Shc mediates ligand-induced internalization of epidermal growth factor receptors

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Shc proteins are known to interact with components of the AP2 complex.
• Adaptins, including alpha-adaptin, are key players in the formation of coated pits during endocytosis.
• Epidermal growth factor (EGF) receptors are internalized upon ligand binding, a process mediated by endocytosis.

Purpose of the Study:

• To investigate the physiological role of the Shc-adaptin interaction in EGF receptor endocytosis.
• To elucidate the mechanism by which Shc influences EGF receptor internalization.

Main Methods:

• In vitro peptide binding assays to assess Shc-alpha-adaptin interaction.
• Use of adenovirus vectors to express wild-type and mutant Shc proteins in cells.
• Co-precipitation assays to study protein-protein interactions in intact cells.
• Internalization assays to quantify EGF receptor uptake.
• Immunofluorescence microscopy to visualize protein localization and endocytosis patterns.

Main Results:

• Alpha-adaptin binds to wild-type Shc in an EGF-dependent manner, with reduced binding to a mutant Shc (Shc FA).
• EGF stimulation enhances the association of alpha-adaptin with Shc and promotes the coprecipitation of alpha-adaptin with EGF receptors.
• Overexpression of Shc FA reduces EGF internalization, while wild-type Shc enhances punctate staining indicative of endocytosis.
• Shc facilitates the formation of Shc-AP2 complexes and their association with EGF receptors, promoting endocytosis.

Conclusions:

• Shc plays a significant role in ligand-induced endocytosis of EGF receptors.
• The interaction between Shc and the AP2 complex is critical for efficient EGF receptor internalization.
• EGF signaling modulates Shc-AP2 complex formation and its subsequent association with EGF receptors, driving endocytosis.