scholarly journals Red-Shifted FRET Biosensors for High-Throughput Fluorescence Lifetime Screening

Biosensors ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 99 ◽  
Author(s):  
Tory Schaaf ◽  
Ang Li ◽  
Benjamin Grant ◽  
Kurt Peterson ◽  
Samantha Yuen ◽  
...  
Keyword(s):  
High Precision ◽  
Small Molecule ◽  
High Throughput ◽  
Fluorescence Lifetime ◽  
High Throughput Screening ◽  
Structural Changes ◽  
Dynamic Range ◽  
Resonance Energy ◽  
Fluorescence Measurements ◽  
Fret Biosensors

We have developed fluorescence resonance energy transfer (FRET) biosensors with red-shifted fluorescent proteins (FP), yielding improved characteristics for time-resolved (lifetime) fluorescence measurements. In comparison to biosensors with green and red FRET pairs (GFP/RFP), FPs that emit at longer wavelengths (orange and maroon, OFP/MFP) increased the FRET efficiency, dynamic range, and signal-to-background of high-throughput screening (HTS). OFP and MFP were fused to specific sites on the human cardiac calcium pump (SERCA2a) for detection of structural changes due to small-molecule effectors. When coupled with a recently improved HTS fluorescence lifetime microplate reader, this red-shifted FRET biosensor enabled high-precision nanosecond-resolved fluorescence decay measurements from microliter sample volumes at three minute read times per 1536-well-plate. Pilot screens with a library of small-molecules demonstrate that the OFP/MFP FRET sensor substantially improves HTS assay quality. These high-content FRET methods detect minute FRET changes with high precision, as needed to elucidate novel structural mechanisms from small-molecule or peptide regulators discovered through our ongoing HTS efforts. FRET sensors that emit at longer wavelengths are highly attractive to the FRET biosensor community for drug discovery and structural interrogation of new therapeutic targets.

scholarly journals High-Throughput Spectral and Lifetime-Based FRET Screening in Living Cells to Identify Small-Molecule Effectors of SERCA

2016 ◽  
Vol 22 (3) ◽  
pp. 262-273 ◽  
Author(s):  
Tory M. Schaaf ◽  
Kurt C. Peterson ◽  
Benjamin D. Grant ◽  
Prachi Bawaskar ◽  
Samantha Yuen ◽  
...  
Keyword(s):  
High Precision ◽  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening ◽  
Fluorescent Protein ◽  
Resonance Energy ◽  
Living Cells ◽  
Spectral Unmixing ◽  
Detection Methods ◽  
Response Curves

A robust high-throughput screening (HTS) strategy has been developed to discover small-molecule effectors targeting the sarco/endoplasmic reticulum calcium ATPase (SERCA), based on a fluorescence microplate reader that records both the nanosecond decay waveform (lifetime mode) and the complete emission spectrum (spectral mode), with high precision and speed. This spectral unmixing plate reader (SUPR) was used to screen libraries of small molecules with a fluorescence resonance energy transfer (FRET) biosensor expressed in living cells. Ligand binding was detected by FRET associated with structural rearrangements of green fluorescent protein (GFP, donor) and red fluorescent protein (RFP, acceptor) fused to the cardiac-specific SERCA2a isoform. The results demonstrate accurate quantitation of FRET along with high precision of hit identification. Fluorescence lifetime analysis resolved SERCA’s distinct structural states, providing a method to classify small-molecule chemotypes on the basis of their structural effect on the target. The spectral analysis was also applied to flag interference by fluorescent compounds. FRET hits were further evaluated for functional effects on SERCA’s ATPase activity via both a coupled-enzyme assay and a FRET-based calcium sensor. Concentration-response curves indicated excellent correlation between FRET and function. These complementary spectral and lifetime FRET detection methods offer an attractive combination of precision, speed, and resolution for HTS.

scholarly journals Spectral Unmixing Plate Reader: High-Throughput, High-Precision FRET Assays in Living Cells

2016 ◽  
Vol 22 (3) ◽  
pp. 250-261 ◽  
Author(s):  
Tory M. Schaaf ◽  
Kurt C. Peterson ◽  
Benjamin D. Grant ◽  
David D. Thomas ◽  
Gregory D. Gillispie
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Structural Changes ◽  
Fluorescent Protein ◽  
Fluorescence Emission ◽  
Resonance Energy ◽  
Living Cells ◽  
Spectral Unmixing ◽  
Fluorescence Emission Spectrum ◽  
Plate Reader

We have developed a microplate reader that records a complete high-quality fluorescence emission spectrum on a well-by-well basis under true high-throughput screening (HTS) conditions. The read time for an entire 384-well plate is less than 3 min. This instrument is particularly well suited for assays based on fluorescence resonance energy transfer (FRET). Intramolecular protein biosensors with genetically encoded green fluorescent protein (GFP) donor and red fluorescent protein (RFP) acceptor tags at positions sensitive to structural changes were stably expressed and studied in living HEK cells. Accurate quantitation of FRET was achieved by decomposing each observed spectrum into a linear combination of four component (basis) spectra (GFP emission, RFP emission, water Raman, and cell autofluorescence). Excitation and detection are both conducted from the top, allowing for thermoelectric control of the sample temperature from below. This spectral unmixing plate reader (SUPR) delivers an unprecedented combination of speed, precision, and accuracy for studying ensemble-averaged FRET in living cells. It complements our previously reported fluorescence lifetime plate reader, which offers the feature of resolving multiple FRET populations within the ensemble. The combination of these two direct waveform-recording technologies greatly enhances the precision and information content for HTS in drug discovery.

scholarly journals Development of a Novel High-Throughput Screen and Identification of Small-Molecule Inhibitors of the Gα–RGS17 Protein–Protein Interaction Using AlphaScreen

2011 ◽  
Vol 16 (8) ◽  
pp. 869-877 ◽  
Author(s):  
Duncan I. Mackie ◽  
David L. Roman
Keyword(s):  
Small Molecule ◽  
High Throughput ◽  
Protein Interaction ◽  
High Throughput Screening ◽  
Drug Targets ◽  
Screening Method ◽  
Fold Increase ◽  
Rgs Proteins ◽  
High Throughput Screen ◽  
Protein Protein Interaction

In this study, the authors used AlphaScreen technology to develop a high-throughput screening method for interrogating small-molecule libraries for inhibitors of the Gαo–RGS17 interaction. RGS17 is implicated in the growth, proliferation, metastasis, and the migration of prostate and lung cancers. RGS17 is upregulated in lung and prostate tumors up to a 13-fold increase over patient-matched normal tissues. Studies show RGS17 knockdown inhibits colony formation and decreases tumorigenesis in nude mice. The screen in this study uses a measurement of the Gαo–RGS17 protein–protein interaction, with an excellent Z score exceeding 0.73, a signal-to-noise ratio >70, and a screening time of 1100 compounds per hour. The authors screened the NCI Diversity Set II and determined 35 initial hits, of which 16 were confirmed after screening against controls. The 16 compounds exhibited IC50 <10 µM in dose–response experiments. Four exhibited IC50 values <6 µM while inhibiting the Gαo–RGS17 interaction >50% when compared to a biotinylated glutathione-S-transferase control. This report describes the first high-throughput screen for RGS17 inhibitors, as well as a novel paradigm adaptable to many other RGS proteins, which are emerging as attractive drug targets for modulating G-protein-coupled receptor signaling.

scholarly journals A small molecule UPR modulator for diabetes identified by high throughput screening

2021 ◽  
Author(s):  
Valeria Marrocco ◽  
Tuan Tran ◽  
Siying Zhu ◽  
Seung Hyuk Choi ◽  
Ana M. Gamo ◽  
...  
Keyword(s):  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening

High-Throughput Screening to Identify Small Molecules That Selectively Inhibit APOL1 Protein Level in Podocytes

2021 ◽  
pp. 247255522110262
Author(s):  
Jonathan Choy ◽  
Yanqing Kan ◽  
Steve Cifelli ◽  
Josephine Johnson ◽  
Michelle Chen ◽  
...  
Keyword(s):  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening ◽  
Screening Strategy ◽  
Time Resolved ◽  
Protein Levels ◽  
Increased Risk ◽  
Compound Screening ◽  
High Throughput Screens ◽  
Screening Library

High-throughput phenotypic screening is a key driver for the identification of novel chemical matter in drug discovery for challenging targets, especially for those with an unclear mechanism of pathology. For toxic or gain-of-function proteins, small-molecule suppressors are a targeting/therapeutic strategy that has been successfully applied. As with other high-throughput screens, the screening strategy and proper assays are critical for successfully identifying selective suppressors of the target of interest. We executed a small-molecule suppressor screen to identify compounds that specifically reduce apolipoprotein L1 (APOL1) protein levels, a genetically validated target associated with increased risk of chronic kidney disease. To enable this study, we developed homogeneous time-resolved fluorescence (HTRF) assays to measure intracellular APOL1 and apolipoprotein L2 (APOL2) protein levels and miniaturized them to 1536-well format. The APOL1 HTRF assay served as the primary assay, and the APOL2 and a commercially available p53 HTRF assay were applied as counterscreens. Cell viability was also measured with CellTiter-Glo to assess the cytotoxicity of compounds. From a 310,000-compound screening library, we identified 1490 confirmed primary hits with 12 different profiles. One hundred fifty-three hits selectively reduced APOL1 in 786-O, a renal cell adenocarcinoma cell line. Thirty-one of these selective suppressors also reduced APOL1 levels in conditionally immortalized human podocytes. The activity and specificity of seven resynthesized compounds were validated in both 786-O and podocytes.

scholarly journals Design of High-Throughput Screening Assays and Identification of a SUMO1-Specific Small Molecule Chemotype Targeting the SUMO-Interacting Motif-Binding Surface

2015 ◽  
Vol 17 (4) ◽  
pp. 239-246 ◽  
Author(s):  
Aileen Y. Alontaga ◽  
Yifei Li ◽  
Chih-Hong Chen ◽  
Chen-Ting Ma ◽  
Siobhan Malany ◽  
...  
Keyword(s):  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening ◽  
Binding Surface ◽  
Screening Assays

scholarly journals Identification of novel small molecule inhibitors of adenovirus gene transfer using a high throughput screening approach

2013 ◽  
Vol 170 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Margaret R. Duffy ◽  
Alan L. Parker ◽  
Eric R. Kalkman ◽  
Katie White ◽  
Dmytro Kovalskyy ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening ◽  
Small Molecule Inhibitors ◽  
Screening Approach

scholarly journals High throughput screening for small molecule inhibitors of heparin-induced tau fibril formation

2007 ◽  
Vol 358 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Alex Crowe ◽  
Carlo Ballatore ◽  
Edward Hyde ◽  
John Q. Trojanowski ◽  
Virginia M.-Y. Lee
Keyword(s):  
Small Molecule ◽  
High Throughput ◽  
High Throughput Screening ◽  
Small Molecule Inhibitors ◽  
Fibril Formation
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