12R-lipoxygenase deficiency disrupts epidermal barrier function.

Area of Science:

• Dermatology
• Biochemistry
• Molecular Biology

Background:

• The 12R-lipoxygenase (12R-LOX) and epidermal LOX-3 (eLOX-3) pathway is implicated in skin terminal differentiation.
• Mutations in 12R-LOX and eLOX-3 are linked to autosomal recessive congenital ichthyosis, a skin barrier disorder.

Purpose of the Study:

• To investigate the role of 12R-LOX in epidermal barrier formation and function.
• To elucidate the molecular mechanisms underlying skin barrier defects in 12R-LOX deficiency.

Main Methods:

• Generation and analysis of 12R-LOX-deficient mice.
• Assessment of skin barrier function, keratinocyte proliferation, and stratification.
• Ultrastructural analysis of the granular layer.
• Analysis of cornified envelope fragility and lipid composition (ceramides).
• Evaluation of profilaggrin processing.

Main Results:

• 12R-LOX deficiency caused severe skin barrier impairment in mice.
• Barrier defects occurred without changes in keratinocyte proliferation or organization.
• Ultrastructural anomalies were observed in the upper granular layer, suggesting lamellar body processing issues.
• Cornified envelopes were fragile, and ceramide composition, particularly ester-bound ceramides, was disordered.
• Profilaggrin processing to filaggrin was impaired.

Conclusions:

• The 12R-LOX-eLOX-3 pathway is essential for epidermal barrier acquisition.
• This pathway influences skin barrier function by regulating lipid metabolism and protein processing.
• Defects in this pathway contribute to ichthyosis pathogenesis through compromised lipid and protein homeostasis.