Polarized SOS activity orchestrates FGF-directed cell migration in vivo

Area of Science:

• Cell Biology
• Developmental Biology
• Molecular Biology

Background:

• Directed cell migration is crucial for animal development and tissue homeostasis.
• Receptor tyrosine kinase (RTK) signaling pathways are vital for interpreting extracellular cues and guiding cell movement.
• Dysregulated RTK activity is linked to various cancers, but in vivo mechanisms remain incompletely understood.

Purpose of the Study:

• To elucidate the in vivo mechanisms by which RTK signaling directs cell migration.
• To dissect the spatial and temporal requirements of key signaling and cytoskeletal proteins in migrating cells.

Main Methods:

• Systematic dissection of signaling and cytoskeletal proteins in migrating C. elegans muscle progenitors.
• Utilized cell-type-specific depletion of endogenous proteins.
• Employed genetic analysis, including intragenic revertants, to uncouple signaling pathways.

Main Results:

• Fibroblast growth factor receptor (FGFR), GRB2, SOS, and Ras homologs control cell migration independently of canonical ERK, PI3K, and PLCγ effectors.
• SOS polarity serves as an intracellular compass for directed migration, with mislocalization disrupting movement.
• Activated Ras facilitates anterior migration, and specific Ras mutations uncouple migration signaling from Ras-ERK pathways.

Conclusions:

• Identified a novel mechanism for RTK-directed cell migration, emphasizing pathway independence from canonical effectors.
• Demonstrated the critical role of SOS polarity in interpreting directional cues.
• Highlighted the utility of cell-type-specific approaches and genetic tools for studying signaling dynamics in vivo.