Diploidy of XXXX imaginal cells is maintained by a transcriptional repressor encoded by escargot.

@entity5700 @entity535 @entity219 @entity44012 @entity728 @entity238 @entity30898 @entity21698
The @entity238 escargot ( @entity44012 ) gene encodes a @entity728 -type zinc finger protein that is expressed in the imaginal discs and histoblasts. In some @entity44012 mutants, the abdominal histoblasts become @entity5700 . It has therefore been suggested that the role of @entity44012 is to maintain diploidy of the imaginal cells. We show that @entity44012 encodes a DNA-binding protein with high affinity for G/ACAGGTG, the consensus-binding sequence for the basic helix-loop-helix (bHLH) family of transcription factors (E2 box). This DNA-binding activity is essential for @entity44012 function in vivo as the strong embryonic lethal allele esgVS8 is caused by an @entity535 change within the @entity219 finger region, leading to reduced affinity for DNA. In cultured cells, a heterodimer of the bHLH proteins @entity30898 and @entity21698 activates transcription from promoters containing E2 boxes. The @entity44012 protein strongly inhibits this activation, suggesting that @entity44012 may regulate developmental processes dependent on bHLH proteins. In larvae, @entity44012 protein expressed by the heat shock promoter can rescue the @entity5700 phenotype of abdominal histoblasts, demonstrating that the phenotype is attributable to a loss of @entity44012 function. @entity44012 must be expressed continuously during the larval period for efficient rescue. Ectopic expression of @entity44012 in the salivary glands inhibits endoreplication of DNA. These results suggest that @entity44012 is involved in transcriptional inhibition of genes required for endoreplication.
