Srinivasan, MythilyBlackburn, CorinneLahiri, Debomoy K.2016-06-282016-06-282014Srinivasan, M., Blackburn, C., & Lahiri, D. K. (2014). Functional characterization of a competitive peptide antagonist of p65 in human macrophage-like cells suggests therapeutic potential for chronic inflammation. Drug Design, Development and Therapy, 8, 2409–2421. http://doi.org/10.2147/DDDT.S597221177-8881https://hdl.handle.net/1805/10208Glucocorticoid-induced leucine zipper (GILZ) is a glucocorticoid responsive protein that links the nuclear factor-kappa B (NFκB) and the glucocorticoid signaling pathways. Functional and binding studies suggest that the proline-rich region at the carboxy terminus of GILZ binds the p65 subunit of NFκB and suppresses the immunoinflammatory response. A widely-used strategy in the discovery of peptide drugs involves exploitation of the complementary surfaces of naturally occurring binding partners. Previously, we observed that a synthetic peptide (GILZ-P) derived from the proline-rich region of GILZ bound activated p65 and ameliorated experimental encephalomyelitis. Here we characterize the secondary structure of GILZ-P by circular dichroic analysis. GILZ-P adopts an extended polyproline type II helical conformation consistent with the structural conformation commonly observed in interfaces of transient intermolecular interactions. To determine the potential application of GILZ-P in humans, we evaluated the toxicity and efficacy of the peptide drug in mature human macrophage-like THP-1 cells. Treatment with GILZ-P at a wide range of concentrations commonly used for peptide drugs was nontoxic as determined by cell viability and apoptosis assays. Functionally, GILZ-P suppressed proliferation and glutamate secretion by activated macrophages by inhibiting nuclear translocation of p65. Collectively, our data suggest that the GILZ-P has therapeutic potential in chronic CNS diseases where persistent inflammation leads to neurodegeneration such as multiple sclerosis and Alzheimer's disease.en-USAttribution-NonCommercial 3.0 United StatesInflammationdrug therapypathologyNF-kappa Bantagonists & inhibitorsPeptidespharmacologyArticle