis of a click-derived Pd-complex merged with a photoswitchable azobenzene unit is presented. While in the trans-form of the switch the complex showed limited solubility, the photogenerated cis-form rendered the molecule soluble in polar solvents. This light-controllable solubility was exploited to affect the catalytic activity in the Suzuki coupling reaction. The effect of the substrate and catalyst concentration and light intensity on the proceeding and outcome of the reaction was studied. Dehalogenation of the aryl iodide starting material was found to be a major side reaction; however, its occurrence was dependent on the applied light intensity.

Controlling the Structure of Carbon Deposit by Nitrogen Doping Catalytic Chemical Vapor Deposition Synthesis

Nitrogen doped multi-walled carbon nanotubes and other carbon nanoparticles were synthesized by catalytic chemical vapor deposition of tripropylamine and acetylene on CaCO₃-supported cobalt catalyst (5 wt%), prepared by impregnation, and various precursors. Each synthesis was performed by using either the pure nitrogenous organic compound or its mixture with acetone. Transmission electron microscopy studies revealed a significant difference both in the yield and the diversity of the carbon deposits. Every synthesis resulted in bamboo-like nanotubes, and nearly all of them also in onion-like structures. Electron energy loss spectroscopy studies of the samples indicated the presence of nitrogen and calcium (caused by the catalyst support). High-resolution transmission electron microscopy and X-ray diffraction measurements were also performed to characterize the samples.

Large Stokes-shift bioorthogonal probes for STED, 2P-STED and multi-color STED nanoscopy

Synthesis and multiple STED imaging applications of four, red-emitting (610-670 nm), tetrazine-functionalized fluorescent probes (CBRD = Chemical Biology Research group Dye 1-4) with large Stokes-shift is presented. Present studies revealed the super-resolution microscopy applicability of the probes as demonstrated through bioorthogonal labeling scheme of cytoskeletal proteins actin and keratin-19, and mitochondrial protein TOMM20. Furthermore, super-resolved images of insulin receptors in live-cell bioorthogonal labeling schemes through a genetically encoded cyclooctynylated non-canonical amino acid are also presented. The large Stokes-shifts and the wide spectral bands of the probes enabled the use of two common depletion lasers (660 nm and 775 nm). The probes were also found suitable for super-resolution microscopy in combination with two-photon excitation (2P-STED) resulting in improved spatial resolution. One of the dyes was also used together with two commercial dyes in the three-color STED imaging of intracellular structures.

Synergistic transport of a fluorescent coumarin probe marks coumarins as pharmacological modulators of Organic anion-transporting polypeptide, OATP3A1

Organic anion-transporting polypeptide 3A1 (OATP3A1) is a membrane transporter mediating the cellular uptake of various hormones such as estrone-3-sulfate, prostaglandins E1 and E2 and thyroxine. OATP3A1 is widely expressed in the human body and its presence in tissue-blood barriers, neurons and muscle cells marks it as a potential pharmacological target. Herein we demonstrate that an otherwise membrane impermeant, zwitterionic fluorescent coumarin probe, bearing a sulfonate function is a potent substrate of human OATP3A1, thus readily transported into HEK-293-OATP3A1 cells allowing functional investigation and the screen of drug interactions of the OATP3A1 transporter. At the same time, dyes lacking either the sulfonate motif or the coumarin scaffold showed a dramatic decrease in affinity or even a complete loss of transport. Furthermore, we observed a distinct inhibition/activation pattern in the OATP3A1-mediated uptake of closely related fluorescent coumarin derivatives differing only in the presence of the sulfonate moiety. Additionally, we detected a synergistic effect between one of the probes tested and the endogenous OATP substrate estrone-3-sulfate. These data, together with docking results indicate the presence of at least two cooperative substrate binding sites in OATP3A1. Besides providing the first sensitive probe for testing OATP3A1 substrate/inhibitor interactions, our results also help to understand substrate recognition and transport mechanism of the poorly characterized OATP3A1. Moreover, coumarins are good candidates for OATP3A1-targeted drug delivery and as pharmacological modulators of OATP3A1.

In Situ Metabolic Characterisation of Breast Cancer and Its Potential Impact on Therapy

In spite of tremendous developments in breast cancer treatment, the relatively high incidence of relapsing cases indicates a great need to find new therapeutic strategies in recurrent, metastatic and advanced cases. The bioenergetic needs of growing tumours at the primary site or in metastases-accumulating genomic alterations and further heterogeneity-are supported by metabolic rewiring, an important hallmark of cancer. Adaptation mechanisms as well as altered anabolic and catabolic processes balance according to available nutrients, energy, oxygen demand and overgrowth or therapeutic resistance. Mammalian target of rapamycin (mTOR) hyperactivity may contribute to this metabolic plasticity and progression in breast carcinomas. We set out to assess the metabolic complexity in breast cancer cell lines and primary breast cancer cases. Cellular metabolism and mTOR-related protein expression were characterised in ten cell lines, along with their sensitivity to specific mTOR and other metabolic inhibitors. Selected immunohistochemical reactions were performed on ~100 surgically removed breast cancer specimens. The obtained protein expression scores were correlated with survival and other clinicopathological data. Metabolic and mTOR inhibitor mono-treatments had moderate antiproliferative effects in the studied cell lines in a subtype-independent manner, revealing their high adaptive capacity and survival/growth potential. Immunohistochemical analysis of p-S6, Rictor, lactate dehydrogenase A, glutaminase, fatty acid synthase and carnitine palmitoyltransferase 1A in human samples identified high mTOR activity and potential metabolic plasticity as negative prognostic factors for breast cancer patients, even in subtypes generally considered as low-risk. According to our results, breast cancer is characterised by considerable metabolic diversity, which can be targeted by combining antimetabolic treatments and recent therapies. Alterations in these pathways may provide novel targets for future drug development in breast cancer. We also propose a set of immunostainings for scoring metabolic heterogeneity in individual cases in order to select patients who may benefit from more accurate follow-up and specific therapies.

Conditionally Activatable Visible-Light Photocages

The proof of concept for conditionally activatable photocages is demonstrated on a new vinyltetrazine-derivatized coumarin. The tetrazine form is disabled in terms of light-induced cargo release, however, bioorthogonal transformation of the modulating tetrazine moiety results in fully restored photoresponsivity. Irradiation of such a “click-armed” photocage with blue light leads to fast and efficient release of a set of caged model species, conjugated via various linkages. Live-cell applicability of the concept was also demonstrated by the conditional release of a fluorogenic probe using mitochondrial pretargeting.

Microscope laser assisted photooxidative activation of bioorthogonal ClickOx probes

A photoactivatable fluorogenic tetrazine-rhodaphenothiazine probe was synthesized and studied in light-assisted, bioorthogonal labeling schemes. Experimental results revealed that the bioorthogonally conjugated probe efficiently sensitizes ¹O₂ generation upon illumination with green or orange light and undergoes self-oxidation leading to an intensely fluorescent sulfoxide product. An added value of the present probe is that it is also suitable for STED super-resolution microscopy using a 660 nm depletion laser.

A Bioorthogonally Applicable, Fluorogenic, Large Stokes-Shift Probe for Intracellular Super-Resolution Imaging of Proteins

Herein, we present the synthesis and application of a fluorogenic, large Stokes-shift (>100 nm), bioorthogonally conjugatable, membrane-permeable tetrazine probe, which can be excited at common laser line 488 nm and detected at around 600 nm. The applied design enabled improved fluorogenicity in the orange/red emission range, thus efficient suppression of background and autofluorescence upon imaging biological samples. Moreover, unlike our previous advanced probes, it does not require the presence of special target platforms or microenvironments to achieve similar fluorogenicity and can be generally applied, e.g., on translationally bioorthogonalized proteins. Live-cell labeling schemes revealed that the fluorogenic probe is suitable for specific labeling of intracellular proteins, site-specifically modified with a cyclooctynylated, non-canonical amino acid, even under no-wash conditions. Furthermore, the probe was found to be applicable in stimulated emission depletion (STED) super-resolution microscopy imaging using a 660 nm depletion laser. Probably the most salient feature of this new probe is that the large Stokes-shift allows dual-color labeling schemes of cellular structures using distinct excitation and the same detection wavelengths for the combined probes, which circumvents chromatic aberration related problems.

Twisted paddlewheel rhodium complexes: Contribution of central and axial chirality to ECD, VCD, and NMR spectra

Dirhodium complexes bearing N-substituted chiral amino acid ligands are investigated. These complexes have an unusual twisted paddlewheel structure, showing inherent chirality. We would like to demonstrate that parallel application of chiroptical spectroscopic methods (ECD and VCD) and NMR spectroscopy combined with quantum chemical calculations constitutes a powerful tool to determine the configuration of the complexes unequivocally. Two chiroptical methods are needed to determine the absolute configuration: ECD for the coordinated nitrogen atom and VCD for the rhodium core. A quick to use NMR method is also presented: Upon the coordination of small molecules in the axial position, the relative configuration of both the rhodium core and the nitrogen atom can be determined simultaneously by studying spatial proximities provided by 1D NOE spectra.

Next-generation sequencing identifies novel mitochondrial variants in pituitary adenomas

PURPOSE

Disrupted mitochondrial functions and genetic variants of mitochondrial DNA (mtDNA) have been observed in different human neoplasms. Next-generation sequencing (NGS) can be used to detect even low heteroplasmy-level mtDNA variants. We aimed to investigate the mitochondrial genome in pituitary adenomas by NGS.

METHODS

We analysed 11 growth hormone producing and 33 non-functioning [22 gonadotroph and 11 hormone immunonegative] pituitary adenomas using VariantPro™ Mitochondrion Panel on Illumina MiSeq instrument. Revised Cambridge Reference Sequence (rCRS) of the mtDNA was used as reference. Heteroplasmy was determined using a 3% cutoff.

RESULTS

496 variants were identified in pituitary adenomas with overall low level of heteroplasmy (7.22%). On average, 35 variants were detected per sample. Samples harbouring the highest number of variants had the highest Ki-67 indices independently of histological subtypes. We identified eight variants (A11251G, T4216C, T16126C, C15452A, T14798C, A188G, G185A, and T16093C) with different prevalences among different histological groups. T16189C was found in 40% of non-recurrent adenomas, while it was not present in the recurrent ones. T14798C and T4216C were confirmed by Sanger sequencing in all 44 samples. 100% concordance was found between NGS and Sanger method.

CONCLUSIONS

NGS is a reliable method for investigating mitochondrial genome and heteroplasmy in pituitary adenomas. Out of the 496 detected variants, 414 have not been previously reported in pituitary adenoma. The high number of mtDNA variants may contribute to adenoma genesis, and some variants (i.e., T16189C) might associate with benign behaviour.

Synthesis of (1,2,3-triazol-4-yl)methyl Phosphinates and (1,2,3-Triazol-4-yl)methyl Phosphates by Copper-Catalyzed Azide-Alkyne Cycloaddition

An efficient and practical method was developed for the synthesis of new (1,2,3triazol4yl)methyl phosphinates and (1,2,3-triazol-4-yl)methyl phosphates by the copper(I)catalyzed azide-alkyne cycloaddition (CuAAC) of organic azides and prop-2-ynyl phosphinate or prop-2-ynyl phosphate. The synthesis of (1benzyl-1H-1,2,3-triazol-4-yl)methyl diphenylphosphinate was optimized with respect to the reaction parameters, such as the temperature, reaction time, and catalyst loading. The approach was applied to a range of organic azides, which confirmed the wide scope and the substituent tolerance of the process. The method elaborated represents a novel approach for the synthesis of the target compounds.

Tracking down protein-protein interactions via a FRET-system using site-specific thiol-labeling

Förster resonance energy transfer is among the most popular tools to follow protein-protein interactions. Although limited to certain cases, site-specific fluorescent labeling of proteins via natural functions by means of chemical manipulations can redeem laborious protein engineering techniques. Herein we report on the synthesis of a heterobifunctional tag and its use in site-specific protein labeling studies aiming at exploring protein-protein interactions. The oxadiazole-methylsulfonyl functionality serves as a thiol specific warhead that enables easy and selective installation of fluorescent labels through a bioorthogonal motif. Mitogen activated protein kinase (MAPK14) and its substrate mitogen activated protein kinase activated kinase (MAPKAP2) or its docking motif, a 22 amino acid-long peptide fragment, were labeled with a donor and an acceptor, respectively. Evolution of strong FRET signals upon protein-protein interactions supported the specific communication between the partners. Using an efficient FRET pair allowed the estimation of dissociation constants for protein-protein and peptide-protein interactions (145 nM and 240 nM, respectively).

A rapid and concise setup for the fast screening of FRET pairs using bioorthogonalized fluorescent dyes

One of the most popular means to follow interactions between bio(macro)molecules is Förster resonance energy transfer (FRET). There is large interest in widening the selection of fluorescent FRET pairs especially in the region of the red/far red range, where minimal autofluorescence is encountered. A set of bioorthogonally applicable fluorescent dyes, synthesized recently in our lab, were paired (Cy3T/Cy5T; Cy1A/Cy3T and Cy1A/CBRD1A) based on their spectral characteristics in order to test their potential in FRET applications. For fast elaboration of the selected pairs we have created a bioorthogonalized platform based on complementary 17-mer DNA oligomers. The cyclooctynylated strands were modified nearly quantitatively with the fluorophores via bioorthogonal chemistry steps, using azide- (Cy1; CBRD1) or tetrazine-modified (Cy3; Cy5) dyes. Reactions were followed by capillary electrophoresis using a method specifically developed for this project. FRET efficiencies of the fluorescent dye pairs were compared both in close proximity (5' and 3' matched) and at larger distance (5' and 5' matched). The specificity of FRET signals was further elaborated by denaturation and competition studies. Cy1A/Cy3T and Cy1A/CBRD1A introduced here as novel FRET pairs are highly recommended for FRET applications based on the significant changes in fluorescence intensities of the donor and acceptor peaks. Application of one of the FRET pairs was demonstrated in live cells, transfected with labeled oligos. Furthermore, the concise installation of the dyes allows for efficient fluorescence modification of any selected DNA strands as was demonstrated in the construction of Cy3T labeled oligomers, which were used in the FISH-based detection of Helicobacter pylori.

[Steroid 21-hydroxylase deficiency, the most frequent cause of congenital adrenal hyperplasia]

Congenital adrenal hyperplasia is a group of genetic diseases due to the disablement of 7 genes; one of them is steroid 21-hydroxylase deficiency. The genes of congenital adrenal hyperplasia encode enzymes taking part in the steroidogenesis of adrenal gland. Steroid 21-hydroxylase deficiency is an autosomal recessive disorder caused by mutations of the steroid 21-hydroxylase gene. The mutations of steroid 21-hydroxylase gene cause 95% of the congenital adrenal hyperplasia cases. Although the non-classic steroid 21-hydroxylase deficiency with mild symptoms is seldom diagnosed, the classic steroid 21-hydroxylase deficiency may lead to life-threatening salt-wasting and adrenal crises due to the insufficient aldosterone and cortisol serum levels. The classic type requires life-long steroid replacement which may result in cushingoid side effects, and typical comorbidities may be also developed. The patients' quality of life is decreased, and their mortality is much higher than that of the population without steroid 21-hydroxylase deficiency. The diagnosis, consequences and the patients' life-long clinical care require a multidisciplinary approach: the specialists in pediatrics, internal medicine, endocrinology, laboratory medicine, genetic diagnostics, surgery, obstetrics-gynecology and psychology need to work together. Orv Hetil. 2018; 159(7): 269-277.

Capillary electrophoresis study on the base-catalyzed formation of bioactive oxidized metabolites of 20-hydroxyecdysone

A novel capillary electrophoretic method was developed for the analysis and monitoring of the base-catalyzed autoxidation of 20-hydroxyecdysone, a worldwide used non-hormonal anabolic food supplement. An effective separation of the starting material and its bioactive oxidized derivatives was achieved by using sulfobutyl-β-cyclodextrin as selector at pH 11 and by fixing the separation voltage at +30kV. Only a dilution step was inserted before injecting the sample, taken from the crude reaction mixture, to the capillary electrophoresis instrument. The same alkaline pH was used for the analysis as for the reaction, unlike the previously reported HPLC study where sample neutralization was required prior to the measurement. Due to the very short analysis time (6min) in capillary electrophoresis, more frequent sampling and more detailed time scale analysis could be carried out. Furthermore, in contrast with the preceding HPLC results, the previously unobserved calonysterone could also be detected by capillary electrophoresis as a minor primary product. Our novel method demonstrated higher resolution than the one before. Baseline separation could be achieved and the resolution values were in the range of 1.9-7.0. The limit of detection was below 71μg/ml, the relative standard deviation values of the migration time and peak area for intra- and inter-day precision were less than 10%. The more precise, direct monitoring of the time dependency of the oxidation process is expected to have a significant impact on yield optimization initiatives to allow related pharmacological studies in the near future.

Altered neurite morphology and cholinergic function of induced pluripotent stem cell-derived neurons from a patient with Kleefstra syndrome and autism

The aim of the present study was to establish an in vitro Kleefstra syndrome (KS) disease model using the human induced pluripotent stem cell (hiPSC) technology. Previously, an autism spectrum disorder (ASD) patient with Kleefstra syndrome (KS-ASD) carrying a deleterious premature termination codon mutation in the EHMT1 gene was identified. Patient specific hiPSCs generated from peripheral blood mononuclear cells of the KS-ASD patient were differentiated into post-mitotic cortical neurons. Lower levels of EHMT1 mRNA as well as protein expression were confirmed in these cells. Morphological analysis on neuronal cells differentiated from the KS-ASD patient-derived hiPSC clones showed significantly shorter neurites and reduced arborization compared to cells generated from healthy controls. Moreover, density of dendritic protrusions of neuronal cells derived from KS-ASD hiPSCs was lower than that of control cells. Synaptic connections and spontaneous neuronal activity measured by live cell calcium imaging could be detected after 5 weeks of differentiation, when KS-ASD cells exhibited higher sensitivity of calcium responses to acetylcholine stimulation indicating a lower nicotinic cholinergic tone at baseline condition in KS-ASD cells. In addition, gene expression profiling of differentiated neuronal cells from the KS-ASD patient revealed higher expression of proliferation-related genes and lower mRNA levels of genes involved in neuronal maturation and migration. Our data demonstrate anomalous neuronal morphology, functional activity and gene expression in KS-ASD patient-specific hiPSC-derived neuronal cultures, which offers an in vitro system that contributes to a better understanding of KS and potentially other neurodevelopmental disorders including ASD.

Expression of G protein-coupled oestrogen receptor in melanoma and in pregnancy-associated melanoma

BACKGROUND

The hormone sensitivity of melanoma and the role of 'classical' oestrogen receptor (ER) α and β in tumour progression have been intensively studied with rather contradictory results. The presence of 'non-classical' G protein-coupled oestrogen receptor (GPER) has not been investigated on human melanoma tissues.

OBJECTIVE

To analyse the expression of GPER, ERα and ERβ in pregnancy-associated (PAM) and in non-pregnancy-associated (NPAM) melanomas in correlation with traditional prognostic markers and disease-free survival (DFS).

METHODS

Receptor protein levels were tested using immunohistochemistry in 81 formalin-fixed paraffin-embedded melanoma tissues. PAMs (n = 38) were compared with age- and Breslow thickness-matched cases (n = 43) including non-pregnant women (NPAM-W) (n = 22) and men (NPAM-M) (n = 21). The association between receptor expression and DFS was analysed by uni- and multivariate Cox proportional hazards regression.

RESULTS

G protein-coupled oestrogen receptor was detected both in PAMs and NPAMs. In 39 of the 41 (95.1%) GPER-positive melanomas, GPER and ERβ were co-expressed. GPER/ERβ-positive melanomas were significantly more common in PAM compared to NPAM (P = 0.0001) with no significant difference between genders (P = 0.4383). In PAMs, the distribution of GPER and ERβ was similar (78.4% vs. 81.6%; P = 0.8504), while in NPAM, ERβ was the representative ER (60.5% vs. 27.9%; P = 0.0010) without gender difference (59.1% vs. 61.9%). GPER-/ERβ-positive melanomas were associated with lower Breslow thickness, lower mitotic rate and higher presence of peritumoral lymphocyte infiltration (PLI) compared to GPER-/ERβ-negative cases (P = 0.0156, P = 0.0036 and P = 0.0001) predicting a better DFS (HR = 0.785, 95% CI 0.582-1.058). Despite the significantly higher frequency of GPER and ERβ expression in PAM, no significant difference was found in DFS between PAM and NPAM. All but one case failed to show ERα expression.

CONCLUSIONS

The presence of GPER and its simultaneous expression with ERβ can serve as a new prognostic indicator in a significant subpopulation of melanoma patients.

Bisazide Cyanine Dyes as Fluorogenic Probes for Bis-Cyclooctynylated Peptide Tags and as Fluorogenic Cross-Linkers of Cyclooctynylated Proteins

Herein we present the synthesis and fluorogenic characterization of a series of double-quenched bisazide cyanine probes with emission maxima between 565 and 580 nm that can participate in covalent, two-point binding bioorthogonal tagging schemes in combination with bis-cyclooctynylated peptides. Compared to other fluorogenic cyanines, these double-quenched systems showed remarkable fluorescence intensity increase upon formation of cyclic dye-peptide conjugates. Furthermore, we also demonstrated that these bisazides are useful fluorogenic cross-linking platforms that are able to form a covalent linkage between monocyclooctynylated proteins.

Correction: A systematic study of protein labeling by fluorogenic probes using cysteine targeting vinyl sulfone-cyclooctyne tags

Correction for 'A systematic study of protein labeling by fluorogenic probes using cysteine targeting vinyl sulfone-cyclooctyne tags' by B. Söveges, et al., Org. Biomol. Chem., 2016, 14, 6071-6078.