Membrane glycoconjugate visualization and biosynthesis in normal and retinoid-treated epidermis

Area of Science:

• Biochemistry
• Cell Biology
• Dermatology

Background:

• Cell-membrane glycoconjugates are crucial for cell function and differentiation.
• Lectins and antibodies are tools for visualizing these glycoconjugates.
• Keratinocyte maturation involves changes in cell-surface sugars.

Purpose of the Study:

• To investigate the role of cell-membrane glycoconjugates in epidermal differentiation using lectin histochemistry.
• To examine the effects of retinoids on glycoconjugate expression during keratinocyte maturation.
• To compare retinoid effects on glycoprotein synthesis in cultured keratinocytes versus organ cultures.

Main Methods:

• Frozen sections of mammalian epidermis treated with rhodamine-conjugated lectins.
• Analysis of lectin staining patterns during keratinocyte maturation.
• Cultured human keratinocytes and epidermal organ cultures treated with retinoids.
• Quantitative assessment of glycoprotein and glycolipid biosynthesis.

Main Results:

• Lectin staining revealed increased sugar complexity on cell membranes during keratinocyte maturation.
• Retinoid treatment at high doses and late stages disrupted this pattern.
• Lectin staining disappeared in the stratum corneum due to glycosidase activity.
• Retinoids depressed glycoprotein synthesis in cultured keratinocytes but stimulated it in organ cultures.

Conclusions:

• Lectin visualization of membrane glycoconjugates is valuable for studying epidermal differentiation, both normal and pathological.
• Subtle quantitative changes in differentiation in vitro can be detected by lectins.
• Retinoid effects on glycoconjugate biosynthesis show species differences or require higher organizational levels than cell culture.
• Retinoid-induced changes in organ culture offer a potential bioassay for retinoid potency.