p300/CREB-Binding Protein Enhances the Prolactin-Mediated Transcriptional Induction through Direct Interaction with the Transactivation Domain of Stat5, but Does Not Participate in the Stat5-Mediated Suppression of the Glucocorticoid Response
Stat5 was discovered as a PRL-induced member of the Stat (signal transducer and activator of transcription) family. Its induction by many other cytokines and interleukins suggests that Stat5 plays a crucial role not only in mammary epithelial, but also in hematopoietic cells. Cell type- and promoter...
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Published in | Molecular endocrinology (Baltimore, Md.) Vol. 12; no. 10; pp. 1582 - 1593 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Endocrine Society
01.10.1998
Oxford University Press |
Subjects | |
Online Access | Get full text |
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Summary: | Stat5 was discovered as a PRL-induced member of
the Stat (signal transducer and activator of transcription) family. Its
induction by many other cytokines and interleukins suggests that Stat5
plays a crucial role not only in mammary epithelial, but also in
hematopoietic cells. Cell type- and promoter- specific
functions of Stat5 are most likely modulated by the interaction with
other transcription factors. We recently showed cross-talk between
Stat5 and the glucocorticoid receptor. The activated glucocorticoid
receptor forms a complex with Stat5 and enhances Stat5-mediated
transcriptional induction. Conversely, Stat5 diminishes the induction
of glucocorticoid-responsive genes. Here, we investigated the role of
p300/CBP(CREB-binding protein), a transcriptional coactivator of
several groups of transcription factors, in Stat5-mediated
transactivation and in the cross-talk between Stat5 and the
glucocorticoid receptor. p300/CBP acts as a coactivator of Stat5. Its
ectopic expression enhances PRL-induced Stat5-mediated transcriptional
activation. Consistent with this observation, we find that the
adenovirus E1A protein, which binds to p300/CBP, suppresses
Stat5-induced transcriptional activation. This inhibition requires the
Stat5 transactivation domain and the p300/CBP binding site of E1A.
Coimmunoprecipitation and mammalian two-hybrid assays demonstrate a
direct interaction between the carboxyl-terminal transactivation domain
of Stat5 and p300/CBP. p300/CBP also positively interacts with the
glucocorticoid receptor and enhances glucocorticoid receptor-dependent
transcriptional activation of the mouse mammary tumor virus-long
terminal repeat promoter. Overexpression of p300/CBP does not
counteract the Stat5-mediated inhibition of glucocorticoid
receptor-dependent transactivation, i.e. the repression of
the glucocorticoid response by Stat5 is not a consequence of
competition for limiting amounts of p300/CBP. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0888-8809 1944-9917 |
DOI: | 10.1210/mend.12.10.0180 |