Canonical wingless signaling regulates cone cell specification in the Drosophila retina

Abstract

Correct tissue patterning during development involves multiple morphogenetic events that include specification of different cell fates, cell proliferation, cell death, and coordinated changes in cell shape, position, and adhesion. Here, we use the Drosophila retina to explore the molecular mechanisms that regulate and integrate these various events. In a previous report, we found that wingless (wg) was required to induce a previously unknown surge of cell death (''early death'') in the pupal retina. Here, we show that wg is also required to induce the more widely studied mid-pupal cell death (''late death'') in a process that involves regulation of DIAP1. Furthermore, our data suggest that wg has a previously unreported role in specifying the glial-like cone cells. This activity requires canonical Wg signaling and is linked with Notch pathway activity. Our work broadens the role of canonical Wg signaling to encompass multiple patterning steps in the emerging Drosophila retina. Developmental Dynamics 239:875-884,

Competition among gene regulatory networks imposes order within the eye-antennal disc of Drosophila

“…The results from these experiments indicate that an epoch of cell death between 72 and 84 hours AEL affects the final size of the eya 2 disc. As Wg signaling has been show to induce cell death in the eye (Cordero et al, 2004;Cordero and Cagan, 2010;Lin et al, 2004;Lim and Tomlinson, 2006;Nicholson et al, 2009), it is a distinct possibility that the induction of wg expression is responsible for the elevated levels of cell death that we see in eya 2 discs. As the eya 2 discs remain smaller throughout the later stages of development, our data also suggests that cell proliferation rates are not elevated to compensate for the earlier apoptosis (see below).…”

“Fitness Fingerprints” Mediate Physiological Culling of Unwanted Neurons in Drosophila

“…winglessGal4 is expressed in cone cells between 28 and 32 hr APF [11], but expression of Flower Lose-B in all cone cells did not affect peripheral ommatidia cell death (Figures 6C, 6I, and 6J). Next, we used sparkling-Gal4 to overexpress the different isoforms in primary pigment cells and cone cells [23] and again no significant difference in the number of apoptotic TUNELpositive cells was found ( Figures 6D, 6K, and 6L).…”

The lens in focus: a comparison of lens development in Drosophila and vertebrates

“…The Wg receptors Frizzled (Fz)-1 and −2 are also critical regulators of PCP decisions in the R3/R4 photoreceptors, although Wg itself may not be responsible for initiating this process (see review by McNeill 2002). More recently, however, studies have begun to place Wg signaling in processes controlling CC specification and their ability to regulate IOC patterning and death (Cordero et al 2004; Cordero and Cagan 2010). During CC specification, Wg is secreted by PRs, signals in CC precursors through both Frizzled receptors and the canonical Wg transcriptional activator TCF, and blocks the formation of a subset of CCs (Cordero and Cagan 2010).…”

“…More recently, however, studies have begun to place Wg signaling in processes controlling CC specification and their ability to regulate IOC patterning and death (Cordero et al 2004; Cordero and Cagan 2010). During CC specification, Wg is secreted by PRs, signals in CC precursors through both Frizzled receptors and the canonical Wg transcriptional activator TCF, and blocks the formation of a subset of CCs (Cordero and Cagan 2010). Pygopus, a downstream effector of Wg that can function as a TCF co-activator (Thompson et al 2002), is not essential for wg ’s role in CC number but is important for CC morphology, suggesting that wg plays multiple and genetically distinct roles during CC development (Cordero and Cagan 2010).…”