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

Area of Science:

• Developmental Biology
• Cell Biology
• Genetics

Background:

• Embryonic gastrulation involves complex cell movements regulated by signaling pathways and extracellular matrix components.
• Fibroblast growth factors (FGFs) are known to be critical for mesoderm migration in Drosophila melanogaster, but the underlying mechanisms and additional contributing factors remain unclear.

Purpose of the Study:

• To identify novel secreted or membrane-associated molecules that support embryonic mesoderm migration.
• To investigate the specific roles of the heparan sulfate proteoglycans (HSPGs) Trol and Syndecan in Drosophila mesoderm migration and their relationship with FGF signaling.

Main Methods:

• An ectopic expression screen was conducted in Drosophila to identify genes affecting mesoderm migration.
• Loss-of-function phenotypes of candidate genes were analyzed, focusing on mesoderm migration defects.
• Mutant embryos for Trol and Syndecan (Sdc) were generated and analyzed to compare their roles in embryonic development.

Main Results:

• An ectopic expression screen identified 10 genes with loss-of-function phenotypes affecting mesoderm migration, including the FGF ligand Pyramus, integrins, E-cadherin, EGFR, JAK/STAT components, and the HSPG Trol.
• Trol, the Drosophila ortholog of mammalian Perlecan, was found to be essential for mesoderm migration and caudal visceral mesoderm (CVM) migration, sharing phenotypes with FGF mutants.
• Syndecan (Sdc) also plays a role, particularly in dorsal mesoderm specification, indicating distinct functions for different HSPGs.

Conclusions:

• Both Trol and Syndecan are important HSPGs that support FGF-dependent processes during embryonic development.
• The choice of HSPG cofactor can modulate the output of FGF signaling, highlighting a layer of regulatory specificity.
• These findings provide new insights into the mechanisms governing embryonic cell migration and the role of HSPGs in developmental signaling.