Bioactivity of PTH/PTHrP analogs lacking the 1–14 N-terminal domain

• Published in: Molecular and cellular endocrinology 2002-03, Vol.189 (1), p.37-49
• Main Authors: Nelson, Anne E., Barden, Julian A., Martin, Erin A., Tasevski, Vitomir, Hogan, Jeremy J., Mason, Rebecca S., Robinson, Bruce G.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analog; cAMP; Cell Line; Cyclic AMP - analogs & derivatives; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Humans; Molecular Sequence Data; Opossum kidney cells; Parathyroid Hormone - chemistry; Parathyroid Hormone - genetics; Parathyroid Hormone - metabolism; Parathyroid Hormone-Related Protein; Peptide Hormones - chemistry; Peptide Hormones - genetics; Peptide Hormones - metabolism; Peptides - genetics; Peptides - metabolism; Phosphate uptake; Phosphates - metabolism; Protein Kinase C - antagonists & inhibitors; PTH/PTHrP; Radioimmunoassay; Signal Transduction - physiology
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/S0303-7207(01)00758-4

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 α helices, inhibited phosphate uptake and stimulated cAMP production in a dose-dependent manner, with half maximal activity in the μM 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 α-helical structure maintained, is sufficient for full activity at reduced potency.