title: Cell-based and in-silico studies on the high intrinsic activity of two boron-containing salbutamol derivatives at the human β₂-adrenoceptor.
abstract: Salbutamol is a well-known β(2) adrenoceptor (β(2)AR) partial agonist. We synthesized two boron-containing salbutamol derivatives (BCSDs) with greater potency and efficacy, compared to salbutamol, for inducing β(2)AR-mediated smooth-muscle relaxation in guinea-pig tracheal rings. However, the mechanism involved in this pharmacological effect remains unclear. In order to gain insight, we carried out binding and functional assays for BCSDs in HEK-293T cells transfected with the human β(2)AR (hβ(2)AR). The transfected hβ(2)AR showed similar affinity for BCSDs and salbutamol, but adenosine 3',5'-cyclic phosphate (cAMP) accumulation induced by both BCSDs was similar to that elicited by isoproterenol and greater than that induced by salbutamol. The boron-containing precursors (boric and phenylboronic acids, 100 μM) had no significant effect on salbutamol binding or salbutamol-induced cAMP accumulation. These experimental results are in agreement with theoretical docking simulations on lipid bilayer membrane-embedded hβ(2)AR structures. These receptors showed slightly higher affinity for BCSDs than for salbutamol. An essential change between putative active and inactive conformational states depended on the interaction of the tested ligands with the fifth, sixth and seventh transmembrane domains. Overall, these data suggest that BCSDs induce and stabilize conformational states of the hβ(2)AR that are highly capable of stimulating cAMP production.
authors.affiliation: Departamentos de Fisiología, Bioquímica Médica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, 11340 México, DF, Mexico. msoriano@ipn.mx
authors.forename: Marvin A
authors.initials: MA
authors.lastname: Soriano-Ursúa
authors.forename: Daniel A
authors.initials: DA
authors.lastname: McNaught-Flores
authors.forename: Gustavo
authors.initials: G
authors.lastname: Nieto-Alamilla
authors.forename: Aldo
authors.initials: A
authors.lastname: Segura-Cabrera
authors.forename: José
authors.initials: J
authors.lastname: Correa-Basurto
authors.forename: José A
authors.initials: JA
authors.lastname: Arias-Montaño
authors.forename: José G
authors.initials: JG
authors.lastname: Trujillo-Ferrara
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D000420:Albuterol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D000494:Allosteric Regulation; D001665:Binding Sites; D001895:Boron / Q000737:chemistry*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D056004:Molecular Dynamics Simulation; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry* / Q000378:metabolism
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D018343:Receptors, Adrenergic, beta-2; D000242:Cyclic AMP; D001895:Boron; D000420:Albuterol