Delta is a ventral to dorsal signal complementary to Serrate, another Notch ligand, in Drosophila wing formation.

Abstract

Wing margin formation in Drosophila requires the Notch receptor and, in the dorsal compartment, one of its ligands, Serrate. We provide evidence that Delta, the other known ligand for Notch, is also essential for this process. Delta is required in ventral cells at the dorsal/ventral compartment boundary, where its expression is specifically elevated in second-instar wing discs during wing margin formation. Moreover, ectopic Delta expression induces wingless, vestigial, and cut and causes adult wing tissue outgrowth in the dorsal compartment. This effect is mediated by Notch, because loss of Notch activity suppresses Delta-induced ectopic wing outgrowth. Whereas ectopic expression of Notch or the truncated activated Notch induces cut in both dorsal and ventral compartments, ectopic Delta expression induces cut only in the dorsal compartment and ectopic Serrate induces cut only in the ventral compartment. These observations indicate that Notch-expressing cells in a given compartment have different responses to Delta and Serrate. We propose that Delta and Serrate function as compartment-specific signals in the wing disc, to activate Notch and induce downstream genes required for wing formation.

Misexpression Screen in Drosophila melanogaster Aiming to Reveal Novel Factors Involved in Formation of Body Parts

“…To find out whether abrupt overexpression can also mimic loss of Notch signaling in other tissues, we looked at the expression of wg in the wing blade primordium of the wing disc (Figure 5,F and K). It has been shown that wg expression in the wing blade margin is dependent on Notch signaling (Diaz-Benjumea and Cohen 1995;Doherty et al 1996). Whereas dpp disc -Gal4-mediated expression of a constitutively active Notch leads to ectopic expression of wg (Diaz-Benjumea and Cohen 1995), dpp disc -Gal4-mediated expression of abrupt suppresses wg expression ( Figure 5K).…”

A Novel Interaction Between hedgehog and Notch Promotes Proliferation at the Anterior–Posterior Organizer of the Drosophila Wing

“…While N can stimulate growth by inducing expression of wg (as it does in the DV organizer), hyper-activation of N signaling near the AP border of the wing pouch causes overgrowth that is independent of wg (Speicher et al 1994;Doherty et al 1996;Go et al 1998). wg is not normally expressed along the AP axis, but we found that N signaling is activated at the AP compartment border in late third instar discs, pupal discs, and pupal wings.…”

“…Del, deletion; Mut, hypomorphic mutation; Ect exp, ectopic expression; NC, no change; ND, not determined; 3/4À, reduction in distance between veins 3 and 4; 3/4++, increased distance between veins 3 and 4; Fused, fusion of veins 3 and 4; E, enhanced; S, suppressed; L, lethal; VT, vein thickening; BDSC, Bloomington Drosophila Stock Center (USA); NIG, National Institute of Genetics (Mishima, Japan); VDRC, Vienna Drosophila RNAi Center. N activates N signaling (Doherty et al 1996), we increased N expression at the wing AP organizer to test this prediction. Whereas expression of activated N (NICD) in the ptc expression domain was lethal under our assay conditions, expression of full-length wild-type N yielded viable adult flies.…”

Localization and requirement for Myosin II at the dorsal‐ventral compartment boundary of the Drosophila wing

“…Second, we created clones of cells ectopically expressing Delta. These induce Notch activation along their edges (Doherty et al, 1996;de Celis and Bray, 1997), and Myosin II was obviously upregulated along the edges of a majority (21/26) of such clones (Fig. 2C).…”