Prostaglandin E2 rapidly stimulates insulin-like growth factor-I gene expression in primary rat osteoblast cultures

Evidence for transcriptional control

David P. Bichell, Peter Rotwein, Thomas L. McCarthy

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Osteoblast-enriched (Ob) cultures isolated from fetal rat bone synthesize insulin-like growth factor-I (IGF-I), which functions as a locally acting growth and differentiation factor in the skeleton. Consistent with prior studies demonstrating that IGF-I production is enhanced in bone by agents that induce cAMP, prostaglandin E2 (PGE2) stimulates both cAMP synthesis and IGF-I mRNA in Ob cells. However, little is known about how cAMP regulates IGF-I expression in this or any other cell system. In rat tissues, multiple mechanisms influence levels of IGF-I mRNA, including transcription from two promoters, differential RNA splicing and stability, and alternative RNA polyadenylation. To determine how cAMP influences IGF-I gene expression in Ob cultures, we examined the responses of these cells to treatment with PGE2. PGE2 rapidly enhanced the accumulation of both large and small IGF-I transcripts, with increases in IGF-I mRNA detected within 2 h of treatment and persisting for 24 h. Analysis of precursor RNA by a highly specific and sensitive ribonuclease protection assay demonstrated a rise in nascent IGF-I mRNA within 30 min of exposure to PGE2, with a peak stimulation of 4-fold above control levels seen by 2 h and levels remaining elevated for up to 24 h. IGF-I transcripts in Ob cells were directed only by promoter 1, the more 5′ of the two rat IGF-I gene promoters. As additionally assessed using the RNA polymerase II inhibitor 5,6-dichloro-1-β-D-ribofuranosyl benzimidazole, PGE1 treatment had little effect on IGF-I mRNA stability. In aggregrate, these studies show that in fetal rat Ob cultures, PGE2 enhances IGF-I gene expression primarily through transcriptional mechanisms that an limited to a single IGF-I gene promoter. Ob cells, therefore, may be an excellent model for determining how cAMP regulates IGF-I gene transcription.

Original languageEnglish (US)
Pages (from-to)1020-1028
Number of pages9
JournalEndocrinology
Volume133
Issue number3
StatePublished - Sep 1993
Externally publishedYes

Fingerprint

Osteoblasts
Insulin-Like Growth Factor I
Dinoprostone
Gene Expression
Messenger RNA
RNA Stability
Growth Differentiation Factors
Genes
RNA Splicing
Bone and Bones
Polyadenylation
RNA Polymerase II
Alprostadil
RNA Precursors
Ribonucleases
Skeleton

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Prostaglandin E2 rapidly stimulates insulin-like growth factor-I gene expression in primary rat osteoblast cultures : Evidence for transcriptional control. / Bichell, David P.; Rotwein, Peter; McCarthy, Thomas L.

In: Endocrinology, Vol. 133, No. 3, 09.1993, p. 1020-1028.

Research output: Contribution to journalArticle

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