High impact information on vn

• We show that in the dorsal follicle cells this initial paracrine signaling event triggers an autocrine amplification by two other EGFR ligands, Spitz and Vein [1].
• Mutations altering the structure of epidermal growth factor-like coding sequences at the Drosophila Notch locus [2].
• Spitz is a potent ligand, whereas Vein is an intrinsically weak activating ligand [3].
• The positive feedback loop of Vein generates a robust mechanism for patterning the ventral ectoderm [3].
• Here we show that the molecular signal for terminal differentiation of tendon cells is the secreted Drosophila neuregulin-like growth factor Vein produced by the myotubes [4].

Biological context of vn

• However, ectopic expression of Vn in other locations does not reorganize ap or Iro-C gene expression [5].
• Here we investigate the tissue-specific regulation of Vn signaling by examining vn transcriptional control and Vn target gene activation in the embryo and the wing [6].
• Developmental analysis shows that cell proliferation stops earlier in larval development the stronger the vn allele considered [7].
• The phenotype and expression analyses show vn has an early role in global proliferation of the wing disc and specific roles in the development of the notum, hinge, longitudinal vein 4, and all intervein regions [8].
• Tendon cell differentiation is initiated by activation of the EGF-receptor signaling pathway within these cells by Vein, a neuregulin-like factor secreted by the approaching myotube [9].

Anatomical context of vn

• The Drosophila neuregulin homolog Vein mediates inductive interactions between myotubes and their epidermal attachment cells [4].
• A major defect in the kakapo mutant tendon cells is the failure of Vein to be localized at the muscle-tendon junctional site; instead, Vein is dispersed and its levels are reduced [9].
• cDNA cloning of a mouse mammary epithelial cell surface protein reveals the existence of epidermal growth factor-like domains linked to factor VIII-like sequences [10].
• Preparations derived from two insect cell lines catalyzed the hydroxylation of the expected asparaginyl residue within a synthetic epidermal growth factor-like module [11].
• We show here that Vein functions like a Neuregulin to maintain glial cell survival [12].

Associations of vn with chemical compounds

• Altogether, these results lead to a model in which integrin-mediated adhesion plays a role in regulating tendon cell differentiation by modulating the activity of the Egfr pathway at the level of its ligand Vein [13].
• Novel type of very high affinity calcium-binding sites in beta-hydroxyasparagine-containing epidermal growth factor-like domains in vitamin K-dependent protein S [14].
• Modification of epidermal growth factor-like repeats with O-fucose. Molecular cloning and expression of a novel GDP-fucose protein O-fucosyltransferase [15].
• A Gain-of-Function Screen Identifying Genes Required for Vein Formation in the Drosophila melanogaster Wing [16].
• An invertebrate alpha-ketoglutarate-dependent aspartyl/asparaginyl beta-hydroxylase, which posttranslationally hydroxylates specific aspartyl or asparaginyl residues within epidermal growth factor-like modules, was identified, partially purified and characterized [11].

Enzymatic interactions of vn

• R8s in turn appear to signal through Rhomboid and Vein to create a patterned array of 'proneural clusters' which contain high levels of phosphorylated ERKA and the bHLH protein Atonal [17].

Regulatory relationships of vn

• Our results favor the possibility that the Drosophila EGF receptor DER/Egfr expressed by the EMA cells functions as a receptor for Vein [4].
• Neuronal Vein activates the MAPKinase signalling pathway in the glia with highest Prospero levels, coupling axon extension with glial proliferation [18].
• In larval wing discs vn is first expressed in the presumptive notum and later in the wing-pouch and hinge regions [8].
• In addition, the ability of ectopic Vein to induce the expression of Delilah and beta1 tubulin depends on the presence of functional Egfrs [4].

Other interactions of vn

• Here we show molecular and genetic evidence that Drosophila vein (vn) encodes a candidate EGFR ligand and that vn expression is spatially restricted [19].
• In the embryo, vn is a target of Spi/DER signaling mediated by the ETS transcription factor PointedP1 (PntP1) [6].
• Repression by Wingless (Wg) signaling further refines the vn expression pattern by causing a discontinuity at the dorsal-ventral boundary [6].
• We show that hh and vein (vn), which encodes a ligand of the Drosophila EGFR (Schnepp, B., Grumbling, G., Donaldson, T. and Simcox, A. (1996) Genes Dev. 10, 2302-13), are expressed in adjacent domains within the imaginal primordium of this region [20].
• We also show that Hh activation of vn is mediated through the gene cubitus interruptus (ci) and that this activation requires the C-terminal region of the Ci protein [20].

References