Figure 12. A coordinated action of temporal patterning factors Eyeless (Ey) and Scarecrow (Scro) and the Notch signaling pathway regulates the expressions of Slp1 and Slp2 in medulla neuroblasts.

(A) A schematic summarizing the main findings of this study. In medulla neuroblasts, transcription of the slp1 and slp2 genes is regulated by other temporal patterning factors Ey and Scro and by the Notch pathway. Ey and Scro both activate slp1/2 transcription by binding to the identified enhancers u8772 220 bp and d5778 850 bp. Su(H) activates slp1/2 transcription by binding to the u8772 220 bp enhancer. (B) The cell cycle in neuroblasts is required for continued activation of Notch signaling in medulla neuroblasts. We show that the cell cycle influences expression of slp1 and slp2 genes via its effects on the Notch signaling pathway; Slp1/2 expression is lost in cell cycle arrested neuroblasts due to a failure of Notch signaling. Restoration of Notch signaling rescues Slp1/2 expression in cell cycle arrested neuroblasts. Cellular processes like the neuroblast cell cycle cooperate with temporal patterning and Notch signaling to attain precise developmental outcomes. Graphic A created using BioRender.