The CBP coactivator functions both upstream and downstream of Dpp/Screw signaling in the early Drosophila embryo.
Dev Biol
; 262(2): 294-302, 2003 Oct 15.
Article
em En
| MEDLINE
| ID: mdl-14550792
ABSTRACT
The CBP histone acetyltransferase plays important roles in development and disease by acting as a transcriptional coregulator. A small reduction in the amount of Drosophila CBP (dCBP) leads to a specific loss of signaling by the TGF-beta molecules Dpp and Screw in the early embryo. We show that the expression of Screw itself, and that of two regulators of Dpp/Screw activity, Twisted-gastrulation and the Tolloid protease, is compromised in dCBP mutant embryos. This prevents Dpp/Screw from initiating a signal transduction event in the receiving cell. Smad proteins, the intracellular transducers of the signal, fail to become activated by phosphorylation in dCBP mutants, leading to diminished Dpp/Screw-target gene expression. At a slightly later stage of development, Dpp/Screw-signaling recovers in dCBP mutants, but without a restoration of Dpp/Screw-target gene expression. In this situation, dCBP acts downstream of Smad protein phosphorylation, presumably via direct interactions with the Drosophila Smad protein Mad. It appears that a major function of dCBP in the embryo is to regulate upstream components of the Dpp/Screw pathway by Smad-independent mechanisms, as well as acting as a Smad coactivator on downstream target genes. These results highlight the exceptional sensitivity of components in the TGF-beta signaling pathway to a decline in CBP concentration.
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Base de dados:
MEDLINE
Assunto principal:
Acetiltransferases
/
Fator de Crescimento Transformador beta
/
Proteínas de Saccharomyces cerevisiae
/
Proteínas de Drosophila
/
Drosophila
Limite:
Animals
Idioma:
En
Revista:
Dev Biol
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Suécia