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Ectopic expression screen identifies genes affecting Drosophila mesoderm development including the HSPG Trol.

Trisnadi N, Stathopoulos A - G3 (Bethesda) (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, MC 114-96, Pasadena, California 91125.

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sdc mutant embryos exhibit mild defects in mesoderm migration. (A–D) In situ hybridization of (A, B) trol and (C, D) sdc in wild-type embryos. At stage 6, trol is upregulated in the ventral-most ectoderm cells surrounding the invaginated furrow (A, arrow). In contrast, sdc is localized to the same position but at a later stage, when mesoderm cells intercalate to form a monolayer (D, arrow). (E) sdc germline clones have normal mesoderm collapse (i.e., symmetrical). (F) sdc germline clones have mild spreading defects as mesoderm cells form a nonmonolayer (arrows). (G) Ectopically expressing sdc in the mesoderm results in a multilayered mesoderm (arrow). (H) Overexpressing sdc in the ectoderm has little effect as mesoderm spreading appears normal (i.e., monolayer). (I, M) sdc germline clones exhibit a range of cuticular phenotypes that range from "tail-up" to twisted/loss-of-head. (J, K) The α-dpERK staining is detected in cross-sections of embryos from sdc germline clones within dorsal-most mesoderm cells (J; magnified view: J′, arrows), possibly at a reduced level compared with wild-type (see Figure 4J). Ectopic expression of sdc within the mesoderm results in ectopic dpERK throughout the tissue (K; K′, arrow), whereas overexpression of Sdc in the ectoderm has little effect (L; L′, arrow).
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fig5: sdc mutant embryos exhibit mild defects in mesoderm migration. (A–D) In situ hybridization of (A, B) trol and (C, D) sdc in wild-type embryos. At stage 6, trol is upregulated in the ventral-most ectoderm cells surrounding the invaginated furrow (A, arrow). In contrast, sdc is localized to the same position but at a later stage, when mesoderm cells intercalate to form a monolayer (D, arrow). (E) sdc germline clones have normal mesoderm collapse (i.e., symmetrical). (F) sdc germline clones have mild spreading defects as mesoderm cells form a nonmonolayer (arrows). (G) Ectopically expressing sdc in the mesoderm results in a multilayered mesoderm (arrow). (H) Overexpressing sdc in the ectoderm has little effect as mesoderm spreading appears normal (i.e., monolayer). (I, M) sdc germline clones exhibit a range of cuticular phenotypes that range from "tail-up" to twisted/loss-of-head. (J, K) The α-dpERK staining is detected in cross-sections of embryos from sdc germline clones within dorsal-most mesoderm cells (J; magnified view: J′, arrows), possibly at a reduced level compared with wild-type (see Figure 4J). Ectopic expression of sdc within the mesoderm results in ectopic dpERK throughout the tissue (K; K′, arrow), whereas overexpression of Sdc in the ectoderm has little effect (L; L′, arrow).

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.


Ectopic expression screen identifies genes affecting Drosophila mesoderm development including the HSPG Trol.

Trisnadi N, Stathopoulos A - G3 (Bethesda) (2014)

sdc mutant embryos exhibit mild defects in mesoderm migration. (A–D) In situ hybridization of (A, B) trol and (C, D) sdc in wild-type embryos. At stage 6, trol is upregulated in the ventral-most ectoderm cells surrounding the invaginated furrow (A, arrow). In contrast, sdc is localized to the same position but at a later stage, when mesoderm cells intercalate to form a monolayer (D, arrow). (E) sdc germline clones have normal mesoderm collapse (i.e., symmetrical). (F) sdc germline clones have mild spreading defects as mesoderm cells form a nonmonolayer (arrows). (G) Ectopically expressing sdc in the mesoderm results in a multilayered mesoderm (arrow). (H) Overexpressing sdc in the ectoderm has little effect as mesoderm spreading appears normal (i.e., monolayer). (I, M) sdc germline clones exhibit a range of cuticular phenotypes that range from "tail-up" to twisted/loss-of-head. (J, K) The α-dpERK staining is detected in cross-sections of embryos from sdc germline clones within dorsal-most mesoderm cells (J; magnified view: J′, arrows), possibly at a reduced level compared with wild-type (see Figure 4J). Ectopic expression of sdc within the mesoderm results in ectopic dpERK throughout the tissue (K; K′, arrow), whereas overexpression of Sdc in the ectoderm has little effect (L; L′, arrow).
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fig5: sdc mutant embryos exhibit mild defects in mesoderm migration. (A–D) In situ hybridization of (A, B) trol and (C, D) sdc in wild-type embryos. At stage 6, trol is upregulated in the ventral-most ectoderm cells surrounding the invaginated furrow (A, arrow). In contrast, sdc is localized to the same position but at a later stage, when mesoderm cells intercalate to form a monolayer (D, arrow). (E) sdc germline clones have normal mesoderm collapse (i.e., symmetrical). (F) sdc germline clones have mild spreading defects as mesoderm cells form a nonmonolayer (arrows). (G) Ectopically expressing sdc in the mesoderm results in a multilayered mesoderm (arrow). (H) Overexpressing sdc in the ectoderm has little effect as mesoderm spreading appears normal (i.e., monolayer). (I, M) sdc germline clones exhibit a range of cuticular phenotypes that range from "tail-up" to twisted/loss-of-head. (J, K) The α-dpERK staining is detected in cross-sections of embryos from sdc germline clones within dorsal-most mesoderm cells (J; magnified view: J′, arrows), possibly at a reduced level compared with wild-type (see Figure 4J). Ectopic expression of sdc within the mesoderm results in ectopic dpERK throughout the tissue (K; K′, arrow), whereas overexpression of Sdc in the ectoderm has little effect (L; L′, arrow).
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.

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.

View Article: PubMed Central - PubMed

Affiliation: Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, MC 114-96, Pasadena, California 91125.

Show MeSH
Related in: MedlinePlus