Scabrous overexpression in the eye affects R3/R4 cell fate specification and inhibits notch signaling

Abstract

Background: Planar cell polarity (PCP) in the Drosophila eye is generated when immature ommatidial preclusters acquire opposite chirality in the dorsal and ventral halves of the eye imaginal disc and rotate 90°toward the equator. The scabrous (sca) gene is involved in R8 differentiation and in the correct spacing of ommatidial clusters in eye imaginal discs, but it was also suggested to be required during ommatidial rotation. However, no clear relationships between sca and other genes involved in the process were established. Results: To explore the role of Sca in PCP establishment, we performed an RNAibased modifier genetic screen using the rough eye phenotype of sca-overexpressing flies. We found that sca overexpression mainly affects R3/R4 cell specification as it was reported in Notch mutants. Of the 86 modifiers identified in the screen, genes encoding components of Notch signaling and proteins involved in intracellular transport were of particular interest. Conclusions: These and other results obtained with a reporter line of Notch activity indicate that sca overexpression antagonizes Notch signaling in the Drosophila eye, and are inconsistent with Sca being an ommatidial rotation-specific factor. We also found that microtubule motors and other proteins involved in intracellular transport are related with Sca function. Developmental Dynamics 245:166-174, 2016. V C 2015 Wiley Periodicals, Inc.

Alcohol Activates Scabrous-Notch to Influence Associated Memories

“…Sca functions as a secreted glycoprotein that likely binds to the extracellular domain of Notch in nearby cells to influence Delta/Notch signaling (Figure 2A; Baker et al, 1990; Powell et al, 2001). Specifically, Sca has been proposed to induce Delta/Notch activation, prevent Notch degradation, or reduce Notch availability in a ligand-dependent manner depending on the spatial and temporal context (Gavish et al, 2016; Giagtzoglou et al, 2013; Lee et al, 1996; Lee et al, 2000; Munoz-Soriano et al, 2016; Renaud and Simpson, 2001). Because the function of the Notch pathway is highly context specific (Bray, 2016), it is critical to understand the relationship between Sca and Delta/Notch in the adult brain.…”

A neural progenitor mitotic wave is required for asynchronous axon outgrowth and morphology

“…In wing discs, ectopic expression of sca inhibits N-pathway by reducing the interactions with its ligands (Lee et al, 2000). In eye discs, some studies indicate that Sca promotes N activation in response to Dl (Li, 2003) and others show that expression of sca in receptor precursor cells reduces N-activity (Muñoz-Soriano et al, 2016;Powell et al, 2001).…”

A neural progenitor mitotic wave is required for asynchronous axon outgrowth and morphology

“…In wing discs, ectopic expression of sca inhibits N-pathway by reducing the interactions with its ligands (Lee et al, 2000). In eye discs, some studies indicate that Sca promotes N activation in response to Dl (Li, 2003) and others show that expression of sca in receptor precursor cells reduces N-activity (Muñoz-Soriano et al, 2016; Powell et al, 2001). Thus, the mechanism by which Sca modulates N-activity seems to be tissue specific.…”

“…In wing discs, ectopic expression of sca inhibits N-pathway by reducing the interactions with its ligands 13 . In eye discs, some studies indicate that Sca promotes N activation in response to Dl 14 and others show that expression of sca in receptor precursor cells reduces N-activity 15,16 .…”