LOZENGE IS EXPRESSED IN PLURIPOTENT PRECURSOR CELLS AND PATTERNS MULTIPLE CELL-TYPES IN THE DROSOPHILA EYE THROUGH THE CONTROL OF CELL-SPECIFIC TRANSCRIPTION FACTORS

In the developing Drosophila eye, individual cell fates are specified when general signaling mechanisms are interpreted in the context of ce ll-specific transcription factors. Lozenge, a Runt/AML1/CBFA1-like tra nscription factor, determines the fates of a number of neuronal and no n-neuronal cells by regulating the expression of multiple fate-determi ning transcription factors. The Lozenge protein is expressed in the nu clei of the cells that it patterns and also in their undifferentiated precursors. An enhancer element located within the second intron of th e lozenge gene is responsible for its eye-specific expression. Lozenge is not itself a cell-specific transcription factor, rather it prepatt erns the eye disc by positioning cell-specific factors in their approp riate locations.