A Toolbox for Glutamine Use in Dissolution Dynamic Nuclear Polarization: from Enzymatic Reaction Monitoring to the Study of Cellular Metabolic Pathways and Imaging.

Glutamine is under scrutiny regarding its metabolic deregulation linked to energetic reprogramming in cancer cells. Many analytical techniques have been used to better understand the impact of the metabolism of amino acids on biological processes, however only a few are suited to work with complex samples. Here, we report the use of a general dissolution dynamic nuclear polarization (D-DNP) formulation using an unexpensive radical as a multipurpose tool to study glutamine, with insights from enzymatic modelling to complex metabolic networks and fast imaging. First, hyperpolarized [5-13 C] glutamine is used as molecular probe to study the kinetic action of two enzymes: L-asparaginase that has been used as an anti-metabolic treatment for cancer, and glutaminase. These results are also compared with those acquired with another hyperpolarized amino acid, [1,4-13 C] asparagine. Second, we explored the use of hyperpolarized (HP) substrates to probe metabolic pathways by monitoring metabolic profiles arising from hyperpolarized glutamine in E. coli extracts. Finally, a highly concentrated sample formulation is proposed for the purpose of fast imaging applications. We think that this approach can be extended to formulate other amino acids as well as other metabolites and provide complementary insights into the analysis of metabolic networks.

Evaluation of Glutaminolysis in T Cells.

The activity of living cells is necessarily dependent on the amount of available bioenergy. In T cells, the latter is mainly derived from ATP, a molecular energy "coin" generated by one of several metabolic processes that differ in their ability to satisfy energy demand. Thus, whereas naïve or quiescent T cells efficiently utilize oxidative phosphorylation to generate ATP, T cells subjected to antigenic stimulation followed by clonal expansion and cytokine production meet their increased need for energy by supplementing ATP generation by oxidative phosphorylation with ATP generation by glycolysis. Yet additional need for ATP can be met by other basic biologic sources of energy such as glutamine, an amino acid that is metabolized through a process called glutaminolysis to result in end products that flows into the TCA cycle and augment ATP generation by oxidative phosphorylation. It is now possible to track the dominant energy supplying processes (i.e., the ATP generation process) in differentiating or activated T cells in a real-time manner. Here, we provide one element of such tracking by describing protocols for the assessment of the contribution of glutaminolysis to overall ATP production within different T cell subsets. © 2022 Wiley Periodicals LLC. This article has been contributed to by US Government employees and their work is in the public domain in the USA. Basic Protocol 1: Evaluation of the role of glutaminolysis during T cell activation/differentiation Basic Protocol 2: Evaluation of the role of glutaminolysis in T cell responses utilizing glutaminolysis inhibitors Basic Protocol 3: Evaluation of the effect of glutaminolysis on cellular oxidative phosphorylation/glycolysis.

Physiological synaptic activity and recognition memory require astroglial glutamine.

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a fluorescent probe that tracks glutamine in live cells, which provides direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

Graphene oxide nanofilm and the addition of L-glutamine can promote development of embryonic muscle cells.

BACKGROUND: Formation of muscular pseudo-tissue depends on muscle precursor cells, the extracellular matrix (ECM)-mimicking structure and factors stimulating cell differentiation. These three things cooperate and can create a tissue-like structure, however, their interrelationships are relatively unknown. The objective was to study the interaction between surface properties, culture medium composition and heterogeneous cell culture. We would like to demonstrate that changing the surface properties by coating with graphene oxide nanofilm (nGO) can affect cell behaviour and especially their need for the key amino acid L-glutamine (L-Glu). RESULTS: Chicken embryo muscle cells and their precursors, cultured in vitro, were used as the experimental model. The mesenchymal stem cell, collected from the hind limb of the chicken embryo at day 8 were divided into 4 groups; the control group and groups treated with nGO, L-Glu and nGO supplied with L-Glu (nGOxL-Glu). The roughness of the surface of the plastic plate covered with nGO was much lower than a standard plate. The test of nGO biocompatibility demonstrated that the cells were willing to settle on the nGO without any toxic effects. Moreover, nGO by increasing hydrophilicity and reducing roughness and presumably through chemical bonds available on the GO surface stimulated the colonisation of primary stromal cells that promote embryonic satellite cells. The viability significantly increased in cells cultured on nGOxL-Glu. Observations of cell morphology showed that the most mature state of myogenesis was characteristic for the group nGOxL-Glu. This result was confirmed by increasing the expression of MYF5 genes at mRNA and protein levels. nGO also increased the expression of MYF5 and also very strongly the expression of PAX7 at mRNA and protein levels. However, when analysing the expression of PAX7, a positive link was observed between the nGO surface and the addition of L-Glu. CONCLUSIONS: The use of nGO and L-Glu supplement may improve myogenesis and also the myogenic potential of myocytes and their precursors by promoting the formation of satellite cells. Studies have, for the first time, demonstrated positive cooperation between surface properties nGO and L-Glu supplementation to the culture medium regarding the myogenic potential of cells involved in muscle formation.

Microbial Transglutaminase as a Tool to Improve the Features of Hydrocolloid-Based Bioplastics.

Several proteins from animal and plant origin act as microbial transglutaminase substrate, a crosslinking enzyme capable of introducing isopeptide bonds into proteins between the aminoacids glutamines and lysines. This feature has been widely exploited to modify the biological properties of many proteins, such as emulsifying, gelling, viscosity, and foaming. Besides, microbial transglutaminase has been used to prepare bioplastics that, because made of renewable molecules, are able to replace the high polluting plastics of petrochemical origin. In fact, most of the time, it has been shown that the microbial enzyme strengthens the matrix of protein-based bioplastics, thus, influencing the technological characteristics of the derived materials. In this review, an overview of the ability of many proteins to behave as good substrates of the enzyme and their ability to give rise to bioplastics with improved properties is presented. Different applications of this enzyme confirm its important role as an additive to recover high value-added protein containing by-products with a double aim (i) to produce environmentally friendly materials and (ii) to find alternative uses of wastes as renewable, cheap, and non-polluting sources. Both principles are in line with the bio-economy paradigm.

The role of glutamine in neurogenesis promoted by the green tea amino acid theanine in neural progenitor cells for brain health.

The green tea amino acid theanine is abundant in green tea rather than black and oolong teas, which are all made of the identical tea plant "Chanoki" (Camellia sinensis). Theanine has a molecular structure close to glutamine (GLN) compared to glutamic acid (Glu), in terms of the absence of a free carboxylic acid moiety from the gamma carbon position. Theanine efficiently inhibits [3H]GLN uptake without affecting [3H]Glu uptake in rat brain synaptosomes. In contrast to GLN, however, theanine markedly stimulates the abilities to replicate and to commit to a neuronal lineage following prolonged exposure in cultured neural progenitor cells (NPCs) prepared from embryonic and adult rodent brains. Upregulation of transcript expression is found for one of the GLN transporter isoforms, Slc38a1, besides the promotion of both proliferation and neuronal commitment along with acceleration of the phosphorylation of mechanistic target of rapamycin (mTOR) and relevant downstream proteins, in murine NPCs cultured with theanine. Stable overexpression of Slc38a1 similarly facilitates both cellular replication and neuronal commitment in pluripotent embryonic carcinoma P19 cells. In P19 cells with stable overexpression of Slc38a1, marked phosphorylation is seen for mTOR and downstream proteins in a manner insensitive to further additional phosphorylation by theanine. Taken together, theanine would exhibit a novel pharmacological property to up-regulate Slc38a1 expression for activation of the intracellular mTOR signaling pathway required for neurogenesis after sustained exposure in undifferentiated NPCs in the brain. In this review, a novel neurogenic property of the green tea amino acid theanine is summarized for embryonic and adult neurogenesis with a focus on the endogenous amino acid GLN on the basis of our accumulating evidence to date.

Side chain to main chain hydrogen bonds stabilize a polyglutamine helix in a transcription factor.

Polyglutamine (polyQ) tracts are regions of low sequence complexity frequently found in transcription factors. Tract length often correlates with transcriptional activity and expansion beyond specific thresholds in certain human proteins is the cause of polyQ disorders. To study the structural basis of the association between tract length, transcriptional activity and disease, we addressed how the conformation of the polyQ tract of the androgen receptor, associated with spinobulbar muscular atrophy (SBMA), depends on its length. Here we report that this sequence folds into a helical structure stabilized by unconventional hydrogen bonds between glutamine side chains and main chain carbonyl groups, and that its helicity directly correlates with tract length. These unusual hydrogen bonds are bifurcate with the conventional hydrogen bonds stabilizing α-helices. Our findings suggest a plausible rationale for the association between polyQ tract length and androgen receptor transcriptional activity and have implications for establishing the mechanistic basis of SBMA.

Synbiotics Combined with Glutamine Stimulate Brain Development and the Immune System in Preterm Pigs.

Background: Preterm infants are born with an immature gut, brain, and immune system, predisposing them to short- and long-term complications. Objective: We hypothesized that a milk diet supplemented with pre- and probiotics (i.e. synbiotics) and glutamine would improve gut, brain, and immune maturation in preterm neonates, using preterm pigs as a model. Methods: Preterm pigs (Landrace x Yorkshire x Duroc, n = 40, delivered by c-section at 90% of gestation) were reared individually until day 23 after birth under highly standardized conditions. Piglets in the intervention group (PPG, n = 20) were fed increasing volumes of bovine milk supplemented with prebiotics (short-chain galacto- and long chain fructo-oligosaccharides 9:1, 4-12 g/L), probiotics (Bifidobacterium breve M16-V, 3 × 109 CFU/d) and l-glutamine [0.15-0.30 g/(kg · d)], and compared with pigs fed bovine milk with added placebo compounds as control (CON, n = 20). Clinical, gastrointestinal, immunological, cognitive, and neurological endpoints were measured. Results: The PPG pigs showed more diarrhea but weight gain, body composition, and gut parameters were similar between the groups. Cognitive performance, assessed in a T-maze, was significantly higher in PPG pigs (P < 0.01), whereas motor function and exploratory interest were similar between the groups. Using ex vivo diffusion imaging, the orientation dispersion index in brain cortical gray matter was 50% higher (P = 0.04), and fractional anisotropy value was 7% lower (P = 0.05) in PPG pigs compared with CON pigs, consistent with increased dendritic branching in PPG. In associative fibers, radial diffusivity was lower and fractional anisotropy was higher in PPG pigs compared with CON pigs (all P < 0.05), while measures in the internal capsule showed a tendency towards reduced radial diffusivity and mean diffusivity (both P = 0.09). On day 23 pigs in the PPG group showed higher blood leukocyte numbers (+43%), neutrophil counts (+100%), and phagocytic rates (+24%), relative to CON, all P < 0.05. Conclusion: Preterm pigs supplemented with Bifidobacterium breve, galacto- and fructo-oligosaccharides, and l-glutamine showed enhanced neuronal and immunological development. The findings indicate the potential for targeted nutritional interventions after preterm birth, to support development of important systems such as immunity and brain.

RNAfitme: a webserver for modeling nucleobase and nucleoside residue conformation in fixed-backbone RNA structures.

BACKGROUND: Computational RNA 3D structure prediction and modeling are rising as complementary approaches to high-resolution experimental techniques for structure determination. They often apply to substitute or complement them. Recently, researchers' interests have directed towards in silico methods to fit, remodel and refine RNA tertiary structure models. Their power lies in a problem-specific exploration of RNA conformational space and efficient optimization procedures. The aim is to improve the accuracy of models obtained either computationally or experimentally. RESULTS: Here, we present RNAfitme, a versatile webserver tool for remodeling of nucleobase- and nucleoside residue conformations in the fixed-backbone RNA 3D structures. Our approach makes use of dedicated libraries that define RNA conformational space. They have been built upon torsional angle characteristics of PDB-deposited RNA structures. RNAfitme can be applied to reconstruct full-atom model of RNA from its backbone; remodel user-selected nucleobase/nucleoside residues in a given RNA structure; predict RNA 3D structure based on the sequence and the template of a homologous molecule of the same size; refine RNA 3D model by reducing steric clashes indicated during structure quality assessment. RNAfitme is a publicly available tool with an intuitive interface. It is freely accessible at http://rnafitme.cs.put.poznan.pl/ CONCLUSIONS: RNAfitme has been applied in various RNA 3D remodeling scenarios for several types of input data. Computational experiments proved its efficiency, accuracy, and usefulness in the processing of RNAs of any size. Fidelity of RNAfitme predictions has been thoroughly tested for RNA 3D structures determined experimentally and modeled in silico.

Polysaccharide-based hydrogels with tunable composition as 3D cell culture systems.

BACKGROUND: To date, cell cultures have been created either on 2-dimensional (2D) polystyrene surfaces or in 3-dimensional (3D) systems, which do not offer a controlled chemical composition, and which lack the soft environment encountered in vivo and the chemical stimuli that promote cell proliferation and allow complex cellular behavior. In this study, pectin-based hydrogels were developed and are proposed as versatile cell culture systems. METHODS: Pectin-based hydrogels were produced by internally crosslinking pectin with calcium carbonate at different initial pH, aiming to control crosslinking kinetics and degree. Additionally, glucose and glutamine were added as additives, and their effects on the viscoelastic properties of the hydrogels and on cell viability were investigated. RESULTS: Pectin hydrogels showed in high cell viability and shear-thinning behavior. Independently of hydrogel composition, an initial swelling was observed, followed by a low percentage of weight variation and a steady-state stage. The addition of glucose and glutamine to pectin-based hydrogels rendered higher cell viability up to 90%-98% after 1 hour of incubation, and these hydrogels were maintained for up to 7 days of culture, yet no effect on viscoelastic properties was detected. CONCLUSIONS: Pectin-based hydrogels that offer tunable composition were developed successfully. They are envisioned as synthetic extracellular matrix (ECM) either to study complex cellular behaviors or to be applied as tissue engineering substitutes.

Rapid analysis of glutamate, glutamine and GABA in mice frontal cortex microdialysis samples using HPLC coupled to electrospray tandem mass spectrometry.

In vivo measurement of multiple neurotransmitters is highly interesting but remains challenging in the field of neuroscience. GABA and l-glutamic acid are the major inhibitory and excitatory neurotransmitters, respectively, in the central nervous system, and their changes are related to a variety of diseases such as anxiety and major depressive disorder. This study described a simple method allowing the simultaneous LC-MS/MS quantification of l-glutamic acid, glutamine and GABA. Analytes were acquired from samples of the prefrontal cortex by microdialysis technique in freely moving mice. The chromatographic separation was performed by hydrophilic interaction liquid chromatography (HILIC) with a core-shell ammonium-sulfonic acid modified silica column using a gradient elution with mobile phases consisting of a 25 mM pH 3.5 ammonium formate buffer and acetonitrile. The detection of l-glutamic acid, glutamine and GABA, as well as the internal standards [d6]-GABA and [d5]-glutamate was performed on a triple quadrupole mass spectrometer in positive electrospray ionization and multiple reaction monitoring mode. The limit of quantification was 0.63 ng/ml for GABA, 1.25 ng/ml for l-glutamic acid and 3.15 ng/ml for glutamine, and the intra-day and inter-day accuracy and precision have been assessed for the three analytes. Therefore, the physiological relevance of the method was successfully applied for the determination of basal extracellular levels and potassium-evoked release of these neuroactive substances in the prefrontal cortex in adult awake C57BL/6 mice.

Proteic and phenolics compounds contents in Bacupari callus cultured with glutamine and nitrogen sources / Conteúdo de proteínas e compostos fenólicos em calos de Bacupari cultivados com glutamina e fontes de nitrogênio

Abstract In this study was evaluated the influence of glutamine supplementation on the endogenous content of amino acids, proteins, total phenolics, flavonoids and proanthocyanidins in Bacupari callus. The explants were inoculated in MS medium, MS with half concentration of the nitrogen salts (MS½) and nitrogen-free MS, supplemented with glutamine (5, 10, 30 and 60mM) named as Gln5, Gln10, Gln30 and Gln60. Amino acids and proteins were analyzed after 20, 80 and 140 days and the secondary metabolites on the 140th day. There was no difference in the amino acids on the 20th day. On the 80th day the treatments MS and MS½ presented the lowest levels. On the 140th day MS and MS½ presented the lowest amino acid concentration and Gln10 the highest. Concerning proteins, there was difference only on the 140th day, being the highest concentrations observed in Gln5, and the lowest in MS½ treatment. Total phenolics content was higher in the treatment Gln60 and lowest in MS. Treatments Gln5, Gln10, Gln30 and MS½ were statistically equal. For flavonoids, the highest values occurred in the treatments Gln30, Gln60 and MS½ and the lowest in Gln5, Gln10 and MS. Similarly, for the proanthocyanidins the highest concentrations were observed in treatment Gln60 and the lowest in Gln5 and MS. In conclusion, the treatment with 60mM of glutamine favors the protein accumulation and production of secondary metabolites in Bacupari callus.

Resumo Nesse estudo foi avaliado o efeito da suplementação com glutamina no conteúdo endógeno de aminoácidos, proteínas, fenólicos totais, flavonoides e proantocianidinas em calos de Bacupari. Os explantes foram inoculados em meio MS, meio MS com metade da concentração de dos sais de nitrogênio (MS½) e meio MS sem nitrogênio suplementado com glutamina (5, 10, 30 e 60mM) denominados como Gln5, Gln10, Gln30 e Gln60. Os aminoácidos e as proteínas foram analisados após 20, 80 e 140 dias e os metabólitos secundários no 140° dia. Não houve diferença nos aminoácidos no 20° dia. No 80° dia os tratamentos MS e MS½ apresentaram os menores níveis. No 140° dia, MS e MS½ apresentaram as menores concentrações de aminoácidos e o Gln10 as maiores. A respeito das proteínas, houve diferença apenas no 140° dia, sendo as maiores concentrações observadas nos tratamentos Gln, e as menores no MS½. O conteúdo de fenólicos totais foi maior no tratamento Gln60 e menor no MS. Os tratamentos Gln5, Gln10, Gln30 e MS½ foram estatisticamente iguais. Para os flavonóides, os maiores valores ocorreram nos tratamentos Gln30, Gln60 e MS½ e os menores no Gln5, Gln10 e MS. Da mesma forma, para as proantocianidinas, as maiores concentrações foram observadas no tratamento Gln60 os menores no Gln5 e MS. Em conclusão, o tratamento com 60 mM de glutamina favorece o acúmulo de proteínas e a produção de metabólitos secundários em calos de Bacupari.

Selective proton-observed, carbon-edited (selPOCE) MRS method for measurement of glutamate and glutamine 13 C-labeling in the human frontal cortex.

PURPOSE: 13 C magnetic resonance spectroscopy (MRS) in combination with infusion of 13 C-labeled substrates has led to unique insights into human brain metabolism and neurotransmitter cycling. However, the low sensitivity of direct 13 C MRS and high radiofrequency power requirements has limited 13 C MRS studies to predominantly data acquisition in large volumes of the occipital cortex. The purpose of this study is to develop an MRS technique for localized detection of 13 C-labeling of glutamate and glutamine in the human frontal lobe. METHODS: We used an indirect (1 H-[13 C]), proton-observed, carbon-edited MRS sequence (selPOCE) for detection of 13 C-labeled metabolites in relatively small volumes located in the frontal lobe at 4 T. The SelPOCE method allows for selective and separate detection of glutamate and glutamine resonances, which significantly overlap at magnetic field strengths used for clinical MRI. RESULTS: Phantom data illustrate how selPOCE can be tuned to selectively detect 13 C labeling in different metabolites. Three-dimensional specific absorption rate simulations of radiofrequency power deposition show that the selPOCE method operates comfortably within the global and local Food and Drug Administration specific absorption rate guidelines. In vivo selPOCE data are presented, which were acquired from a 45-mL volume in the frontal lobe of healthy subjects. The in vivo data show the time-dependent 13 C-labeling of glutamate and glutamine during intravenous infusion of [1-13 C]-glucose. Metrics describing spectral fitting quality of the glutamate and glutamine resonances are reported. CONCLUSIONS: The SelPOCE sequence allows the detection of 13 C-labeling in glutamate and glutamine from a relatively small volume in the human frontal lobe at low radiofrequency power requirements. Magn Reson Med 80:11-20, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Effect of amino acids and frequency of reuse frying oils at different temperature on acrylamide formation in palm olein and soy bean oils via modeling system.

This work investigated the underlying formation of acrylamide from amino acids in frying oils during high temperatures and at different times via modeling systems. Eighteen amino acids were used in order to determine which one was more effective on acrylamide production. Significantly the highest amount of acrylamide was produced from asparagine (5987.5µg/kg) and the lowest from phenylalanine (9.25µg/kg). A constant amount of asparagine and glutamine in palm olein and soy bean oils was heated up in modelling system at different temperatures (160, 180 and 200°C) and times (1.5, 3, 4.5, 6, 7.5min). The highest amount of acrylamide was found at 200°C for 7.5min (9317 and 8511µg/kg) and lowest at 160°C for 1.5min (156 and 254µg/kg) in both frying oils and both amino acids. Direct correlations have been found between time (R2=0.884), temperature (R2=0.951) and amount of acrylamide formation, both at p<0.05.

Proteic and phenolics compounds contents in Bacupari callus cultured with glutamine and nitrogen sources.

In this study was evaluated the influence of glutamine supplementation on the endogenous content of amino acids, proteins, total phenolics, flavonoids and proanthocyanidins in Bacupari callus. The explants were inoculated in MS medium, MS with half concentration of the nitrogen salts (MS½) and nitrogen-free MS, supplemented with glutamine (5, 10, 30 and 60mM) named as Gln5, Gln10, Gln30 and Gln60. Amino acids and proteins were analyzed after 20, 80 and 140 days and the secondary metabolites on the 140th day. There was no difference in the amino acids on the 20th day. On the 80th day the treatments MS and MS½ presented the lowest levels. On the 140th day MS and MS½ presented the lowest amino acid concentration and Gln10 the highest. Concerning proteins, there was difference only on the 140th day, being the highest concentrations observed in Gln5, and the lowest in MS½ treatment. Total phenolics content was higher in the treatment Gln60 and lowest in MS. Treatments Gln5, Gln10, Gln30 and MS½ were statistically equal. For flavonoids, the highest values occurred in the treatments Gln30, Gln60 and MS½ and the lowest in Gln5, Gln10 and MS. Similarly, for the proanthocyanidins the highest concentrations were observed in treatment Gln60 and the lowest in Gln5 and MS. In conclusion, the treatment with 60mM of glutamine favors the protein accumulation and production of secondary metabolites in Bacupari callus.

Discovery of Novel Potent Reversible and Irreversible Myeloperoxidase Inhibitors Using Virtual Screening Procedure.

The heme enzyme myeloperoxidase (MPO) participates in innate immune defense mechanism through formation of microbicidal reactive oxidants. However, evidence has emerged that MPO-derived oxidants contribute to propagation of inflammatory diseases. Because of the deleterious effects of circulating MPO, there is a great interest in the development of new efficient and specific inhibitors. Here, we have performed a novel virtual screening procedure, depending on ligand-based pharmacophore modeling followed by structure-based virtual screening. Starting from a set of 727842 compounds, 28 molecules were selected by this virtual method and tested on MPO in vitro. Twelve out of 28 compounds were found to have an IC50 less than 5 µM. The best inhibitors were 2-(7-methoxy-4-methylquinazolin-2-yl)guanidine (28) and (R)-2-(1-((2,3-dihydro-1H-imidazol-2-yl)methyl)pyrrolidin-3-yl)-5-fluoro-1H-benzo[d]imidazole (42) with IC50 values of 44 and 50 nM, respectively. Studies on the mechanism of inhibition suggest that 28 is the first potent mechanism-based inhibitor and inhibits irreversibly MPO at nanomolar concentration.

Methionine sulfoximine supplementation enhances productivity in GS-CHOK1SV cell lines through glutathione biosynthesis.

In Lonza Biologics' GS Gene Expression System™, recombinant protein-producing GS-CHOK1SV cell lines are generated by transfection with an expression vector encoding both GS and the protein product genes followed by selection in MSX and glutamine-free medium. MSX is required to inhibit endogenous CHOK1SV GS, and in effect create a glutamine auxotrophy in the host that can be complemented by the expression vector encoded GS in selected cell lines. However, MSX is not a specific inhibitor of GS as it also inhibits the activity of GCL (a key enzyme in the glutathione biosynthesis pathway) to a similar extent. Glutathione species (GSH and GSSG) have been shown to provide both oxidizing and reducing equivalents to ER-resident oxidoreductases, raising the possibility that selection for transfectants with increased GCL expression could result in the isolation of GS-CHOKISV cell lines with improved capacity for recombinant protein production. In this study we have begun to address the relationship between MSX supplementation, the amount of intracellular GCL subunit and mAb production from a panel of GS-CHOK1SV cell lines. We then evaluated the influence of reduced GCL activity on batch culture of an industrially relevant mAb-producing GS-CHOK1SV cell line. To the best of our knowledge, this paper describes for the first time the change in expression of GCL subunits and recombinant mAb production in these cell lines with the degree of MSX supplementation in routine subculture. Our data also shows that partial inhibition of GCL activity in medium containing 75 µM MSX increases mAb productivity, and its more specific inhibitor BSO used at a concentration of 80 µM in medium increases the specific rate of mAb production eight-fold and the concentration in harvest medium by two-fold. These findings support a link between the inhibition of glutathione biosynthesis and recombinant protein production in industrially relevant systems and provide a process-driven method for increasing mAb productivity from GS-CHOK1SV cell lines. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:17-25, 2017.

Non-Invasive Glutamine PET Reflects Pharmacological Inhibition of BRAFV600E In Vivo.

PURPOSE: This study aimed to study whether cancer cells possess distinguishing metabolic features compared with surrounding normal cells, such as increased glutamine uptake. Given this, quantitative measures of glutamine uptake may reflect critical processes in oncology. Approximately, 10 % of patients with colorectal cancer (CRC) express BRAF V600E , which may be actionable with selective BRAF inhibitors or in combination with inhibitors of complementary signaling axes. Non-invasive and quantitative predictive measures of response to these targeted therapies remain poorly developed in this setting. The primary objective of this study was to explore 4-[18F]fluoroglutamine (4-[18F]F-GLN) positron emission tomography (PET) to predict response to BRAFV600E-targeted therapy in preclinical models of colon cancer. PROCEDURES: Tumor microarrays from patients with primary human colon cancers (n = 115) and CRC liver metastases (n = 111) were used to evaluate the prevalence of ASCT2, the primary glutamine transporter in oncology, by immunohistochemistry. Subsequently, 4-[18F]F-GLN PET was evaluated in mouse models of human BRAF V600E -expressing and BRAF wild-type CRC. RESULTS: Approximately 70 % of primary colon cancers and 53 % of metastases exhibited positive ASCT2 immunoreactivity, suggesting that [18F]4-F-GLN PET could be applicable to a majority of patients with colon cancer. ASCT2 expression was not associated selectively with the expression of mutant BRAF. Decreased 4-[18F]F-GLN predicted pharmacological response to single-agent BRAF and combination BRAF and PI3K/mTOR inhibition in BRAF V600E -mutant Colo-205 tumors. In contrast, a similar decrease was not observed in BRAF wild-type HCT-116 tumors, a setting where BRAFV600E-targeted therapies are ineffective. CONCLUSIONS: 4-[18F]F-GLN PET selectively reflected pharmacodynamic response to BRAF inhibition when compared with 2-deoxy-2[18F]fluoro-D-glucose PET, which was decreased non-specifically for all treated cohorts, regardless of downstream pathway inhibition. These findings illustrate the utility of non-invasive PET imaging measures of glutamine uptake to selectively predict response to BRAF-targeted therapy in colon cancer and may suggest further opportunities to inform colon cancer clinical trials using targeted therapies against MAPK activation.

Guhong injection protects against focal cerebral ischemia-reperfusion injury via anti-inflammatory effects in rats.

Guhong injection (GHI), composed of aceglutamide and safflower aqueous extract, has been used clinically for the treatment of cerebrovascular diseases such as cerebral embolism, hemorrhage and mental deterioration. In this paper, we reported the results of the first study on the anti-inflammatory effects of GHI in murine focal cerebral ischemia-reperfusion (I/R) injury. Adult male SD rats were randomly divided into six groups: Sham group, I/R group, GHI-L group (2.5 mL/kg), GHI-M group (5 mL/kg), GHI-H group (10 mL/kg) and Nimodipine group. I/R injury was induced by middle cerebral artery occlusion (MCAO) for 1.5 h followed by reperfusion for 24 h. Compared with I/R group, rats treated with GHI showed dose dependent reductions in neurological defect scores and cerebral infarct volume. GHI obviously down-regulated nitric oxide (NO), inducible NO synthase (iNOS), myeloperoxidase (MPO), interleukin-1ß (IL-1ß), TNF-α (tumor necrosis factor-α) and C reactive protein (CRP) levels in serum. Moreover, histological examination by H&E staining showed that clear cell outline, less vacuolated spaces and largely surviving neurons were observed in GHI-treated rats. The immunohistochemical staining revealed that GHI administration significantly diminished the positive expressions of intercellular cell adhesion molecule-1 (ICAM-1) and nuclear factor-κB p65 (NF-κB p65) in brain tissues. Western blot analysis for ICAM, NF-κB p65 and iNOS further solidified the above findings. All these results demonstrate that GHI exerts a strong and ameliorative effect on cerebral I/R injury in rats possibly through the inhibition of inflammation.

Membrane Topology and Biochemical Characterization of the Escherichia coli BacA Undecaprenyl-Pyrophosphate Phosphatase.

Several integral membrane proteins exhibiting undecaprenyl-pyrophosphate (C55-PP) phosphatase activity were previously identified in Escherichia coli that belonged to two distinct protein families: the BacA protein, which accounts for 75% of the C55-PP phosphatase activity detected in E. coli cell membranes, and three members of the PAP2 phosphatidic acid phosphatase family, namely PgpB, YbjG and LpxT. This dephosphorylation step is required to provide the C55-P carrier lipid which plays a central role in the biosynthesis of various cell wall polymers. We here report detailed investigations of the biochemical properties and membrane topology of the BacA protein. Optimal activity conditions were determined and a narrow-range substrate specificity with a clear preference for C55-PP was observed for this enzyme. Alignments of BacA protein sequences revealed two particularly well-conserved regions and several invariant residues whose role in enzyme activity was questioned by using a site-directed mutagenesis approach and complementary in vitro and in vivo activity assays. Three essential residues Glu21, Ser27, and Arg174 were identified, allowing us to propose a catalytic mechanism for this enzyme. The membrane topology of the BacA protein determined here experimentally did not validate previous program-based predicted models. It comprises seven transmembrane segments and contains in particular two large periplasmic loops carrying the highly-conserved active site residues. Our data thus provide evidence that all the different E. coli C55-PP phosphatases identified to date (BacA and PAP2) catalyze the dephosphorylation of C55-PP molecules on the same (outer) side of the plasma membrane.