bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of N‐terminal Acetylation on the Protein Tau
Authors: Fleurima Abigail , Holmes William 
Published: April 2020

The microtubule‐associated protein tau (MAPT) plays a critical role in many neurodegenerative diseases such as Alzheimer’s Disease. Tau functions to stabilize microtubule structures that are essential for transport within the neuron, and disruption of transport leads to a loss of neuronal function. Tau binding is regulated by phosphorylation, a post‐translational modification (PTM) where a phosphate group is added by a specific kinase. Phosphorylated Tau blocks the microtubule binding sites, then phosphatases remove these phosphate groups which expose the microtubule‐binding regions. Tau is also found in a hyper‐phosphorylated state, which causes Tau to self‐assemble into oligomers and higher order aggregates. It's clear that post‐translational modification of Tau plays a key role in the dysregulation of neuronal function due to abnormal conformational changes, however not all PTMs are as thoroughly studied as phosphorylation.However, N‐terminal acetylation is the most common and overlooked PTM of all protein, this is adjacent to the proven idea of Tau being a predicted target of N‐terminal acetylation. N‐terminal acetylation is a co‐translational process that is catalyzed by N‐terminal Acetyltransferases (NATs), which adds an acetyl group to the N‐terminus of a Tau polypeptide, thus neutralizing the positive charge on the N‐terminus.The objective of this research is to understand how the N‐terminal modification of a Tau polypeptide effects the behavior of Tau and its aggregation. Commonly, studies endogenously express Tau in a prokaryotic system that lack PTMs. Here we utilize a co‐expression system in E. coli that allows us to purify Tau with a modified N‐terminus. Purifying modified Tau with Fast Protein Liquid Chromatography (FPLC) will allow us to probe the structural and functional effects of N‐terminal acetylation by assessing changes in Tau’s aggregation and microtubule binding affinity. Furthermore, our studies of the N‐terminus of Tau will provide insight into the role of the N‐terminal projection domain and potentially provide new targets for therapeutic intervention in the treatment of Tau related diseases.Support or Funding InformationCollaborative Award through RI‐INBRE from the National Institute of General Medical Sciences of the National Institute of Health under grant #P20GM103430.
Buprenorphine Analogs to Treat Relapse
Authors: Olson Keith M. , Hillhouse Todd E. , Sears Bryan F. , Rysztak Lauren , Husband Stephen M. , Jutkiewicz Emily M. , Traynor John R. 
Published: April 2020

Substance use disorders (SUDs) – the overuse and dependence on at least one substance – have a lifetime prevalence of ~10% in the U.S. While buprenorphine (BUP) treatment reduces relapse rates, it is only marginally effective, as 70% of SUD patients relapse within a year. Due to BUP’s marginal effectiveness and abuse potential, there is a need to improve SUD therapies that prevent relapse to multiple drugs of abuse after exposure to stress, drug‐associated context and drug priming. Here we evaluate BUP and two analogs for their ability to inhibit cocaine‐ and stress‐induced relapse using a conditioned place preference (CPP) paradigm. Pharmacologically, BUP is a potent (sub nM) partial agonist at the m‐opioid receptor (MOR) with potent antagonist activity at the k‐(KOR), and d‐opioid receptors (DOR). In vitro BUP can act as a weak (mM) partial agonist at the nociceptin/OrphaninFQ (NOP) receptor with uncertain in vivo consequences. We measured in vitro potency and efficacy using [35S]GTPgS functional assays in CHO cells separately expressing DOR, KOR, MOR or NOP. Since NOP receptor agonists reduce relapse in animal models, we compared BU10119 with NOP agonist activity (EC50 = 120 nM ± 20; EMAX = 44% ± 5%) or BU12004 with NOP antagonist activity (KB = 190 nM ±30) to BUP (EC50 = 1300 nM ± 320; EMAX = 39% ± 7%). Furthermore, BU12004 and BU10119 were MOR antagonists (KB = 0.42 nM ± 0.08 and KB = 1.1 nM ± 0.2, respectively) with less abuse liability than the MOR partial agonist BUP (EC50 = 0.79 nM ± 0.31; EMAX = 34% ± 6%). BUP, BU10119, and BU12004 were all potent antagonists at DOR and KOR. BU10119 (1.0 mg/kg) attenuated cocaine‐primed reinstatement in CPP, but 10 mg/kg BU12004 did not. BUP trended toward reduced drug‐primed reinstatement. The in vivo rank order of BU10119 >BUP >BU12004 matches the rank order for NOP agonism in vitro. Additionally, 1.0 mg/kg of either BU10119 or BU12004 blocked swim stress‐primed reinstatement, ostensibly due to their KOR antagonist activity. Taken together, BU10119 provides a promising lead to treat SUDs with better effectiveness and reduced abuse potential compared to BUP.Support or Funding InformationSupported by NIDA R01 DA07315 and 035316.
Nutrient modulation of DNA repair in lung cancer
Authors: Eroglu Abdulkerim , Balbuena Emilio 
Published: April 2020

Noncommunicable diseases associated with aging and inflammation is rising in recent decades, contributing global burden of disease globally. Among them are cardiovascular diseases, diabetes, and cancer. Our objective is to illustrate the molecular mechanisms behind the chemoprotective effects of major dietary carotenoids. We hypothesize that carotenoids play a role in modulating genome stability. Telomeres are essential for the stability of our genome, and oxidative stress caused by the reactive oxygen species poses a risk for telomere shortening, thereby contributing to the pathogenesis of chronic diseases, including lung cancer. Human telomeres are composed of 10–15 kilobases of TTAGGG repeats. Guanine is the most readily oxidized of the natural bases, and TTAGG repeats are preferred sites for conversion of Guanine to 8‐oxoG, which repaired by base excision repair through an enzyme called OGG1. In the current study, we investigated mRNA and protein expression of OGG1 and retinoic acid receptors (RARs) in human alveolar epithelial cells exposed to cigarette smoke. Cells pre‐treated with various doses of β‐carotene for 24 hours, and the following day exposed to smoke using a smoking chamber. We found out that while β‐carotene increased OGG1 expression at lower doses, it led to a dramatic decrease at higher concentrations suggesting that at higher doses β‐carotene exerted a pro‐oxidant effect. Previously it was reported that the expression of the RARβ, putative tumor suppressor gene, is reduced in lung cancer. In parallel to OGG1 inhibition, we observed decreased levels of RARβ. We are in the process of quantifying 8‐oxoG by HPLC‐MS/MS. We believe that these novel findings will shed light on the mechanism of action of β‐carotene at the molecular level.Support or Funding InformationUSDA‐NIFA Hatch Project
The Effects of Histidine Tags on the Energy Landscape on Acyl Co‐A Binding Protein
Authors: Van Dyck Papa Kobina , Guinn Emily 
Published: April 2020

Protein epitope tags play an important role in protein characterization, allowing for easy detection, tracking and isolation in cellular and biochemical experiments. A polyhistidine tag is an amino acid motif that consists of at least six histidine (His) residues, often located at the N‐ or C‐terminus of the protein. Affinity tags, like His tags, are routinely employed as convenient means of purifying recombinantly expressed proteins. However there have been increasing reports suggesting that His tags interfere with the structure and function of proteins. We hypothesize that His tags affect the energy landscape of proteins. Acyl Co‐A Binding Protein (ACBP) is a single‐domain protein that is thought to fold in a two‐state process To test our hypothesis we studied the stability and folding kinetics of ACBP with differentially located His tags in the presence of buffers with varying pHs with a fluorimeter and a stopped‐flow spectrometer. First, we found that buffer pH differentially affected the charge of the His tag: At a pH of 5.3 Histidine is protonated and at 7 Histidine is deprotonated. Second, we observed a significant difference in the kinetics and thermodynamics of the C‐Terminus His tagged ACBP relative to the taglesss ACBP. In a pH of 5.3, the C‐Term His tagged ACBP was less stable whereas in a pH of 7 it was more stable. On the other hand, there was no significant difference in the thermodynamics or the kinetics of the N‐term ACBP to the tagless ACBP. Taken together our studies suggest that the location of the His tag (and ionic environment) markedly affected the energy landscape of ACBP.Support or Funding InformationDePauw University‐PDF
Sighs Originating in the PreBötC are Driven by Neuroglial Interactions
Authors: Severs Liza , Baertsch Nathan A. , Ramirez Jan-Marino 
Published: April 2020

Sighs are large amplitude inspirations that occur periodically during normal breathing and are physiologically important for preventing alveolar collapse. Normal or “eupneic” inspirations and sighs originate from the same neural network, the preBötzinger Complex (preBötC), in the ventral medulla. Given that both sighs and eupnea arise from the same network, it has been challenging to differentiate the underlying mechanisms that concurrently generate both rhythmic behaviors. Using the in vitro brainstem slice preparation, we have recently demonstrated that this is possible through neuroglial coupling. We found that modulating purinergic signaling through P2Y1 receptors strongly alters sigh frequency without altering eupnea. Then, we used optogenetics in combination with extracellular population recordings to drive ChR2 expression under control of the astrocytic promoter, Aldh1l1. Light activation of Aldh1l1 expressing preBötC astrocytes evoked both eupnea and sigh bursts. Evoked sighs and eupnea had the same characteristics of spontaneous bursts, including comparable amplitudes, burst durations, and post‐burst intervals. Furthermore, optogenetic stimulations showed that sighs are tightly coupled to the eupneic frequency, as they occurred with a significantly higher probability when stimulated during the inspiratory cycle. Next, we demonstrated that light‐evoked sighs could be inhibited by applying P2Y1 blockade and low concentrations of the Ca2+ channel blocker cadmium (4μM, to selectively target P/Q‐type receptors). Sighs under control conditions and with application of the muscarinic receptor agonist oxotremorine were elicited within the limits defined by the refractory period. Utilizing calcium imaging with Fura‐2, we next identified a population of brainstem astrocytes that displayed an increase in intracellular calcium corresponding to both sigh and eupnea activity. We hypothesize that this increase in calcium facilitates neuroglial coupling through release of ATP, as preliminary data indicates that release of ATP from astrocytes and conversion to ADP contributes to this calcium change. Taken together, our experiments suggest that the timing characteristics underlying sigh generation are a coordinated action between glial calcium oscillations and the recruitment of preBötC neurons along the inspiratory column through purinergic signaling.Support or Funding InformationNIH Ruth L. Kirschstein Predoctoral Individual National Research Service AwardNIH R01 HL126523
Investigating the Functions of Endogenous Neuraminidases Neu1 and Neu3 in Blood Cell and Protein Homeostasis
Authors: Westman Julia S. , Yang Won Ho , Marth Jamey D. 
Published: April 2020

Neuraminidases cleave terminal sialic acid linkages on the glycans of glycoproteins and glycolipids. In some cases this exposes underlying galactose linkages that can be recognized by lectins including the endocytic hepatic Ashwell‐Morell receptor that thereby modulate protein function through endocytic clearance. Neuraminidases are widely distributed in vertebrates and microorganisms, although the neuraminidases of mammalian origin seems to differ from the microbial variants in genetic sequences and enzymatic properties. Four mammalian neuraminidases, encoded by NEU1‐4, have been identified and characterized. Mice deficient in the lysosomal resident Neu1 have been reported with molecular features resembling sialidosis, a severe human lysosomal storage disorder, whilst Neu3 deficiency does not result in an obvious physiological phenotype. Neu1 is found in a complex with b‐galactosidase and protective protein/cathepsin A in the lysosome. The subcellular localization of Neu3 has been suggested to be the plasma membrane and endosomal compartments. Interestingly, the membrane attachment mechanism and topology is yet to be fully clarified, however Neu3 is commonly reported to be membrane‐associated. A variety of mammalian cell types express neuraminidases, including endothelial cells as well as hematopoietic lineages spanning platelets, monocytes, and the erythrocyte surface. Both Neu1 and Neu3 have been found in the bloodstream and in extracellular compartments, by one or more secretion mechanisms that are not fully defined. We have previously noted that circulating neuraminidase activity is measurable in normal mammalian blood at physiological pH, and de‐sialylate plasma proteins with increasing molecular age, and this was further demonstrated to result in lectin‐mediated clearance in the determinations of glycoprotein half‐lives. To further investigate the roles of each of these mammalian neuraminidases, we are using multiple approaches in Neu1‐ and Neu3‐deficient mice, including measurements with novel lectins that detect different types of sialic acid linkages and their modifications, among the endothelium and the surfaces of hematopoietic cells in parallel with comparative blood proteomics, flow cytometry, and other molecular identification strategies. These studies will be presented with our current findings that may provide further information regarding mammalian Neu activation and function in glycoprotein homeostasis.Support or Funding InformationNIH grant HL131474.Post Doctoral Fellowship: Swedish Research Council dnr 2017‐00192.
Desmopressin inhibit the proliferation and cellular migration in the OV‐90 ovarian cancer cell line
Authors: Calvillo-Robledo Argelia , González-Sánchez Zaira Samantha , Valdez-Urias Fernando , Gómora-Herrera María José , Quintanar-Stephano Andrés 
Published: April 2020

Epithelial ovarian cancer (EOC) is the most common and lethal of the ovarian neoplasms, frequently it is detected at advanced stages of the disease resulting in 60–70% of the cases in recurrence and less responsive to chemotherapy. Currently the role played by the neurohypophyseal hormone arginine vasopressin (AVP) and its receptors in the development of EOC is unknown. The purpose of this study was to evaluate the action of desmopressin (DDAVP), an AVP V2 receptor agonist on the cell proliferation and cell migration in cells from the OV‐90 cell line. Cell proliferation was evaluated with the proliferation marker Ki67, whereas the cells migration was evaluated by the wound assay. The AVP V1a and V2 receptors expression were assessed by immunofluorescence. Cell cultures were stimulated during 12, 24, 36 and 48 hours with DDAVP (500 to 1500 mM). In order to discard the cytotoxicity of DDAVP on the OV‐90 cell cultures in control and stimulated cultures the Cytotox 96 kit was used. The experiments were performed three times by duplicate. The results showed that the expression of AVP V1a and V2 receptors are present in both DDAVP stimulated and‐non stimulated cultures. On the other hand in comparison with the control cultures, doses of 1000mM of DDAVP significantly (p<0.05) inhibit both cell proliferation and cellular migration. Present results also suggests a possible inhibitory role of DDAVP on proliferation and cellular migration in the OV‐90 cell lines of epithelial ovarian cancer.Support or Funding InformationUniversidad Autónoma de Aguascalientes PIFF14‐1 and CONACYT 221262. México
THE CONTRIBUTION OF “In Vitro” SKELETAL MUSCLE FIBER BIOCHEMICAL TIMING ANALYSIS IN THE UNDERSTANDING OF ELECTROMYOGRAPHIC SPECTRUM
Authors: Acero-Mondragon Edward Javier , Urdaneta-Paredes Daniel Antonio , Chaustre-Nieto Luis Carlos , Gallego John Jairo , Leon-Ariza Henry , Botero-Rosas Daniel , Gutierrez-Arenaza Gerardo 
Published: April 2020

Introduction“In vivo” electromyography usually reports a frequency domain muscle activity in a broad Hertz spectrum that ranges from 1 Hz to 500 Hz. However, when the contiguous nicotinic biochemical events in rhabdomyocytes type Ia, IIa and IIb are timed “in vitro”, and then converted to Hertz. A reduced electromyographic frequency domain is obtained.Materials and MethodsGoogle Scholar databases and National Library of Medicine, were searched for articles published from 1990 to 2019 containing times of kynetic cell signalig in raddomiocytes type Ia IIa and IIB join terms like 1) “Title (TI)= ‘Time Acetylcholine exocytosis’ AND ‘Time Activation nicotinic receptor’ AND ‘Time Depolarization of sarcolemma’ AND ‘Excitation–contraction coupling’ AND ‘Time depolarization T‐tubule” AND ‘Cross‐bridge cycle’. The inclusion criteria were that each study involving a types of striated muscle fiber “In vitro” as an objective measure interaction Acetylcholine‐Nicotinic Recepptor and cascade cell signaling to evaluating speed of despolarizatig and every physiological contraction subphases of contraction. Once every time of physiological event of contraction was found, the time was added and then the mathematical inverse of the period in seconds was converted to frequency in Hertz.Results“In vitro” the total time events of contraction summed to striated muscle fiber Type IA were 3,33 ms; Fibers Type IIA were 6,81 ms; and Fibers Type IIB were 7,41 ms. Times that converted to Hertz show fiber type Ia, IIa IIb with 3,03 Hz, 1,46 Hz, 1,34 HzConclusionsThe electromiographic Hertz domain is made of a series of “noise” such as the different extracellular events that occur between inferior motor neurons and sarcolemmas. The present work aims to rationalize the obtained “in vitro” frequency spectrum values of 3,03 Hz, 1,46 Hz, 1,34 Hz for type Ia, IIa and IIb respectively.Support or Funding InformationUNIVERSIDAD DE LA SABANA
A Physical Model for Exploring Drug Design to Treat Break‐bone Fever
Authors: Jordan Sarah , Martindale Aidan W. , Heuss Aaron , Miller Dylan , Tamse Joshua , Hall Bonnie L. 
Published: April 2020

Annually, dengue fever affects an estimated 390 million people worldwide (more than the population of the entire United States). Symptoms include high fever, headache, vomiting, and muscle and joint pain so extreme it is also known as “break‐bone fever”. Severe infection can lead to dengue hemorrhagic fever, dengue shock syndrome, and can be fatal. The disease is transmitted by mosquitos in tropical areas, and is caused by the single‐stranded RNA dengue virus (DENV). Currently the only treatment for patients infected with DENV is rest and hydration. The Schiffer lab has focused on the DENV NS2/NS3 serine protease as a potential drug target, because it is essential for DENV maturation. The serine protease inhibitor aprotinin (CP1) was the starting point for design of cyclic peptide (CP) inhibitors targeting DENV protease. A series of CP‐inhibitors were designed and tested, each with varying chemical properties. We designed a physical model of the DENV protease active site that displays the interactions with six different CP‐inhibitors. The model demonstrates how CP‐inhibitor binding is impacted by drug size, flexibility, polarity, and ability to form intermolecular interactions (Lipinski’s Rule of Five). Our model also highlights how drug structure drives drug function, and connects meaningfully to undergraduate studies of biology and chemistry at many levels. The DENV protease active site model, with the set of six CP‐inhibitors, is a useful classroom tool to show how basic biological and chemical principals are relevant to modern drug design.Support or Funding InformationThe CREST Program is funded through DUE‐IUSE #1725940 awarded to Milwaukee School of Engineering Center for BioMolecular Modeling.
Cloning and Expression of Palmitoyl Protein Thioesterases and Acyl Protein Thioesterases for Use in Depalmitoylation Reactions
Authors: Esoe Dave-Preston I. , Erickson Jeffery A. , Hamann Michael J. 
Published: April 2020

Palmitoylation is a dynamic process for regulating protein function and localization. It involves the attachment of palmitate to protein cysteine residues by palmitoyl transferases and its removal by palmitoyl protein thioesterase (PPTs) or acyl protein thioesterases (APTs). Techniques to study palmitoylation are difficult to perform and use harsh depalmitoylating reagents like hydroxylamine (HAM), often leading to destruction of the protein being studied. Using recombinant or over‐expressed PPT/APTs could be used as an alternative to HAM for studying protein palmitoylation/depalmitoylation dynamics, as well as investigating PPT/APT substate specificities. We have cloned human APT and PPT cDNA for the production of GST or MBP‐tagged fusion proteins to be used in acyl‐biotin exchange assays. We have also produced mCherry‐tagged versions for co‐expression with a target protein of interest to evaluate their activities. In these experiments, we will focus on the Rho GTPase TCL/RhoJ, which was recently shown to associate with the plasma membrane through palmitoylation. Cherry‐tagged APT/PPTs will be co‐transfected with YFP‐tagged TCL to determine if TCL membrane association diminishes. Overall, the goal of these experiments is to improve techniques for studying protein palmitoylation/depalmitoylation.Support or Funding InformationThis work was supported by Bemidji State University Biology Department and the College of Business, Mathematics, and Science. Support was also provided through the Neilson Foundation, Bemidji, MN and Regenerative Medicine Minnesota (RMM‐2017‐EP‐04).
Letrozole modulates tyrosine phosphorylation in liver and kidney of polycystic ovarian syndrome rats
Authors: Chaiyamoon Arada , Bunsueb Sudtida , Reabroi Somrudee , Iamsaard Sitthichai 
Published: April 2020

Letrozole (Letro), a non‐steroidal aromatase inhibitor, is commonly used to reduce estrogen level for breast cancer treatment and delay cancer cell metastasis. Recently, Letro is used to induce the polycystic ovarian syndrome (PCOS) in rat model. Protein phosphorylation on tyrosine residues is a posttranslational modification known to regulate biological processes and physiological functions including reproduction. Although the adverse effects of Letro have been reported, the alterations of tyrosine phosphorylation responsible for liver and kidney functions are not demonstrated. In present investigation, PCOS in rats was induced by daily oral administration of Letro (1 mg/kg BW) for consecutive 21 days. After induction, the effects of Letro on serum biochemical components, liver, and kidney functions were examined. In addition, both tissues were subjected for expression of protein tyrosine phosphorylation using Western blotting analysis. Histopathology of liver and kidney was performed by Masson’s trichrome staining. The results showed that Letro did not affect histological features but markedly increased the serum levels of urea nitrogen, cholesterol, triglyceride, high‐density lipoprotein (HDL), low‐density lipoprotein (LDL), alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP). Interestingly, expressions of tyrosine phosphorylation of 32 and 27 kDa in liver and of 55 and 43 kDa in kidney were increased in PCOS group. In contrast, such expression of a 26 kDa in PCOS kidney was decreased as compared to those of control. Our findings suggest that alterations of liver and kidney parameters in the Letro‐induced PCOS rat model may associate with modulation of the tyrosine phosphorylation.Support or Funding InformationKhon Kaen University