Ectopic expression screen identifies genes affecting Drosophila mesoderm development including the HSPG Trol.
Bottom Line: These include the FGF ligand Pyramus, α-integrins, E-cadherin, Cueball, EGFR, JAK/STAT signaling components, as well as the heparan sulfate proteoglycan (HSPG) Terribly reduced optic lobes (Trol).Our data support the view that both HSPGs function to support FGF-dependent processes in the early embryo as they share phenotypes with FGF mutants: Trol in terms of effects on mesoderm migration and caudal visceral mesoderm (CVM) migration and Sdc in terms of dorsal mesoderm specification.The differential roles uncovered for these two HSPGs suggest that HSPG cofactor choice may modify FGF-signaling outputs.
Affiliation: Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, MC 114-96, Pasadena, California 91125.Show MeSH
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Mentions: Because both Trol (Figure 4) and Sdc (Knox et al. 2011) mutants exhibit phenotypes that affect the mesoderm of early embryos, we investigated their expression patterns during the stages of early mesoderm development to provide more specific insights into these genes' functions. Both genes are maternally expressed and present ubiquitously at low levels; however, at two stages, localized expression was detected. Once the furrow is formed, trol is upregulated in the ventral-most cells where the mesoderm will collapse onto the ectoderm; in contrast, Sdc at this stage remains ubiquitously diffuse (compare Figure 5A arrow and Figure 5C). Conversely, sdc becomes localized to the ectoderm later, when the mesoderm intercalates to form a single layer of cells (Figure 5D arrow); in contrast, trol at this later stage is no longer spatially upregulated and instead is present uniformly at low levels (Figure 5B). The dynamics of sdc expression suggest that Sdc, like zygotic Trol, may be required only for monolayer formation at later stages.
Affiliation: Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, MC 114-96, Pasadena, California 91125.