Drosophila single-minded represses gene transcription by activating the expression of repressive factors.
The Drosophila single-minded gene controls CNS midline cell development by both activating midline gene expression and repressing lateral CNS gene expression in the midline cells. The mechanism by which Single-minded represses transcription was examined using the ventral nervous system defective gene as a target gene. Transgenic-lacZ analysis of constructs containing fragments of the ventral nervous system defective regulatory region identified sequences required for lateral CNS transcription and midline repression. Elimination of Single-minded:Tango binding sites within the ventral nervous system defective gene did not affect midline repression. Mutants of Single-minded that removed the DNA binding and transcriptional activation regions abolished ventral nervous system defective repression, as well as transcriptional activation of other genes. The replacement of the Single-minded transcriptional activation region with a heterologous VP16 transcriptional activation region restored the ability of Single-minded to both activate and repress transcription. These results indicate that Single-minded indirectly represses transcription by activating the expression of repressive factors. Single-minded provides a model system for how regulatory proteins that act only as transcriptional activators can control lineage-specific transcription in both positive and negative modes.
Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7260, USA.
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D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D002352:Carrier Proteins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila; D029721:Drosophila Proteins; D004475:Ectoderm / Q000502:physiology; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C089449:sim protein, Drosophila; C109766:tgo protein, Drosophila; C094797:vnd protein, Drosophila