Glycoproteins modulate adhesion in terminally differentiated keratinocytes

Area of Science:

• Dermatology
• Biochemistry
• Cell Biology

Background:

• The stratum corneum, the outermost skin layer, provides a protective barrier.
• Understanding corneocyte adhesion is vital for skin barrier function research.
• Previous studies suggested lipids mask cell surface binding sites.

Purpose of the Study:

• To investigate the mechanism of corneocyte adhesion in the stratum corneum.
• To identify key molecules involved in maintaining the integrity of the skin barrier.
• To validate the role of a specific cell-surface glycoprotein in corneocyte aggregation.

Main Methods:

• Dissociation of stratum corneum into single corneocytes using ether homogenization.
• Reaggregation of corneocytes into a lamellar structure in an acetone-based system.
• Utilizing fluorescein-conjugated lectins to probe saccharide sites.
• Inhibition studies using antibodies and specific sugars against a 40 kD glycoprotein.

Main Results:

• Reconstituted stratum corneum showed lectin binding, unlike intact tissue, indicating lipid masking of saccharide sites.
• A 40 kD cell-surface glycoprotein, an endogenous lectin specific for amino sugars, was isolated.
• This glycoprotein was found to be instrumental in corneocyte adhesion by cross-linking adjacent cell surfaces.
• Reaggregation was inhibited by antibodies to the glycoprotein, free amino sugars, or exogenous lectins.

Conclusions:

• Lipids in the intact stratum corneum mask cell-surface saccharide binding sites.
• A 40 kD endogenous lectin (glycoprotein) plays a critical role in corneocyte adhesion.
• This lectin mediates adhesion by cross-linking amino sugar sites on adjacent corneocytes, essential for skin barrier formation.