THE TRANSCRIPTION FACTOR CF2 IS A MEDIATOR OF EGF-R-ACTIVATED DORSOVENTRAL PATTERNING IN DROSOPHILA OOGENESIS

Establishment of dorsoventral polarity during Drosophila oogenesis req uires localized intercellular communication between the follicular cel ls and the oocyte. This is initiated by the transmission of a ''dorsal signal'' from the oocyte to the anterior dorsal follicle cells by the EGF receptor (EGF-R) pathway and is followed by transmission of a sec ond signal from the ventral follicle cells back to the embryo. We show that the zinc finger transcription factor CF2 participates in these p rocesses. CF2 is suppressed by EGF-R signaling in the anterior dorsal follicle cells. Altered expression patterns of CF2 result in specific dorsoventral patterning defects in egg chambers and in embryos, as dem onstrated phenotypically and with molecular markers. CF2 appears to ac t as a repressor of dorsal follicle cell fates and specifically as a r epressor of the rhomboid gene transcription.