pannier encodes two structurally related isoforms that are differentially expressed during Drosophila development and display distinct functions during thorax patterning.

Previous studies have shown that the pannier (pnr) gene of Drosophila encodes a GATA transcription factor which is involved in various biological processes, including heart development, dorsal closure during embryogenesis as well as neurogenesis and regulation of wingless (wg) expression during imaginal development. We demonstrate here that pnr encodes two highly related isoforms that share functional domains but are differentially expressed during development. Moreover, we describe two genomic regions of the pnr locus that drive expression of a reporter in transgenic flies in patterns that recapitulate essential features of the expression of the isoforms, suggesting that these regions encompass crucial regulatory elements.

Toutatis, a TIP5-related protein, positively regulates Pannier function during Drosophila neural development.

The GATA factor Pannier (Pnr) activates proneural expression through binding to a remote enhancer of the achaete-scute (ac-sc) complex. Chip associates both with Pnr and with the (Ac-Sc)-Daughterless heterodimer bound to the ac-sc promoters to give a proneural complex that facilitates enhancer-promoter communication during development. Using a yeast two-hybrid screening, we have identified Toutatis (Tou), which physically interacts with both Pnr and Chip.

Enhancer-promoter communication mediated by Chip during Pannier-driven proneural patterning is regulated by Osa.

The GATA factor Pannier activates proneural achaete/scute (ac/sc) expression during development of the sensory organs of Drosophila through enhancer binding. Chip bridges Pannier with the (Ac/Sc)-Daughterless heterodimers bound to the promoter and facilitates the enhancer-promoter communication required for proneural development. We show here that this communication is regulated by Osa, which is recruited by Pannier and Chip.