The cell adhesion molecule Echinoid defines a new pathway that antagonizes the Drosophila EGF receptor signaling pathway

Abstract

Photoreceptor and cone cells in the Drosophila eye are recruited following activation of the epidermal growth factor receptor (EGFR) pathway. We have identified echinoid (ed) as a novel putative cell adhesion molecule that negatively regulates EGFR signaling. The ed mutant phenotype is associated with extra photoreceptor and cone cells. Conversely, ectopic expression of ed in the eye leads to a reduction in the number of photoreceptor cells. ed expression is independent of EGFR signaling and ED is localized to the plasma membrane of every cells throughout the eye disc. We present evidence that ed acts nonautonomously to generate extra R7 cells by a mechanism that is sina-independent but upstream of Tramtrack (TTK88). Together, our results support a model whereby ED defines an independent pathway that antagonizes EGFR signaling by regulating the activity, but not the level, of the TTK88 transcriptional repressor.

RASSF8-mediated transport of Echinoid via the exocyst promotesDrosophilawing elongation and epithelial ordering

“…Whether this role involves cytoskeletal modulation or an Ed adhesive function through homophilic association or heterophilic interactions with other partners, such as its paralog Friend of Echinoid ( Özkan et al, 2013 ) remains to be investigated. Alternatively, as Ed has been shown to modulate several signalling pathways, such as Notch ( Chandra et al, 2003 ; Escudero et al, 2003 ; Rawlins et al, 2003a ), Hippo ( Yue et al, 2012 ) and Epidermal growth factor receptor ( Bai et al, 2001 ; Fetting et al, 2009 ; Islam et al, 2003 ; Rawlins et al, 2003b ; Spencer and Cagan, 2003 ), it may be acting via cell-cell signalling.…”

MIGGRI: A multi-instance graph neural network model for inferring gene regulatory networks for Drosophila from spatial expression images

“…The EGFR signaling pathway is essential during eye development, and the expression of a dominant-negative EGFR completely prevents retinal formation [46]. Activation of the EGFR pathway recruits photoreceptor cells and cone cells in the Drosophila eye, and ED, a cell adhesion molecule, can inhibit EGFR signaling by regulating the activity of the ttk transcriptional repressor [47]. In addition, the degradation of the gene ttk through the gene phyl binds to the BTB domain of ttk during eye development [48,49].…”

Signaling Pathways Controlling Axonal Wrapping in Drosophila

“…The transmembrane protein Kekkon1 is strongly expressed by many neurons and can directly interact with the EGF receptor [66,68,69]. Similarly, the Ig domaincontaining protein encoded by echinoid (ed) negatively regulates the EGF-receptor signaling during Drosophila development [70]. Echinoid functions as a homophilic adhesion molecule.…”

“…It can also show heterophilic interaction in trans with Drosophila Neuroglian, which leads to inhibition of EGF-receptor signaling [67,[71][72][73]. Interestingly, Echinoid can also interact with Turtle which affects glial wrapping [53,70,74]. In addition, gap junctions might contribute to increased glia-glia cell adhesion [75][76][77].…”