The dorsal-related immunity factor, Dif, is a sequence-specific trans-activator of Drosophila Cecropin gene expression

EMBO J. 1995 Jul 3;14(13):3146-58.

Abstract

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'-GGGGATTTTT 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Cells, Cultured
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • Drosophila / genetics*
  • Drosophila / metabolism
  • Drosophila Proteins*
  • Feedback
  • Genes, Insect / genetics*
  • Genes, Reporter
  • Hemocytes / metabolism
  • Insect Hormones / biosynthesis
  • Insect Hormones / genetics*
  • Larva / genetics
  • Larva / metabolism
  • Molecular Sequence Data
  • Mutation
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / genetics
  • Phosphoproteins / biosynthesis
  • Phosphoproteins / genetics
  • Promoter Regions, Genetic
  • RNA, Messenger / biosynthesis
  • Transcription Factors*
  • Transcriptional Activation*
  • Transfection

Substances

  • DNA-Binding Proteins
  • Dif protein, Drosophila
  • Drosophila Proteins
  • Insect Hormones
  • Nuclear Proteins
  • Phosphoproteins
  • RNA, Messenger
  • Transcription Factors
  • dl protein, Drosophila