Macromolecular Synthesis Research Articles

Macromolecular Design and Synthesis of Polymers from Silicon- Containing Norbornenes for Membrane Gas Separation

Macromolecular Design and Synthesis of Polymers from Silicon- Containing Norbornenes for Membrane Gas Separation

The EU approved antimalarial pyronaridine shows antitubercular activity and synergy with rifampicin, targeting RNA polymerase

The search for compounds with biological activity for many diseases is turning increasingly to drug repurposing. In this study, we have focused on the European Union-approved antimalarial pyronaridine which was found to have in vitro activity against Mycobacterium tuberculosis (MIC 5 μg/mL). In macromolecular synthesis assays, pyronaridine resulted in a severe decrease in incorporation of 14C-uracil and 14C-leucine similar to the effect of rifampicin, a known inhibitor of M. tuberculosis RNA polymerase. Surprisingly, the co-administration of pyronaridine (2.5 μg/ml) and rifampicin resulted in in vitro synergy with an MIC 0.0019–0.0009 μg/mL. This was mirrored in a THP-1 macrophage infection model, with a 16-fold MIC reduction for rifampicin when the two compounds were co-administered versus rifampicin alone. Docking pyronaridine in M. tuberculosis RNA polymerase suggested the potential for it to bind outside of the RNA polymerase rifampicin binding pocket. Pyronaridine was also found to have activity against a M. tuberculosis clinical isolate resistant to rifampicin, and when combined with rifampicin (10% MIC) was able to inhibit M. tuberculosis RNA polymerase in vitro. All these findings, and in particular the synergistic behavior with the antitubercular rifampicin, inhibition of RNA polymerase in combination in vitro and its current use as a treatment for malaria, may suggest that pyronaridine could also be used as an adjunct for treatment against M. tuberculosis infection. Future studies will test potential for in vivo synergy, clinical utility and attempt to develop pyronaridine analogs with improved potency against M. tuberculosis RNA polymerase when combined with rifampicin.

Role of the ERK1/2 Signaling Pathway in the Replication of Junín and Tacaribe Viruses.

We have previously shown that the infection of cell cultures with the arenaviruses Junín (JUNV), Tacaribe (TCRV), and Pichindé promotes the phosphorylation of mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinases 1 and 2 (ERK1/2) and that this activation is required for the achievement of a productive infection. Here we examined the contribution of ERK1/2 in early steps of JUNV and TCRV multiplication. JUNV adsorption, internalization, and uncoating were not affected by treatment of cultured cells with U0126, an inhibitor of the ERK1/2 signaling pathway. In contrast, U0126 caused a marked reduction in viral protein expression and RNA synthesis, while JUNV RNA synthesis was significantly augmented in the presence of an activator of the ERK1/2 pathway. Moreover, U0126 impaired the expression of a reporter gene in a TCRV-based replicon system, confirming the ability of the compound to hinder arenavirus macromolecular synthesis. By using a cell-based assay, we determined that the inhibitor did not affect the translation of a synthetic TCRV-like mRNA. No changes in the phosphorylation pattern of the translation factor eIF2α were found in U0126-treated cells. Our results indicate that U0126 impairs viral RNA synthesis, thereby leading to a subsequent reduction in viral protein expression. Thus, we conclude that ERK1/2 signaling activation is required for an efficient arenavirus RNA synthesis.

Elucidating the Metabolic Plasticity of Cancer: Mitochondrial Reprogramming and Hybrid Metabolic States.

Aerobic glycolysis, also referred to as the Warburg effect, has been regarded as the dominant metabolic phenotype in cancer cells for a long time. More recently, it has been shown that mitochondria in most tumors are not defective in their ability to carry out oxidative phosphorylation (OXPHOS). Instead, in highly aggressive cancer cells, mitochondrial energy pathways are reprogrammed to meet the challenges of high energy demand, better utilization of available fuels and macromolecular synthesis for rapid cell division and migration. Mitochondrial energy reprogramming is also involved in the regulation of oncogenic pathways via mitochondria-to-nucleus retrograde signaling and post-translational modification of oncoproteins. In addition, neoplastic mitochondria can engage in crosstalk with the tumor microenvironment. For example, signals from cancer-associated fibroblasts can drive tumor mitochondria to utilize OXPHOS, a process known as the reverse Warburg effect. Emerging evidence shows that cancer cells can acquire a hybrid glycolysis/OXPHOS phenotype in which both glycolysis and OXPHOS can be utilized for energy production and biomass synthesis. The hybrid glycolysis/OXPHOS phenotype facilitates metabolic plasticity of cancer cells and may be specifically associated with metastasis and therapy-resistance. Moreover, cancer cells can switch their metabolism phenotypes in response to external stimuli for better survival. Taking into account the metabolic heterogeneity and plasticity of cancer cells, therapies targeting cancer metabolic dependency in principle can be made more effective.

1-((2,4-Dichlorophenethyl)Amino)-3-Phenoxypropan-2-ol Kills Pseudomonas aeruginosa through Extensive Membrane Damage

The ever increasing multidrug-resistance of clinically important pathogens and the lack of novel antibiotics have resulted in a true antibiotic crisis where many antibiotics are no longer effective. Further complicating the treatment of bacterial infections are antibiotic-tolerant persister cells. Besides being responsible for the recalcitrant nature of chronic infections, persister cells greatly contribute to the observed antibiotic tolerance in biofilms and even facilitate the emergence of antibiotic resistance. Evidently, eradication of these persister cells could greatly improve patient outcomes and targeting persistence may provide an alternative approach in combatting chronic infections. We recently characterized 1-((2,4-dichlorophenethyl)amino)-3-phenoxypropan-2-ol (SPI009), a novel anti-persister molecule capable of directly killing persisters from both Gram-negative and Gram-positive pathogens. SPI009 potentiates antibiotic activity in several in vitro and in vivo infection models and possesses promising anti-biofilm activity. Strikingly, SPI009 restores antibiotic sensitivity even in resistant strains. In this study, we investigated the mode of action of this novel compound using several parallel approaches. Genetic analyses and a macromolecular synthesis assays suggest that SPI009 acts by causing extensive membrane damage. This hypothesis was confirmed by liposome leakage assay and membrane permeability studies, demonstrating that SPI009 rapidly impairs the bacterial outer and inner membranes. Evaluation of SPI009-resistant mutants, which only could be generated under severe selection pressure, suggested a possible role for the MexCD-OprJ efflux pump. Overall, our results demonstrate the extensive membrane-damaging activity of SPI009 and confirm its clinical potential in the development of novel anti-persister therapies.

The Expanding Diversity of Mycobacterium tuberculosis Drug Targets.

After decades of relative inactivity, a large increase in efforts to discover antitubercular therapeutics has brought insights into the biology of Mycobacterium tuberculosis (Mtb) and promising new drugs such as bedaquiline, which inhibits ATP synthase, and the nitroimidazoles delamanid and pretomanid, which inhibit both mycolic acid synthesis and energy production. Despite these advances, the drug discovery pipeline remains underpopulated. The field desperately needs compounds with novel mechanisms of action capable of inhibiting multi- and extensively drug -resistant Mtb (M/XDR-TB) and, potentially, nonreplicating Mtb with the hope of shortening the duration of required therapy. New knowledge about Mtb, along with new methods and technologies, has driven exploration into novel target areas, such as energy production and central metabolism, that diverge from the classical targets in macromolecular synthesis. Here, we review new small molecule drug candidates that act on these novel targets to highlight the methods and perspectives advancing the field. These new targets bring with them the aspiration of shortening treatment duration as well as a pipeline of effective regimens against XDR-TB, positioning Mtb drug discovery to become a model for anti-infective discovery.

Glutamine metabolism via glutaminase 1 in autosomal-dominant polycystic kidney disease.

Metabolism of glutamine by glutaminase 1 (GLS1) plays a key role in tumor cell proliferation via the generation of ATP and intermediates required for macromolecular synthesis. We hypothesized that glutamine metabolism also plays a role in proliferation of autosomal-dominant polycystic kidney disease (ADPKD) cells and that inhibiting GLS1 could slow cyst growth in animal models of ADPKD. Primary normal human kidney and ADPKD human cyst-lining epithelial cells were cultured in the presence or absence of two pharmacologic inhibitors of GLS1, bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide 3 (BPTES) and CB-839, and the effect on proliferation, cyst growth in collagen and activation of downstream signaling pathways were assessed. We then determined if inhibiting GLS1 in vivo with CB-839 in the Aqp2-Cre; Pkd1fl/fl and Pkhd1-Cre; Pkd1fl/fl mouse models of ADPKD slowed cyst growth. We found that an isoform of GLS1 (GLS1-GAC) is upregulated in cyst-lining epithelia in human ADPKD kidneys and in mouse models of ADPKD. Both BPTES and CB-839 blocked forskolin-induced cyst formation in vitro. Inhibiting GLS1 in vivo with CB-839 led to variable outcomes in two mouse models of ADPKD. CB-839 slowed cyst growth in Aqp2-Cre; Pkd1fl/fl mice, but not in Pkhd1-Cre; Pkd1fl/fl mice. While CB-839 inhibited mammalian target of rapamycin (mTOR) and MEK activation in Aqp2-Cre; Pkd1fl/fl, it did not in Pkhd1-Cre; Pkd1fl/fl mice. These findings provide support that alteration in glutamine metabolism may play a role in cyst growth. However, testing in other models of PKD and identification of the compensatory metabolic changes that bypass GLS1 inhibition will be critical to validate GLS1 as a drug target either alone or when combined with inhibitors of other metabolic pathways.

Overexpression of S-adenosylmethionine decarboxylase impacts polyamine homeostasis during development of Dictyostelium discoideum.

The polyamines putrescine, spermidine and spermine are essential polycations involved in the regulation of cellular proliferation. They exert dynamic effects on nucleic acids and macromolecular synthesis in vitro but their specific functions in vivo are poorly understood. Here, we have modulated the spermidine levels either by overexpressing the S-adenosylmethionine decarboxylase (samdc) gene or treating the cells with methylglyoxal-bis (guanylhydrazone) (MGBG), an inhibitor of SAMDC. In Dictyostelium, overexpression of SAMDC slowed cell proliferation, delayed development and arrested cells in the S-phase of the cell cycle. Treatment with MGBG reduced cell proliferation and stimulated development, but in samdcOE cells, it increased cell proliferation suggesting critical levels of spermidine to be important. In samdcOE cells, spermidine levels remained high throughout development but only small changes in the spermine levels were observed. Initial putrescine levels did increase but reverted to wild-type levels after the mound stage. As tight regulation of polyamine homeostasis is required, we identified genes that could be involved in its maintenance. In conclusion, we characterised samdcOE cells and observed the maintenance of polyamine homeostasis during the development of Dictyostelium cells.

Back Cover: Comprehensive Profiling of Lysine Acetylome in Baculovirus Infected Silkworm (Bombyx mori) Cells

DOI: 10.1002/pmic.201700133 Bombyx mori nucleopolyhedrovirus and Bombyx mori are important natural biological models for studying host-pathogen interactions. In article number 1700133, Dongbing Hu et al. applied an integrated proteomics approach including TMT labeling, HPLC fractionation, and LC-MS/MS to quantify acetylome of BmN cells infected with BmNPV. BmNPV infection may globally impact host acetylome involving in energy metabolism, macromolecular synthesis and metabolism, gene expression and transport of substances.

Novel duplex real-time Taqman PCR assay for rapid detection of Enterobacter sakazakii in powdered infant formula

To develop a dulplex real-time Taqman polymerase chain reaction(PCR)assay for the detection of Enterobacter sakazakii. Primers and probes were designed based on the sequences of the macromolecular synthesis(MMS)operon and outer member protein A(ompA). Sensitivity and specificity of the assay were evaluated. Detection limit of the assay in pure culture was 4.3×103 CFU/mL and as few as 2 CFU/100 g of Enterobacter sakazakii could be detected in artificially contaminated infant formula through 24 h of enrichment. All of 15 Enterobacter sakazakii strains were successfully identified,no specific amplification were presented when 24 non-Enterobacter sakazakii were tested. The duplex real time Taqman PCR assay developed in study was sensitivity,specific and rapid. It could be used for detection of Enterobacter sakazakii from infant milk powder for food safety.

Vacuole-mediated selective regulation of TORC1-Sch9 signaling following oxidative stress.

Target of rapamycin complex 1 (TORC1) is a central cellular signaling coordinator that allows eukaryotic cells to adapt to the environment. In the budding yeast, Saccharomyces cerevisiae, TORC1 senses nitrogen and various stressors and modulates proteosynthesis, nitrogen uptake and metabolism, stress responses, and autophagy. There is some indication that TORC1 may regulate these downstream pathways individually. However, the potential mechanisms for such differential regulation are unknown. Here we show that the serine/threonine protein kinase Sch9 branch of TORC1 signaling depends specifically on the integrity of the vacuolar membrane, and this dependency originates in changes in Sch9 localization reflected by phosphatidylinositol 3,5-bisphosphate. Moreover, oxidative stress induces the delocalization of Sch9 from vacuoles, contributing to the persistent inhibition of the Sch9 branch after stress. Thus, our results establish that regulation of the vacuolar localization of Sch9 serves as a selective switch for the Sch9 branch in divergent TORC1 signaling. We propose that the Sch9 branch integrates the intrinsic activity of TORC1 kinase and vacuolar status, which is monitored by the phospholipids of the vacuolar membrane, into the regulation of macromolecular synthesis.

High Hydrostatic Treatment of Foods

Heat Treatment (cooking, boiling, roasting, pasteurisation, sterilisation etc.) has always been for centuries the principal method used in Food Preservation. Lately, recent trends in processing are aimed at more healthy, nutritious and convenient food. New food preservation techniques, new concepts (Hurdle Technology) have been developed and are currently being used in the Food Industry. One of the most promising and already applied,tested in the international market, novel techniques is the High Hydrostatic Pressure treatment. Principal usage of High Hydrostatic Pressure treatment (200-600 MPa) is the pasteurization of foods, where the use of heat treatment is not applicable or in cases where maximum retention of the nutritional value of food is needed. In contrast to thermal processing, High Hydrostatic Pressure treatment can inactivate microorganisms and unfavourable enzymes at ambient or low temperatures, without affecting flavour, colour or nutritional constituents within a food system. High Hydrostatic Pressure could also inactivate food parasites, prions viruses and prionsviruses. It is an excellent pasteurisation and in the future it will turn to be even a sterilisation method. High Hydrostatic Pressure treatment affects almost all cellular processes and parts ofthe cell, with more prominent targets the macromolecular synthesis, the proteins and the cellular membrane. The main problem of this method is the occurrence of piezotolerant strains of microorganisms with great deviations regarding their piezotolerance, that could cause problems in the design of the treatment. This phenomenon is mosdy related with the production of stress proteins. The problem could be solved by the use of combined processes of High Hydrostatic Pressure with other methods or with higher pressures achieved by the technological development of the method. Despite the above-mentioned problems, High Hydrostatic Pressure is a method that advances fast and is taking its place in the modern Food Industry, considering that only a decade passed since the first High Hydrostatic Pressure treated products were presented in the market. The Greek Food Industry and Research Sector should take advantage of the developments in HHP, as this method could improve substantially the quality and competitiveness of the Greek agricultural products.

Ragulator and GATOR1 complexes promote fission yeast growth by attenuating TOR complex 1 through Rag GTPases

TOR complex 1 (TORC1) is an evolutionarily conserved protein kinase complex that promotes cellular macromolecular synthesis and suppresses autophagy. Amino-acid-induced activation of mammalian TORC1 is initiated by its recruitment to the RagA/B-RagC/D GTPase heterodimer, which is anchored to lysosomal membranes through the Ragulator complex. We have identified in the model organism Schizosaccharomyces pombe a Ragulator-like complex that tethers the Gtr1-Gtr2 Rag heterodimer to the membranes of vacuoles, the lysosome equivalent in yeasts. Unexpectedly, the Ragulator-Rag complex is not required for the vacuolar targeting of TORC1, but the complex plays a crucial role in attenuating TORC1 activity independently of the Tsc1-Tsc2 complex, a known negative regulator of TORC1 signaling. The GATOR1 complex, which functions as Gtr1 GAP, is essential for the TORC1 attenuation by the Ragulator-Rag complex, suggesting that Gtr1GDP-Gtr2 on vacuolar membranes moderates TORC1 signaling for optimal cellular response to nutrients.

4-Hydroxy-2-pyridones: Discovery and evaluation of a novel class of antibacterial agents targeting DNA synthesis

The continued emergence of bacteria resistant to current standard of care antibiotics presents a rapidly growing threat to public health. New chemical entities (NCEs) to treat these serious infections are desperately needed. Herein we report the discovery, synthesis, SAR and in vivo efficacy of a novel series of 4-hydroxy-2-pyridones exhibiting activity against Gram-negative pathogens. Compound 1c, derived from the N-debenzylation of 1b, preferentially inhibits bacterial DNA synthesis as determined by standard macromolecular synthesis assays. The structural features of the 4-hydroxy-2-pyridone scaffold required for antibacterial activity were explored and compound 6q, identified through further optimization of the series, had an MIC90 value of 8 μg/mL against a panel of highly resistant strains of E. coli. In a murine septicemia model, compound 6q exhibited a PD50 of 8 mg/kg in mice infected with a lethal dose of E. coli. This novel series of 4-hydroxy-2-pyridones serves as an excellent starting point for the identification of NCEs treating Gram-negative infections.

Precise Synthesis of Macromolecular Architectures by Novel Iterative Methodology Combining Living Anionic Polymerization with Specially Designed Linking Chemistry.

This article reviews the development of a novel all-around iterative methodology combining living anionic polymerization with specially designed linking chemistry for macromolecular architecture syntheses. The methodology is designed in such a way that the same reaction site is always regenerated after the polymer chain is introduced in each reaction sequence, and this “polymer chain introduction and regeneration of the same reaction site” sequence is repeatable. Accordingly, the polymer chain can be successively and, in principle, limitlessly introduced to construct macromolecular architectures. With this iterative methodology, a variety of synthetically difficult macromolecular architectures, i.e., multicomponent μ-star polymers, high generation dendrimer-like hyperbranched polymers, exactly defined graft polymers, and multiblock polymers having more than three blocks, were successfully synthesized.

Antibacterial and immunomodulatory activities of insect defensins-DLP2 and DLP4 against multidrug-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA), are the most frequent cause of sepsis, which urgently demanding new drugs for treating infection. Two homologous insect CSαβ peptides-DLP2 and DLP4 from Hermetia illucens were firstly expressed in Pichia pastoris, with the yields of 873.5 and 801.3 mg/l, respectively. DLP2 and DLP4 displayed potent antimicrobial activity against Gram-positive bacteria especially MRSA and had greater potency, faster killing, and a longer postantibiotic effect than vancomycin. A 30-d serial passage of MRSA in the presence of DLP2/DLP4 failed to produce resistant mutants. Macromolecular synthesis showed that DLP2/DLP4 inhibited multi-macromolecular synthesis especially for RNA. Flow cytometry and electron microscopy results showed that the cell cycle was arrested at R-phase; the cytoplasmic membrane and cell wall were broken by DLP2/DLP4; mesosome-like structures were observed in MRSA. At the doses of 3‒7.5 mg/kg DLP2 or DLP4, the survival of mice challenged with MRSA were 80‒100%. DLP2 and DLP4 reduced the bacterial translocation burden over 95% in spleen and kidneys; reduced serum pro-inflammatory cytokines levels; promoted anti-inflammatory cytokines levels; and ameliorated lung and spleen injury. These data suggest that DLP2 and DLP4 may be excellent candidates for novel antimicrobial peptides against staphylococcal infections.

A quinolinol-based small molecule with anti-MRSA activity that targets bacterial membrane and promotes fermentative metabolism.

In a loss-of-viability screen of small molecules against methicillin resistant S. aureus (MRSA) USA300, we found a small molecule, designated DNAC-2, which has an MIC of 8 μg/ml. DNAC-2 is a quinolinol derivative that is bactericidal at 2X MIC. Macromolecular synthesis assays at 2X MIC of DNAC-2 inhibited DNA, cell wall, RNA and protein synthesis within fifteen to thirty minutes of treatment when compared to the untreated control. Transmission electron microscopy of DNAC-2 treated cells revealed a significantly thicker cell wall and impaired daughter cell separation. Exposure of USA300 cells to 1X MIC of DNAC-2 resulted in mislocalization of PBP2 away from the septum in an FtsZ independent manner. In addition, membrane localization with FM4-64, as well as depolarization study with DiOC2 and lipophilic cation TPP+ displayed membrane irregularities and rapid membrane depolarization in DNAC-2 treated cells vs. untreated control. However, DNAC-2 exhibited almost no toxicity towards eukaryotic membranes. Notably, DNAC-2 drives energy generation towards substrate level phosphorylation and the bacteria become more sensitive to DNAC-2 under anaerobic conditions. We propose that DNAC-2 affects USA300 by targeting the membrane, leading to partial membrane depolarization and subsequently affecting aerobic respiration and energy-dependent functional organization of macromolecular biosynthetic pathways. The multiple effects may have the desirable consequence of limiting the emergence of resistance to DNAC-2.

Abstract 5434: Tumor necrosis factor receptor-associated protein 1 (TRAP1) as a potential target for glutamine addicted cancer cells

Abstract Glutamine, a non-essential amino acid, is an important nutrient which is involved in many biochemical pathways such as energy production, macromolecular synthesis, and oxidative stress scavenging. Glutamine metabolism is dysregulated in many cancers which mostly display glutamine addiction for cell proliferation. Thus, glutamine metabolism has become a potential target for treating cancer. Here we report that glutamine-dependent cancer cells are more susceptible for inhibiting cell proliferation with inhibitor treatment of Tumor Necrosis Factor Receptor-Associated Protein 1 (TRAP1), a downstream factor of oncogenic c-Myc involved in glutamine metabolism. Using cell proliferation and cell viability assays, we examined growth inhibitory effects of TRAP1 inhibitor, gamitrinib-triphenylphosphonium (G-TPP), on two groups of cell lines, glutamine-deprivation sensitive versus resistant cell lines. Included are cell lines for each group: HCC827 acquired gefitinib resistance and A549 for the sensitive; HuH7 for the resistant group. Glutamine-deprivation sensitive cell lines showed significant growth inhibition with TRAP1 inhibitor treatment while the corresponding resistant group of cell lines showed no growth inhibitory effects in the same treatment condition. This suggests a potential mechanistic connection of TRAP1 to c-Myc regulation in glutamine metabolism. Taken together, this finding provides a better understanding of oncogene-driven glutamine metabolism as well as evidence that TRAP1 is a promising therapeutic target for glutamine addicted cancer cells. Citation Format: Vu T. Vo, Ai N. Phan, Tuyen N. Hua, Yangsik Jeong, Byoung Heon Kang, Hyun-Won Kim, Jong-Whan Choi. Tumor necrosis factor receptor-associated protein 1 (TRAP1) as a potential target for glutamine addicted cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5434. doi:10.1158/1538-7445.AM2017-5434

Abstract 1998: Transcriptome analysis of hypoxic head and neck cancer cells uncovers intron retention in EIF2B5 as a mechanism to reduce protein synthesis

Abstract Hypoxia is a key feature of solid tumors that contributes to resistance to therapy and reduced overall survival. Cellular adaptation to the hypoxic tumor microenvironment involves attenuation of energy-consuming processes such as macromolecular synthesis. We have identified RNA processing as another major process which is globally downregulated under hypoxic stress. By sequencing RNA of normoxic and hypoxic head and neck cancer cells, we observed widespread repression of genes that regulate RNA splicing and processing. As a result, we observed over 1,000 changes in relative mRNA isoform expression, including a significant increase in hypoxia-induced intron retention in nearly 100 genes. Genes observed to undergo intron retention in hypoxia included major regulators of RNA processing and protein synthesis, such as the translation initiation factor EIF2B5. Surprisingly, hypoxia-induced intron retention in EIF2B5 creates a premature termination codon, which results in a truncated protein isoform of eIF2Bϵ. We provide evidence that this isoform acts in opposition to the full-length protein to inhibit translation under stringent hypoxic conditions. Moreover, this intron is expressed in solid cancers known to contain hypoxic fractions and is overexpressed in head and neck cancer in a stage-dependent manner compared to normal tissue. To investigate how this intron is retained, we are examining the role of hypoxia-mediated changes in phosphorylation of the C-terminal domain (CTD) of RNA polymerase II. Our data suggest that increased phosphorylation of the CTD may lead to transcriptional pausing and subsequent retention of intron 12 in EIF2B5. Furthermore, distinct sequence features at this locus, such as a weak splice site at the intron12:exon13 junction, may explain how this intron is selectively retained in hypoxic cells. These results implicate mRNA splicing as a key mechanism to induce alternate transcripts and subsequent protein isoforms under hypoxia that influence cellular adaptation to stress. Citation Format: Lauren K. Brady, Hejia Wang, Caleb Radens, Milan Radovich, Amit Maity, Cristina Ivan, Mircea Ivan, Yoseph Barash, Constantinos Koumenis. Transcriptome analysis of hypoxic head and neck cancer cells uncovers intron retention in EIF2B5 as a mechanism to reduce protein synthesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1998. doi:10.1158/1538-7445.AM2017-1998

A Highly Potent Class of Halogenated Phenazine Antibacterial and Biofilm-Eradicating Agents Accessed Through a Modular Wohl-Aue Synthesis

Unlike individual, free-floating planktonic bacteria, biofilms are surface-attached communities of slow- or non-replicating bacteria encased within a protective extracellular polymeric matrix enabling persistent bacterial populations to tolerate high concentrations of antimicrobials. Our current antibacterial arsenal is composed of growth-inhibiting agents that target rapidly-dividing planktonic bacteria but not metabolically dormant biofilm cells. We report the first modular synthesis of a library of 20 halogenated phenazines (HP), utilizing the Wohl-Aue reaction, that targets both planktonic and biofilm cells. New HPs, including 6-substituted analogues, demonstrate potent antibacterial activities against MRSA, MRSE and VRE (MIC = 0.003–0.78 µM). HPs bind metal(II) cations and demonstrate interesting activity profiles when co-treated in a panel of metal(II) cations in MIC assays. HP 1 inhibited RNA and protein biosynthesis while not inhibiting DNA biosynthesis using 3H-radiolabeled precursors in macromolecular synthesis inhibition assays against MRSA. New HPs reported here demonstrate potent eradication activities (MBEC = 0.59–9.38 µM) against MRSA, MRSE and VRE biofilms while showing minimal red blood cell lysis or cytotoxicity against HeLa cells. PEG-carbonate HPs 24 and 25 were found to have potent antibacterial activities with significantly improved water solubility. HP small molecules could have a dramatic impact on persistent, biofilm-associated bacterial infection treatments.