Regulation of PTH/PTH-related protein receptor expression by endogenous PTH-related protein in the rat osteosarcoma cell line ROS 17/2.8.

Abstract

We have utilized clonal lines of the rat osteoblastic cell line ROS 17/2.8 stably transfected with full-length parathyroid hormone-related protein (PTHrP) cDNA in a sense or an antisense orientation to examine the effects of alteration in the production of endogenous PTHrP on expression of the PTH/PTHrP receptor. In the stably transfected clonal cell lines, changes in PTH/PTHrP receptor expression were evaluated by Northern blot analysis, whole-cell ligand binding of 125I-[Tyr36] PTHrP (1-36), and exogenous PTHrP (1-34)-stimulated cyclic adenosine monophosphate (cAMP) accumulation. Compared to control (vector-transfected) cells, PTHP-overproducing (sense-transfected) cells exhibited a marked decrease in the expression of PTH/PTHrP receptor mRNA and PTHrP ligand binding, as well as a corresponding decrease in the PTHrP (1-34)-stimulated cAMP response. By contrast, the antisense-transfected cells showed a marked increase in expression of PTH/PTHrP receptor mRNA and PTHrP (1-34) ligand binding, but a significant increase in the PTHrP (1-34)-stimulated cAMP response was not detected. Using antisense-transfected ROS cells, PTH/PTHrP receptor mRNA expression and 125I-[Tyr36] PTHrP (1-36) binding were downregulated by treatment for 24 h with exogenous PTHrP (1-36), forskolin, or dibutyryl cAMP. The findings extend those of earlier studies showing receptor downregulation by exogenous PTH by indicating that endogenous PTHrP, as well as circulating PTH, may help regulate receptor production; and suggesting that even very low concentrations of the peptide may influence receptor production.

• Authors: P Du, P K Seitz, C W Cooper
• Journal: Endocrine (Endocrine) Vol. 12 Issue 1 Pg. 25-33 (Feb 2000) ISSN: 1355-008X [Print] United States
• PMID: 10855687 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• PTHLH protein, human
• Parathyroid Hormone-Related Protein
• Proteins
• RNA, Antisense
• RNA, Messenger
• Receptors, Parathyroid Hormone
• Colforsin
• Bucladesine
• Cyclic AMP

Topics

• Animals
• Blotting, Northern
• Bucladesine (pharmacology)
• Colforsin (pharmacology)
• Cyclic AMP (metabolism)
• Gene Expression Regulation (drug effects)
• Humans
• Osteoblasts (metabolism)
• Osteosarcoma (metabolism)
• Parathyroid Hormone-Related Protein
• Proteins (genetics, metabolism, pharmacology)
• RNA, Antisense (analysis)
• RNA, Messenger (analysis)
• Rats
• Receptors, Parathyroid Hormone (genetics, metabolism)
• Transfection
• Tumor Cells, Cultured