Calcitonin receptors of human osteoclastoma |
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Authors: | G C Nicholson M A Horton P M Sexton C S D'Santos J M Moseley B E Kemp J A Pringle T J Martin |
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Affiliation: | University of Melbourne, Department of Medicine, Repatriation General Hospital, Heidelberg, Victoria, Australia. |
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Abstract: | Osteoclast-rich cultures were prepared by disaggregation of osteoclastomas (giant cell tumour of bone) and settlement onto glass or plastic surfaces. Autoradiography using 125I]-salmon calcitonin (125I]-sCT) revealed specific binding only to multinucleate giant cells (osteoclasts) and a minor population of mononuclear cells. 125I]-sCT competitive binding studies indicated a Kd of 5 x 10(-10) M and receptor number of approximately 1 million sites/osteoclast. sCT treatment resulted in a dose-dependent rise in cAMP (EC50 10(-10) M). Homogenates of an osteoclastoma also demonstrated specific binding of 125I]-sCT. Chemical cross-linking of a labelled synthetic sCT derivative. 125I]-Arg11,18,Lys14]-sCT, using disuccinimidyl suberate, resulted in labelling of a receptor component of approximate Mr 85-90,000. The multinucleate giant cells (osteoclasts) of human osteoclastomas possess large number of CT receptors which exhibit the same binding kinetics and apparent Mr as those of other CT target cells. |
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