oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2673 )

( 2672 )

( 2208 )

( 2024 )

自定义范围…

匹配条件： “Larry A. Sklar” ，找到相关结果约552049条。
列表显示的所有文章，均可免费获取
第1页/共552049条
每页显示 条
Targeting GTPases in Parkinson’s disease: comparison to the historic path of kinase drug discovery and perspectives
Lin Hong,Larry A. Sklar
Frontiers in Molecular Neuroscience , 2014, DOI: 10.3389/fnmol.2014.00052
Abstract: Neurological diseases have placed heavy social and financial burdens on modern society. As the life expectancy of humans is extended, neurological diseases, such as Parkinson’s disease, have become increasingly common among senior populations. Although the enigmas of Parkinson’s diseases await resolution, more vivid pictures on the cause, progression, and control of the illness are emerging after years of research. On the molecular level, GTPases are implicated in the etiology of Parkinson’s disease and are rational pharmaceutical targets for their control. However, targeting individual GTPases, which belong to a superfamily of proteins containing multiple members with a conserved guanine nucleotide binding domain, has proven to be challenging. In contrast, pharmaceutical pursuit of inhibition of kinases, which constitute another superfamily of proteins with more than 500 members, has been fairly successful. We reviewed the breakthroughs in the history of kinase drug discovery to provide guidance for the GTPase field. We summarize recent progress made in the regulation of GTPase activity. We also present an efficient and cost effective approach to drug screening, which uses multiplex flow cytometry and mixture-based positional scanning libraries. These methods allow simultaneous measurements of both the activity and the selectivity of the screened library. Several GTPase activator clusters were identified which showed selectivity against different GTPase subfamilies. While the clusters need to be further deconvoluted to identify individual active compounds, the method described here and the structure information gathered create a foundation for further developments to build upon.
Nitric oxide/cGMP pathway signaling actively down-regulates α4β1-integrin affinity: an unexpected mechanism for inducing cell de-adhesion
Alexandre Chigaev, Yelena Smagley, Larry A Sklar
BMC Immunology , 2011, DOI: 10.1186/1471-2172-12-28
Abstract: Using fluorescent ligand binding to evaluate the integrin activation state on live cells in real-time, we show that several small molecules, which specifically modulate nitric oxide/cGMP signaling pathway, as well as a cell permeable cGMP analog, can rapidly down-modulate binding of a VLA-4 specific ligand on cells pre-activated through three Gαi-coupled receptors: wild type CXCR4, CXCR2 (IL-8RB), and a non-desensitizing mutant of formyl peptide receptor (FPR ΔST). Upon signaling, we detected rapid changes in the ligand dissociation rate. The dissociation rate after inside-out integrin de-activation was similar to the rate for resting cells. In a VLA-4/VCAM-1-specific myeloid cell adhesion system, inhibition of the VLA-4 affinity change by nitric oxide had a statistically significant effect on real-time cell aggregation.We conclude that nitric oxide/cGMP signaling pathway can rapidly down-modulate the affinity state of the VLA-4 binding pocket, especially under the condition of sustained Gαi-coupled GPCR signaling, generated by a non-desensitizing receptor mutant. This suggests a fundamental role of this pathway in de-activation of integrin-dependent cell adhesion.Integrins are ubiquitous cell adhesion molecules that play an essential role in the regulation of leukocyte traffic, stem cell mobilization and homing, immune responses, development, hemostasis, and cancer [1-3]. On the cell surface at rest, a variety of integrin exhibit a non-adhesive inactive state and multiple signaling cascades are capable of rapidly and reversibly regulating integrin-dependent cell adhesion. Typically, this regulation is achieved without altering the integrin expression level. Conformational changes within the molecule, together with a spatial reorganization of integrins, are responsible for the rapid modulation of cell adhesion [1,4-6]. Understanding signaling pathways that regulate activation and, especially, inactivation of integrin-mediated cell adhesion is crucial, as integrins a
Galphas-coupled receptor signaling actively down-regulates α4β1-integrin affinity: A possible mechanism for cell de-adhesion
Alexandre Chigaev, Anna Waller, Or Amit, Larry A Sklar
BMC Immunology , 2008, DOI: 10.1186/1471-2172-9-26
Abstract: Using real-time fluorescent ligand binding to assess affinity and a FRET based assay to probe α4β1-integrin unbending, we show that two Gαs-coupled GPCRs (H2-histamine receptor and β2-adrenergic receptor) as well as several cAMP agonists can rapidly down modulate the affinity of VLA-4 activated through two Gαi-coupled receptors (CXCR4 and FPR) in U937 cells and primary human peripheral blood monocytes. This down-modulation can be blocked by receptor-specific antagonists. The Gαs-induced responses were not associated with changes in the expression level of the Gαi-coupled receptors. In contrast, the molecular unbending of VLA-4 was not significantly affected by Gαs-coupled GPCR signaling. In a VLA-4/VCAM-1-specific myeloid cell adhesion system, inhibition of the VLA-4 affinity change by Gαs-coupled GPCR had a statistically significant effect upon cell aggregation.We conclude that Gαs-coupled GPCRs can rapidly down modulate the affinity state of VLA-4 binding pocket through a cAMP dependent pathway. This plays an essential role in the regulation of cell adhesion. We discuss several possible implications of this described phenomenon.Integrins, one of the largest families of cell adhesion molecules play an important role in the regulation of immune responses and leukocyte traffic, development, hemostasis, and cancer [1]. A unique feature of integrins is in their ability to rapidly and reversibly regulate cell adhesion, and thereby modulate cell recruitment and homing, without a significant change in the expression of the molecule. Understanding the molecular mechanisms that regulate rapid changes in cell adhesion avidity is essential, since integrins are known to play roles in many human diseases. They represent an attractive target for several existing and emerging drugs for treatment of inflammatory diseases, anti-angiogenic cancer therapy, anti-thrombotic therapy, and others [2-5].α4β1-integrin (CD49d/CD29, Very Late Antigen-4, VLA-4) is expressed on peripheral blood
High
Alexandre Chigaev,Bruce S. Edwards,Dominique R. Perez,Larry A. Sklar
- , 2018, DOI: 10.1177/2472555218775913
Abstract: Classical therapeutic regimens are subject to toxicity, low efficacy, and/or the development of drug resistance. Thus, the discovery of synergistic drug combinations would permit treatment with lower, tolerable dosages of each agent and restored sensitivity. We describe the development and use of the SynScreen software application, which allows for visual and mathematical determinations of compound concentrations that produce super-additive effects. This software uses nonlinear regression fits of dose responses to determine synergism by the Bliss independence and Loewe additivity analysis models. We demonstrate the utility of SynScreen with data analysis from in vitro high-throughput flow cytometry (HTFC) combination screens with repurposed drugs and multiplexed synergy analysis of multiple biologic parameters in parallel. The applicability of SynScreen was confirmed by testing open-source data sets used in published drug combination literature. A key benefit of SynScreen for high-throughput drug combination screening is that observed measurements are graphically depicted in comparison with a three-dimensional surface that represents the theoretical responses at which Bliss additivity would occur. These images and summary tables for the calculated drug interactions are automatically exported. This allows for substantial data sets to be visually assessed, expediting the quick identification of efficacious drug combinations and thereby facilitating the design of confirmatory studies and clinical trials
The Mathematics of a Successful Deconvolution: A Quantitative Assessment of Mixture-Based Combinatorial Libraries Screened Against Two Formylpeptide Receptors
Radleigh G. Santos,Jon R. Appel,Marc A. Giulianotti,Bruce S. Edwards,Larry A. Sklar,Richard A. Houghten,Clemencia Pinilla
Molecules , 2013, DOI: 10.3390/molecules18066408
Abstract: In the past 20 years, synthetic combinatorial methods have fundamentally advanced the ability to synthesize and screen large numbers of compounds for drug discovery and basic research. Mixture-based libraries and positional scanning deconvolution combine two approaches for the rapid identification of specific scaffolds and active ligands. Here we present a quantitative assessment of the screening of 32 positional scanning libraries in the identification of highly specific and selective ligands for two formylpeptide receptors. We also compare and contrast two mixture-based library approaches using a mathematical model to facilitate the selection of active scaffolds and libraries to be pursued for further evaluation. The flexibility demonstrated in the differently formatted mixture-based libraries allows for their screening in a wide range of assays.
Identification of Isoxsuprine Hydrochloride as a Neuroprotectant in Ischemic Stroke through Cell-Based High-Throughput Screening
Jeff W. Hill, Jeffrey F. Thompson, Mark B. Carter, Bruce S. Edwards, Larry A. Sklar, Gary A. Rosenberg
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096761
Abstract: Stroke is a leading cause of death and disability and treatment options are limited. A promising approach to accelerate the development of new therapeutics is the use of high-throughput screening of chemical libraries. Using a cell-based high-throughput oxygen-glucose deprivation (OGD) model, we evaluated 1,200 small molecules for repurposed application in stroke therapy. Isoxsuprine hydrochloride was identified as a potent neuroprotective compound in primary neurons exposed to OGD. Isoxsuprine, a β2-adrenergic agonist and NR2B subtype-selective N-methyl-D-aspartate (NMDA) receptor antagonist, demonstrated no loss of efficacy when administered up to an hour after reoxygenation in an in vitro stroke model. In an animal model of transient focal ischemia, isoxsuprine significantly reduced infarct volume compared to vehicle (137±18 mm3 versus 279±25 mm3, p<0.001). Isoxsuprine, a peripheral vasodilator, was FDA approved for the treatment of cerebrovascular insufficiency and peripheral vascular disease. Our demonstration of the significant and novel neuroprotective action of isoxsuprine hydrochloride in an in vivo stroke model and its history of human use suggest that isoxsuprine may be an ideal candidate for further investigation as a potential stroke therapeutic.
A High
Bruce S. Edwards,Catherine Gineste,Dominique Perez,Kaylin R. Lake,Larry A. Sklar,Tione Buranda,Virginie Bondu,Yang Wu
- , 2018, DOI: 10.1177/2472555218766623
Abstract: Hantaviruses cause hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS), which infects more than 200,000 people worldwide. Sin Nombre virus (SNV) and Andes virus (ANDV) cause the most severe form of HCPS, with case fatality ratios of 30%–40%. There are no specific therapies or vaccines for SNV. Using high-throughput flow cytometry, we screened the Prestwick Chemical Library for small-molecule inhibitors of the binding interaction between UV-inactivated and fluorescently labeled SNVR18 particles, and decay-accelerating factor (DAF) expressed on Tanoue B cells. Eight confirmed hit compounds from the primary screen were investigated further in secondary screens that included infection inhibition, cytotoxicity, and probe interference. Antimycin emerged as a bona fide hit compound that inhibited cellular infection of the major HCPS (SNV)- and HCPS (Hantaan)-causing viruses. Confirming our assay’s ability to detect active compounds, orthogonal testing of the hit compound showed that antimycin binds directly to the virus particle and blocks recapitulation of physiologic integrin activation caused by SNV binding to the integrin PSI domain
Far away from the lamppost
Avi Ma’ayan,Brian K. Shoichet,Bryan L. Roth,Gary L. Johnson,Larry A. Sklar,Lily Jan,Michael T. McManus,Stephan Schürer,Tudor I. Oprea
- , 2018, DOI: 10.1371/journal.pbio.3000067
Abstract:
High
Abigail J. Morales,Andrea L. Bredemeyer,Anna Waller,Barry P. Sleckman,Bruce S. Edwards,Larry A. Sklar,Mark K. Haynes,Oleg Ursu,Yinan Wang
- , 2018, DOI: 10.1177/2472555217746324
Abstract: DNA double-strand breaks (DSBs) are repaired primarily by homologous recombination (HR) or nonhomologous end joining (NHEJ). Compounds that modulate HR have shown promise as cancer therapeutics. The V(D)J recombination reaction, which assembles antigen receptor genes in lymphocytes, is initiated by the introduction of DNA DSBs at two recombining gene segments by the RAG endonuclease, followed by the NHEJ-mediated repair of these DSBs. Here, using HyperCyt automated flow cytometry, we develop a robust high-throughput screening (HTS) assay for NHEJ that utilizes engineered pre-B-cell lines where the V(D)J recombination reaction can be induced and monitored at a single-cell level. This approach, novel in processing four 384-well plates at a time in parallel, was used to screen the National Cancer Institute NeXT library to identify compounds that inhibit V(D)J recombination and NHEJ. Assessment of cell light scattering characteristics at the primary HTS stage (83,536 compounds) enabled elimination of 60% of apparent hits as false positives. Although all the active compounds that we identified had an inhibitory effect on RAG cleavage, we have established this as an approach that could identify compounds that inhibit RAG cleavage or NHEJ using new chemical libraries
A Novel Flow Cytometric HTS Assay Reveals Functional Modulators of ATP Binding Cassette Transporter ABCB6
Kishore Polireddy, Mohiuddin Md. Taimur Khan, Hemantkumar Chavan, Susan Young, Xiaochao Ma, Anna Waller, Matthew Garcia, Dominique Perez, Stephanie Chavez, Jacob J. Strouse, Mark K. Haynes, Cristian G. Bologa, Tudor I. Oprea, George P. Tegos, Larry A. Sklar, Partha Krishnamurthy
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040005
Abstract: ABCB6 is a member of the adenosine triphosphate (ATP)-binding cassette family of transporter proteins that is increasingly recognized as a relevant physiological and therapeutic target. Evaluation of modulators of ABCB6 activity would pave the way toward a more complete understanding of the significance of this transport process in tumor cell growth, proliferation and therapy-related drug resistance. In addition, this effort would improve our understanding of the function of ABCB6 in normal physiology with respect to heme biosynthesis, and cellular adaptation to metabolic demand and stress responses. To search for modulators of ABCB6, we developed a novel cell-based approach that, in combination with flow cytometric high-throughput screening (HTS), can be used to identify functional modulators of ABCB6. Accumulation of protoporphyrin, a fluorescent molecule, in wild-type ABCB6 expressing K562 cells, forms the basis of the HTS assay. Screening the Prestwick Chemical Library employing the HTS assay identified four compounds, benzethonium chloride, verteporfin, tomatine hydrochloride and piperlongumine, that reduced ABCB6 mediated cellular porphyrin levels. Validation of the identified compounds employing the hemin-agarose affinity chromatography and mitochondrial transport assays demonstrated that three out of the four compounds were capable of inhibiting ABCB6 mediated hemin transport into isolated mitochondria. However, only verteporfin and tomatine hydrochloride inhibited ABCB6’s ability to compete with hemin as an ABCB6 substrate. This assay is therefore sensitive, robust, and suitable for automation in a high-throughput environment as demonstrated by our identification of selective functional modulators of ABCB6. Application of this assay to other libraries of synthetic compounds and natural products is expected to identify novel modulators of ABCB6 activity.
第1页/共552049条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.