The Integration of Proteogenomics and Ribosome Profiling Circumvents Key Limitations to Increase the Coverage and Confidence of Novel Microproteins.

There has been a dramatic increase in the identification of non-conical translation and a significant expansion of the protein-coding genome and proteome. Among the strategies used to identify novel small ORFs (smORFs), Ribosome profiling (Ribo-Seq) is the gold standard for the annotation of novel coding sequences by reporting on smORF translation. In Ribo-Seq, ribosome-protected footprints (RPFs) that map to multiple sites in the genome are computationally removed since they cannot unambiguously be assigned to a specific genomic location, or to a specific transcript in the case of multiple isoforms. Furthermore, RPFs necessarily result in short (25-34 nucleotides) reads, increasing the chance of ambiguous and multi-mapping alignments, such that smORFs that reside in these regions cannot be identified by Ribo-Seq. Here, we show that the inclusion of proteogenomics to create a Ribosome Profiling and Proteogenomics Pipeline (RP3) bypasses this limitation to identify a group of microprotein-encoding smORFs that are missed by current Ribo-Seq pipelines. Moreover, we show that the microproteins identified by RP3 have different sequence compositions from the ones identified by Ribo-Seq-only pipelines, which can affect proteomics identification. In aggregate, the development of RP3 maximizes the detection and confidence of protein-encoding smORFs and microproteins.

Bacterial Enoyl-Reductases: The Ever-Growing List of Fabs, Their Mechanisms and Inhibition.

Enoyl-ACP reductases (ENRs) are enzymes that catalyze the last step of the elongation cycle during fatty acid synthesis. In recent years, new bacterial ENR types were discovered, some of them with structures and mechanisms that differ from the canonical bacterial FabI enzymes. Here, we briefly review the diversity of structural and catalytic properties of the canonical FabI and the new FabK, FabV, FabL, and novel ENRs identified in a soil metagenome study. We also highlight recent efforts to use the newly discovered Fabs as targets for drug development and consider the complex evolutionary history of this diverse set of bacterial ENRs.

Evaluation of 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthase (DAHPS) as a Vulnerable Target in Mycobacterium tuberculosis.

Tuberculosis (TB) remains one of the leading causes of death due to a single pathogen. The emergence and proliferation of multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) represent compelling reasons to invest in the pursuit of new anti-TB agents. The shikimate pathway, responsible for chorismate biosynthesis, which is a precursor of important aromatic compounds, is required for Mycobacterium tuberculosis growth. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (MtbDAHPS) catalyzes the first step in the shikimate pathway and it is an attractive target for anti-tubercular agents. Here, we used a CRISPRi system to evaluate the DAHPS as a vulnerable target in M. tuberculosis. The silencing of aroG significantly reduces the M. tuberculosis growth in both rich medium and, especially, in infected murine macrophages. The supplementation with amino acids was only able to partially rescue the growth of bacilli, whereas the Aro supplement (aromix) was enough to sustain the bacterial growth at lower rates. This study shows that MtbDAHPS protein is vulnerable and, therefore, an attractive target to develop new anti-TB agents. In addition, the study contributes to a better understanding of the biosynthesis of aromatic compounds and the bacillus physiology. IMPORTANCE Determining the vulnerability of a potential target allows us to assess whether its partial inhibition will impact bacterial growth. Here, we evaluated the vulnerability of the enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) from M. tuberculosis by silencing the DAHPS-coding aroG gene in different contexts. These results could lead to the development of novel and potent anti-tubercular agents in the near future.

Short-chain fatty acid acetate triggers antiviral response mediated by RIG-I in cells from infants with respiratory syncytial virus bronchiolitis.

BACKGROUND: Gut microbiota-derived short-chain fatty-acid (SFCA) acetate protects mice against RSV A2 strain infection by increasing interferon-ß production and expression of interferon-stimulated genes (ISGs). However, the role of SFCA in RSV infection using strains isolated from patients is unknown. METHODS: We first used RSV clinical strains isolated from infants hospitalized with RSV bronchiolitis to investigate the effects of in vitro SCFA-acetate treatment of human pulmonary epithelial cells. We next examined whether SCFA-acetate treatment is beneficial in a mouse model of RSV infection using clinical isolates. We sought to investigate the relationship of gut microbiota and fecal acetate with disease severity among infants hospitalized with RSV bronchiolitis, and whether treating their respiratory epithelial cells with SCFA-acetate ex-vivo impacts viral load and ISG expression. We further treated epithelial cells from SARS-CoV-2 infected patients with SCFA-acetate. FINDINGS: In vitro pre-treatment of A549 cells with SCFA-acetate reduced RSV infection with clinical isolates and increased the expression of RIG-I and ISG15. Animals treated with SCFA-acetate intranasally recovered significantly faster, with reduction in the RSV clinical isolates viral load, and increased lung expression of IFNB1 and the RIG-I. Experiments in RIG-I knockout A549 cells demonstrated that the protection relies on RIG-I presence. Gut microbial profile was associated with bronchiolitis severity and with acetate in stool. Increased SCFA-acetate levels were associated with increasing oxygen saturation at admission, and shorter duration of fever. Ex-vivo treatment of patients' respiratory cells with SCFA-acetate reduced RSV load and increased expression of ISGs OAS1 and ISG15, and virus recognition receptors MAVS and RIG-I, but not IFNB1. These SCFA-acetate effects were not found on cells from SARS-CoV-2 infected patients. INTERPRETATION: SCFA-acetate reduces the severity of RSV infection and RSV viral load through modulation of RIG-I expression. FUNDING: FAPERGS (FAPERGS/MS/CNPq/SESRS no. 03/2017 - PPSUS 17/2551-0001380-8 and COVID-19 20/2551-0000258-6); CNPq 312504/2017-9; CAPES) - Finance Code 001.

Handling the Hurdles on the Way to Anti-tuberculosis Drug Development.

The global epidemic of tuberculosis (TB) imposes a sustained epidemiologic vigilance and investments in research by governments. Mycobacterium tuberculosis, the main causative agent of TB in human beings, is a very successful pathogen, being the main cause of death in the population among infectious agents. In 2018, ~10 million individuals were contaminated with this bacillus and became ill with TB, and about 1.2 million succumbed to the disease. Most of the success of the M. tuberculosis to linger in the population comes from its ability to persist in an asymptomatic latent state into the host and, in fact, the majority of the individuals are unaware of being contaminated. Even though TB is a treatable disease and is curable in most cases, the treatment is lengthy and laborious. In addition, the rise of resistance to first-line anti-TB drugs elicits a response from TB research groups to discover new chemical entities, preferably with novel mechanisms of action. The pathway to find a new TB drug, however, is arduous and has many barriers that are difficult to overcome. Fortunately, several approaches are available today to be pursued by scientists interested in anti-TB drug development, which goes from massively testing chemical compounds against mycobacteria, to discovering new molecular targets by genetic manipulation. This review presents some difficulties found along the TB drug development process and illustrates different approaches that might be used to try to identify new molecules or targets that are able to impair M. tuberculosis survival.

Mycobacterium tuberculosis Shikimate Pathway Enzymes as Targets for the Rational Design of Anti-Tuberculosis Drugs.

Roughly a third of the world's population is estimated to have latent Mycobacterium tuberculosis infection, being at risk of developing active tuberculosis (TB) during their lifetime. Given the inefficacy of prophylactic measures and the increase of drug-resistant M. tuberculosis strains, there is a clear and urgent need for the development of new and more efficient chemotherapeutic agents, with selective toxicity, to be implemented on patient treatment. The component enzymes of the shikimate pathway, which is essential in mycobacteria and absent in humans, stand as attractive and potential targets for the development of new drugs to treat TB. This review gives an update on published work on the enzymes of the shikimate pathway and some insight on what can be potentially explored towards selective drug development.

Nonclinical evaluation of IQG-607, an anti-tuberculosis candidate with potential use in combination drug therapy.

New effective compounds to treat tuberculosis are urgently needed. IQG-607 is an orally active anti-tuberculosis drug candidate, with promising preliminary safety profile and anti-mycobacterial activity in both in vitro and in vivo models of tuberculosis infection. Here, we evaluated the mutagenic and genotoxic effects of IQG-607, and its interactions with CYP450 isoforms. Moreover, we describe for the first time a combination study of IQG-607 in Mycobacterium tuberculosis-infected mice. Importantly, IQG-607 had additive effects when combined with the first-line anti-tuberculosis drugs rifampin and pyrazinamide in mice. IQG-607 presented weak to moderate inhibitory potential against CYP450 isoforms 3A4, 1A2, 2C9, 2C19, 2D6, and 2E1. The Salmonella mutagenicity test revealed that IQG-607 induced base pair substitution mutations in the strains TA100 and TA1535. However, in the presence of human metabolic S9 fraction, no mutagenic effect was detected in any strain. Additionally, IQG-607 did not increase micronucleus frequencies in mice, at any dose tested, 25, 100, or 250 mg/kg. The favorable activity in combination with first-line drugs and mild to moderate toxic events described in this study suggest that IQG-607 represents a candidate for clinical development.

Pre-clinical evaluation of quinoxaline-derived chalcones in tuberculosis.

New effective compounds for tuberculosis treatment are needed. This study evaluated the effects of a series of quinoxaline-derived chalcones against laboratorial strains and clinical isolates of M. tuberculosis. Six molecules, namely N5, N9, N10, N15, N16, and N23 inhibited the growth of the M. tuberculosis H37Rv laboratorial strain. The three compounds (N9, N15 and N23) with the lowest MIC values were further tested against clinical isolates and laboratory strains with mutations in katG or inhA genes. From these data, N9 was selected as the lead compound for further investigation. Importantly, this chalcone displayed a synergistic effect when combined with moxifloxacin. Noteworthy, the anti-tubercular effects of N9 did not rely on inhibition of mycolic acids synthesis, circumventing important mechanisms of resistance. Interactions with cytochrome P450 isoforms and toxic effects were assessed in silico and in vitro. The chalcone N9 was not predicted to elicit any mutagenic, genotoxic, irritant, or reproductive effects, according to in silico analysis. Additionally, N9 did not cause mutagenicity or genotoxicity, as revealed by Salmonella/microsome and alkaline comet assays, respectively. Moreover, N9 did not inhibit the cytochrome P450 isoforms CYP3A4/5, CYP2C9, and CYP2C19. N9 can be considered a potential lead molecule for development of a new anti-tubercular therapeutic agent.

Is IQG-607 a Potential Metallodrug or Metallopro-Drug With a Defined Molecular Target in Mycobacterium tuberculosis?

The emergence of strains of Mycobacterium tuberculosis resistant to isoniazid (INH) has underscored the need for the development of new anti-tuberculosis agents. INH is activated by the mycobacterial katG-encoded catalase-peroxidase, forming an acylpyridine fragment that is covalently attached to the C4 of NADH. This isonicotinyl-NAD adduct inhibits the activity of 2-trans-enoyl-ACP(CoA) reductase (InhA), which plays a role in mycolic acid biosynthesis. A metal-based INH analog, Na3[FeII(CN)5(INH)]·4H2O, IQG-607, was designed to have an electronic redistribution on INH moiety that would lead to an intramolecular electron transfer to bypass KatG activation. HPLC and EPR studies showed that the INH moiety can be oxidized by superoxide or peroxide yielding similar metabolites and isonicotinoyl radical only when associated to IQG-607, thereby supporting redox-mediated drug activation as a possible mechanism of action. However, IQG-607 was shown to inhibit the in vitro activity of both wild-type and INH-resistant mutant InhA enzymes in the absence of KatG activation. IQG-607 given by the oral route to M. tuberculosis-infected mice reduced lung lesions. Experiments using early and late controls of infection revealed a bactericidal activity for IQG-607. HPLC and voltammetric methods were developed to quantify IQG-607. Pharmacokinetic studies showed short half-life, high clearance, moderate volume of distribution, and low oral bioavailability, which was not altered by feeding. Safety and toxic effects of IQG-607 after acute and 90-day repeated oral administrations in both rats and minipigs showed occurrence of mild to moderate toxic events. Eight multidrug-resistant strains (MDR-TB) were resistant to IQG-607, suggesting an association between katG mutation and increasing MIC values. Whole genome sequencing of three spontaneous IQG-607-resistant strains harbored katG gene mutations. MIC measurements and macrophage infection experiments with a laboratorial strain showed that katG mutation is sufficient to confer resistance to IQG-607 and that the macrophage intracellular environment cannot trigger the self-activation mechanism. Reduced activity of IQG-607 against an M. tuberculosis strain overexpressing S94A InhA mutant protein suggested both the need for KatG activation and InhA as its target. Further efforts are suggested to be pursued toward attempting to translate IQG-607 into a chemotherapeutic agent to treat tuberculosis.

Effect of the bradykinin 1 receptor antagonist SSR240612 after oral administration in Mycobacterium tuberculosis-infected mice.

The role, if any, played by the kinin system in tuberculosis infection models, either in vivo or in vitro, was investigated. The effects of Mycobacterium tuberculosis infection on C57BL/6 wild type, B1R-/-, B2R-/- and double B1R/B2R knockout mice were evaluated. Immunohistochemistry analysis was carried out to assess B1R and B2R expression in spleens and lungs of M. tuberculosis-infected mice. In addition, in vitro experiments with M. tuberculosis-infected macrophages were performed. The in vivo effects of HOE-140 and SSR240612 on the mice model of infection were also evaluated. Infected B2R-/- mice exhibited increased splenomegaly, whereas decreased spleen weight in infected double B1R/B2R knockout mice was observed. The bacterial load, determined as colony-forming units, did not differ in the spleens and lungs of the studied mouse strains. Importantly, immunohistochemical analysis revealed that B1R was upregulated in both spleens and lungs of infected mice. M. tuberculosis-infected macrophages incubated with SSR240612, alone or in combination with des-Arg9-BK, for four days, displayed a marked inhibitory effect on CFU counts. However, the pre-incubation of the selective B1R (des-Arg9-BK and SSR240612) and B2R (BK and HOE-140) agonists and antagonists, respectively, did not significantly affect the bacterial loads. A statistically significant reduction in the CFU of M. tuberculosis in lungs and spleens of animals treated with SSR240612, but not with HOE-140, was observed. Further efforts should be pursued to clarify whether or not SSR240612 might be considered an option for the treatment of tuberculosis.

Revisiting Activation of and Mechanism of Resistance to Compound IQG-607 in Mycobacterium tuberculosis.

IQG-607 is a metal complex previously reported as a promising anti-tuberculosis (TB) drug against isoniazid (INH)-resistant strains of Mycobacterium tuberculosis Unexpectedly, we found that INH-resistant clinical isolates were resistant to IQG-607. Spontaneous mutants resistant to IQG-607 were subjected to whole-genome sequencing, and all sequenced colonies carried alterations in the katG gene. The katG(S315T) mutation was sufficient to confer resistance to IQG-607 in both MIC assays and inside macrophages. Moreover, overexpression of the InhA(S94A) protein caused IQG-607's resistance.

Preclinical pharmacokinetic profiling of IQG-607, a potential oral metallodrug to treat tuberculosis.

IQG-607 is an analog of isoniazid with anti-tuberculosis activity. This work describes the development and validation of an HPLC method to quantify pentacyano(isoniazid)ferrate(II) compound (IQG-607) and the pharmacokinetic studies of this compound in mice. The method showed linearity in the 0.5-50µg/mL concentration range (r=0.9992). Intra- and inter-day precision was <5%, and the recovery ranged from 92.07 to 107.68%. IQG-607 was stable in plasma for at least 30days at -80°C and, after plasma processing, for 4h in the auto-sampler maintained on ice (recovery >85%). The applicability of the method for pharmacokinetic studies was determined after intravenous (i.v.) and oral (fasted and fed conditions) administration to mice. IQG-607 levels in plasma were quantified at time points for up to 2.5h. A short half-life (t1/2) (1.14h), a high clearance (CL) (3.89L/h/kg), a moderate volume of distribution at steady state (Vdss) of 1.22L/kg, were observed after i.v. (50mg/kg) administration. Similar results were obtained for oral administration (250mg/kg) under fasted and fed conditions. The oral bioavailability (F), approximately 4%, was not altered by feeding. Plasma protein binding was 88.87±0.9%. The results described here provide novel insights into a pivotal criterion to warrant further efforts to be pursued towards attempts to translate this chemical compound into a chemotherapeutic agent to treat TB.

Inhibitory activity of pentacyano(isoniazid)ferrate(II), IQG-607, against promastigotes and amastigotes forms of Leishmania braziliensis.

M. tuberculosis and parasites of the genus Leishmania present the type II fatty acid biosynthesis system (FASII). The pentacyano(isoniazid)ferrate(II) compound, named IQG-607, inhibits the enzyme 2-trans-enoyl-ACP(CoA) reductase from M. tuberculosis, a key component in the FASII system. Here, we aimed to evaluate the inhibitory activity of IQG-607 against promastigote and amastigote forms of Leishmania (Viannia) braziliensis isolated from patients with different clinical forms of L. braziliensis infection, including cutaneous, mucosal and disseminated leishmaniasis. Importantly, IQG-607 inhibited the proliferation of three different isolates of L. braziliensis promastigotes associated with cutaneous, mucosal and disseminated leishmaniasis. The IC50 values for IQG-607 ranged from 32 to 75 µM, for these forms. Additionally, IQG-607 treatment decreased the proliferation of intracellular amastigotes in infected macrophages, after an analysis of the percentage of infected cells and the number of intracellular parasites/100 cells. IQG-607 reduced from 58% to 98% the proliferation of L. braziliensis from cutaneous, mucosal and disseminated strains. Moreover, IQG-607 was also evaluated regarding its potential toxic profile, by using different cell lines. Cell viability of the lineages Vero, HaCat and HepG2 was significantly reduced after incubation with concentrations of IQG-607 higher than 2 mM. Importantly, IQG-607, in a concentration of 1 mM, did not induce DNA damage in HepG2 cells, when compared to the untreated control group. Future studies will confirm the mechanism of action of IQG-607 against L. braziliensis.

Observed crowding effects on Mycobacterium tuberculosis 2-trans-enoyl-ACP (CoA) reductase enzyme activity are not due to excluded volume only.

The cellular milieu is a complex and crowded aqueous solution. Macromolecular crowding effects are commonly studied in vitro using crowding agents. The aim of the present study was to evaluate the effects, if any, of macromolecular synthetic crowding agents on the apparent steady-state kinetic parameters (K m , k cat , and k cat /K m ) of Mycobacterium tuberculosis 2-trans-enoyl-ACP (CoA) reductase (InhA). Negligible effects on InhA activity were observed for ficoll 70, ficoll 400 and dextran 70. A complex effect was observed for PEG 6000. Glucose and sucrose showed, respectively, no effect on InhA activity and decreased k cat /K m for NADH and k cat for 2-trans-dodecenoyl-CoA. Molecular dynamics results suggest that InhA adopts a more compact conformer in sucrose solution. The effects of the crowding agents on the energy (E a and E η ), enthalpy (∆H # ), entropy (∆S # ), and Gibbs free energy (∆G # ) of activation were determined. The ∆G # values for all crowding agents were similar to buffer, suggesting that excluded volume effects did not facilitate stable activated ES # complex formation. Nonlinear Arrhenius plot for PEG 6000 suggests that "soft" interactions play a role in crowding effects. The results on InhA do not unequivocally meet the criteria for crowding effect due to exclude volume only.

EPSP synthase flexibility is determinant to its function: computational molecular dynamics and metadynamics studies.

Flexibility is involved in a wide range of biological processes, such as protein assembly and binding recognition. EPSP synthase is an enzyme that must undergo a large conformational change to accommodate its ligands into its binding cavity. However, although the structure of EPSP synthase has been determined, its plasticity has not been explored in depth. Therefore, in this work, we extensively examined the influence of the flexibility of Mycobacterium tuberculosis EPSP (MtEPSP) synthase on the function of this protein using classical and replica-exchange metadynamics simulations. We were able to identify five well-populated conformational clusters for MtEPSP synthase: two corresponding to open, one to ajar, and two to closed conformations. We also pinpointed three hydrophobic regions that are responsible for guiding transitions among these states. Taken together, the new findings presented here indicate how the hydrophobic regions modulate the flexibility of MtEPSP synthase, and they highlight the importance of considering these dynamic features in drug design projects employing this enzyme as a target. Graphical abstract The flexibility of EPSP synthase as a function of the pincer angles.

Functional, thermodynamics, structural and biological studies of in silico-identified inhibitors of Mycobacterium tuberculosis enoyl-ACP(CoA) reductase enzyme.

Novel chemotherapeutics agents are needed to kill Mycobacterium tuberculosis, the main causative agent of tuberculosis (TB). The M. tuberculosis 2-trans-enoyl-ACP(CoA) reductase enzyme (MtInhA) is the druggable bona fide target of isoniazid. New chemotypes were previously identified by two in silico approaches as potential ligands to MtInhA. The inhibition mode was determined by steady-state kinetics for seven compounds that inhibited MtInhA activity. Dissociation constant values at different temperatures were determined by protein fluorescence spectroscopy. van't Hoff analyses of ligand binding to MtInhA:NADH provided the thermodynamic signatures of non-covalent interactions (ΔH°, ΔS°, ΔG°). Phenotypic screening showed that five compounds inhibited in vitro growth of M. tuberculosis H37Rv strain. Labio_16 and Labio_17 compounds also inhibited the in vitro growth of PE-003 multidrug-resistant strain. Cytotoxic effects on Hacat, Vero and RAW 264.7 cell lines were assessed for the latter two compounds. The Labio_16 was bacteriostatic and Labio_17 bactericidal in an M. tuberculosis-infected macrophage model. In Zebrafish model, Labio_16 showed no cardiotoxicity whereas Labio_17 showed dose-dependent cardiotoxicity. Accordingly, a model was built for the MtInhA:NADH:Labio_16 ternary complex. The results show that the Labio_16 compound is a direct inhibitor of MtInhA, and it may represent a hit for the development of chemotherapeutic agents to treat TB.

Preclinical safety evaluation of IQG-607 in rats: Acute and repeated dose toxicity studies.

In the present study, we evaluated the safety and the possible toxic effects of IQG-607 after acute and 90-day repeated administrations in rats. Single oral administration of IQG-607 (300 or 2000 mg/kg) on female rats did not result in any mortality. No gross lesions were observed in the animals at necropsy. Ninety-day administration test resulted in 20% of deaths, in both male and female rats administered with the highest dose of IQG-607, 300 mg/kg. Repeated administration of the IQG 607 (25, 100 and 300 mg/kg) did not result in any significant body mass alteration, or changes in food and water consumption. The most important clinical sign observed was salivation in both sexes. Importantly, long-term treatment with IQG-607 did not induce alterations in any hematological (for both sex) and serum biochemical (for female) parameters evaluated, even at the highest dose tested. Treatment of male rats with 100 or 300 mg/kg of IQG-607 decreased total cholesterol levels, while animals treated with 100 mg/kg also presented reduction on triglyceride levels. Of note, no treatment induced significant histopathological alterations in tissues of all organs and glands analyzed, even in that group that received the highest dose of IQG-607.

Protective effects of resveratrol on hepatotoxicity induced by isoniazid and rifampicin via SIRT1 modulation.

Acute liver injury was induced in male BALB/c mice by coadministering isoniazid and rifampicin. In this work, the effects of resveratrol (1) were investigated in the hepatotoxicity caused by isoniazid-rifampicin in mice. Compound 1 was administered 30 min prior to isoniazid-rifampicin. Serum biochemical tests, liver histopathological examination, oxidative stress, myeloperoxidase activity, cytokine production (TNF-α, IL-12p70, and IL-10), and mRNA expression of SIRT1-7 and PPAR-γ/PGC1-α were evaluated. The administration of 1 significantly decreased aspartate transaminase and alanine aminotransferase levels, myeloperoxidase activity, and cytokine levels. Furthermore, 1 reverted the decrease of catalase and glutathione activities and ameliorated the histopathological alterations associated with antituberculosis drugs. Modulation of SIRT1 and PPAR-γ/PGC1-α expression is likely involved in the protective effects of 1. The results presented herein show that 1 was able to largely prevent the hepatotoxicity induced by isoniazid and rifampicin in mice, mainly by modulating SIRT1 mRNA expression.

Human uridine phosphorylase-1 inhibitors: a new approach to ameliorate 5-fluorouracil-induced intestinal mucositis.

PURPOSE: 5-fluorouracil (5-FU) has been broadly used to treat solid tumors for more than 50 years. One of the major side effects of fluoropyrimidines therapy is oral and intestinal mucositis. Human uridine phosphorylase (hUP) inhibitors have been suggested as modulators of 5-FU toxicity. Therefore, the present study aimed to test the ability of hUP blockers in preventing mucositis induced by 5-FU. METHODS: We induced intestinal mucositis in Wistar rats with 5-FU, and the intestinal damage was evaluated in presence or absence of two hUP1 inhibitors previously characterized. We examined the loss of weight and diarrhea following the treatment, the villus integrity, uridine levels in plasma, and the neutrophil migration by MPO activity. RESULTS: We found that one of the compounds, 6-hydroxy-4-methyl-1H-pyridin-2-one-3-carbonitrile was efficient to promote intestinal mucosa protection and to inhibit the hUP1 enzyme, increasing the uridine levels in the plasma of animals. However, the loss of body weight, diarrhea intensity or neutrophil migration remained unaffected. CONCLUSION: Our results bring support to the hUP1 inhibitor strategy as a novel possibility of prevention and treatment of mucositis during the 5-FU chemotherapy, based on the approach of uridine accumulation in plasma and tissues.

Production of recombinant human annexin V by fed-batch cultivation.

BACKGROUND: Annexin V, a 35.8 kDa intracellular protein, is a Ca⁺²-dependent phospholipid binding protein with high affinity to phosphatidylserine (PS), which is a well-known hallmark of apoptosis. Annexin V is a sensitive probe for PS exposure upon the cell membrane, and used for detection of apoptotic cells both in vivo and in vitro. Large-scale production of recombinant human annexin V is worth optimization, because of its wide use in nuclear medicine, radiolabeled with (99m)Tc, for the evaluation of cancer chemotherapy treatments, and its use in identification of apoptotic cells in histologic studies. Here we describe the high-yield production of a tag-free version of human annexin V recombinant protein by linear fed-batch cultivation in a bioreactor. RESULTS: We cloned the human ANXA5 coding sequence into the pET-30a (+) expression vector and expressed rhANXA5 in batch and fed-batch cultures. Using E. coli BL21 (DE3) in a semi-defined medium at 37°C, pH 7 in fed-batch cultures, we obtained a 45-fold increase in biomass production, respective to shaker cultivations. We developed a single-step protocol for rhANXA5 purification using a strong anion-exchange column (MonoQ HR16/10). Using these procedures, we obtained 28.5 mg of homogeneous, nontagged and biologically functional human annexin V recombinant protein from 3 g wet weight of bacterial cells from bioreactor cultures. The identity and molecular mass of rhANXA5 was confirmed by mass spectrometry. Moreover, the purified rhANXA5 protein was functionally evaluated in a FITC-annexin V binding experiment and the results demonstrated that rhANXA5 detected apoptotic cells similarly to a commercial kit. CONCLUSIONS: We describe a new fed-batch method to produce recombinant human annexin V in large scale, which may expand the commercial utilities for rhANXAV to applications such as in vivo imaging studies.