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Mol Cell Biol, June 1998, p. 3310-3320, Vol. 18, No. 6
Department of Cellular and Molecular
Physiology1 and
Department of
Pathology,2 Tufts University School of
Medicine, Boston, Massachusetts 02111
Received 5 December 1997/Returned for modification 19 January
1998/Accepted 20 March 1998
The transcription factor TFII-I was initially isolated as a factor
that can bind to initiator elements in core promoters. Recent evidence
suggests that TFII-I may also have a role in signal transduction. We
have found that overexpression of TFII-I can enhance the response of
the wild-type c-fos promoter to a variety of stimuli. This
effect depends on the c-fos
c-sis-platelet-derived growth factor-inducible factor
binding element (SIE) and serum response element (SRE). There is no
effect of cotransfected TFII-I on the TATA box containing the
c-fos basal promoter. Three TFII-I binding sites can be
found in c-fos promoter. Two of these overlap the
c-fos SIE and SRE, and another is located just upstream of the TATA box. Mutations that distinguish between serum response factor
(SRF), STAT, and TFII-I binding to the c-fos SIE and SRE suggest that the binding of TFII-I to these elements is important for
c-fos induction in conjunction with the SRF and STAT
transcription factors. Moreover, TFII-I can form in vivo
protein-protein complexes with the c-fos upstream
activators SRF, STAT1, and STAT3. These results suggest that TFII-I may
mediate the functional interdependence of the c-fos SIE and
SRE elements. In addition, the ras pathway is required for
TFII-I to exert its effects on the c-fos promoter, and
growth factor stimulation enhances tyrosine phosphorylation of TFII-I.
These results indicate that TFII-I is involved in signal transduction
as well as transcriptional activation of the c-fos promoter.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
TFII-I Enhances Activation of the c-fos
Promoter through Interactions with Upstream Elements
*
Corresponding author. Mailing address: Department of
Physiology, Tufts University School of Medicine, 136 Harrison Ave.,
Boston, MA 02111. Phone: (617) 636-0442. Fax: (617) 636-6745. E-mail: cochran{at}opal.tufts.edu.
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