title: Dissociation of cAMP accumulation and phosphate uptake in opossum kidney (OK) cells with parathyroid hormone (PTH) and parathyroid hormone related protein (PTHrP).
abstract: Bovine parathyroid hormone (PTH) 1-34 [bPTH(1-34)] and human PTH related protein [hPTHrP(1-34)] stimulated cAMP accumulation in opossum kidney (OK) cells with Km of 5 x 10(-9) M, but inhibition of phosphate uptake was obtained with 17-fold lower Km of 3 x 10(-10) M. Phosphate uptake was partially inhibited with [Nle8.18Tyr34]bPTH(3-34)NH2 without concomitant cAMP stimulation. With hPTHrP(7-34)NH2, cAMP accumulation was increased in parallel to inhibition of phosphate uptake. [D-Trp12Tyr34]bPTH(7-34)NH2 and [Tyr34]hPTH(7-34)NH2 had no agonist activity on cellular cAMP and inhibition of phosphate uptake. bPTH(1-34)-stimulated cAMP accumulation was antagonized by [Nle8.18Tyr34]bPTH(3-34)NH2, [D-Trp12Tyr34]bPTH(7-34)NH2, hPTHrP(7-34)NH2 and [Tyr34]hPTH(7-34)NH2 with Ki of 1.4 x 10(-7), 2 x 10(-7), 4.7 x 10(-7) and 3.7 x 10(-6) M, respectively. But [Nle8.18Tyr34]bPTH(3-34)NH2 and [D-Trp12Tyr34]bPTH(7-34)NH2 reversed the inhibition of phosphate uptake only marginally, and hPTHrP(7-34)NH2 and [Tyr34]hPTH(7-34)NH2 were inactive. With hPTHrP(1-34) the Ki for cAMP accumulation of [Nle8,18Tyr34]bPTH(3-34)NH2 and hPTHrP(7-34)NH2 were 1.9 x 10(-7) and 7.2 x 10(-7) M, and inhibition of phosphate uptake was partially reversed with [Nle8,18Tyr34]bPTH(3-34)NH2, but not with hPTHrP(7-34)NH2. The present results indicate that truncated hPTHrP(7-34)NH2, unlike [Tyr34]hPTH(7-34)NH2 and [D-Trp12Tyr34]bPTH(7-34)NH2, elevates cellular cAMP and inhibits phosphate uptake. bPTH(1-34)- and hPTHrP(1-34)-evoked cAMP accumulation is suppressed by PTH and PTHrP fragments while inhibition of phosphate uptake remains largely unaltered.
authors.affiliation: Department of Orthopedic Surgery and Medicine, University of Zurich, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Muff
authors.forename: M P
authors.initials: MP
authors.lastname: Caulfield
authors.forename: J A
authors.initials: JA
authors.lastname: Fischer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009893:Opossums; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism; D018016:Receptors, Parathyroid Hormone; D013329:Structure-Activity Relationship; D019379:Teriparatide
chemical_list: D009363:Neoplasm Proteins; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D010710:Phosphates; D011506:Proteins; D011956:Receptors, Cell Surface; D018016:Receptors, Parathyroid Hormone; D019379:Teriparatide; C054296:parathyroid hormone-related protein (1-34); C064776:parathyroid hormone-related protein (7-34)amide; C057402:parathyroid hormone (7-34)amide,12-Trp,34-Tyr-, bovine; C025497:parathyroid hormone (3-34) amide, Nle(8,18)-Nle(34)-; C038040:parathyroid hormone (7-34)amide, Tyr(34)-; D000242:Cyclic AMP