Identification of a Novel and Selective Series of Itk Inhibitors via a Template-Hopping Strategy.

Inhibition of Itk potentially constitutes a novel, nonsteroidal treatment for asthma and other T-cell mediated diseases. In-house kinase cross-screening resulted in the identification of an aminopyrazole-based series of Itk inhibitors. Initial work on this series highlighted selectivity issues with several other kinases, particularly AurA and AurB. A template-hopping strategy was used to identify a series of aminobenzothiazole Itk inhibitors, which utilized an inherently more selective hinge binding motif. Crystallography and modeling were used to rationalize the observed selectivity. Initial exploration of the SAR around this series identified potent Itk inhibitors in both enzyme and cellular assays.

Increased expression of G protein-coupled receptor kinases in cystic fibrosis lung.

A reduction in airway beta-adrenoceptor density has been reported in cystic fibrosis lung but the mechanism underlying this defect remains unclear. In this study, we have investigated whether the decrease in beta2-adrenoceptor associates with altered G protein-coupled receptor kinase (GRK) levels. We assessed GRK activity by rhodopsin phosphorylation, and beta2-adrenoceptor and GRK at the mRNA and protein levels by Northern and Western blotting in peripheral lung samples from normal donors and patients with cystic fibrosis. GRK activity was significantly increased in peripheral cystic fibrosis lung with parallel increases in GRK2/5 mRNAs and protein expression. Functionally, isoproterenol-stimulated adenylyl cyclase activity was also diminished by 65% in cystic fibrosis lung homogenates. These data suggest that the increase in GRK activity may be one of the mechanisms underlying alterations in the coupling between beta2-adrenoceptor and adenylyl cyclase via G-protein and may thus contribute to the downregulation of beta2-adrenoceptor in cystic fibrosis lung.