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A high-throughput fluorescence-anisotropy screen that identifies small molecule inhibitors of the DNA binding of B-ZIP transcription factors.

We have developed a high-throughput fluorescence anisotropy screen, using a 384-well format, to identify small molecules that disrupt the DNA binding of B-ZIP proteins. Binding of a B-ZIP dimer to fluorescently labeled DNA can be monitored by fluorescence anisotropy. We screened the National Cancer Institute diversity set of 1990 compounds to identify small molecules that disrupt the B-ZIP|DNA complex of CREB, C/EBPbeta, VBP, and AP-1 (FOS|JUND) bound to their cognate DNA sequence. We identified 21 compounds that inhibited the DNA binding of at least one B-ZIP protein, and 12 representative compounds were grouped depending on whether they displaced ethidium bromide from DNA. Of the 6 compounds that did not displace ethidium bromide, 2 also inhibited B-ZIP binding to DNA in a secondary electrophoretic mobility shift assay screen with some specificity. Thermal stability monitored by circular dichroism spectroscopy demonstrated that both compounds bound the basic region of the B-ZIP motif. NSC13778 preferentially binds C/EBPalpha 1000-fold better than it binds C/EBPbeta. Chimeric proteins combining C/EBPalpha and C/EBPbeta mapped the binding of NSC13778 to three amino acids immediately N terminal of the leucine zipper of C/EBPalpha. These experiments suggest that the DNA binding of B-ZIP transcription factors is a potential target for clinical intervention.

Amino Acid Sequence↗

Cyclolignans from Scyphocephalium ochocoa via high-throughput natural product chemistry methods.

Two 2,7'-cyclolignans, ocholignans A and B, were obtained as mass-limited samples from Scyphocephalium ochocoa via high-throughput natural products chemistry methods. The rapid structure elucidation of each compound was primarily facilitated by NMR data acquisition using a capillary-scale NMR probe, CapNMR probe. Ocholignan A was found to possess significant in vitro antibacterial activity against Gram-positive bacteria methicillin-resistant Staphylococcus aureus ATCC 33591 and S. aureus 78-13607A with a MIC of 16 microg/mL, respectively.

Anti-Bacterial Agents↗

High-throughput assay to monitor formation of the E2-ubiquitin thioester intermediate.

Targeting components of ubiquitination pathways for drug discovery necessitates the development of high-capacity assays that monitor the ubiquitination process at defined steps of the E1-E2-E3 cascade. This chapter describes the development of an assay based on time-resolved fluorescence to monitor formation of the thioester intermediate between ubiquitin-conjugating enzymes (E2s) and ubiquitin. The methodology is exemplified by an assay tailored for the ubiquitin-conjugating enzyme Cdc34. This assay setup can be easily adapted to other E2s and is suitable to screen small molecule inhibitors of E2-thioester formation in a high-throughput mode.

Anaphase-Promoting Complex-Cyclosome↗

Antibodies in proteomics II: screening, high-throughput characterization and downstream applications.

There are many ways in which the use of antibodies and antibody selection can be improved and developed for high-throughput characterization. Standard protocols, such as immunoprecipitation, western blotting and immunofluorescence, can be used with antibody fragments generated by display technologies. Together with novel approaches, such as antibody chips and intracellular immunization, these methods will yield useful proteomic data following adaptation of the protocols for increased reliability and robustness. To date, most work has focused on the use of standard, well-characterized commercial antibodies. Such protocols need to be adapted for broader use, for example, with antibody fragments or other binders generated by display technologies, because it is unlikely that traditional approaches will provide the required throughput.

Antibodies↗

High-throughput fingerprinting of bacterial artificial chromosomes using the snapshot labeling kit and sizing of restriction fragments by capillary electrophoresis.

We have developed an automated, high-throughput fingerprinting technique for large genomic DNA fragments suitable for the construction of physical maps of large genomes. In the technique described here, BAC DNA is isolated in a 96-well plate format and simultaneously digested with four 6-bp-recognizing restriction endonucleases that generate 3' recessed ends and one 4-bp-recognizing restriction endonuclease that generates a blunt end. Each of the four recessed 3' ends is labeled with a different fluorescent dye, and restriction fragments are sized on a capillary DNA analyzer. The resulting fingerprints are edited with a fingerprint-editing computer program and contigs are assembled with the FPC computer program. The technique was evaluated by repeated fingerprinting of several BACs included as controls in plates during routine fingerprinting of a BAC library and by reconstruction of contigs of rice BAC clones with known positions on rice chromosome 10.

Chromosome Mapping↗

Analysis of a high-throughput yeast two-hybrid system and its use to predict the function of intracellular proteins encoded within the human MHC class III region.

High-throughput (HTP) protein-interaction assays, such as the yeast two-hybrid (Y2H) system, are enormously useful in predicting the functions of novel gene-products. HTP-Y2H screens typically do not include all of the reconfirmation and specificity tests used in small-scale studies, but the effects of omitting these steps have not been assessed. We performed HTP-Y2H screens that included all standard controls, using the predicted intracellular proteins expressed from the human MHC class III region, a region of the genome associated with many autoimmune diseases. The 91 novel interactions identified provide insight into the potential functions of many MHC genes, including C6orf47, LSM2, NELF-E (RDBP), DOM3Z, STK19, PBX2, RNF5, UAP56 (BAT1), ATP6G2, LST1/f, BAT2, Scythe (BAT3), CSNK2B, BAT5, and CLIC1. Surprisingly, our results predict that 1/3 of the proteins may have a role in mRNA processing, which suggests clustering of functionally related genes within the human genome. Most importantly, our analysis shows that omitting standard controls in HTP-Y2H screens could significantly compromise data quality.

Genes, Reporter↗

Integrative analysis of genome-wide experiments in the context of a large high-throughput data compendium.

Biological systems are orchestrated by heterogeneous regulatory programs that control complex processes and adapt to a dynamic environment. Recent advances in high-throughput experimental methods provide genome-wide perspectives on such regulatory programs. A considerable amount of data on the behavior of model systems in a variety of conditions is rapidly accumulating. Still, the dominant paradigm is to analyze new genome-wide experiments separately from any other extant data, for example, by clustering the new data alone. Here we introduce a new methodology for analyzing the results of a new functional genomic study vis-à-vis a large compendium of previously published results from heterogeneous experimental techniques. We demonstrate our methodology on Saccharomyces cerevisiae, using a compendium of some 2000 experiments from 60 different publications. Most importantly, we show how the integrated analysis reveals unexpected connections among biological processes, and differentiates between novel and known effects in the analyzed experiments. Such characterization is impossible when new data sets are studied in isolation. Our results exemplify the power of the integrative approach in the analysis of genomic scale data sets and call for a paradigm shift in their study.

Algorithms↗

Joining high-throughput technology with in silico modelling advances genome-wide screening towards targeted discovery.

Genome research has entered the functional evaluation phase now and high-throughput (HT) methods provide an enormous amount of raw data for that purpose. However, functional verification still requires experimental regimens not suitable for application in a HT style, requiring an efficient discovery and selection process pinpointing biological mechanisms and processes for subsequent targeted verification. Regulatory networks and underlying molecular mechanisms can now be deduced through the interpretation of HT-data in the context of biologic knowledge. Computational models of promoter structures are suitable for genome-wide searches and a number of recent examples demonstrate their usefulness in prediction and selection of functional targets for experimental verification.

Computer Simulation↗

A novel high-throughput (HTP) cloning strategy for site-directed designed chimeragenesis and mutation using the Gateway cloning system.

There is an increasing demand for easy, high-throughput (HTP) methods for protein engineering to support advances in the development of structural biology, bioinformatics and drug design. Here, we describe an N- and C-terminal cloning method utilizing Gateway cloning technology that we have adopted for chimeric and mutant genes production as well as domain shuffling. This method involves only three steps: PCR, in vitro recombination and transformation. All three processes consist of simple handling, mixing and incubation steps. We have characterized this novel HTP method on 96 targets with >90% success. Here, we also discuss an N- and C-terminal cloning method for domain shuffling and a combination of mutation and chimeragenesis with two types of plasmid vectors.

Cloning, Molecular↗

Validation of FLIPR membrane potential dye for high throughput screening of potassium channel modulators.

A fluorescence-based assay using the FLIPR Membrane Potential Assay Kit (FMP) was evaluated for functional characterization and high throughput screening (HTS) of potassium channel (ATP-sensitive K+ channel; K(ATP)) modulators. The FMP dye permits a more sensitive evaluation of changes in membrane potential with a more rapid response time relative to DiBAC4(3). The time course of responses is comparable to ligand-evoked activation of the channel measured by patch-clamp studies. The pharmacological profile of the K+ channel evaluated by using reference K(ATP) channel openers is in good agreement with that derived previously by DiBAC4(3)-based FLIPR assays. Improved sensitivity of responses together with the diminished susceptibility to artifacts such as those evoked by fluorescent compounds or quenching agents makes the FMP dye an alternative choice for HTS screening of potassium channel modulators.

Animals↗

Assay for ubiquitin ligase activity: high-throughput screen for inhibitors of HDM2.

An assay for the autoubiquitination activity of the E3 ligase HDM2 (Mdm2) was developed and adapted to a high-throughput format to identify inhibitors of this activity. The assay can also be used to measure the activity of other E3s and may be useful in finding both inhibitors and activators of a wide range of different ubiquitin ligases.

Animals↗

A Simple Statistical Parameter for Use in Evaluation and Validation of High Throughput Screening Assays.

The ability to identify active compounds (³hits²) from large chemical libraries accurately and rapidly has been the ultimate goal in developing high-throughput screening (HTS) assays. The ability to identify hits from a particular HTS assay depends largely on the suitability or quality of the assay used in the screening. The criteria or parameters for evaluating the ³suitability² of an HTS assay for hit identification are not well defined and hence it still remains difficult to compare the quality of assays directly. In this report, a screening window coefficient, called ³Z-factor,² is defined. This coefficient is reflective of both the assay signal dynamic range and the data variation associated with the signal measurements, and therefore is suitable for assay quality assessment. The Z-factor is a dimensionless, simple statistical characteristic for each HTS assay. The Z-factor provides a useful tool for comparison and evaluation of the quality of assays, and can be utilized in assay optimization and validation.

Journal Article↗

Performance of high-throughput DNA quantification methods.

BACKGROUND: The accuracy and precision of estimates of DNA concentration are critical factors for efficient use of DNA samples in high-throughput genotype and sequence analyses. We evaluated the performance of spectrophotometric (OD) DNA quantification, and compared it to two fluorometric quantification methods, the PicoGreen assay (PG), and a novel real-time quantitative genomic PCR assay (QG) specific to a region at the human BRCA1 locus. Twenty-Two lymphoblastoid cell line DNA samples with an initial concentration of approximately 350 ng/uL were diluted to 20 ng/uL. DNA concentration was estimated by OD and further diluted to 5 ng/uL. The concentrations of multiple aliquots of the final dilution were measured by the OD, QG and PG methods. The effects of manual and robotic laboratory sample handling procedures on the estimates of DNA concentration were assessed using variance components analyses. RESULTS: The OD method was the DNA quantification method most concordant with the reference sample among the three methods evaluated. A large fraction of the total variance for all three methods (36.0-95.7%) was explained by sample-to-sample variation, whereas the amount of variance attributable to sample handling was small (0.8-17.5%). Residual error (3.2-59.4%), corresponding to un-modelled factors, contributed a greater extent to the total variation than the sample handling procedures. CONCLUSION: The application of a specific DNA quantification method to a particular molecular genetic laboratory protocol must take into account the accuracy and precision of the specific method, as well as the requirements of the experimental workflow with respect to sample volumes and throughput. While OD was the most concordant and precise DNA quantification method in this study, the information provided by the quantitative PCR assay regarding the suitability of DNA samples for PCR may be an essential factor for some protocols, despite the decreased concordance and precision of this method.

Analysis of Variance↗

Investigation of different transcript quantitation tools for high-throughput mapping of brain gene expression using voxelation.

Voxelation is a new approach for genome scale acquisition of brain gene expression patterns. The method employs high-throughput analysis of spatially registered voxels (cubes) to create multiple volumetric images of brain gene expression, similar to those obtained from biomedical imaging systems. The spatial resolution of voxelation depends on voxel size, with smaller voxels giving higher resolution. An important question is the applicability of different transcript profiling tools for the various levels of resolution that can be employed. Here, we describe the use of three methods to analyze voxel transcript abundance: real-time PCR, microarray analysis and linear amplification coupled with microarrays. We show statistically significant concordance between real-time PCR and microarray analysis for the myelin basic protein gene in human brain specimens at differing levels of spatial resolution. In addition, we also demonstrate the feasibility of using linear amplification coupled with microarray analysis to create voxelation maps from the mouse brain at high resolution, 1 microl. These data indicate the suitability of a number of transcript profiling tools for various levels of spatial resolution in voxelation.

Brain↗

High-throughput bioanalytical LC/MS/MS determination of benzodiazepines in human urine: 1000 samples per 12 hours.

The analytical capabilities of liquid chromatography tandem mass spectrometry for sensitive and highly selective determination of target compounds in complex biological samples makes it well suited for high-throughput analysis. We report the fast separation of six benzodiazepines isolated from human urine via selected reaction monitoring liquid chromatography/mass spectrometry using short dwell times to accommodate fast-eluting chromatographic peaks. The analytes were extracted from human urine samples along with their deuterium-labeled internal standards by a simple liquid-liquid extraction in 96-well plates. Using four autosamplers coupled to one chromatographic column and one tandem mass spectrometer operated in the turbo ion spray mode with positive ion detection, 1152 samples (12 96-well plates) were analyzed in less than 12 h. Through an electronic switching box designed and constructed in-house, the autosamplers were synchronized with the mass spectrometer so that injections were made as soon as the mass spectrometer was ready to collect data. Each run required 30 s to complete with another 7-8 s for the data system to load the next data file to be collected. Chromatographic integrity and ion current response remained relatively constant for the duration of the analyses. The results show acceptable precision and accuracy and demonstrate the feasibility of using fast separations with tandem mass spectrometry for high-throughout analysis of biological samples containing multiple analytes.

Benzodiazepines↗

High-throughput liquid chromatography ultraviolet/mass spectrometric analysis of combinatorial libraries using an eight-channel multiplexed electrospray time-of-flight mass spectrometer.

We report a high-throughput liquid chromatography/mass spectrometry (LC/MS) protocol for analyzing large combinatorial libraries using an eight-channel parallel LC/UV/MS (MUX-LCT) system. System configuration, linear response range in UV absorbance, LC column selection, and flow rate were optimized for 24 h/7 day unattended operations. Combinatorial libraries were analyzed on this system at a rate of 3200 compounds per day for a 3.5 min cycle time per injection. This parallel system is compared with a single-channel system in terms of performance and operation.

Journal Article↗

A novel high throughput quantum dot-based fluorescence assay for quantitation of virus binding and attachment.

Quantum dots (QDots) are fluorescent semiconductor nanocrystals with a narrow emission spectrum, high quantum yield, and excellent photostability. These unique properties of QDots have been utilized to develop a fluorescent binding assay using biotinylated human T cell leukemia virus type 1 (biot-HTLV-1) conjugated with streptavidin-coated QDots that enabled both qualitative and quantitative analyses of viral binding. The specificity and linearity of the assay was demonstrated utilizing T cells, the primary HTLV-1-susceptible cell population. Furthermore, differential binding of HTLV-1 was analyzed in additional cell types of clinical relevance including primary CD4(+) and CD8(+) T cells, dendritic cells (DCs), monocytes, bone marrow progenitor cells, and epithelial cells. DCs exhibited maximum binding affinity when compared to other examined cell types except the Jurkat and SUP-T1 T cell lines. Finally, blocking antibodies directed against a putative HTLV-1 receptor on DCs; DC-SIGN (dendritic cell-specific ICAM-3-grabbing non-integrin), were utilized to study the inhibition of HTLV-1 binding to target cells. Overall, these results demonstrated that this novel high throughput assay can be utilized to study the binding of a biotinylated virus and has implications for screening of viral binding inhibitors as well as host membrane proteins that may serve as receptors for viral entry.

Biotinylation↗

High-throughput synthesis optimization of sulfonamide NPY Y5 antagonists.

A series of sulfonamide neuropeptide Y Y5 antagonists was optimized by preparation of sets of analogues using high-throughput synthesis and purification techniques. Testing of these compounds for their ability to bind to the human NPY Y5 receptor revealed separate SAR trends for sulfonamide amides versus sulfonamide ureas versus sulfonamide amines. By understanding these SAR trends, potent compounds were identified in all three series.

Amines↗