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The dorsal‐related immunity factor, Dif, is a sequence‐specific trans‐activator of Drosophila Cecropin gene expression.
Author(s) -
Petersen U.M.,
Björklund G.,
Ip Y.T.,
Engström Y.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb07317.x
Subject(s) - arrhenius equation , biology , chemistry , activation energy , organic chemistry
A new member of the Rel family of transcription factors, the dorsal‐related immunity factor, Dif, was recently cloned and suggested to be involved in regulating the immune response in Drosophila. Despite its classification as a Rel family member, the Dif cDNA‐encoded product has not been proven previously to be a transcription factor. We now present evidence that the Dif gene product trans‐activates the Drosophila Cecropin A1 gene in co‐transfection assays. The transactivation requires a 40 bp upstream element including an insect kappa B‐like motif. A dimer of the kappa B‐like motif 5′‐GGGGA inserted into a minimal promoter conferred high levels of reporter gene expression by Dif, while a multimer of several mutated versions of this motif was not activated, demonstrating the sequence specificity of Dif. Full trans‐activation by Dif requires the C‐terminal part of the protein. The morphogen dorsal (dl) can also activate the Cecropin A1 promoter, but to a lesser extent and in a less sequence‐specific manner than Dif. Simultaneous overexpression of Dif and dl in co‐transfection assays revealed that dl possesses a dominant negative effect on Dif transactivation. This study establishes that Dif is a sequence‐specific transcription factor and is probably a key activator of the immune response in Drosophila.

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