Epidermal growth factor (EGF) stimulates EGF receptor synthesis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Epidermal growth factor (EGF) binds to its receptor, a 170,000-dalton glycoprotein.
• Ligand binding triggers receptor internalization and degradation from the cell surface.
• In WB cells, EGF receptor degradation occurs after ligand binding.

Purpose of the Study:

• To investigate if EGF binding influences EGF receptor replenishment.
• To determine if EGF stimulates EGF receptor synthesis.
• To identify the mechanism by which EGF affects receptor levels.

Main Methods:

• Biosynthetic labeling of EGF receptors with [35S]methionine.
• Immunoprecipitation of EGF receptors from WB cells.
• Northern blot analysis of EGF receptor mRNA using cDNA probes.

Main Results:

• EGF binding stimulates EGF receptor synthesis in a dose-dependent manner.
• Increased synthesis of nascent EGF receptors was observed within 2 hours.
• EGF treatment led to a 3-5 fold increase in EGF receptor mRNA levels.

Conclusions:

• EGF binding to its receptor triggers a counterbalancing increase in receptor synthesis.
• EGF enhances the expression of EGF receptor mRNA, promoting receptor replenishment.
• Cellular response to EGF involves both receptor degradation and stimulated synthesis.