title: Functional characterization of a competitive peptide antagonist of p65 in human macrophage-like cells suggests therapeutic potential for chronic inflammation.
abstract: Glucocorticoid-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.
authors.affiliation: Department of Oral Pathology, Medicine and Radiology, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Mythily
authors.initials: M
authors.lastname: Srinivasan
authors.affiliation: Department of Oral Pathology, Medicine and Radiology, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Corinne
authors.initials: C
authors.lastname: Blackburn
authors.affiliation: Institute of Psychiatry Research, Department of Psychiatry, Indiana University-Purdue University, Indianapolis, IN, USA ; Department of Medical and Molecular Genetics, School of Medicine, Indiana University-Purdue University, Indianapolis, IN, USA.
authors.forename: Debomoy K
authors.initials: DK
authors.lastname: Lahiri
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000473:pathology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D016328:NF-kappa B; D010455:Peptides; C011083:polyproline
keywords: chronic inflammation; glucocorticoid-induced leucine zipper; therapeutic potential; translational impact