Modification of human prekeratin during epidermal differentiation

Area of Science:

• Biochemistry
• Dermatology
• Molecular Biology

Background:

• Human epidermis contains prekeratin and keratin, essential structural proteins.
• Understanding the distinct polypeptide components of prekeratin and keratin is crucial for comprehending epidermal structure and differentiation.

Purpose of the Study:

• To analyze and compare the polypeptide chain components of human epidermal prekeratin and keratin.
• To investigate the relationship between prekeratin and keratin during epidermal differentiation.

Main Methods:

• High-resolution SDS (sodium dodecyl sulphate)/polyacrylamide-gradient-gel electrophoresis was employed to analyze polypeptide components.
• Extraction of prekeratin and keratin from various human epidermal sites (scale, plantar, forearm, scalp) under different buffer conditions.

Main Results:

• Prekeratin exhibited size heterogeneity with at least ten polypeptides (46,000-70,000 MW) in epidermal extracts.
• Keratin differed significantly from prekeratin, requiring denaturing and reducing conditions for extraction and showing distinct electrophoretic profiles.
• Keratin polypeptide profiles varied anatomically, with palmar and plantar keratin containing additional chains compared to forearm and scalp keratin.

Conclusions:

• The modification of prekeratin components to form the keratin polypeptide profile is a key event during epidermal differentiation.
• These structural changes appear to occur within the granular layer of the epidermis.