Autoregulation of the Drosophila disconnected gene in the developing visual system

The Drosophila disconnected (disco) gene is required for the formation of a ppropriate connections between the larval optic nerve and its target cells in the brain. The disco gene encodes a nuclear protein with two zinc finger s, which suggests that the gene product is a transcription factor. Here, we present data supporting this notion. We find that disco expression in the optic lobe primordium, a group of cells contacted by the developing optic n erve, depends on an autoregulatory feedback loop. We show that wild-type di sco function is required for maintenance of disco mRNA and protein expressi on in the developing optic lobe. In addition, we demonstrate that ubiquitou s Disco activity supplied by a heat-inducible gene construct activates expr ession from the endogenous disco gene specifically in the optic lobe primor dium. Consistent with a role of Disco as a transcriptional regulatory prote in, we show that portions of the Disco protein are capable of activating th e transcription of reporter constructs in a heterologous system. Moreover, we find that the zinc finger portion of Disco binds in vitro to sequences l ocated near the disco transcription unit, suggesting that Disco autoregulat es its transcription in the optic lobe primordium by direct binding to a re gulatory element in its own promoter, (C) 1999 Academic Press.