Pines, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Fukayama, S., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Costas, K., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Meurer, E., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Goldsmith, P.K., Metabolic Diseases Branch, Natl. Inst. Diabet., Digest. Kindey, National Institutes of Health, Bethesda, MD, United States Xu, X., Department of Physiology, Univ. Texas Southwestern Med. Ctr., Dallas, TX, United States Muallem, S., Department of Physiology, Univ. Texas Southwestern Med. Ctr., Dallas, TX, United States Behar, V., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Chorev, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Rosenblatt, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Tashjian Jr., A.H., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Suva, L.J., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States, Div. Bone Mineral Metab. RW563, Beth Israel Hospital, 330 Brookline Avenue, Boston, MA 02215, United States
We previously reported the preparation and partial characterization of a series of human embryonic kidney cell lines (HEK-293) stably expressing various numbers of the recombinant human (h) parathyroid hormone (PTH)/PTH-related protein (PTHrP) receptor (Rc). Using this expression system we examined ligand (PTH or PTHrP) binding characteristics and cyclic AMP responsiveness. We have now extended these studies to investigate the calcium signal transduction pathways activated by the hPTH/PTHrP Rc. In parental HEK-293 cells, which lack endogenous PTH/PTHrP Rc, incubation with hPTH(1-34) had no effect on cytosolic free Ca2+ concentration [Ca2+]i. In HEK-293 clone C-21, stably expressing ∼400,000 Rc/cell, PTH stimulated an increase in [Ca2+]i by Ca2+ release from intracellular stores; PTH released Ca2+ exclusively from the IP3 sensitive Ca2+ pool. Unlike previous studies, the ability of PTH to elicit both cAMP responses and [Ca2+]i transients occurred over a wide range of Rc numbers (between 400,000 and 3000 Re/cell); both responses were al-ways observed at PTH concentrations in the same dose range although the magnitude of the responses decrease with Rc number. Pretreatment of C-21 cells with pertussis toxin for 24 h, which significantly enhanced PTH-stimulated cAMP accumulation, did not modulate PTH-stimulated [Ca2+]i transients. At each PTH concentration tested which resulted in increased cAMP levels, there was also an increase in [Ca2+]i transients. Treatment of C-21 cells with a battery of midregion and C-terminal PTH or PTHrP peptides showed no effect on either [Ca2+]i transients or cAMP accumulation, indicating a lack of functional interactions between these peptides and the form of the hPTH/PTHrP Rc stably expressed in these cells. Immunological analysis of G-protein expression demonstrated the presence of Gs, Gj, and Gq in all parental and transfected cell lines examined. Taken together, these data demonstrate that the hPTH/PTHrP Rc, stably expressed in HEK-293 cells, elicits responses in both the cAMP and IP3-dependent [Ca2+]; pathways and is responsive only to N-terminal PTH/PTHrP peptides. (Bone 18;381-389; 1996).
Inositol 1-,4-,5-trisphosphate-dependent Ca2+ signaling by the recombinant human PTH/PTHrP receptor stably expressed in a human kidney cell line
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Pines, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Fukayama, S., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Costas, K., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Meurer, E., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Goldsmith, P.K., Metabolic Diseases Branch, Natl. Inst. Diabet., Digest. Kindey, National Institutes of Health, Bethesda, MD, United States Xu, X., Department of Physiology, Univ. Texas Southwestern Med. Ctr., Dallas, TX, United States Muallem, S., Department of Physiology, Univ. Texas Southwestern Med. Ctr., Dallas, TX, United States Behar, V., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Chorev, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Rosenblatt, M., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States Tashjian Jr., A.H., Dept. of Molec. and Cell. Toxicology, Dept. Biol. Chem. Molec. Pharmacol., Harvard Medical School, Boston, MA, United States Suva, L.J., Div. of Bone and Mineral Metabolism, Department of Medicine, Beth Israel Hospital, Boston, MA, United States, Div. Bone Mineral Metab. RW563, Beth Israel Hospital, 330 Brookline Avenue, Boston, MA 02215, United States
Inositol 1-,4-,5-trisphosphate-dependent Ca2+ signaling by the recombinant human PTH/PTHrP receptor stably expressed in a human kidney cell line
We previously reported the preparation and partial characterization of a series of human embryonic kidney cell lines (HEK-293) stably expressing various numbers of the recombinant human (h) parathyroid hormone (PTH)/PTH-related protein (PTHrP) receptor (Rc). Using this expression system we examined ligand (PTH or PTHrP) binding characteristics and cyclic AMP responsiveness. We have now extended these studies to investigate the calcium signal transduction pathways activated by the hPTH/PTHrP Rc. In parental HEK-293 cells, which lack endogenous PTH/PTHrP Rc, incubation with hPTH(1-34) had no effect on cytosolic free Ca2+ concentration [Ca2+]i. In HEK-293 clone C-21, stably expressing ∼400,000 Rc/cell, PTH stimulated an increase in [Ca2+]i by Ca2+ release from intracellular stores; PTH released Ca2+ exclusively from the IP3 sensitive Ca2+ pool. Unlike previous studies, the ability of PTH to elicit both cAMP responses and [Ca2+]i transients occurred over a wide range of Rc numbers (between 400,000 and 3000 Re/cell); both responses were al-ways observed at PTH concentrations in the same dose range although the magnitude of the responses decrease with Rc number. Pretreatment of C-21 cells with pertussis toxin for 24 h, which significantly enhanced PTH-stimulated cAMP accumulation, did not modulate PTH-stimulated [Ca2+]i transients. At each PTH concentration tested which resulted in increased cAMP levels, there was also an increase in [Ca2+]i transients. Treatment of C-21 cells with a battery of midregion and C-terminal PTH or PTHrP peptides showed no effect on either [Ca2+]i transients or cAMP accumulation, indicating a lack of functional interactions between these peptides and the form of the hPTH/PTHrP Rc stably expressed in these cells. Immunological analysis of G-protein expression demonstrated the presence of Gs, Gj, and Gq in all parental and transfected cell lines examined. Taken together, these data demonstrate that the hPTH/PTHrP Rc, stably expressed in HEK-293 cells, elicits responses in both the cAMP and IP3-dependent [Ca2+]; pathways and is responsive only to N-terminal PTH/PTHrP peptides. (Bone 18;381-389; 1996).