Endogenous Nucleotides Research Articles

P2Y11 Receptors: Properties, Distribution and Functions.

The P2Y11 receptor is a G protein-coupled receptor that is stimulated by endogenous purine nucleotides, particularly ATP. Amongst P2Y receptors it has several unique properties; (1) it is the only human P2Y receptor gene that contains an intron in the coding sequence; (2) the gene does not appear to be present in the rodent genome; (3) it couples to stimulation of both phospholipase C and adenylyl cyclase. Its absence in mice and rats, along with a limited range of selective pharmacological tools, has hampered the development of our knowledge and understanding of its properties and functions. Nonetheless, through a combination of careful use of the available tools, suppression of receptor expression using siRNA and genetic screening for SNPs, possible functions of native P2Y11 receptors have been identified in a variety of human cells and tissues. Many are in blood cells involved in inflammatory responses, consistent with extracellular ATP being a damage-associated signalling molecule in the immune system. Thus proposed potential therapeutic applications relate, in the main, to modulation of acute and chronic inflammatory responses.

Identifying Glyceraldehyde 3-Phosphate Dehydrogenase as a Cyclic Adenosine Diphosphoribose Binding Protein by Photoaffinity Protein-Ligand Labeling Approach.

Cyclic adenosine diphosphoribose (cADPR), an endogenous nucleotide derived from nicotinamide adenine dinucleotide (NAD+), mobilizes Ca2+ release from endoplasmic reticulum (ER) via ryanodine receptors (RyRs), yet the bridging protein(s) between cADPR and RyRs remain(s) unknown. Here we synthesized a novel photoaffinity labeling (PAL) cADPR agonist, PAL-cIDPRE, and subsequently applied it to purify its binding proteins in human Jurkat T cells. We identified glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as one of the cADPR binding protein(s), characterized the binding affinity between cADPR and GAPDH in vitro by surface plasmon resonance (SPR) assay, and mapped cADPR's binding sites in GAPDH. We further demonstrated that cADPR induces the transient interaction between GAPDH and RyRs in vivo and that GAPDH knockdown abolished cADPR-induced Ca2+ release. However, GAPDH did not catalyze cADPR into any other known or novel compound(s). In summary, our data clearly indicate that GAPDH is the long-sought-after cADPR binding protein and is required for cADPR-mediated Ca2+ mobilization from ER via RyRs.

ChemInform Abstract: Recent Trends in Nucleotide Synthesis

AbstractReview: 270 refs.

Ocular Purine Receptors as Drug Targets in the Eye.

Agonists and antagonists of various subtypes of G protein coupled adenosine receptors (ARs), P2Y receptors (P2YRs), and ATP-gated P2X receptor ion channels (P2XRs) are under consideration as agents for the treatment of ocular diseases, including glaucoma and dry eye. Numerous nucleoside and nonnucleoside modulators of the receptors are available as research tools and potential therapeutic molecules. Three of the 4 subtypes of ARs have been exploited with clinical candidate molecules for treatment of the eye: A1, A2A, and A3. An A1AR agonist is in clinical trials for glaucoma, A2AAR reduces neuroinflammation, A3AR protects retinal ganglion cells from apoptosis, and both A3AR agonists and antagonists had been reported to lower intraocular pressure (IOP). Extracellular concentrations of endogenous nucleotides, including dinucleoside polyphosphates, are increased in pathological states, activating P2Y and P2XRs throughout the eye. P2YR agonists, including P2Y2 and P2Y6, lower IOP. Antagonists of the P2X7R prevent the ATP-induced neuronal apoptosis in the retina. Thus, modulators of the purinome in the eye might be a source of new therapies for ocular diseases.

Recent Trends in Nucleotide Synthesis

Focusing on the recent literature (since 2000), this review outlines the main synthetic approaches for the preparation of 5'-mono-, 5'-di-, and 5'-triphosphorylated nucleosides, also known as nucleotides, as well as several derivatives, namely, cyclic nucleotides and dinucleotides, dinucleoside 5',5'-polyphosphates, sugar nucleotides, and nucleolipids. Endogenous nucleotides and their analogues can be obtained enzymatically, which is often restricted to natural substrates, or chemically. In chemical synthesis, protected or unprotected nucleosides can be used as the starting material, depending on the nature of the reagents selected from P(III) or P(V) species. Both solution-phase and solid-support syntheses have been developed and are reported here. Although a considerable amount of research has been conducted in this field, further work is required because chemists are still faced with the challenge of developing a universal methodology that is compatible with a large variety of nucleoside analogues.

Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16INK4a or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection

Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16INK4a or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection

Tenofovir/emtricitabine metabolites and endogenous nucleotide exposures are associated with p16INK4a expression in subjects on combination therapy

Tenofovir/emtricitabine metabolites and endogenous nucleotide exposures are associated with p16INK4a expression in subjects on combination therapy

Citicoline Treatment Improves Measures of Impulsivity and Task Performance in Chronic Marijuana Smokers: A Pilot BOLD fMRI Study

Citicoline is an endogenous nucleotide that has historically been used to treat stroke, traumatic brain injury, and cognitive dysfunction. Research has also shown that citicoline treatment is associated with improved cognitive performance in substance-abusing populations. We hypothesized that marijuana (MJ) smokers who received citicoline would demonstrate improvement in cognitive performance as well as increased neural efficiency during tasks of cognitive control relative to those who received placebo. The current study tested this hypothesis by examining the effects of citicoline in treatment-seeking chronic MJ smokers. In an 8-week double-blind, placebo-controlled study, 19 MJ smokers were randomly assigned via a double-blind procedure to the citicoline (8 Males, 2 Females) or placebo group (9 Males, 0 Females). All participants completed fMRI scanning at baseline and after 8 weeks of treatment during two cognitive measures of inhibitory processing, the Multi Source Interference Test (MSIT) and Stroop Color Word Test, and also completed the Barratt Impulsiveness Scale (BIS-11), a self-report measure of impulsivity. Following the 8 week trial, MJ smokers treated with citicoline demonstrated significantly lower levels of behavioral impulsivity, improved task accuracy on both the MSIT and Stroop tasks, and exhibited significantly different patterns of brain activation relative to baseline levels and relative to those who received placebo. Findings suggest that citicoline may facilitate the treatment of MJ use disorders by improving the cognitive skills necessary to fully engage in comprehensive treatment programs.

NT5C2 As a Major Contributor to Thiopurine Resistance at ALL Relapse Via Multiple Mechanisms

Background Relapse remains as a formidable challenge for acute lymphoblastic leukemia (ALL), particularly because it is associated with dramatic drug resistance and thus dismal prognosis. It is crucial to understand the genetic basis of relapsed ALL to develop new therapeutic strategies. Recently, somatic mutations in NT5C2 were identified as one of the most common genomic lesions specific to relapsed ALL and were directly linked to thiopurine resistance (Nat Genet 2013, Nat Med 2013, Nat Commun 2015). A nucleotidase, NT5C2 dephosphorylates purine monophosphate nucleotides and is important for cellular nucleic acid homeostasis. However, the exact mechanisms by which NT5C2 mutations influence thiopurine resistance in ALL are not completely understood.Methods Wildtype and mutant human NT5C2 (p.R39Q, p.R238W, and p.R367Q) were expressed in E. Coli and purified by affinity chromatography followed by gel filtration. Nucleotidase activity was measured by quantifying the release of free phosphate with the Malachite Green assay. NT5C2 enzyme kinetics (Vmax and Km) were determined for endogenous purine nucleotide substrates (inosine monophosphate [IMP] and guanosine monophosphate [GMP]) and thiopurine drug metabolite substrates (thioinosine monophosphate [TIMP] and thioguanosine monophosphate [TGMP]). Human ALL cell lines (Nalm6 and REH) stably overexpressing wildtype or mutant NT5C2 were established by lentiviral transduction. Thiopurine transport was characterized in vitro by quantifying the influx and efflux of 14 C labeled mercaptopurine (MP) and its metabolites.Results To characterize NT5C2 substrate specificity, we first determined the nucleotidase activity of wildtype and mutant proteins with endogenous purine nucleotides (IMP and GMP) and thiopurine metabolites (TIMP and TGMP). Wildtype NT5C2 exhibited nucleotidase activity against all 4 nucleotide metabolites, but IMP and TIMP were clearly the preferred substrates with up to 4-fold higher reaction velocities compared to GMP and TGMP, respectively. All leukemia-derived NT5C2 mutations resulted in substantial increase in nucleotidase activity across substrates, with the p.R367Q mutant consistently exhibiting the greatest gain of activity. By comparison, mutant NT5C2 proteins showed similar substrate preference of IMP over GMP (e.g., reaction rate of 26.6 pmol/min and 10.4 pmol/min for IMP and GMP, respectively, with the p.R367Q NT5C2). However, this inosine over guanosine bias in substrate specificity was reversed with thiopurine metabolites: leukemia-derived mutant NT5C2s were substantially more efficient to dephosphorylate TGMP than TIMP (e.g., reaction rate of 27.8 pmol/min and 41.5 pmol/min for TIMP and TGMP, respectively, with the p.R367Q NT5C2). The "mutant to wildtype" ratio of NT5C2 nucleotidase activity (e.g., the relative increase of Vmax) was significantly greater for thiopurine metabolites than what was observed when endogenous purine nucleotides were used as substrates (e.g., 15.2- and 1.6-fold increase in Vmax for TIMP and IMP with the p.R367Q NT5C2). These results suggest that ALL relapse-associated NT5C2 mutations likely confer not only increase in endogenous nucleotidase activity but also novel enzymatic functions that specially affect thiopurine metabolism.In addition to the increase in thiopurine resistance, human ALL cell lines expressing mutant NT5C2 also showed significant reduction in intracellular levels of thiopurine metabolites after drug treatment, pointing to influence of NT5C2 mutations on thiopurine drug transport. Using 14 C labeled MP, we traced both the influx and efflux of drug metabolites in isogenic cell lines expressing wildtype or mutant NT5C2 s. In both Nalm6 and REH cells, intracellular uptake of MP was reduced by 51% in mutant cells compared to cells with wildtype protein. In contrast, the level of MP metabolites in the extracellular medium was 3 times higher with mutant cells, reflecting increased drug efflux. Therefore, expression of mutant NT5C2 resulted in a net reduction of intracellular exposure to thiopurine, suggesting disturbance of the drug transport pathway as a distinct mechanism for NT5C2-mediated thiopurine resistance.ConclusionsNT5C2 mutations specifically influence thiopurine metabolism and transport, and therefore are critical determinants for drug resistance in relapsed ALL. DisclosuresNo relevant conflicts of interest to declare.

Expanded acceptor substrates flexibility study of flavonol 7-O-rhamnosyltransferase, AtUGT89C1 from Arabidopsis thaliana

Acceptor substrates flexibility of previously characterized flavonol 7-O-rhamnosyltransferase (AtUGT89C1) from Arabidopsis thaliana was explored with an endogenous nucleotide diphosphate sugar and five different classes of flavonoids (flavonols, flavones, flavanones, chalcone and stilbenes) through a biotransformation approach. In contrast to the previous reports, this study highlights the expanded acceptor substrate promiscuity of AtUGT89C1 for the regiospecific glycosylation of diverse class of flavonoids at 7-hydroxyl position using microbial thymidine diphosphate (TDP)-l-rhamnose as sugar donor instead of uridine diphosphate-l-rhamnose. We examine the biocatalytic potential of AtUGT89C1 using endogenous sugar (TDP-l-rhamnose) from E. coli to generate a library of flavonoid 7-O-rhamnosides.

Liquid chromatography/tandem mass spectrometry method for simultaneous quantification of eight endogenous nucleotides and the intracellular gemcitabine metabolite dFdCTP in human peripheral blood mononuclear cells.

Quantification of endogenous nucleotides is of interest for investigation of numerous cellular biochemical processes, such as energy metabolism and signal transduction, and may also be applied in cancer and antiretroviral therapies in which nucleoside analogues are used. For these purposes we developed and validated a sensitive and high accuracy ion-pair liquid chromatography tandem mass spectrometry (IP LC-MS/MS) method for simultaneous quantification of eight endogenous nucleotides (ATP, CTP, GTP, UTP, dATP, dCTP, dGTP, dTTP) and 2',2'-difluoro-2'-deoxycytidine triphosphate (dFdCTP), an intracellular metabolite of the nucleoside analogue gemcitabine. The assay was validated using 200μL aliquots of peripheral blood mononuclear cell (20×10(6)cells/ml, 4×10(6)cells) extracts, pretreated with activated charcoal and spiked with unlabeled nucleotides, deoxynucleotides and dFdCTP. Analytes were extracted by simple precipitation with cold 60% methanol containing isotope labeled internal standards and separated on a porous graphitic carbon column. For method validation, the concentration ranges were: 0.125-20.8pmol injected for deoxynucleotides, 0.25-312.5pmol injected for dFdCTP and 5-3200pmol injected for nucleotides. The highest coefficients of variation (CV) were 12.1% for within run assay and 11.4% for between run assay, both representing the precision at the lowest analyte concentrations. The method was applied to monitor dFdCTP and changes in endogenous nucleotides in patients who were receiving gemcitabine infusions.

MicroRNA-206: Effective Inhibition of Gastric Cancer Progression through the c-Met Pathway.

MicroRNAs are endogenous short chain nucleotide RNAs that regulate gene function by direct binding of target mRNAs. In this study, we investigated the effects of microRNA-206 (miR-206) on the development of gastric cancer. miR-206 was first confirmed to be downregulated in gastric cancer specimens. Conversely, upregulation of c-Met was confirmed in tissue samples of human gastric cancer, with its level inversely correlated with miR-206 expression. Introduction of miR-206 inhibited cellular proliferation by inducing G1 cell cycle arrest, as well as migration and invasion. Moreover, important proliferation and/or migration related molecules such as c-Met, CDK4, p-Rb, p-Akt and p-ERK were confirmed to be downregulated by Western blot analysis. Targeting of c-Met also directly affected AGS cell proliferation, migration and invasion. In vivo, miR-206 expressing tumor cells also displayed growth delay in comparison to unaffected tumor cells. Our results demonstrated that miR-206 suppressed c-Met expression in gastric cancer and could function as a potent tumor suppressor in c-Met overexpressing tumors. Inhibition of miR-206 function could contribute to aberrant cell proliferation and migration, leading to gastric cancer development.

Tenofovir/emtricitabine metabolites and endogenous nucleotide exposures are associated with p16(INK4a) expression in subjects on combination therapy.

HIV may amplify immunological, physiological and functional changes of ageing. We determined associations of frailty phenotype, a T-cell senescence marker (p16(INK4a) expression), age and demographics with exposures of the intracellular metabolites (IM) and endogenous nucleotides (EN) of tenofovir/emtricitabine (TFV/FTC), efavirenz (EFV), atazanavir (ATV) and ritonavir (RTV). Plasma and peripheral blood mononuclear cell samples for drug, IM and EN concentrations were collected at four time points in HIV+ adults receiving TFV/FTC with EFV or ATV/RTV. Subjects underwent frailty phenotyping and p16(INK4a) expression analysis. Non-compartmental analysis generated an area under the curve (AUC) for each analyte. Spearman rank correlation and Kruskal-Wallis tests were used to assess associations between AUC, demographics and ageing markers, adjusting for multiple comparisons with the Holm procedure. Subjects (n=79) ranged in age from 22-73 years (median 48 years); 48 were African-American, 24 were female, 54 received EFV. Three subjects (range 51-60 years) demonstrated frailty, with 17 subjects (range 26-60 years) demonstrating pre-frailty. Negative associations were observed between p16(INK4a) expression and each of FTC-triphosphate (r=-0.45), deoxyadenosine triphosphate (dATP; r=-0.47) and deoxycytidine triphosphate (dCTP; r=-0.57) AUCs (P-values <0.02). TFV and FTC AUCs were larger among subjects with lower renal function or higher chronological age (P-values ≤0.05). No associations were observed for EFV, ATV or RTV AUCs. Associations of IM/EN exposure and p16(INK4a) expression observed here suggest that senescence may alter drug phosphorylation, metabolism or transport. This finding warrants further mechanistic study to ensure optimal treatment in the ageing HIV+ population. Clinicaltrials.gov NCT01180075.

UDP-galactose (SLC35A2) and UDP-N-acetylglucosamine (SLC35A3) Transporters Form Glycosylation-related Complexes with Mannoside Acetylglucosaminyltransferases (Mgats)

UDP-galactose transporter (UGT; SLC35A2) and UDP-N-acetylglucosamine transporter (NGT; SLC35A3) form heterologous complexes in the Golgi membrane. NGT occurs in close proximity to mannosyl (α-1,6-)-glycoprotein β-1,6-N-acetylglucosaminyltransferase (Mgat5). In this study we analyzed whether NGT and both splice variants of UGT (UGT1 and UGT2) are able to interact with four different mannoside acetylglucosaminyltransferases (Mgat1, Mgat2, Mgat4B, and Mgat5). Using an in situ proximity ligation assay, we found that all examined glycosyltransferases are in the vicinity of these UDP-sugar transporters both at the endogenous level and upon overexpression. This observation was confirmed via the FLIM-FRET approach for both NGT and UGT1 complexes with Mgats. This study reports for the first time close proximity between endogenous nucleotide sugar transporters and glycosyltransferases. We also observed that among all analyzed Mgats, only Mgat4B occurs in close proximity to UGT2, whereas the other three Mgats are more distant from UGT2, and it was only possible to visualize their vicinity using proximity ligation assay. This strongly suggests that the distance between these protein pairs is longer than 10 nm but at the same time shorter than 40 nm. This study adds to the understanding of glycosylation, one of the most important post-translational modifications, which affects the majority of macromolecules. Our research shows that complex formation between nucleotide sugar transporters and glycosyltransferases might be a more common phenomenon than previously thought.

Ultrasensitive method to quantify intracellular zidovudine mono-, di- and triphosphate concentrations in peripheral blood mononuclear cells by liquid chromatography-tandem mass spectrometry.

Although zidovudine (AZT) is not the preferred antiretroviral drug for adult HIV-infected patients, it is still widely used in infants for both prevention of mother-to-infant HIV-1 transmission and treatment of HIV-infected children. However, it is difficult to measure intracellular concentrations of AZT metabolites in small blood samples due to their extremely low concentrations in peripheral blood mononuclear cells and interference by endogenous nucleotide triphosphates, residual plasma phosphates and electrolytes. We developed an ultrasensitive assay using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measurement of intracellular concentrations of zidovudine (AZT)-monophosphate (AZT-MP), -diphosphate (AZT-DP) and -triphosphate (AZT-TP). The high sensitivity was due to the improvement of peripheral blood mononuclear cells extraction for complete removal of plasma and electrolytes, alkalization of LC buffer and use of alkaline-stable high performance liquid chromatography column and tetrabutylammonium hydroxide as the ion pair. Using this method, the lower limits of quantification of AZT, AZT-MP, -DP and -TP were 6, 6, 10 and 10 fmol per sample, respectively. Accuracy ranged 89-115% and precision was lower than 15% in the quantification range of 6-6000 fmol/sample for plasma AZT and intracellular AZT-MP and 10-10 000 fmol/sample for AZT-DP and -TP. The validation parameters met the international requirements. Among nine AZT-treated HIV-infected adult patients, five had low AZT-TP levels (<10 fmol/10(6) cells). Our assay has high sensitivity and is advantageous for evaluation of AZT phosphates in children and infants based on minimum blood sampling requirement.

Development of an LC–MS/MS assay for the quantitative determination of the intracellular 5-fluorouracil nucleotides responsible for the anticancer effect of 5-fluorouracil

5-Fluorouracil (5-FU) and its oral prodrug capecitabine are among the most widely used chemotherapeutics. For cytotoxic activity, 5-FU requires cellular uptake and intracellular metabolic activation. Three intracellular formed metabolites are responsible for the antineoplastic effect of 5-FU: 5-fluorouridine 5′-triphosphate (FUTP), 5-fluoro-2′-deoxyuridine 5′-triphosphate (FdUTP) and 5-fluoro-2′-deoxyuridine 5′-monophosphate (FdUMP).In this paper, we describe the development of an LC–MS/MS assay for quantification of these active 5-FU nucleotides in peripheral blood mononuclear cells (PBMCs). Because the intracellular 5-FU nucleotide concentrations were very low, maximization of the release from the cell matrix and minimization of interference were critical factors. Therefore, a series of experiments was performed to select the best method for cell lysis and nucleotide extraction. Chromatography was optimized to obtain separation from endogenous nucleotides, and the effect of different cell numbers was examined.The assay was validated for the following concentration ranges in PBMC lysate: 0.488–19.9nM for FUTP, 1.66–67.7nM for FdUTP and 0.748–30.7nM for FdUMP. Accuracies were between −2.2 and 7.0% deviation for all analytes, and the coefficient of variation values were ≤4.9%.The assay was successfully applied to quantify 5-FU nucleotides in PBMC samples from patients treated with capecitabine and patients receiving 5-FU intravenously. FUTP amounts up to 3054fmol/106 PBMCs and FdUMP levels up to 169fmol/106 PBMCs were measured. The FdUTP concentrations were below the lower limit of quantification. To our knowledge, this is the first time that 5-FU nucleotides were quantified in cells from patients treated with 5-FU or capecitabine without using a radiolabel.

TNAP and Pain Control.

Chronic pain is one of the most debilitating and expensive diseases, yet current therapies are often insufficient in bringing about long-term relief. Further, many treatments for chronic pain also carry significant side effects. The molecule adenosine has long been identified as a potent inhibitor of nociceptive circuits in the spinal cord; however, the widespread expression of adenosine receptors in many organ systems has limited its use as an analgesic. Recently several 5' ectonucleotidases, including tissue non-specific alkaline phosphatase (TNAP), have been characterized for their ability to generate endogenous adenosine in nociceptive circuitry of the dorsal spinal cord. These ectonucleotidases have the ability to hydrolyze the endogenous pronociceptive nucleotides like adenosine triphosphate (ATP) into the antinociceptive nucleoside adenosine. This chapter discusses the role of TNAP and other ectonucleotidases in nociceptive circuits, and their potential as future targets of new therapeutics to treat chronic pain.

U2AF1 Mutations Cause Allele-Specific Alterations in 3′ Splice Site Recognition in Myeloid Malignancies

Mutations affecting the spliceosomal protein U2AF1 are among the most common mutations observed in patients with MDS and related disorders. However, it is unclear how these mutations affect the normal RNA splicing process, and how the resulting changes in splicing contribute to myeloid dysplasia. Here, we combined the strengths of data from primary AML patient samples with the controlled context of isogenic cell lines. We generated K562 erythroleukemic cell lines stably expressing each of the four common U2AF1 mutations (S34F, S34Y, Q157P, and Q157R). We compared expression of each of these mutant alleles with knock down of endogenous U2AF1 to compare the relative consequences of U2AF1 mutations versus loss of function.We first sought to identify changes in splicing driven by U2AF1 mutations that contribute to myeloid dysplasia. We compared the splicing of ~125,000 annotated alternative splicing events and ~160,000 constitutively spliced junctions between AML samples with or without mutations (TCGA cohort), as well as our isogenic K562 cell lines stably expressing either mutant (S34F, S34Y, Q157P, and Q157R) or wild-type (WT) alleles of U2AF1. Unsupervised cluster analysis revealed that S34F/Y versus Q157P/R samples clustered together in both the AML data and our cell lines, suggesting that U2AF1 mutations affecting different residues of the protein have different molecular consequences. Intersecting the AML and K562 data, we identified >300 splicing events that were consistently differentially spliced in association with S34 mutations, and a similar number for Q157 mutations. Many of these splicing events affected biological pathways that have been implicated in myeloid malignancies, including DNA methylation (DNMT3B), X chromosome inactivation (H2AFY), the DNA damage response (ATR, FANCA), and apoptosis (CASP8). For example, two exons of DNMT3B are differentially spliced in both AML samples and our K562 cells (Figure A), including an exon lying within the methyltransferase domain.We next identified mechanistic changes in the splicing process caused by U2AF1 mutations. U2AF1 binds the intron-exon boundary by sequence-specifically recognizing the AG dinucleotide and flanking sequence positions that define the 3′ splice site. Comparing AML samples and K562 cells with and without U2AF1 mutations, we found that S34 and Q157 mutations give rise to specific and distinct alterations in 3′ splice site preference. S34 mutations alter the consensus nucleotide immediately before the AG dinucleotide, while Q157 mutations alter the consensus nucleotide immediately after the AG (Figure B). We observed highly similar allele-specific alterations in 3′ splice site preference in every AML patient with a U2AF1 mutation, as well as all K562 cell lines expressing a U2AF1 mutant allele. In contrast, knock down of endogenous U2AF1 caused no alterations in the consensus sequence at those positions, indicating that U2AF1 mutations do not cause loss of function at the level of RNA splicing.To confirm that the nucleotides immediately before and after the AG determine whether a splice site responds to U2AF1 mutations, we created minigenes of cassette exons within the ATR and EPB49 genes. We found that response to U2AF1 S34 and Q157 mutations requires the endogenous nucleotides immediately before and after the AG, as predicted by our genomics analysis, and that mutating these positions abolishes response to U2AF1 mutations. Finally, we recapitulated the RNA splicing process in vitro using nuclear extract from blood cells expressing either wild-type or mutant U2AF1 to show that identical changes in splice site preference occur in a controlled in vitro context (Figure C).Together, our data show that U2AF1 mutations cause allele-specific alterations in normal 3′ splice site recognition in patients, in isogenic cell lines, and in vitro. These alterations in splice site preference give rise to mis-splicing that affects many genes previously implicated in myeloid malignancies. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Effects of partial inhibition of respiratory complex I on H2O 2 production by isolated brain mitochondria in different respiratory states.

The aim of this work was to characterize the effects of partial inhibition of respiratory complex I by rotenone on H2O2 production by isolated rat brain mitochondria in different respiratory states. Flow cytometric analysis of membrane potential in isolated mitochondria indicated that rotenone leads to uniform respiratory inhibition when added to a suspension of mitochondria. When mitochondria were incubated in the presence of a low concentration of rotenone (10nm) and NADH-linked substrates, oxygen consumption was reduced from 45.9±1.0 to 26.4±2.6nmol O2mg(-1)min(-1) and from 7.8±0.3 to 6.3±0.3nmol O2mg(-1)min(-1) in respiratory states 3 (ADP-stimulated respiration) and 4 (resting respiration), respectively. Under these conditions, mitochondrial H2O2 production was stimulated from 12.2±1.1 to 21.0±1.2pmol H2O2mg(-1)min(-1) and 56.5±4.7 to 95.0±11.1pmol H2O2mg(-1)min(-1) in respiratory states 3 and 4, respectively. Similar results were observed when comparing mitochondrial preparations enriched with synaptic or nonsynaptic mitochondria or when 1-methyl-4-phenylpyridinium ion (MPP(+)) was used as a respiratory complex I inhibitor. Rotenone-stimulated H2O2 production in respiratory states 3 and 4 was associated with a high reduction state of endogenous nicotinamide nucleotides. In succinate-supported mitochondrial respiration, where most of the mitochondrial H2O2 production relies on electron backflow from complex II to complex I, low rotenone concentrations inhibited H2O2 production. Rotenone had no effect on mitochondrial elimination of micromolar concentrations of H2O2. The present results support the conclusion that partial complex I inhibition may result in mitochondrial energy crisis and oxidative stress, the former being predominant under oxidative phosphorylation and the latter under resting respiration conditions.

Predicting Effective Truvada® PrEP Dosing Strategies With a Novel PK-PD Model Incorporating Tissue Active Metabolites and Endogenous Nucleotides (EN)

AIDS Research and Human RetrovirusesVol. 30, No. S1 Cell and Tissue Models of ARVs for PreventionPredicting Effective Truvada® PrEP Dosing Strategies With a Novel PK-PD Model Incorporating Tissue Active Metabolites and Endogenous Nucleotides (EN)Mackenzie L. Cottrell, Kuo H. Yang, Heather M.A. Prince, Craig Sykes, Nicole White, Stephanie Malone, Evan S. Dellon, Ryan D. Madanick, Nicholas J. Shaheen, Julie A. Nelson, Ronald Swanstrom, Kristine B. Patterson, and Angela D.M. KashubaMackenzie L. CottrellUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Kuo H. YangUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Heather M.A. PrinceUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Craig SykesUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Nicole WhiteUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Stephanie MaloneUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this author, Evan S. DellonUniversity of North Carolina School of Medicine, Chapel Hill, NC, United StatesSearch for more papers by this author, Ryan D. MadanickUniversity of North Carolina School of Medicine, Chapel Hill, NC, United StatesSearch for more papers by this author, Nicholas J. ShaheenUniversity of North Carolina School of Medicine, Chapel Hill, NC, United StatesSearch for more papers by this author, Julie A. NelsonUniversity of North Carolina Center for AIDS Research, Chapel Hill, NC, United StatesSearch for more papers by this author, Ronald SwanstromUniversity of North Carolina Center for AIDS Research, Chapel Hill, NC, United StatesSearch for more papers by this author, Kristine B. PattersonUniversity of North Carolina School of Medicine, Chapel Hill, NC, United StatesSearch for more papers by this author, and Angela D.M. KashubaUniversity of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, United StatesSearch for more papers by this authorPublished Online:30 Oct 2014https://doi.org/10.1089/aid.2014.5107a.abstractAboutSectionsView articleView Full TextPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View article"Predicting Effective Truvada® PrEP Dosing Strategies With a Novel PK-PD Model Incorporating Tissue Active Metabolites and Endogenous Nucleotides (EN)." AIDS Research and Human Retroviruses, 30(S1), p. A60FiguresReferencesRelatedDetailsCited ByNondaily preexposure prophylaxis for HIV preventionCurrent Opinion in HIV and AIDS, Vol. 11, No. 1What people want from sex and preexposure prophylaxisCurrent Opinion in HIV and AIDS, Vol. 11, No. 1Animal and human mucosal tissue models to study HIV biomedical interventions: can we predict success?2 November 2015 | Journal of the International AIDS Society, Vol. 18, No. 1 Volume 30Issue S1Oct 2014 InformationCopyright 2014, Mary Ann Liebert, Inc.To cite this article:Mackenzie L. Cottrell, Kuo H. Yang, Heather M.A. Prince, Craig Sykes, Nicole White, Stephanie Malone, Evan S. Dellon, Ryan D. Madanick, Nicholas J. Shaheen, Julie A. Nelson, Ronald Swanstrom, Kristine B. Patterson, and Angela D.M. Kashuba.Predicting Effective Truvada® PrEP Dosing Strategies With a Novel PK-PD Model Incorporating Tissue Active Metabolites and Endogenous Nucleotides (EN).AIDS Research and Human Retroviruses.Oct 2014.A60-A60.http://doi.org/10.1089/aid.2014.5107a.abstractPublished in Volume: 30 Issue S1: October 30, 2014PDF download