FRS2-dependent SRC activation is required for fibroblast growth factor receptor-induced phosphorylation of Sprouty...

Area of Science:

• Cellular signalling
• Signal transduction pathways
• Molecular biology

Background:

• Fibroblast growth factor receptor (FGFR) signalling plays a critical role in cellular processes.
• Human Sprouty 2 (hSpry2) is a known signalling attenuator.
• The precise mechanism by which hSpry2 is activated and regulates downstream pathways remains under investigation.

Purpose of the Study:

• To elucidate the upstream signalling events leading to hSpry2 phosphorylation.
• To identify the kinase responsible for hSpry2 phosphorylation.
• To determine the role of hSpry2 phosphorylation in regulating the extracellular signal-regulated kinase (ERK) pathway.

Main Methods:

• Utilized SRC family kinase-specific inhibitors.
• Employed mutant cell lines lacking specific signalling components.
• Investigated protein-protein interactions using co-immunoprecipitation assays.

Main Results:

• FGFR activation leads to the phosphorylation of hSpry2 at residue Y55, dependent on fibroblast growth factor receptor substrate 2 (FRS2).
• SRC family kinases, including SRC itself, were identified as direct kinases for hSpry2.
• SRC activation by FGFR signalling requires FRS2 and FGFR kinase activity.
• SRC forms a complex with hSpry2, an interaction enhanced by hSpry2 phosphorylation.
• hSpry2 phosphorylation is essential for its inhibitory function on ERK pathway activation.

Conclusions:

• FGFR signalling activates SRC kinases, which then phosphorylate hSpry2.
• Phosphorylation of hSpry2 by SRC is a key step in the recruitment of SRC to FRS2, leading to signal attenuation.
• This study reveals a novel mechanism where SRC-mediated hSpry2 phosphorylation regulates the ERK pathway.