Endocrinology, Vol 125, 2594-2599, Copyright © 1989 by Endocrine Society

ARTICLES

Inactivation of pertussis toxin-sensitive guanyl nucleotide-binding proteins increase parathyroid hormone receptors and reverse agonist- induced receptor down-regulation in ROS 17/2.8 cells

AB Abou-Samra, H Jueppner, JT Potts Jr and GV Segre
Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.

We examined mechanisms of down-regulation of PTH receptors and desensitization of the PTH-stimulated increase in intracellular cAMP in clonal rat osteosarcoma cells, ROS 17/2.8. ROS cells treated with 10 nM [Nle8,Nle18,Tyr34] bovine (b) PTH-(1-34) amide (NlePTH) for 3 days showed loss of specific PTH binding and PTH-stimulated cAMP accumulation to 10% of that in vehicle-treated control cells. Treatment of these cells with both 0.5 mM 8-bromo-cAMP (8-Br-cAMP) and 1 mM methylisobutylxanthine or 100 ng/ml cholera toxin for 3 days elicited no change in either of these responses. Treatment with 10 nM NlePTH for 3 days did not modify the cAMP accumulation stimulated by 30 microM forskolin or 1 micrograms/ml cholera toxin, indicating that agonist- specific desensitization of PTH-stimulated cAMP accumulation is not due to diminished activity of either the stimulatory guanyl nucleotide regulatory subunit (Gs) or the catalytic subunit of the adenylate cyclase. Treatment of ROS cells with pertussis toxin (PT; 10 ng/ml) for 12, 24, 48, and 72 h increased specific PTH binding by 21%, 28%, 35%, and 39%. The increase in PTH binding was associated with a parallel increase in PTH-stimulated cAMP accumulation and was due to an increase in the number of PTH receptors. PTH receptor affinity remained constant (apparent Kd = 0.3 nM). PT treatment of the cells partially blocked agonist-specific PTH receptor down-regulation. PT catalyzed ADP ribosylation of 41K and 39K membrane proteins, consistent with the alpha-subunits of Gi and Go, respectively. In conclusion, agonist- induced PTH receptor down-regulation in ROS 17/2.8 cells is cAMP independent and can be reversed by PT treatment. PTH receptor expression in these cells appears to be under tonic inhibitory control by mechanisms involving a PT-sensitive G protein(s).

This article has been cited by other articles:

				G. S. Bounoutas, H. Tawfeek, L. F. Frohlich, U.-i. Chung, and A. B. Abou-Samra Impact of Impaired Receptor Internalization on Calcium Homeostasis in Knock-In Mice Expressing a Phosphorylation-Deficient Parathyroid Hormone (PTH)/PTH-Related Peptide Receptor Endocrinology, October 1, 2006; 147(10): 4674 - 4679. [Abstract] [Full Text] [PDF]

				M. J. Mahon, T. M. Bonacci, P. Divieti, and A. V. Smrcka A Docking Site for G Protein {beta}{gamma} Subunits on the Parathyroid Hormone 1 Receptor Supports Signaling through Multiple Pathways Mol. Endocrinol., January 1, 2006; 20(1): 136 - 146. [Abstract] [Full Text] [PDF]

				T. M. Murray, L. G. Rao, P. Divieti, and F. R. Bringhurst Parathyroid Hormone Secretion and Action: Evidence for Discrete Receptors for the Carboxyl-Terminal Region and Related Biological Actions of Carboxyl- Terminal Ligands Endocr. Rev., February 1, 2005; 26(1): 78 - 113. [Abstract] [Full Text] [PDF]

				H. A. W. Tawfeek, F. Qian, and A. B. Abou-Samra Phosphorylation of the Receptor for PTH and PTHrP Is Required for Internalization and Regulates Receptor Signaling Mol. Endocrinol., January 1, 2002; 16(1): 1 - 13. [Abstract] [Full Text] [PDF]

				H. A. W. Tawfeek, J. Che, F. Qian, and A. B. Abou-Samra Parathyroid hormone receptor internalization is independent of protein kinase A and phospholipase C activation Am J Physiol Endocrinol Metab, September 1, 2001; 281(3): E545 - E557. [Abstract] [Full Text] [PDF]

				T. MASSFELDER, N. TAESCH, N. ENDLICH, A. EICHINGER, B. ESCANDE, K. ENDLICH, M. BARTHELMEBS, and J.-J. HELWIG Paradoxical actions of exogenous and endogenous parathyroid hormone-related protein on renal vascular smooth muscle cell proliferation: reversion in the SHR model of genetic hypertension FASEB J, March 1, 2001; 15(3): 707 - 718. [Abstract] [Full Text] [PDF]

				S. Tetradis, O. Bezouglaia, and A. Tsingotjidou Parathyroid Hormone Induces Expression of the Nuclear Orphan Receptor Nurr1 in Bone Cells Endocrinology, February 1, 2001; 142(2): 663 - 670. [Abstract] [Full Text] [PDF]

				A. J. Koh, C. A. Beecher, T. J. Rosol, and L. K. McCauley 3',5'-Cyclic Adenosine Monophosphate Activation in Osteoblastic Cells: Effects on Parathyroid Hormone-1 Receptors and Osteoblastic Differentiation in Vitro Endocrinology, July 1, 1999; 140(7): 3154 - 3162. [Abstract] [Full Text]

				L. Y. Xie and A. B. Abou-Samra Epitope Tag Mapping of the Extracellular and Cytoplasmic Domains of the Rat Parathyroid Hormone (PTH)/PTH-Related Peptide Receptor Endocrinology, November 1, 1998; 139(11): 4563 - 4567. [Abstract] [Full Text] [PDF]

				A. Iida-Klein, J. Guo, L. Y. Xie, H. Jüppner, J. T. Potts Jr., H. M. Kronenberg, F. R. Bringhurst, A. B. Abou-Samra, and G. V. Segre Truncation of the Carboxyl-terminal Region of the Rat Parathyroid Hormone (PTH)/PTH-related Peptide Receptor Enhances PTH Stimulation of Adenylyl Cyclase but Not Phospholipase C J. Biol. Chem., April 14, 1995; 270(15): 8458 - 8465. [Abstract] [Full Text] [PDF]