scholarly journals Metal-independent ribonucleotide reduction powered by a DOPA radical in Mycoplasma pathogens

2018 ◽  
Author(s):  
Vivek Srinivas ◽  
Hugo Lebrette ◽  
Daniel Lundin ◽  
Yuri Kutin ◽  
Margareta Sahlin ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Ribonucleotide Reductase ◽  
De Novo ◽  
Spectroscopic Characterization ◽  
Radical Species ◽  
Metal Site ◽  
Absolute Requirement ◽  
Radical Generation

AbstractRibonucleotide reductase (RNR) catalyzes the only known de-novo pathway for production of all four deoxyribonucleotides required for DNA synthesis. In aerobic RNRs, a di-nuclear metal site is viewed as an absolute requirement for generating and stabilizing an essential catalytic radical. Here we describe a new group of RNRs found in Mollicutes, including Mycoplasma pathogens, that possesses a metal-independent stable radical residing on a modified tyrosyl residue. Structural, biochemical and spectroscopic characterization reveal a stable DOPA radical species that directly supports ribonucleotide reduction in vitro and in vivo.The cofactor synthesis and radical generation processes are fundamentally different from established RNRs and require the flavoprotein NrdI. Several of the pathogens encoding this RNR variant are involved in diseases of the urinary tract and genitalia. Conceivably, this remarkable RNR variant provides an advantage under metal starvation induced by the immune system. We propose that the new RNR subclass is denoted class Ie.

scholarly journals Cell Cycle Inhibition To Treat Sleeping Sickness

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Conrad L. Epting ◽  
Brian T. Emmer ◽  
Nga Y. Du ◽  
Joann M. Taylor ◽  
Ming Y. Makanji ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ribonucleotide Reductase ◽  
De Novo ◽  
Protozoan Parasite ◽  
Parasite Growth ◽  
High Rate ◽  
Mammalian Host ◽  
African Trypanosomiasis

ABSTRACTAfrican trypanosomiasis is caused by infection with the protozoan parasiteTrypanosoma brucei. During infection, this pathogen divides rapidly to high density in the bloodstream of its mammalian host in a manner similar to that of leukemia. Like all eukaryotes,T. bruceihas a cell cycle involving thede novosynthesis of DNA regulated by ribonucleotide reductase (RNR), which catalyzes the conversion of ribonucleotides into their deoxy form. As an essential enzyme for the cell cycle, RNR is a common target for cancer chemotherapy. We hypothesized that inhibition of RNR by genetic or pharmacological means would impair parasite growthin vitroand prolong the survival of infected animals. Our results demonstrate that RNR inhibition is highly effective in suppressing parasite growth bothin vitroandin vivo. These results support drug discovery efforts targeting the cell cycle, not only for African trypanosomiasis but possibly also for other infections by eukaryotic pathogens.IMPORTANCEThe development of drugs to treat infections with eukaryotic pathogens is challenging because many key virulence factors have closely related homologues in humans. Drug toxicity greatly limits these development efforts. For pathogens that replicate at a high rate, especially in the blood, an alternative approach is to target the cell cycle directly, much as is done to treat some hematologic malignancies. The results presented here indicate that targeting the cell cycle via inhibition of ribonucleotide reductase is effective at killing trypanosomes and prolonging the survival of infected animals.

Computational study for suppression of CD25/IL-2 interaction

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Moein Dehbashi ◽  
Zohreh Hojati ◽  
Majid Motovali-bashi ◽  
Mazdak Ganjalikhani-Hakemi ◽  
Akihiro Shimosaka ◽  
...  
Keyword(s):  
Small Molecules ◽  
Cancer Progression ◽  
Immune Escape ◽  
De Novo ◽  
Computational Study ◽  
Treg Cells ◽  
Homology Search ◽  
Small Interfering Rnas

AbstractCancer recurrence presents a huge challenge in cancer patient management. Immune escape is a key mechanism of cancer progression and metastatic dissemination. CD25 is expressed in regulatory T (Treg) cells including tumor-infiltrating Treg cells (TI-Tregs). These cells specially activate and reinforce immune escape mechanism of cancers. The suppression of CD25/IL-2 interaction would be useful against Treg cells activation and ultimately immune escape of cancer. Here, software, web servers and databases were used, at which in silico designed small interfering RNAs (siRNAs), de novo designed peptides and virtual screened small molecules against CD25 were introduced for the prospect of eliminating cancer immune escape and obtaining successful treatment. We obtained siRNAs with low off-target effects. Further, small molecules based on the binding homology search in ligand and receptor similarity were introduced. Finally, the critical amino acids on CD25 were targeted by a de novo designed peptide with disulfide bond. Hence we introduced computational-based antagonists to lay a foundation for further in vitro and in vivo studies.

scholarly journals EXTH-51. ANTI-INVASIVE EFFICACY AND SURVIVAL BENEFIT OF THE YAP-TEAD INHIBITOR VERTEPORFIN IN PRECLINICAL GLIOBLASTOMA MODELS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii98-ii98
Author(s):  
Anne Marie Barrette ◽  
Alexandros Bouras ◽  
German Nudelman ◽  
Zarmeen Mussa ◽  
Elena Zaslavsky ◽  
...  
Keyword(s):  
Survival Benefit ◽  
De Novo ◽  
Epithelial Mesenchymal Transition ◽  
Intraperitoneal Administration ◽  
Standard Of Care ◽  
Tumor Burden ◽  
Mesenchymal Transition ◽  
Protein Levels

Abstract Glioblastoma (GBM) remains an incurable disease, in large part due to its malignant infiltrative spread, and current clinical therapy fails to target the invasive nature of tumor cells in disease progression and recurrence. Here, we use the YAP-TEAD inhibitor Verteporfin to target a convergence point for regulating tumor invasion/metastasis and establish the robust anti-invasive therapeutic efficacy of this FDA-approved drug and its survival benefit across several preclinical glioma models. Using patient-derived GBM cells and orthotopic xenograft models (PDX), we show that Verteporfin treatment disrupts YAP/TAZ-TEAD activity and processes related to cell adhesion, migration and epithelial-mesenchymal transition. In-vitro, Verteporfin impairs tumor migration, invasion and motility dynamics. In-vivo, intraperitoneal administration of Verteporfin in mice with orthotopic PDX tumors shows consistent drug accumulation within the brain and decreased infiltrative tumor burden, across three independent experiments. Interestingly, PDX tumors with impaired invasion after Verteporfin treatment downregulate CDH2 and ITGB1 adhesion protein levels within the tumor microenvironment. Finally, Verteporfin treatment confers survival benefit in two independent PDX models: as monotherapy in de-novo GBM and in combination with standard-of-care chemoradiation in recurrent GBM. These findings indicate potential therapeutic value of this FDA-approved drug if repurposed for GBM patients.

scholarly journals PAICS contributes to gastric carcinogenesis and participates in DNA damage response by interacting with histone deacetylase 1/2

2020 ◽  
Vol 11 (7) ◽  
Author(s):  
Nan Huang ◽  
Chang Xu ◽  
Liang Deng ◽  
Xue Li ◽  
Zhixuan Bian ◽  
...  
Keyword(s):  
Dna Damage ◽  
Histone Deacetylase ◽  
Dna Damage Response ◽  
De Novo ◽  
Dna Damage Repair ◽  
Histone Deacetylase 1 ◽  
Damage Repair ◽  
Damage Response

AbstractPhosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), an essential enzyme involved in de novo purine biosynthesis, is connected with formation of various tumors. However, the specific biological roles and related mechanisms of PAICS in gastric cancer (GC) remain unclear. In the present study, we identified for the first time that PAICS was significantly upregulated in GC and high expression of PAICS was correlated with poor prognosis of patients with GC. In addition, knockdown of PAICS significantly induced cell apoptosis, and inhibited GC cell growth both in vitro and in vivo. Mechanistic studies first found that PAICS was engaged in DNA damage response, and knockdown of PAICS in GC cell lines induced DNA damage and impaired DNA damage repair efficiency. Further explorations revealed that PAICS interacted with histone deacetylase HDAC1 and HDAC2, and PAICS deficiency decreased the expression of DAD51 and inhibited its recruitment to DNA damage sites by impairing HDAC1/2 deacetylase activity, eventually preventing DNA damage repair. Consistently, PAICS deficiency enhanced the sensitivity of GC cells to DNA damage agent, cisplatin (CDDP), both in vitro and in vivo. Altogether, our findings demonstrate that PAICS plays an oncogenic role in GC, which act as a novel diagnosis and prognostic biomarker for patients with GC.

Hippokampale Estrogensynthese und synaptische Plastizität

e-Neuroforum ◽  
2007 ◽  
Vol 13 (4) ◽  
Author(s):  
Lars Fester ◽  
Janine Prange-Kiel ◽  
Gabriele M. Rune
Keyword(s):  
De Novo ◽  
Synaptische Plastizität

ZusammenfassungUnsere Untersuchungen der letzten Jahre haben gezeigt, dass nicht das Ovar die Quelle für Estrogen induzierte synaptische Plastizität im Hippokampus ist, sondern dieses aus dem Hippokampus selber stammt und haben damit einen Paradigmawechsel eingeleitet, der Estrogen als Neuromodulator unabhängig vom Geschlecht identifiziert. Hippokampale Neurone von Ratten beiderlei Geschlechts sind in der Lage, aus Cholesterol Estrogene de novo zu synthetisieren. Diese hippokampale Estrogensynthese ist sowohl für den Erhalt von Spinesynapsen in vivo als auch in vitro essenziell. Die Hemmung der Estrogensynthese zieht einen Synapsenverlust nach sich und Langzeitpotenzierung ist nicht mehr induzierbar. Die Effekte von hippokampalem Estrogen sind auto-/parakriner Natur, die über die bekannten Estrogenrezeptor-Subtypen, ERα und ERβ, vermittelt werden. Die Regulation der hippokampalen Estrogensynthese erfolgt über GnRH und erklärt die Korrelation der Spinesynapsendichte mit dem weiblichen genitalen Zyklus, die für den Hippokampus spezifisch ist.

scholarly journals Investigation of in Vivo Roles of the C-terminal Tails of the Small Subunit (ββ′) of Saccharomyces cerevisiae Ribonucleotide Reductase

2013 ◽  
Vol 288 (20) ◽  
pp. 13951-13959 ◽  
Author(s):  
Yan Zhang ◽  
Xiuxiang An ◽  
JoAnne Stubbe ◽  
Mingxia Huang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribonucleotide Reductase ◽  
Large Subunit ◽  
Small Subunit ◽  
Cluster Assembly ◽  
E Coli ◽  
Viability Assay ◽  
Docking Model

The small subunit (β2) of class Ia ribonucleotide reductase (RNR) houses a diferric tyrosyl cofactor (Fe2III-Y•) that initiates nucleotide reduction in the large subunit (α2) via a long range radical transfer (RT) pathway in the holo-(α2)m(β2)n complex. The C-terminal tails of β2 are predominantly responsible for interaction with α2, with a conserved tyrosine residue in the tail (Tyr356 in Escherichia coli NrdB) proposed to participate in cofactor assembly/maintenance and in RT. In the absence of structure of any holo-RNR, the role of the β tail in cluster assembly/maintenance and its predisposition within the holo-complex have remained unknown. In this study, we have taken advantage of the unusual heterodimeric nature of the Saccharomyces cerevisiae RNR small subunit (ββ′), of which only β contains a cofactor, to address both of these issues. We demonstrate that neither β-Tyr376 nor β′-Tyr323 (Tyr356 equivalent in NrdB) is required for cofactor assembly in vivo, in contrast to the previously proposed mechanism for E. coli cofactor maintenance and assembly in vitro. Furthermore, studies with reconstituted-ββ′ and an in vivo viability assay show that β-Tyr376 is essential for RT, whereas Tyr323 in β′ is not. Although the C-terminal tail of β′ is dispensable for cofactor formation and RT, it is essential for interactions with β and α to form the active holo-RNR. Together the results provide the first evidence of a directed orientation of the β and β′ C-terminal tails relative to α within the holoenzyme consistent with a docking model of the two subunits and argue against RT across the β β′ interface.

scholarly journals Biological Cost of Single and Multiple Norfloxacin Resistance Mutations in Escherichia coli Implicated in Urinary Tract Infections

2005 ◽  
Vol 49 (6) ◽  
pp. 2343-2351 ◽  
Author(s):  
Patricia Komp Lindgren ◽  
Linda L. Marcusson ◽  
Dorthe Sandvang ◽  
Niels Frimodt-Møller ◽  
Diarmaid Hughes
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Infection Model ◽  
Resistance Mutations ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Tract Infections ◽  
Subsequent Selection

ABSTRACT Resistance to fluoroquinolones in urinary tract infection (UTIs) caused by Escherichia coli is associated with multiple mutations, typically those that alter DNA gyrase and DNA topoisomerase IV and those that regulate AcrAB-TolC-mediated efflux. We asked whether a fitness cost is associated with the accumulation of these multiple mutations. Mutants of the susceptible E. coli UTI isolate Nu14 were selected through three to five successive steps with norfloxacin. Each selection was performed with the MIC of the selected strain. After each selection the MIC was measured; and the regions of gyrA, gyrB, parC, and parE, previously associated with resistance mutations, and all of marOR and acrR were sequenced. The first selection step yielded mutations in gyrA, gyrB, and marOR. Subsequent selection steps yielded mutations in gyrA, parE, and marOR but not in gyrB, parC, or acrR. Resistance-associated mutations were identified in almost all isolates after selection steps 1 and 2 but in less than 50% of isolates after subsequent selection steps. Selected strains were competed in vitro, in urine, and in a mouse UTI infection model against the starting strain, Nu14. First-step mutations were not associated with significant fitness costs. However, the accumulation of three or more resistance-associated mutations was usually associated with a large reduction in biological fitness, both in vitro and in vivo. Interestingly, in some lineages a partial restoration of fitness was associated with the accumulation of additional mutations in late selection steps. We suggest that the relative biological costs of multiple mutations may influence the evolution of E. coli strains that develop resistance to fluoroquinolones.

scholarly journals Serine synthesis pathway inhibition cooperates with dietary serine and glycine limitation for cancer therapy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mylène Tajan ◽  
Marc Hennequart ◽  
Eric C. Cheung ◽  
Fabio Zani ◽  
Andreas K. Hock ◽  
...  
Keyword(s):  
Therapeutic Efficacy ◽  
De Novo ◽  
Carbon Availability ◽  
Global Protein Synthesis ◽  
Enhanced Expression ◽  
One Carbon Metabolism ◽  
Amino Acid Depletion ◽  
Pathway Inhibition

AbstractMany tumour cells show dependence on exogenous serine and dietary serine and glycine starvation can inhibit the growth of these cancers and extend survival in mice. However, numerous mechanisms promote resistance to this therapeutic approach, including enhanced expression of the de novo serine synthesis pathway (SSP) enzymes or activation of oncogenes that drive enhanced serine synthesis. Here we show that inhibition of PHGDH, the first step in the SSP, cooperates with serine and glycine depletion to inhibit one-carbon metabolism and cancer growth. In vitro, inhibition of PHGDH combined with serine starvation leads to a defect in global protein synthesis, which blocks the activation of an ATF-4 response and more broadly impacts the protective stress response to amino acid depletion. In vivo, the combination of diet and inhibitor shows therapeutic efficacy against tumours that are resistant to diet or drug alone, with evidence of reduced one-carbon availability. However, the defect in ATF4-response seen in vitro following complete depletion of available serine is not seen in mice, where dietary serine and glycine depletion and treatment with the PHGDH inhibitor lower but do not eliminate serine. Our results indicate that inhibition of PHGDH will augment the therapeutic efficacy of a serine depleted diet.

Lipidated Methotrexate Microbubbles: A Promising Rheumatoid Arthritis Theranostic Medicine Manipulated via Ultrasonic Irradiation

2021 ◽  
Vol 17 (7) ◽  
pp. 1293-1304
Author(s):  
Zhuofei Zhao ◽  
Xiaona Lin ◽  
Lulu Zhang ◽  
Xia Liu ◽  
Qingwen Wang ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
De Novo ◽  
Low Ph ◽  
Curative Effect ◽  
Inflammatory Microenvironment ◽  
Raw 264.7 Cell ◽  
Infection Focus ◽  
Raw 264.7 Cell Line

De novo designed lipidated methotrexate was synthesized and self-assembled into microbubbles for targeted rheumatoid arthritis theranostic treatment. Controlled lipidatedmethotrexate delivery was achieved by ultrasound-targetedmicrobubble destruction technique. Methotrexate was dissociated inflammatory microenvironment of synovial cavity, owing to representive low pH and enriched leucocyte esterase. We first manipulated methotrexate controlled release with RAW 264.7 cell line in vitro and further verified with rheumatoid arthritis rabbits in vivo. Results showed that lipidated methotrexate microbubbles precisely affected infection focus and significantly enhanced rheumatoid arthritis curative effect comparing with dissociative methotrexate. This study indicates that lipidated methotrexate microbubbles might be considered as a promising rheumatoid arthritis theranostics medicine.

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