This is a pre-copyedited, author-produced PDF of an article accepted for publication in Mutagenesis following peer review. The definitive publisher-authenticated version is available online at:http://mutage.oxfordjournals.org/content/early/2015/08/03/mutage.gev055.full. / 京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19588号 / 医博第4095号 / 新制||医||1014(附属図書館) / 32624 / 京都大学大学院医学研究科医学専攻 / (主査)教授 小泉 昭夫, 教授 渡邊 直樹, 教授 高田 穣 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Our ability to sense small molecules with high specificity, over a broad range of concentrations, is limited and difficult to accomplish in a way that is inexpensive and continuous. The most commercially successful biosensor is the enzyme-based blood glucose electrochemical biosensor, yet for nearly all other biomolecules, detection and monitoring require specialized equipment, trained personnel, and long lead times, and are not amenable to continuous monitoring. Industries in need of enzyme-based small-molecule biosensors, including medical diagnostics, industrial production, environmental monitoring, food safety analysis, and international security, would benefit greatly from the development of new devices capable of measuring biomolecules of interest. Environmental microbes have been gaining attention because of the vast array of biomolecules that they are capable of sensing and degrading. These microbes do so, in part, through redox enzymes with diverse substrate specificities that represent an immense resource for developing electrochemical biosensors. However, the development of new enzyme biosensors has largely been limited by the lack of a general high-throughput method to identify these redox enzymes, making discovery slow, laborious, and ad hoc. To address this need, a high-throughput functional screening approach has been developed to isolate microbial oxidase enzymes from complex metagenomic DNA libraries based solely on the enzyme-mediated degradation of any target analyte. The approach can be applied to DNA isolated from any complex microbial sample, including unidentified or unculturable bacteria. In this research, I first describe the development of a general assay to capture the activity of oxidase enzymes expressed in E. coli cells. I then demonstrate how the assay can be used to screen for the nicotine degrading oxidase NicA2 from a genomic DNA library generated from the microbe P. putida. Lastly, I describe the use of this screen to identify a new hydrocortisone-responsive oxidase from a pooled genomic DNA library of eight microbes, representing over 43 Mb of DNA sequence space. This hydrocortisone oxidase represents the first of many new enzymes that can be discovered leveraging our screening platform, which is poised to revolutionize the electrochemical biosensing field and substantially broaden the number of molecules these electrochemical biosensors can detect continuously and quantitatively. / 2023-02-17T00:00:00Z

No description available.

Malaria is vectored by the mosquito Anopheles gambiae (Ag) in Sub-Saharan Africa and infects approximately 500 million people annually. The increasing prevalence of pyrethroid-resistant mosquitoes has amplified the need for development of new, selective mosquitocides for use on insecticide-treated nets. We have developed several phenyl-substituted N-methylcarbamates producing a high degree of selectivity for Anopheles gambiae acetylcholinesterase (AgAChE) over human AChE. Molecular models suggest alternate conformations (flexibility) of W84 and W431 (Ag numbering) at the hydrophobic subpocket of the AgAChE active site and poor flexibility within human AChE, allowing for the high selectivity of our novel carbamates. Initial selectivity data was obtained through screening of these insecticides while using ethanol as a solvent. Re-screening of these carbamates in the presence of 0.1% DMSO (v/v) resulted in antagonism of inhibition for AgAChE, thus reducing the AgAChE-selectivity by at least 10-fold. However, the presence of 0.1% DMSO did not antagonize the inhibition of human, Drosophila melanogaster, or Musca domestica AChE. Non-selective carbamates also displayed no solvent-dependent antagonism of inhibition in any species studied, including AgAChE. Molecular models provide an explanation for antagonism of inhibition when DMSO is present. I, and collaborators, propose that W84 and W431 in AgAChE comprise an allosteric pocket that is stabilized by DMSO and is responsible for the solvent-dependent antagonism of inhibition observed with AgAChE. / Master of Science in Life Sciences

<p dir="ltr">Phospholipase C (PLC) enzymes are essential for normal cardiovascular function. These enzymes hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP₂) at the inner leaflet of the plasma membrane, producing diacylglycerol (DAG) and inositol phosphates (IP₃). IP₃ increases intracellular Ca²⁺, a key secondary messenger in cardiovascular activity. Changes in PLC expression and activity, specifically PLCβ3, have been found to play a critical role in cardiac hypertrophy and contractility. Cardiac hypertrophy, especially left ventricular hypertrophy, is a primary cause of ischemic heart disease, the leading cause of mortality worldwide. Despite the importance of these enzymes, a selective inhibitor for studying their function in cells and animal models has not yet been discovered. To address this unmet need, a lentiviral system for expressing human PLCβ3 and its two major activators, the heterotrimeric G protein subunits Ga_q and Gβγ was developed. These constructs were then utilized to establish a high-throughput screening methodology with the aim of identifying a novel allosteric inhibitor of PLCβ3, and ultimately other PLCs.</p>

Due to the increasing resistance demonstrated by insects to conventional insecticides, the need for compounds with novel modes of action is becoming more urgent. Also, the discovery and production of new insecticides is vital as regulations and restrictions on conventional insecticides become increasingly stringent (Casida and Quistad 1998). Research in this area requires screening of many candidate compounds which is costly and time-consuming. The goal of this research was to produce in vitro insect neurons from Sf21 insect ovarian cell lines, which could lead to new high throughput screening methods and a way to mass produce insect material for basic research. This study used a culture of Sf21 cells and a mixture of differentiation agents to produce viable neuron-like cells. In the presence of the molting hormone 20-hydroxyecdysone (20-HE), or insulin, in the growth medium, Sf21 cells began to express neuronal morphology, or the production of elongated, axon-like processes within 2-3 days. Maximal differentiation occurred when in the presence of 42 μM 20-HE or 10 μM insulin. Effects were maximal on day 2 for 20-E and day 3 for insulin. Insulin was more potent at day 2 for inducing differentiation (EC₅₀ = 247 nM) than 20-HE (EC₅₀ = 13 μM). In combination, 20-HE and insulin produced apparent synergistic effects on differentiation. Caffeine, a central nervous system (CNS) stimulant, inhibited induction of elongated processes by 20-HE and/or insulin. Caffeine was a potent inhibitor of 42 μM 20-HE, with an IC50 of 9 nM, and the inhibition was incomplete, resulting in about one quarter of the differentiated cells remaining, even at high concentrations (up to 1 mM). The ability to induce a neural phenotype simplifies studies with of insect cells, compared to either the use of primary nervous tissue or genetic engineering techniques. The presence of ion channels or receptors in the differentiated cells remains to be determined. If they are present, high throughput screening for new insecticides will be accelerated and made more economical by the utility of this method. / Master of Science

This thesis shows advancements towards the development of engineered bacteria for sensing and responding to environmental pollutants by exploring the use of UDP-glycosyltransferases (UGTs) for their metabolism of toxins, along with the use of engineered tetracycline repressor protein (TetR) based transcriptional regulators as sensors for environmental toxins. The importance and applicability of UGTs as well as the adaptability of TetR systems for future developments are shown through a function-based review of UGTs, the development of high-throughput fluorescent UGT assay technique, and the creation of novel TetR transcription regulatory sequences. The assays effectively measured UGT71G1 activity based on the presence of reaction byproducts, leading to the identification of several new substrates including the toxin bisphenol A. Next, hybrid TetRs were assembled from complementary DNA-binding and ligand-binding domains of TetR homologs. The ability to interchange these domains while retaining their function multiplies the unique TetR systems available for use in cellular systems. In future, novel TetR and UGT71G1 systems may be developed to detect and respond to substrates like bisphenol A.

Die Blut-Hirn-Schranke (BHS) stellt eine selektiv durchlässige Barriere dar, die den Austausch von Stoffen zwischen Blut und ZNS kontrolliert und so neuroprotektiv wirkt. Sie verhindert allerdings nicht nur die Passage toxischer Metaboliten, sondern verwehrt auch vielen therapeutischen Wirkstoffen den Zugang zum Gehirn. Die Forschung an Methoden zum Erreichen höherer Arzneimittelkonzentrationen im Gehirn ist deshalb essenziell für die Behandlung zerebraler Erkrankungen wie dem zerebral metastasierten Mammakarzinom. Ziel dieser Arbeit war es deshalb, Wirkstoffe zu identifizieren, die die Permeabilität der BHS erhöhen. Die Substanzdatenbank LO1208 von Sigma-Aldrich wurde im Rahmen eines HTS auf ihre permeabilitätsbeeinflussenden Eigenschaften untersucht. Hierbei konnten 31 Substanzen identifiziert werden, welche die Permeabilität von BLECs um mindestens 50 % erhöhen. Aus diesen wurden 4-Amino-1,8-naphthalimid (PARP-Inhibitor) und GW2974 (TKI) für eine genauere Analyse ausgewählt. Als dritter Wirkstoff wurde Ibuilast (Inhibitor der PDE4, des MIF sowie des Toll-like-Rezeptor-4) untersucht, wobei dieser keine signifikante Veränderung der Permeabilität bewirkt. Die Messung des TEERs und der Permeabilität für Fluorescein bestätigten die Ergebnisse aus dem HTS, welches demnach zukünftig für Permeabilitätstests eingesetzt werden kann. Die Zellviabilität wird durch 4 Amino-1,8-naphthalmid nicht beeinflusst. GW2974 und Ibudilast zeigen bei 500 µM einen toxischen Einfluss auf MCF-7-Zellen. BLECs werden durch 100 µM GW2974 gehemmt. Es konnte gezeigt werden, dass die erhöhte Permeabilität mit einer Veränderung der TJ-Proteinexpression einhergeht. 4-Amino-1,8-naphthalimid senkt die Expression von Occludin auf mRNA- und Proteinebene. GW2974 vermindert zusätzlich die Expression von VE-Cadherin, Claudin-5 und ZO-1. Darüber hinaus wurde die Wirkung auf Effluxpumpen untersucht. Die Ergebnisse der mRNA- und Protein-expression weichen voneinander ab, weshalb eine genauere Untersuchung der Translationsvorgänge sinnvoll erscheint. Glut-1 wird in GW2974 behandelten Zellen überexprimiert, was auf eine erhöhte Aktivität der BLECs hinweist. GW2974 und 4-Amino-1,8-naphthalimid könnten durch ihre permeabilitätssteigernde Wirkung die Ansprechrate einer systemischen Behandlung von PatientInnen mit einem zerebral metastasierten Mammakarzinom erhöhen und somit ihre Prognose verbessern. Detaillierte Studien zu Kombinationstherapien, den notwendigen Wirkstoff-konzentrationen und eventuellen negativen neurologischen Wirkungen sollten erwogen werden. / The Blood-Brain Barrier (BBB) represents a selectively permeable barrier that controls the exchange of substances between the blood and the brain and thus has a neuroprotective effect. However, it not only prevents the passage of toxic metabolites, but also limits the access of therapeutic agents to the brain. Further research into methods to achieve higher drug concentrations in the brain is essential for the treatment of cerebral diseases such as cerebral metastatic breast cancer. The goal of this study was to identify drugs that increase the permeability of the BBB. The substance database LO1208 from Sigma-Aldrich was examined for its permeability-influencing properties as part of a high throughput drug screening (HTS). 31 of the examined substances showed an increase of the permeability on brain-like endothelial cells (BLECs) by at least 50%. Thereof 4-amino-1,8-naphthalimide (PARP inhibitor) and GW2974 (TKI) were selected for a more detailed analysis. Ibudilast (inhibitor of PDE4, MIF and Toll-like receptor-4) was found to be the third most active substance, although it did not cause any significant change in permeability. The measurement of the trans endothelial electrical resistance (TEER) and the permeability for fluorescein confirmed the results from the HTS and therefore is suggested to be used in further permeability tests in the future. Cell viability is not affected by 4 amino-1,8-naphthalmide. GW2974 and Ibudilast have a toxic effect on MCF-7 cells at a concentration of 500 µM, whereas BLECs are inhibited at a concentration of 100 µM of GW2974. The results show that the increased permeability is associated with a change in tight junction protein expression. 4-Amino-1,8-naphthalimide decreases the expression of occludin at mRNA and protein level. GW2974 also reduces the expression of VE-cadherin, claudin-5 and ZO-1. In addition to the abovementioned analysis, also the effect on efflux pumps was investigated. As the results of the mRNA and protein expression differ from each other, a more detailed analysis will be necessary to investigate the translation process. Glut-1 is overexpressed in GW2974-treated cells, which indicates an increased activity of the BLECs. GW2974 and 4-amino-1,8-naphthalimide could increase the response rate to systemic therapy of patients with cerebral metastatic breast cancer through their permeability-enhancing effect and thereby improve their prognosis. Detailed studies on combination therapies, the necessary drug concentrations and possible negative neurological effects are recommended to gain further insight.

Thesis (Ph.D.)--Indiana University, 2009. / Title from screen (viewed on February 2, 2010). Department of Biochemistry and Molecular Biology, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Mark R. Kelley, Millie M. Georgiadis, John J. Turchi, Martin L. Smith. Includes vitae. Includes bibliographical references (leaves 114-133).

Receptores nucleares controlam a transcrição em células eucarióticas quando ativados por ligantes e, além do sítio de interação com ligantes, há outros sítios alternativos em sua superfície que podem ser alvo de compostos capazes de interferir com as interações proteína-proteína desativando o RN. A ativação do Receptor X de Pregnano (RXP) e do Receptor Constitutivo de Androstano (RCA) resulta na indução do metabolismo e efluxo de fármacos. Portanto, RXP/RCA sao responsáveis por causar reações adversas ou falhar terapias. Uma abordagem combinando a triagem experimental à nível cellular, em uma biblioteca de fármacos, e validação com ensaios in vitro e in silico, conseguimos identificar três novos antagonistas de RXP e cinco novos contra RCA, cada um com um perfil único de interação. / Nuclear receptors can control transcription in eukaryotic cells in a ligand-dependent manner and, besides the ligand-binding pocket there is evidence of the existence of alternative ligand-binding sites on the surface, which can be addressed by small organic molecules that disrupt specific protein-protein interactions and thereby may antagonise NR function. Activation of pregnane X receptor (PXR) and constitutive androstane receptor (CAR) results in the induction of first-pass metabolism and drug efflux. Hereby PXR/CAR may cause adverse drug reactions or therapeutic failure of drugs. Therefore, PXR and/or CAR antagonists can minimise adverse effects or improve therapeutic efficiencies. Combination of cellular high-throughput screen identified CAR and PXR potent antagonists in a library of approved and investigational drugs. Further validated by cellular and in vitro assays, as well as molecular docking, suggesting additional or exclusive binding outside the classical ligand binding pocket. In conclusion, we here have identified three approved drugs as novel potent PXR antagonists and five potential CAR inverse agonists with differential receptor interaction profiles.