The Drosophila daughterless gene autoregulates and is controlled by both positive and negative cis regulation.

As the only class I helix-loop-helix transcription factor in Drosophila, Daughterless (Da) has generally been regarded as a ubiquitously expressed binding partner for other developmentally regulated bHLH transcription factors. From analysis of a novel tissue-specific allele, da(lyh), we show that da expression is not constitutive, but is dynamically regulated. This transcriptional regulation includes somatic ovary-specific activation, autoregulation and negative regulation. Unexpectedly, the diverse functions of da may require that expression levels be tightly controlled in a cell and/or tissue-specific manner. Our analysis of da(lyh) identifies it as the first springer insertion that functions as an insulating element, with its disruptive activity mediated by the product of a fourth chromosome gene, Suppressor of lyh [Su(lyh)].