Duvos C, Scutt A, Mayer H. hPTH-fragments (53-84) and (28-48) antagonize the stimulation of calcium release and repression of alkaline phosphatase activity by hPTH-(1-34) in vitro.
FEBS Lett 2006;
580:1509-14. [PMID:
16466718 DOI:
10.1016/j.febslet.2006.01.076]
[Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 01/23/2006] [Accepted: 01/24/2006] [Indexed: 11/19/2022]
Abstract
Different C-terminal fragments of parathyroid hormone (PTH)-(1-84) in blood participate in the regulation of calcium homeostasis by PTH-(1-84), and an antagonizing effect for the large carboxyl-terminal parathyroid hormone (C-PTH)-fragment (7-84) on calcium release has been described in vivo and in vitro. In this study the smaller C-PTH-fragment (53-84) and mid-regional PTH fragment (28-48), which represent discrete areas of activity in the PTH-(7-84) molecule, were assayed for their effects on calcium release and alkaline phosphatase (ALP) activity in a chick bone organ culture system. Neither PTH-(28-48) nor PTH-(53-84) had any effect on calcium release into the medium and both fragments stimulated ALP activity in the bone tissue, suggesting that the cAMP/PKA signalling pathway was not affected by these fragments. However they suppressed the calcium release induced by PTH-(1-34) and attenuated the down regulation of ALP activity caused by PTH-(1-34), suggesting that the effect on the cAMP/PKA signalling pathway may be indirectly. In conclusion, the study shows that the PTH-fragments (53-84) and (28-48) antagonize the PTH-(1-34) induced effects on calcium release and inhibition of ALP activity in a chick bone organ culture system.
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