Point mutation in the fibroblast growth factor receptor eliminates phosphatidylinositol hydrolysis without affecting...

Area of Science:

• Cell Biology
• Molecular Biology
• Neuroscience

Background:

• Fibroblast growth factors (FGF) are known to induce growth arrest and differentiation in rat pheochromocytoma PC12 cells.
• The precise signaling pathways mediating FGF-induced differentiation are complex and involve multiple molecular players.

Purpose of the Study:

• To investigate the role of phosphatidylinositol (PI) hydrolysis in FGF-induced differentiation of PC12 cells.
• To determine if PI hydrolysis is essential for the neuronal differentiation of PC12 cells stimulated by acidic FGF (aFGF).

Main Methods:

• Utilized a mutant FGF receptor 1 (flg) defective in PI hydrolysis stimulation (Y766F mutation).
• Assessed tyrosine phosphorylation of phospholipase C gamma, Shc, and mitogen-activated protein kinase.
• Analyzed the association of Shc with GRB2 and the electrophoretic mobility shift of Sos.
• Observed neurite outgrowth in PC12 cells expressing wild-type or mutant FGF receptors upon aFGF stimulation.

Main Results:

• The Y766F mutation in the FGF receptor prevented tyrosine phosphorylation of phospholipase C gamma and abolished aFGF-induced PI hydrolysis.
• aFGF stimulation led to Shc tyrosine phosphorylation, Shc-GRB2 association, Sos mobility shift, and enhanced mitogen-activated protein kinase phosphorylation in cells with both wild-type and mutant receptors.
• Neurite outgrowth, a hallmark of PC12 cell differentiation, occurred normally in response to aFGF regardless of the FGF receptor's PI hydrolysis activity.

Conclusions:

• Phosphatidylinositol hydrolysis is not a critical component for FGF-induced neuronal differentiation in PC12 cells.
• The Ras signaling pathway, crucial for PC12 cell differentiation, operates independently of PI hydrolysis stimulated by FGF.