Genetic and developmental mechanisms underlying the formation of the Drosophila compound eye

Abstract

The compound eye of Drosophila melanogaster consists of individual subunits (''ommatidia''), each containing photoreceptors and support cells. These cells derive from an undifferentiated epithelium in the eye imaginal disc and their differentiation follows a highly stereotypic pattern. Sequential commitment of pluripotent cells to become specialized cells of the visual system serves as a unique model system to study basic mechanisms of tissue development. In the past years, many regulatory genes that govern the development of the compound eye have been identified and their mode of action genetically dissected. Transcription factor networks in combination with cell-cell signalling pathways regulate the development of the eye tissue in a precise temporal and spatial manner. Here, we review the recent advances on how a single-cell-layered epithelium is patterned to give rise to the compound eye. We discuss the molecular pathways controlling differentiation of individual photoreceptors, through which they acquire their functional specificity. Developmental Dynamics 241:40-56,

The transcription factor glass links eye field specification with photoreceptor differentiation in Drosophila

“…After the passage of the morphogenetic furrow, the proneural transcription factor Atonal (Ato) triggers specification of the R8 PR precursors, which sequentially recruit other PR precursors into the developing ommatidia by EGFR signalling: first R2/R5, then R3/R4, R1/R6 and finally, R7 (Ready et al, 1976;Treisman, 2013). A number of genes that are differentially expressed in the distinct PR subtypes control their subtype identity, and regulate how these cells develop during metamorphosis into adult PRs (Mollereau and Domingos, 2005;Tsachaki and Sprecher, 2012;Treisman, 2013).…”

dEHBP1 regulates Scabrous secretion during Notch mediated lateral inhibition

“…The adult Drosophila eye is comprised of a highly specialized lattice of ,800 ommatidia (reviewed by Kumar, 2012;Tsachaki and Sprecher, 2012). Each ommatidium contains eight photoreceptors, R1-R8, that emerge sequentially from undifferentiated imaginal tissue in a tightly regulated manner.…”

Regulation of long-range planar cell polarity by Fat-Dachsous signaling

“…In the eye, the Wingless, Hedgehog, Decapentaplegic, and JAK/STAT pathways regulate long-range developmental processes (reviewed in Tsachaki and Sprecher, 2012). But these pathways all seem to act upstream of polarity establishment, for example in regulating morphogenetic furrow progression or overall dorso-ventral identity (as opposed to ommatidial polarity).…”

“…Eye development in Drosophila initiates with a group of ~10 cells in the late embryo (Kumar, 2012). Eye tissue is specified by genes of the retinal determination network, some of which function in mammalian eye development as well, despite the evolutionary distance and structural and developmental dissimilarities between insect and mammalian eyes (reviewed in Tsachaki and Sprecher, 2012). Early dorsal-localized Wingless expression regulates selector genes of the Iroquois complex, which in turn set up a boundary of Fringe activity that results in Notch activation in a stripe along the dorso-ventral boundary, which establishes the equator (reviewed in Kumar, 2011).…”