Thursday, January 31, 2013

Applications Thursday: Discovery of Low Affinity Inhibitors of IP signaling using HTRF

G-protein coupled receptors (GPCR's) represent a major class of cellular signaling receptors that play a vital role in a number of physiological responses. As such they are a vital target to be analyzed for drug discovery. The PHERAstar FS from BMG LABTECH is a great tool for this type of analysis as exemplified in the application note: HTS Instrument Discovers Low Affinity Inhibitors of the Inositol Phosphate (IP) Signaling Pathway

Biosynthesis of IP1
One of the second messengers that is produced upon GPCR activation is IP3 which in turn leads to calcium release. However, since IP3 has a very short half life detection of a downstream metabolite IP1 is prefered. This is the basis of  Cisbio's HTRF IP-One assay which employs monoclonal antibodies raised to IP1 which are linked to a donor molecule and IP1 linked to an acceptor molecule. In the absence of endogenously produced IP1 energy transfer will occur between donor and acceptor. Stimulation of IP1 production will lead to competition with the IP1 linked to an acceptor and a resulting decrease in FRET. Using the dual emission detection capabilities of the PHERAstar FS you can monitor not only the emission due to FRET but also emission of the donor when FRET does not occur and determine the ratio of these emissions.

HTRF® ratios obtained for the IP-One assay with the PHERAstar FS
The 1536 well screen exhibits a robust assay window and reveals hits that are 20-30% of maximal inhibition that represent compounds with excellent potential as drug candidates.

For more information please visit BMG LABTECH where you can read this application note and many others.