Wing Vein Patterning in Drosophila and the Analysis of Intercellular Signaling

Abstract

The positioning and elaboration of ectodermal veins in the wing of Drosophila melanogaster rely on widely utilized developmental signals, including those mediated by EGF, BMP, Hedgehog, Notch, and Wnt. Analysis of vein patterning mutants, using the molecular and genetic mosaic techniques available in Drosophila, has provided important insights into how a combination of short-range and long-range signaling can pattern a simple epidermal tissue. Moreover, venation has become a powerful system for isolating and analyzing novel components in these signaling pathways. I here review the basic events of vein patterning and give examples of how changes in venation have been used to identify important features of cell signaling pathways.

Widespread regulation of gene expression in the Drosophila genome by the histone acetyltransferase dTip60

“…During development, at least five different signaling pathways contribute to the establishment of vein and intervein territories: Hedgehog (Hh) signaling, bone morphogenetic protein (BMP) signaling, epidermal growth factor receptor (Egfr) signaling, Wingless (Wg) and Notch (N) signaling (Blair, 2007). dTip60 might be affecting any of these pathways, which would result in disturbed vein formation in the absence of dTip60.…”

The BTB/POZ-ZF Transcription Factor dPLZF Is Involved in Ras/ERK Signaling During Drosophila Wing Development

“…In addition, we demonstrated that dPLZF overexpression induces the expression of vein-specific genes, such as rho and spitz, but not dpp and vn, which are required for the specification of vein fate. Rho signaling is required for the maintenance of vein cell fate and activates spitz (Blair, 2007;Lee, 2010) as well as the canonical Ras/ERK pathway via the activation of Egfr ligands (Roch et al, 2002). These results demonstrate that dPLZF is both a downstream component of the Ras/ERK pathway and an activator of Ras/ERK signaling during the development of the Drosophila wing.…”

“…Furthermore, the rhomboid (rho), decapentaplegic (dpp), spitz, and vein (vn) genes perform crucial functions in vein specification during wing development (Blair, 2007). Indeed, rho-mediated hyperactivation of the MAPK pathway is required for vein formation throughout late larval and early pupal development.…”

“…In fact, the human promyelocytic leukemia zinc finger gene (PLZF) encodes a 673-amino acid transcription factor with a conserved BTB/POZ protein-protein interaction domain as well as a DNA-binding motif constructed from nine C 2 H 2 Krüppel-like type zinc fingers (ZFs). PLZF has been linked both directly and indirectly to tumorigenic and developmental processes, including pattern formation, metamorphosis, eye development, and limb development (Blair, 2007;Kelly and Daniel, 2006). Specifically, a transgenic Drosophila strain that ectopically expresses the human hepatocytic ∆BTB-PLZF, a 45-kDa isoform of PLZF that lacks the BTB domain, showed phenotypic changes in eye and wing development via enhanced extracellular signalregulated kinase (ERK) signaling (Ko et al, 2006).…”

“…In Drosophila, Ras/ERK signaling has been implicated in the regulation of a variety of processes, including cell proliferation (Karim and Rubin, 1998), differentiation (Fortini et al, 1992), patterning (Schnorr and Berg, 1996), apoptosis (Bergmann et al, 1998;Kurada and White, 1998), cell migration (Lee et al, 1996), cellular growth, and wing development (Blair, 2007;O'Keefe et al, 2007). Ras activation results in the sequential activation of the highly conserved mitogen-activated protein kinase (MAPK) cascade, which includes Raf, MAP kinase kinase (MEK), and ERK.…”