Elastase Release of Basic Fibroblast Growth Factor in Pulmonary Fibroblast Cultures Results in Down-regulation of Elastin Gene Transcription
A ROLE FOR BASIC FIBROBLAST GROWTH FACTOR IN REGULATING LUNG REPAIR*
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
- ‡ To whom correspondence should addressed: Dept. of Biochemistry, Boston University School of Medicine, 80 E. Concord St., Boston, MA 02118. Tel.: 617-638-4361; Fax: 617-638-5339; E-mail: foster{at}med-biochm.bu.edu
Abstract
We have reported previously that a factor released by elastase treatment of pulmonary fibroblast cultures is capable of down-regulating elastin gene expression. In the present study we have pursued the identification of the factor released by elastase treatment and the characterization of the level of elastin gene expression at which this factor exerts its effect. We have found by immunologic and biochemical procedures that elastase treatment results in the release of basic fibroblast growth factor (bFGF) that is bound within the matrix. Both purified bFGF and bFGF released by elastase from cell matrices decrease the transcriptional level of the elastin gene by 70-80% within 24 h. Transient transfections of pulmonary fibroblasts with a series of elastin promoter deletion constructs show that the region of the elastin gene responsive to bFGF is located within sequences spanning −900 to −200 base pairs. The biological implications of these findings coupled with our previous report are significant, since they demonstrate that elastase digestion of pulmonary fibroblast matrices not only results in the proteolysis of elastin but also results in the release of a potent regulator of elastin gene transcription whose activity can influence repair mechanisms.
Footnotes
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↵* This work was supported by National Institutes of Health Grant HL 46100 and HL 46902 and a Whitaker Foundation biomedical engineering research grant. 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.
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↵1 The abbreviations used are:
- bFGF
-
basic fibroblast growth factor
- Ab
-
antibody
- bp
-
base pair(s)
- BSA
-
bovine serum albumin
- CAT
-
chloramphenicol acetyl-CoA transferase
- CLSM
-
confocal laser scanning microscope
- DMEM
-
Dulbecco's modified Eagle's medium
- FBS
-
fetal bovine serum
- FGF
-
fibroblast growth factor
- PBS
-
phosphate-buffered saline
- PAGE
-
polyacrylamide gel electrophoresis
- TGF-β
-
transforming growth factor-β.
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↵2 C. B. Rich, M. A. Nugent, P. Stone, and J. A. Foster, unpublished data.
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- Received March 26, 1996.
- Revision received June 25, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
