Ca(2+) and extracellular acidification rate responses to parathyroid hormone fragments in rat ROS 17/2 and human SaOS-2 cells.
To examine the importance of the N- or C-termini of PTH(1-34) the effects of truncated fragments of PTH on human receptors in osteoblast-like SaOS-2 cells and rat receptors in rats ROS 17/2 cells were examined. Fura-2-loaded cells were used to monitor cytosolic free Ca(2+) concentration ([Ca2+]i), and the Cytosensor microphysiometer was used to monitor extracellular acidification rate (ECAR). C-terminally truncated fragments (1-31) and (1-28) of hPTH(1-34)NH(2) stimulated an increase in [Ca(2+)](i) and ECAR in both cell lines. hPTH(3-34)NH(2) and other N-terminally truncated fragments did not stimulate [Ca(2+)](i) or ECAR in either cell type. The signal transduction pathway of PTH-induced ECAR in ROS 17/2 cells was investigated to compare with previous results in SaOS-2 cells. Potentiation by IBMX, attenuation by 8Br-cAMP and lack of effect of the PKC inhibitor chelerythrine chloride support a cAMP/PKA-mediated signal transduction pathway in ROS 17/2, while the protein kinase C pathway was predominant in SaOS-2 cells. We conclude that the intact N-terminus of PTH is essential in PTH signaling mediated via either the cAMP/PKA or inositol lipid/Ca(2+)/PKC pathways in osteoblast-like cells.
Belinsky
G S
GS
Department of Cancer Cell Biology, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Morley
P
P
Whitfield
J F
JF
Tashjian
A H
AH
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D016257:Fura-2; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D010617:Phenanthridines / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D053119:Benzophenanthridines; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010617:Phenanthridines; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; C016299:chelerythrine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine; D016257:Fura-2