Co-Authors:
Schwindinger, W.F., Div. of Endocrinology and Metabolism, Johns Hopkins University, School of Medicine, Baltimore, MD, United States, Div. of Endocrinology and Metabolism, Johns Hopkins University, School of Medicine, Ross 1029, 720 Rutland Ave., Baltimore, MD 21205, United States
Fredericks, J., Div. of Endocrinology and Metabolism, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
Watkins, L., Div. of Endocrinology and Metabolism, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
Robinson, H., Division of Rheumatology, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
Bathon, J.M., Division of Rheumatology, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
Pines, M., Div. of Bone and Mineral Metabolism, Beth Israel Hospital, Boston, MA, United States
Suva, L.J., Div. of Bone and Mineral Metabolism, Beth Israel Hospital, Boston, MA, United States
Levine, M.A., Div. of Endocrinology and Metabolism, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
Abstract:
Parathyroid hormone (PTH) elicits many of its physiological effects by activating distinct G-protein-coupled signaling cascades that lead to synthesis of cyclic AMP and hydrolysis of phosphatidylinositol 4,5- bisphosphate. Using the nonhydrolyzable photoreactive GTP analog [α- 32p]GTP-γ-azidoanilide (GTP-AA) and peptide antisera raised against G- protein α-sub-units, we studied coupling of the PTH receptor to G-proteins in rat osteoblast-like cells (ROS 17/2.8), and in human embryonal kidney cells expressing the cloned human PTH/parathyroid hormone-related peptide (PTHrP) receptor at 40,000 receptors/cell (C20) or 400,000 receptors/cell (C21). Incubation of C21 membranes (but not C20 membranes) with [Nle 8,18, Tyr 34]-bovine PTH(1-34) amide (bPTH[1-34]) led to concentration-dependent incorporation of GTP-AA into the two isoforms of Gα(s), into Gα(q/11), and to a much lesser extent into G(α(i(1)). In ROS 17/2.8 cells, bPTH(1-34) increased the incorporation of GTP-AA into Gα(s), but not into Gα(q/11) or Gα(i). The ability of bPTH(1-34) to increase labeling of Gα(s) and Gα(q/11) was correlated with the receptor-dependent sensitivity of the adenylyl cyclase and phospholipase C signaling pathways to the hormone.
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