Unbinding Pathways from the Glucocorticoid Receptor Shed Light on the Reduced Sensitivity of Glucocorticoid Ligands to a Naturally Occurring, Clinically Relevant Mutant Receptor

Glucocorticoids are endogenous steroid hormones that regulate essential biological functions, including metabolism, growth, and apoptosis. Glucocorticoids represent the most effective anti-inflammatory agents for the treatment of several inflammatory conditions:However, the clinical use of such drugs is hampered by severe side effects. Therefore, the development of novel glucocorticoid receptor, (GR) modulators with an increased therapeutic index is impelling. Herein, using steered molecular dynamics (SMD) simulations, we provide a detailed picture of the unbinding process of three clinically relevant GR modulators from GR ligand binding domains. The SMD protocol described here can be used to prioritize the synthesis of structural analogues on the basis of their potentials of mean force and calculated unbinding energies. Moreover, our results are instrumental in explaining at atomic resolution the weakened ability of dexamethasone to activate the naturally occurring mutant I747M GR, which is implicated in rare familial glucocorticoid resistance, clinically characterized by glucocorticoid insensitivity.