当前位置： SCI文献检索 > JOURNAL OF CELLULAR BIOCHEMISTRY期刊下所有文献 > Growth factor regulation of insulin-like growth factor binding protein-6 expression in osteoblasts.

Growth factor regulation of insulin-like growth factor binding protein-6 expression in osteoblasts.

Abstract：

:Previously we have shown that transforming growth factor beta (TGF beta) 1, basic fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) BB inhibit the synthesis of insulin-like growth factor (IGF) II, but their effects on IGF binding protein (IGFBP)-6 in osteoblast cultures are not known. IGFBP-6 binds IGF II with high affinity and prevents IGF II-mediated effects, so that a possible mode of regulating the IGF II available to bone cells would be by changing the levels of IGFBP-6. To enhance our understanding of the actions of growth factors on the IGF II axis in bone, we tested the effects of TGF beta 1, basic FGF, PDGF BB, IGF I, and IGF II on the expression of IGFBP-6 in cultures of osteoblast-enriched cells from 22 day fetal rat calvariae (Ob cells). Treatment of Ob cells with TGF beta 1 caused a time- and dose-dependent decrease in IGFBP-6 mRNA levels, as determined by Northern blot analysis. The effect was maximal after 48 h and observed with TGF beta 1 concentrations of 0.04 nM and higher. TGF beta 1 also decreased IGFBP-6 polypeptide levels in the medium, as determined by Western immunoblot analysis. Cycloheximide at 3.6 microM decreased IGFBP-6 transcripts and prevented the effect of TGF beta 1. The decay of IGFBP-6 mRNA in transcriptionally arrested Ob cells was not modified by TGF beta 1. In addition, TGF beta 1 decreased the rates of IGFBP-6 transcription as determined by a nuclear run-on assay. In contrast, basic FGF, PDGF BB, IGF I, and IGF II did not change IGFBP-6 mRNA levels in Ob cells. In conclusion, TGF beta 1 inhibits IGFBP-6 expression in Ob cells by transcriptional mechanisms. Since IGFBP-6 binds IGF II and prevents its effects on bone cells, decreased synthesis of IGFBP-6 induced by TGF beta 1 could be a local feedback mechanism to increase the amount of IGF II available in the bone microenvironment.

journal_name

J Cell Biochem

journal_title

Journal of cellular biochemistry

authors

Gabbitas B,Canalis E

doi

10.1002/(sici)1097-4644(19970701)66:1<77::aid-jcb9

subject

Has Abstract

pub_date

1997-07-01 00:00:00

pages

77-86

issue

eissn

0730-2312

issn

1097-4644

pii

10.1002/(SICI)1097-4644(19970701)66:1<77::AID-JCB9

journal_volume

pub_type

杂志文章

在线工具

Growth factor regulation of insulin-like growth factor binding protein-6 expression in osteoblasts.