Evidence that c-src is involved in the process of osteoclastic bone resorption.
Transgenic mice lacking a functional c-src gene have osteopetrosis, a bone disorder characterized by defective osteoclast function. We have investigated the effects of selective protein tyrosine kinase inhibitors that are known to inhibit c-src, on osteoclast activity in the bone slice assay. Geldanamycin, herbimycin A and monorden (0.001-10 microM) all dose-dependently inhibited bone resorption with IC50 values of 8, 70 and 86 nM, respectively. At concentrations of 0.001-1 microM, the compounds were not cytotoxic as judged by osteoclast morphology and survival on bone slices. In order to determine whether c-src plays a role in signal transduction associated with osteoclast activation prior to bone resorption commencing, or in the resorptive process itself, we performed kinetic experiments using human calcitonin as a positive control. Calcitonin inhibited all bone resorption subsequent to its addition at t = 0, 3 or 6 hr (100%, approximately 90% and approximately 50% inhibition, respectively), after the start of the 24 hr bone slice assay. Similar results were obtained with herbimycin A and geldanamycin (1 microM) added at t = 0, 3 or 6 hr, and with monorden (1 microM) added at t = 0 and 6 hr. These results indicate that c-src plays a crucial and continuous role in the process of osteoclastic bone resorption, most likely related to the translocation and/or fusion of exocytic vesicles to the ruffled border membrane.
Hall
T J
TJ
Ciba-Geigy Ltd., Research Department, Basel, Switzerland.
Schaeublin
M
M
Missbach
M
M
D000818:Animals; D000831:Animals, Newborn; D016227:Benzoquinones; D001862:Bone Resorption; D002116:Calcitonin / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016391:Genes, src / Q000187:drug effects; D006801:Humans; D047029:Lactams, Macrocyclic; D007783:Lactones / Q000494:pharmacology; D018942:Macrolides; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011809:Quinones / Q000494:pharmacology*; D051381:Rats; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction
D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D007783:Lactones; D018942:Macrolides; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; D002116:Calcitonin; D011505:Protein-Tyrosine Kinases; C035359:monorden; C001277:geldanamycin