title: Bioactivity of PTH/PTHrP analogs lacking the 1-14 N-terminal domain.
abstract: The N-terminal regions of 1-34 parathyroid hormone (PTH) and 1-34 parathyroid hormone related protein (PTHrP) are thought to be required for full agonist activity of these molecules and for signal transduction by cyclic AMP (cAMP). The C-terminal regions are thought to be involved in receptor binding and protein kinase C activation. In this study, two analogs of PTH/PTHrP lacking the segment 1-14 exhibited agonist activity in opossum kidney (OK) 3B2 cells. Analogs cPTHrP(15-34) and ANA NPY(13-36), an analog of neuropeptide Y, which both have amphipathic alpha helices, inhibited phosphate uptake and stimulated cAMP production in a dose-dependent manner, with half maximal activity in the microM range, compared to the nM range for hPTHrP(1-34) and hPTH(1-34). They also exhibited proportionately lower receptor binding affinities. cAMP production by these analogs was suppressed by the antagonist hPTHrP(7-34). Inhibition of phosphate uptake in response to the analogs was partially suppressed by H-89, but not by bisindolylmaleimide. The analogs also inhibited phosphate uptake and stimulated cAMP in parent OK cells and stimulated cAMP production in UMR-106 cells. These studies present the novel finding that in these cell types, a C-terminal region encompassing PTH/PTHrP(24-31), with the alpha-helical structure maintained, is sufficient for full activity at reduced potency.
authors.affiliation: Cancer Genetics Department, Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards NSW, 2065, Sydney, Australia. annen@med.usyd.edu.au
authors.forename: Anne E
authors.initials: AE
authors.lastname: Nelson
authors.forename: Julian A
authors.initials: JA
authors.lastname: Barden
authors.forename: Erin A
authors.initials: EA
authors.lastname: Martin
authors.forename: Vitomir
authors.initials: V
authors.lastname: Tasevski
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Hogan
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Mason
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Robinson
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D006801:Humans; D008969:Molecular Sequence Data; D010281:Parathyroid Hormone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011863:Radioimmunoassay; D015398:Signal Transduction / Q000502:physiology
chemical_list: C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones; D010455:Peptides; D010710:Phosphates; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C