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Epithelial sodium channels are upregulated during epidermal differentiation
1Department of Medicine, University of California San Francisco, VA Medical Center San Francisco, 94121, USA. y2073@itsa.ucsf.edu
The Journal of Investigative Dermatology
|November 26, 1999
Summary
Amiloride-sensitive epithelial sodium channels are crucial for skin development and keratinocyte differentiation. Their specific subunits are expressed in adult epidermis, suggesting a role in regulating ion transport for terminal differentiation.
Area of Science:
- Dermatology
- Molecular Biology
- Cell Biology
Background:
- Terminal differentiation of epidermal keratinocytes is intrinsically linked to transmembrane ion flux.
- Amiloride, an inhibitor of epithelial sodium channels, has been previously shown to impede the synthesis of differentiation-specific proteins in human keratinocytes.
Purpose of the Study:
- To identify specific subunits of amiloride-sensitive human epithelial sodium channels (hENaC).
- To investigate the role of these channels in cultured human keratinocyte differentiation and fetal epidermal development.
Main Methods:
- Northern hybridization
- RNase protection assay
- Reverse transcription-polymerase chain reaction (RT-PCR)
- Localization studies in human adult epidermis and fetal skin.
Main Results:
- Transcripts for functional alpha and regulatory beta subunits of hENaC were expressed in cultured keratinocytes and adult epidermis.
- mRNA expression of hENaC-alpha and hENaC-beta increased during calcium-induced keratinocyte differentiation.
- hENaC-alpha and hENaC-beta were localized in the nucleated layers of adult epidermis but absent in early fetal development.
Conclusions:
- Co-ordinated expression of hENaC subunits suggests a significant role in epidermal differentiation.
- Epithelial sodium channels likely modulate ion transport essential for epidermal terminal differentiation and skin development.