ABSTRACT
A structure-activity relationship study for a 2-chloroanilide derivative of pyrazolo[1,5-a]pyridine revealed that increased EphB3 kinase inhibitory activity could be accomplished by retaining the 2-chloroanilide and introducing a phenyl or small electron donating substituents to the 5-position of the pyrazolo[1,5-a]pyridine. In addition, replacement of the pyrazolo[1,5-a]pyridine with imidazo[1,2-a]pyridine was well tolerated and resulted in enhanced mouse liver microsome stability. The structure-activity relationship for EphB3 inhibition of both heterocyclic series was similar. Kinase inhibitory activity was also demonstrated for representative analogs in cell culture. An analog (32, LDN-211904) was also profiled for inhibitory activity against a panel of 288 kinases and found to be quite selective for tyrosine kinases. Overall, these studies provide useful molecular probes for examining the in vitro, cellular and potentially in vivo kinase-dependent function of EphB3 receptor.
Subject(s)
Imidazoles/chemistry , Protein Kinase Inhibitors/chemistry , Pyrazoles/chemistry , Pyridines/chemistry , Receptor, EphB3/antagonists & inhibitors , Animals , Cell Line , Humans , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Mice , Microsomes, Liver/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Pyrazoles/chemical synthesis , Pyrazoles/pharmacology , Pyridines/chemical synthesis , Pyridines/pharmacology , Receptor, EphB3/metabolism , Structure-Activity RelationshipABSTRACT
Loss of the dystrophin-glycoprotein complex from muscle sarcolemma in Duchenne's muscular dystrophy (DMD) renders the membrane susceptible to mechanical injury, leaky to Ca(2+), and disrupts signaling, but the precise mechanism(s) leading to the onset of DMD remain unclear. To assess the role of mechanical injury in the onset of DMD, extensor digitorum longus (EDL) muscles from C57 (control), mdx, and mdx-utrophin-deficient [mdx:utrn(-/-); dystrophic] pups aged 9-12 days were subjected to an acute stretch-injury or no-stretch protocol in vitro. Before the stretches, isometric stress was attenuated for mdx:utrn(-/-) compared with control muscles at all stimulation frequencies (P < 0.05). During the stretches, EDL muscles for each genotype demonstrated similar mean stiffness values. After the stretches, isometric stress during a tetanus was decreased significantly for both mdx and mdx:utrn(-/-) muscles compared with control muscles (P < 0.05). Membrane injury assessed by uptake of procion orange dye was greater for dystrophic compared with control EDL (P < 0.05), but, within each genotype, the percentage of total cells taking up dye was not different for the no-stretch vs. stretch condition. These data suggest that the sarcolemma of maturing dystrophic EDL muscles are resistant to acute mechanical injury.
