ABSTRACT
Through medicinal chemistry lead optimization studies focused on calculated properties and guided by X-ray crystallography and computational modeling, potent pan-JNK inhibitors were identified that showed submicromolar activity in a cellular assay. Using in vitro ADME profiling data, 9t was identified as possessing favorable permeability and a low potential for efflux, but it was rapidly cleared in liver microsomal incubations. In a mouse pharmacokinetics study, compound 9t was brain-penetrant after oral dosing, but exposure was limited by high plasma clearance. Brain exposure at a level expected to support modulation of a pharmacodynamic marker in mouse was achieved when the compound was coadministered with the pan-cytochrome P450 inhibitor 1-aminobenzotriazole.
Subject(s)
Mitogen-Activated Protein Kinase 10/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Animals , Blood-Brain Barrier/drug effects , Chemistry Techniques, Synthetic , Crystallography, X-Ray , Cytochrome P-450 Enzyme Inhibitors/chemistry , Cytochrome P-450 Enzyme Inhibitors/pharmacology , Disease Models, Animal , Dogs , Drug Evaluation, Preclinical/methods , Half-Life , Humans , Huntington Disease/drug therapy , Huntington Disease/metabolism , Inhibitory Concentration 50 , Madin Darby Canine Kidney Cells/drug effects , Mice , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 10/chemistry , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Pyrazoles/chemistry , Pyrimidines/chemistry , Structure-Activity RelationshipABSTRACT
We investigated the coregulator (coactivator and corepressor) interactions with the mineralocorticoid receptor (MR) that lead to activation and inhibition of the receptor in the presence of agonist and/or antagonist. Our results indicate that MR ligand binding domain (LBD) interacts strongly with only a few specific coactivator peptides in the presence of the agonist aldosterone and that these interactions are blocked by the antagonist eplerenone. We also discovered that cortisol, the preferred physiological ligand for the glucocorticoid receptor in humans, is a partial MR agonist/antagonist, providing a possible molecular explanation of the tissue-selective effects of glucocorticoids on MR. However, when we examined the coactivator and corepressor peptide interactions in the presence of cortisol, we found that MR bound with cortisol or aldosterone interacted with the same set of peptides. Thus, the partial agonism shown by cortisol is unlikely to be the result of differential interaction with known coactivators and corepressors. On the other hand, we have identified coactivator binding groove mutations that are critical for cortisol activation but not for aldosterone activation, suggesting that the two steroids induce different MR LBD conformations. In addition, we also show that cortisol becomes full agonist when S810L mutation is introduced in the LBD of MR. Interestingly, MR antagonists, such as eplerenone and progesterone, become partial agonist/antagonist of S810L but are still able to recruit LXXLL peptides to the mutant receptor. Together, these findings suggest a model to explain the MR activation by various ligands.
