Extracellular point mutations in FGFR2 elicit unexpected changes in intracellular signalling

Area of Science:

• Cellular Biology
• Molecular Biology
• Systems Biology

Background:

• Systems biology approaches require robust models to predict cellular signaling responses to protein mutations.
• Understanding how extracellular modifications to receptor proteins impact intracellular signaling is crucial for interpreting biological processes and disease states.

Purpose of the Study:

• To investigate the impact of specific point mutations in fibroblast growth factor receptor 2 (FGFR2) on cellular signaling pathways.
• To elucidate the downstream effects of altered receptor-ligand interactions and intracellular trafficking.

Main Methods:

• Utilized point mutations (S252W and P253R) in the extracellular domain of FGFR2.
• Analyzed receptor localization and dynamics following ligand stimulation using techniques like fluorescent lifetime imaging microscopy (FLIM).
• Assessed downstream signaling events, including ERK phosphorylation and FGFR substrate 2 (FRS2) recruitment.

Main Results:

• Mutant FGFR2 receptors (S252W and P253R) exhibited prolonged cell membrane presence compared to wild-type receptors after ligand stimulation.
• Altered intracellular phenotypes were observed, including differential recruitment of FRS2 to the plasma membrane versus vesicular membranes.
• Mutations led to modified protein recruitment and elevated downstream extracellular-signal-regulated kinase (ERK) phosphorylation.

Conclusions:

• Extracellular point mutations in FGFR2 significantly alter receptor behavior and downstream signaling.
• Altered FRS2 recruitment by mutant FGFR2 receptors suggests a novel mechanism of abnormal cellular signaling.
• These findings highlight the complexity introduced by extracellular receptor modifications, challenging current systems biology interpretations.