Combinatorial Chemistry & High Throughput Screening - Volume 11, Issue 7, 2008

Although in vitro biochemical assays, such as enzyme activity and receptor binding, have been used extensively in the past to discover new drugs, there is a rapid increase in the use of assays based on living cells. Cell-based assays provide a target in a more physiologically relevant environment than biochemical assays. According to a worldwide survey involving more than 50 pharmaceutical and biotech companies, Read More

Functional cell-based assays have gained increasing importance for microplate-based high throughput screening (HTS). The use of high-density microplates, most prominently 1536-well plates, and miniaturized assay formats allow screening of comprehensive compound collections with more than 1 million compounds at ultra-high throughput, i.e. in excess of 100,000 samples per day. uHTS operations with numerous ca Read More

A fluorescent probe is a fluorophore designed to localize within a specific region of a biological specimen or to respond to a specific stimulus. Fluorescent probes have been used for nearly a century to study cellular processes due to their exquisite sensitivity and selectivity. Fluorescent probes have also gained in popularity as safety and environmental concerns over the use of radioactive probes have grown. At the sam Read More

Ion channels are attractive targets for drug discovery with recent estimates indicating that voltage and ligandgated channels account for the third and fourth largest gene families represented in company portfolios after the G protein coupled and nuclear hormone receptor families. A historical limitation on ion channel targeted drug discovery in the form of the extremely low throughput nature of the gold standard assay for ass Read More

High-content analysis (HCA) is a term used to describe techniques involving multiplexed analysis of fluorescent markers to measure multiple cellular responses to biological stimuli or drug treatment. HCA is usually based on automated microscopy or related technologies, and its value lies in providing multiparametric information on single cells within a population. During the last decade, several HCA approaches have been de Read More

Multiplexing of GFP based and immunofluorescence translocation assays enables easy acquisition of multiple readouts from the same cell in a single assay run. Immunofluorescence assays monitor translocation, phosphorylation, and up/down regulation of endogenous proteins. GFP-based assays monitor translocation of stably expressed GFP-fusion proteins. Such assays may be multiplexed along (vertical), across (horizonta Read More

Nuclear translocation is an important step in glucocorticoid receptor (GR) signaling and assays that measure this process allow the identification of nuclear receptor ligands independent of subsequent functional effects. To facilitate the identification of GR-translocation agonists, an enzyme fragment complementation (EFC) cell-based assay was scaled to a 1536-well plate format to evaluate 9,920 compounds using a quantit Read More

For most membrane-bound molecular targets, including G protein linked receptors (GPCRs), the optimal approach in drug discovery involves the use of cell based high throughput screening (HTS) technologies to identify compounds that modulate target activity. Most GPCRs have been cloned and can therefore be routinely expressed in immortalized cell lines. These cells can be easily and rapidly grown in unlimited quantities m Read More

Cellular technologies are widely used in drug discovery to treat human diseases. Most studies involve the expression of recombinant targets in immortalized cells and measure drug interactions using simple, quantifiable responses. Such cells are also amenable to high throughput screening (HTS) methods. However, the cell phenotype employed in HTS is often determined by the assay technology available, rather than the ph Read More

Label-free technologies based on electrical impedance or refractive index are new tools for measuring a cellbased functional response. Although the technologies are relatively new to high throughput screening cell-based applications, they are rapidly generating interest in that they are able to measure a phenotypic response using cells natively expressing the target protein without using dyes or cellular extracts. In addition, o Read More

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