ABSTRACT
This letter describes the discovery of a novel series of tetrahydroisoquinoline (THIQ)-derived small molecules that potently inhibit both human T-cell migration and super-antigen induced T-cell activation through disruption of the binding of integrin LFA-1 to its receptor, ICAM-1. In addition to excellent in vitro potency, 6q shows good pharmacokinetic properties and its ethyl ester (6t) demonstrates good oral bioavailability in both mouse and rat. Either intravenous administration of 6q or oral administration of its ethyl ester (6t) produced a significant reduction of neutrophil migration in a thioglycollate-induced murine peritonitis model.
Subject(s)
Intercellular Adhesion Molecule-1/drug effects , Lymphocyte Function-Associated Antigen-1/drug effects , Tetrahydroisoquinolines/pharmacology , Animals , Biological Availability , Drug Discovery , Humans , Tetrahydroisoquinolines/administration & dosage , Tetrahydroisoquinolines/pharmacokineticsABSTRACT
We have identified a small-molecule inhibitor of tumor necrosis factor alpha (TNF-alpha) that promotes subunit disassembly of this trimeric cytokine family member. The compound inhibits TNF-alpha activity in biochemical and cell-based assays with median inhibitory concentrations of 22 and 4.6 micromolar, respectively. Formation of an intermediate complex between the compound and the intact trimer results in a 600-fold accelerated subunit dissociation rate that leads to trimer dissociation. A structure solved by x-ray crystallography reveals that a single compound molecule displaces a subunit of the trimer to form a complex with a dimer of TNF-alpha subunits.
Subject(s)
Indoles/chemistry , Indoles/pharmacology , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Tumor Necrosis Factor-alpha/chemistry , Biotinylation , Chemical Phenomena , Chemistry, Physical , Crystallography, X-Ray , Dimerization , Fluorescence , Hydrogen/chemistry , Hydrophobic and Hydrophilic Interactions , Indoles/chemical synthesis , Kinetics , Mass Spectrometry , Models, Chemical , Models, Molecular , Molecular Conformation , Molecular Structure , Protein Conformation , Protein Subunits/chemistry , Receptors, Tumor Necrosis Factor, Type I/metabolism , Tumor Necrosis Factor-alpha/metabolismABSTRACT
An IL-4 antagonist was designed based on structural and biochemical analysis of unbound IL-4 and IL-4 in complex with its high-affinity receptor (IL-4Ralpha). Our design strategy sought to capture a protein-protein interaction targeting the high affinity that IL-4 has for IL-4Ralpha. This strategy has impact due to the potential relevance of IL-4Ralpha as a drug target in the treatment of asthma. To mimic the IL-4 binding surface, critical side chains for receptor binding were identified, and these side chains were transplanted onto a previously characterized, de novo-designed four-helix protein called designed helical protein 1 (DHP-1). This first-generation design resolved the ambiguity previously described for the connectivity between helices in DHP-1 and resulted in a protein capable of binding to IL-4Ralpha. The second-generation antagonist was based upon further molecular modeling, and it succeeded in binding IL-4Ralpha better than the first-generation. This protein, termed DHP-14-AB, yielded a protein with a cooperative unfolding transition (DeltaGu0=8.1 kcal/mol) and an IC50 of 27 microM when in competition with IL-4 whereas DHP-1 had no affinity for IL-4Ralpha. The crystal structure of DHP-14-AB was determined to 1.9-A resolution and was compared with IL-4. This comparison revealed how design strategies targeting protein-protein interactions require high-resolution 3D data and the incorporation of orientation-specific information at the level of side-chains and secondary structure element interactions.
