scholarly journals Polyethylene Particle-Induced Bone Resorption in α-Calcitonin Gene-Related Peptide-Deficient Mice

2007 ◽  
Vol 22 (7) ◽  
pp. 1011-1019 ◽  
Author(s):  
Christian Wedemeyer ◽  
Carl Neuerburg ◽  
Anne Pfeiffer ◽  
Anja Heckelei ◽  
David Bylski ◽  
...  
1987 ◽  
Vol 40 (3) ◽  
pp. 149-154 ◽  
Author(s):  
Mone Zaidi ◽  
Karen Fuller ◽  
Peter J. R. Bevis ◽  
Rose E. GainesDas ◽  
Timothy J. Chambers ◽  
...  

1990 ◽  
Vol 269 (3) ◽  
pp. 775-780 ◽  
Author(s):  
M Zaidi ◽  
S D Brain ◽  
J R Tippins ◽  
V Di Marzo ◽  
B S Moonga ◽  
...  

The calcitonin-calcitonin-gene-related peptide (CGRP) gene complex encodes a small family of peptides: calcitonin, CGRP and katacalcin. Calcitonin is a circulating hormone that prevents skeletal breakdown by inhibiting the resorption of bone by osteoclasts. CGRP, a potent vasodilator, is involved in normal regulation of blood flow. The calcitonins structurally resemble the CGRP peptides, and both are known to cross-react at each others' receptors. The present study was undertaken to examine the structural prerequisites for biological activity of the intact CGRP molecule. We therefore prepared eight chymotryptic and tryptic fragments of CGRP and synthesized its acetylated and S-carboxyamidomethylcysteinyl analogues. The analogues were purified by h.p.l.c. and their structures were confirmed by fast-atom bombardment mass spectrometry. We have examined the effects of structurally modified analogues and fragments of human CGRP in a calcitonin-receptor-mediated assay, the osteoclast bone resorption assay, and in one or two CGRP-receptor-mediated assays, the rabbit skin blood flow assay and the oedema formation assay. The results showed that (1) in the osteoclast bone resorption assay, both CGRP peptides, alpha and beta, were equipotent, and were both at least 1000-fold were both approx. 1000-fold more potent than salmon calcitonin; human calcitonin had no effect; (3) the bis- and N-acetylated CGRP analogues retained reduced levels of biological activity in all assays, whereas S-carboxyamidomethylcysteinyl-human CGRP was without activity; and (4) all tryptic and chymotryptic fragments of CGRP were without biological activity, with the exception of hCGRP-(Ala1-Lys35): this fragment had much reduced activity compared with the intact peptide in inhibiting osteoclastic bone resorption and increasing blood flow in the rabbit skin. The results suggest that: (1) calcitonin and CGRP act at distinct receptors to mediate different physiological effects; (2) minor amino acid substitutions, as between the alpha and beta forms of CGRP (these two forms have 94% structural similarity) do not result in differences in biological activity; (3) the intact peptide is required for full biological activity of the CGRP molecule, and even the loss of two amino acids at the C-terminus of the molecule results in a marked decrease in activity; (4) the disulphide bridge appears to play an important role in the interaction of the intact CGRP molecule with its receptor; and (5) the C-terminal region is probably necessary for the peptide to assume the right conformation in the interaction with the receptor.


1987 ◽  
Vol 115 (3) ◽  
pp. 511-518 ◽  
Author(s):  
M. Zaidi ◽  
T. J. Chambers ◽  
R. E. Gaines Das ◽  
H. R. Morris ◽  
I. MacIntyre

ABSTRACT The calcitonin gene encodes a small family of peptides: calcitonin, calcitonin gene-related peptide (CGRP) and katacalcin. Whereas calcitonin is concerned with skeletal maintenance, the function, if any, of katacalcin is still unknown. In the present study we have assessed resorption of human cortical bone substrate by isolated rat osteoclasts and have shown that CGRP acts directly on the osteoclast to inhibit bone resorption. The three CGRP peptides (rat, human(a) and human(β)) caused an almost equivalent decrease in osteoclastic bone resorption and were approximately 1000-fold less potent than human calcitonin in this respect. The responses of human calcitonin and human CGRP(α) were additive. Furthermore, prior treatment with trypsin to destroy receptors abolished the responsiveness of osteoclasts to CGRP and calcitonin. The carboxyl- and amino-terminal fragments of CGRP were found not to inhibit bone resorption, suggesting that the whole molecule of CGRP is necessary for biological activity. We have therefore suggested that the calcitonin-like effects of CGRP, seen both in vivo in the rat bioassay and in vitro in organ cultures, are due to the direct action of CGRP on the osteoclast, probably mediated through the calcitonin receptor. Though it is unlikely that CGRP is involved in the regulation of plasma calcium, the peptide may be an important local regulator of bone cell function. J. Endocr. (1987) 115,511–518


Bone ◽  
1986 ◽  
Vol 7 (4) ◽  
pp. 307-307 ◽  
Author(s):  
P.J.R. Bevis ◽  
M. Zaidi ◽  
C. Lynch ◽  
J. Beacham ◽  
P.M.J. McSheehy ◽  
...  

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