Parathyroid Hormone Induces c-fos Promoter Activity in Osteoblastic Cells through Phosphorylated cAMP Response Element (CRE)-binding protein Binding to the Major CRE

doi:10.1074/jbc.271.41.25715

Parathyroid Hormone Induces c-fos Promoter Activity in Osteoblastic Cells through Phosphorylated cAMP Response Element (CRE)-binding protein Binding to the Major CRE*

From the Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104

^‡ To whom correspondence should be addressed:
Dept. of Pharmacological and Physiological Science, St. Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104
. Tel.: 314-577-8239; Fax: 314-577-8233; E-mail: partrinc{at}sluvca.slu.edu

Abstract

Many parathyroid hormone (PTH)-mediated events in osteoblasts are thought to require immediate early gene expression. PTH induces the immediate early gene, c-fos, in this cell type through a cAMP-dependent pathway. The present work investigated the nuclear mechanisms involved in PTH regulation of c-fos in the osteoblastic cell line, UMR 106-01. By transiently transfecting c-fos promoter 5′ deletion constructs into UMR cells, we demonstrated that PTH induction of the c-fos promoter requires the major cAMP response element (CRE). Point mutations created in the major CRE within the largest construct inhibited both PTH-stimulated and basal expression. This element, therefore, performs concerted basal and PTH-responsive cis-acting functions. Gel retardation and Western blotting techniques revealed that CRE-binding protein (CREB) constitutively binds the major CRE but becomes phosphorylated at its cAMP-dependent protein kinase consensus recognition site following PTH treatment. CREB was functionally implicated in c-fos regulation by coexpressing a dominant CREB repressor, KCREB (killer CREB), with the c-fos promoter constructs. KCREB suppressed both basal and PTH-mediated c-fos induction. We conclude that PTH activates c-fos in osteoblasts through cAMP-dependent protein kinase-phosphorylated CREB interaction with the major CRE in the promoter region of the c-fos gene.

Footnotes

↵* This work was supported in part by National Institutes of Health Grants AR39743, DK47420, and DK48109 (to N. C. P). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PTH

parathyroid hormone

ATF

activating transcription factor

AP-1

activator protein-1

CRE

cyclic AMP response element

CREB

CRE-binding protein

CAT

chloramphenicol acetyltransferase

PMA

phorbol 12-myristate 13-acetate

CTF/NF1

CAAT transcription factor/nuclear factor-1

PKA

cAMP-dependent protein kinase

PBS

phosphate-buffered saline

8-Br-cAMP

8-bromo-cAMP.
- Received March 18, 1996.
- Revision received July 11, 1996.