Novel Technology for Screening Receptor and Compound Libraries in Drug Discovery

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DESCRIPTION (provided by applicant): Discovery research in the pharmaceutical/biotech industries utilizes high throughput, label-free drug binding cell-based assays, many of which are functional assays. In such instances, the receptor-ligand interaction is only an indirect measurement of binding and might depend on a threshold of binding for activation of the pathway. Radiation Monitoring Devices, Inc. (RMD) proposes to develop a platform technology and device capable of high throughput screening for association between biologically/pharmacologically active molecules and their cognate receptors. This technology is based on assaying magnetic birefringence relaxation of nanoparticles and will be particularly designed for screening nociceptin receptor and interacting ligands. RMD has demonstrated that maghemite nanoparticles, decorated with ligand molecules, exhibit longer magnetic birefringence relaxation times when associated with proteins, viruses and small size microorganisms. The absolute magnitude of birefringence and the relaxation time depends only on the hydrodynamic volume change upon formation of the "receptor-ligand complex" and is not affected by excess unbound ligand. These properties make this assay ideal for screening molecules immobilized on the surface of magnetic nanoparticles against receptors. The assay platform to demonstrate the proof of concept will utilize a peptide ligand (nociceptin and derivatives) immobilized on the surface of magnetic nanoparticles, which will be screened for a change in magnetic birefringence relaxation upon binding to nociceptin receptor overexpressed on the cell surface of microorganisms such as bacteria and yeast. The rationale for using magneto-optical birefringence to identify ligand and receptor interactions is that it eliminates th need for separating the unbound ligands from ligands captured by receptors. The time to identification is reduced since there is no need to segregate sample from the capture particle before detection. Importantly, attachment of an exogenous fluorescent or radioactive label to the receptor or ligand is not required. Further, this novel approach is applicable in systems where the interaction of ligand with cognate receptor does not activate intracellular pathways that are easy to monitor with a ratiofluorometric platform. This procedure/device will be useful for a broad range of applications in the pharmaceutical/biotechnological industry including discovery research to develop small molecule drugs and the identification of biologically active peptides and proteins from display libraries. Another application is the identification of orphan receptors and discovery of receptors for ligands of interest. PUBLIC HEALTH RELEVANCE: The endogenous neuropeptide ligand-receptor system, the nociceptin/nociceptin receptor, is involved in a wide range of physiological responses including in reward elicited by ethanol consumption and drug abuse and represents a viable drug target. We will develop a strategy and platform for screening compound libraries for the development of novel agonists and antagonists for the nociceptin/nociceptin receptor system. Such technology carries the potential of great health and socioeconomic impact as the underlying molecular components that define drug and alcohol addiction behavior will provide insight into ways that addiction can be treated more effectively.