Category: Assay Development and Screening
Cyclic nucleotide phosphodiesterases (PDEs) are intracellular enzymes that catalyze the hydrolysis of 3', 5'-cyclic nucleotides and are found throughout all cells within the body. These enzymes are especially important in the regulation of cell signaling by terminating cellular responses related to the secondary messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). PDEs are potentially powerful drug targets for a variety of different diseases including atherosclerosis, diabetes, asthma, Parkinson's, Alzheimer's, etc. 11 PDE subfamilies have been identified in human genome. Among those PDEs, PDE4s are predominantly responsible for hydrolyzing cAMP within both immune cells and the cells in the central nervous system (CNS). At least four isoforms of PDE4 are known: PDE4A, PDE4B, PDE4C and PDE4D. Here we report the development of cell-based assays for PDE4 isoforms. The assays are based on the ACTOne™ technology which utilizes a modified cyclic nucleotide-gated channel (CNG) to monitor intracellular cAMP changes in live cells. Our preliminary data suggests that the assays can differentiate the compound responses on different PDE4 isoforms. The characterizations of some of the PDE4 inhibitors on our cell based assays differ from known research data derived from biochemical models. We conclude that this assay could be used as an additional screening method for the PDE4 selective inhibitors and can be useful in the more accurate identification and characterizations of PDE4 specific inhibitors. The assay is currently run at 384-well format on Hamamatsu FDSS 7000 and can be potentially miniaturized to 1536-well format.
Jimmy Lu– President, Codex BioSolutions, Inc., Gaithersburg, MD
Codex BioSolutions, Inc.
Jimmy Lu, Ph.D., is a founder of Codex BioSolutions Inc. which developed cell based assays for GPCR and PDE with ACTOne™ technology. The assays have been widely accepted by pharmaceutical industry and research institutes. In that period, Codex also developed mitochondrial membrane potential dye kit, calcium dye kit, potassium dye kits, cAMP-HTRF kit, cell growth assay kit and many others. Dr. Lu served as a PI for many SBIR grants and contracts. Prior to that, Dr. Lu worked at BD Biosciences for 8 years as a senior scientist developing ACTOne™ technology. Dr. Lu obtained his Ph.D. from Georgetown University Medical School and did his postdoctoral training at the National Institute of Health. Dr. Lu has many years of experience to work on the custom projects.