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Platelet‐derived growth factor induces collagenase 3 transcription in osteoblasts through the activator protein 1 complex
Author(s) -
Rydziel Sheila,
Durant Deena,
Canalis Ernesto
Publication year - 2000
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/1097-4652(200009)184:3<326::aid-jcp6>3.0.co;2-s
Subject(s) - collagenase , microbiology and biotechnology , platelet derived growth factor receptor , electrophoretic mobility shift assay , activator (genetics) , transcription factor , biology , transfection , transcription (linguistics) , growth factor , chemistry , cell culture , gene , biochemistry , genetics , enzyme , receptor , linguistics , philosophy
Platelet‐derived growth factor (PDGF) BB is a mitogen that stimulates bone resorption and increases collagenase 3 transcription in osteoblasts, although the mechanisms involved are as yet unknown. We examined the effect of PDGF BB on collagenase 3 transcription in cultures of osteoblasts from fetal rat calvariae (Ob cells). PDGF BB increased the activity of collagenase 3 promoter fragments transiently transfected into Ob cells. Deletion analysis of the collagenase promoter revealed three regions that impaired the induction of collagenase 3 by PDGF BB. A construct spanning base pair −53 to +28 collagenase 3 sequences, in relation to the start site of transcription +1, was fully responsive to PDGF BB and was studied in detail. Targeted mutations of an AP‐1 site in this fragment decreased basal collagenase promoter activity and the responsiveness to PDGF BB, whereas mutations of Stat3 and Ets binding sites did not alter the response to PDGF. Electrophoretic mobility shift assay, using nuclear extracts from control and treated cells, revealed AP‐1 nuclear protein complexes that were enhanced in extracts from PDGF BB–treated Ob cells. Supershift assays revealed that antibodies to c‐Fos, Fos B, Fra‐2, c‐Jun, Jun B, and Jun D shifted the binding of nuclear extracts from cells treated with PDGF BB to AP‐1 sequences. In conclusion, PDGF BB induces collagenase 3 transcription in osteoblasts by regulating nuclear proteins interacting with AP‐1 sequences. J. Cell. Physiol. 184:326–333, 2000. © 2000 Wiley‐Liss, Inc.