Immediate cell signal by bone-related peptides in human osteoclast-like cells.
We tested whether recognition of bone-related peptides regulates intracellular Ca2+ concentration ([Ca2+]i) of giant cell tumor of bone (GCT). [Ca2+]i was measured in single cells by fura 2 fluorometry. GCT cells were sensitive to bone sialoprotein-II (BSP-II), osteopontin (OPN), and related fragments. Responses consisted of a prompt increase of [Ca2+]i, mostly transient, with a peak followed by a rapid return toward baseline. Responses were not mimicked by bovine plasma fibronectin. Sensitivity of GCT cells to bone peptides was specific, since BALB/3T3 fibroblasts and U-937 histiocytic lymphoma cells with monocytic phenotype failed to respond to BSP-II and OPN fragments. GRGDSP synthetic esapeptide, carrying the Arg-Gly-Asp adhesive motif, and GRGESP (Asp replaced by Glu), but not the GRADSP (Gly replaced by Ala), were active in inducing [Ca2+]i transients as well. Responses were observed also in cells treated with the BSP-II 1C fragment, lacking any known adhesive sequence, indicating that the active peptides inducing [Ca2+]i increments may be multiple. Sensitivity to extracellular matrix peptides was present in a variable fraction of the cells and was downregulated on long-term culture. The mechanism inducing [Ca2+]i elevations was mostly related to Ca2+ release from thapsigargin-sensitive intracellular pools.
Paniccia
R
R
Institute of Human Anatomy, School of Pharmacy, University of Bari, Italy.
Colucci
S
S
Grano
M
M
Serra
M
M
Zallone
A Z
AZ
Teti
A
A
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001859:Bone Neoplasms; D001862:Bone Resorption; D002116:Calcitonin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D018212:Giant Cell Tumor of Bone; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D007700:Kinetics; D016403:Lymphoma, Large B-Cell, Diffuse; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology*; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology*; D053495:Osteopontin; D012516:Osteosarcoma; D010446:Peptide Fragments / Q000494:pharmacology*; D010750:Phosphoproteins; D011392:Proline / Q000032:analysis; D012795:Sialoglycoproteins / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured
C546871:IBSP protein, human; C546872:Ibsp protein, mouse; D058574:Integrin-Binding Sialoprotein; D009842:Oligopeptides; D010446:Peptide Fragments; D010750:Phosphoproteins; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; D053495:Osteopontin; D004533:Egtazic Acid; D002116:Calcitonin; D011392:Proline; D000242:Cyclic AMP; D002118:Calcium