Rat epidermal growth factors: purification and tissue content

Area of Science:

• Biochemistry
• Molecular Biology
• Endocrinology

Background:

• Epidermal Growth Factor (EGF) is a key signaling molecule.
• Understanding EGF's role in mammalian physiology requires its isolation and quantification.

Purpose of the Study:

• To isolate and purify rat epidermal growth factor (rEGF).
• To develop a radioimmunoassay (RIA) for rEGF.
• To determine the tissue distribution and age-dependent changes of rEGF in male rats.

Main Methods:

• Reversed-phase high-performance liquid chromatography (RP-HPLC) and ion-exchange chromatography for rEGF isolation.
• Binding assays with human carcinoma cells (A-431) and tritiated thymidine uptake assays on rat epidermal fibroblast cells (FR).
• Development of a rabbit anti-rEGF antiserum and establishment of a RIA system.

Main Results:

• Purified rEGF exhibited similar biological activity to mouse EGF (mEGF).
• The RIA system demonstrated an assay range of 1.0–100 ng/ml with acceptable coefficients of variation.
• High rEGF concentrations were found in the submaxillary gland (214 µg/g), prostate (65.6 ng/g), and seminal vesicle (2,268 ng/g).
• Digestive tissues showed lower concentrations, and submaxillary gland rEGF levels increased significantly after 7 weeks of age.

Conclusions:

• Rat EGF can be effectively isolated and quantified using chromatographic and RIA methods.
• The submaxillary gland is a major source of rEGF in male rats.
• The presence of rEGF in reproductive tissues and its age-dependent increase suggest a role in gonadal function.