Related Experiment Videos
Cornified cell envelope assembly: a model based on electron microscopic determinations of thickness and projected
M Jarnik1, M N Simon, A C Steven
1Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Cell Science
|June 17, 1998
Summary
The cornified cell envelope (CE), crucial for epithelial barrier function, maintains a uniform thickness across different tissues. This uniformity suggests loricrin forms a single molecular layer, influencing tissue mechanical properties.
Area of Science:
- Cell Biology
- Biophysics
- Dermatology
Background:
- The cornified cell envelope (CE) is a critical structural component of stratified squamous epithelia, providing mechanical resilience and barrier function.
- Loricrin is the major protein component of the CE, comprising 60-80% of its mass, but its precise structural contribution remains unclear.
Purpose of the Study:
- To investigate the structural properties, specifically thickness and uniformity, of the cornified cell envelope (CE) in different murine epithelia.
- To elucidate the molecular organization of the CE and its major component, loricrin.
Main Methods:
- Isolation and analysis of CEs from murine epidermis, forestomach, and footpad.
- Electron microscopy (metal-shadowed) to visualize surface topography.
- Scanning transmission electron microscopy (STEM) to measure mass-per-unit-area.
Main Results:
- CEs exhibited a uniform average thickness of 15.3+/-1.2 nm across all studied tissues.
- Mass-per-unit-area measurements were consistently around 7.0+/-0.8 kDa/nm², indicating a defined density.
- Electron microscopy revealed a smooth cytoplasmic surface and a corrugated extracellular surface.
Conclusions:
- The mature CE possesses a uniquely defined and uniform thickness, irrespective of tissue type.
- Loricrin likely forms a molecular monolayer, explaining the observed uniformity.
- Inter-tissue variations in CE mechanical properties are attributed to protein composition and cross-linking, not thickness differences.