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Stratum corneum-derived caspase-14 is catalytically active
Heinz Fischer1, Martin Stichenwirth, Michael Dockal
1Department of Dermatology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
FEBS Letters
|November 24, 2004
Summary
Caspase-14 is the main protease in the stratum corneum (SC) of human skin. This enzyme is crucial for skin barrier function, as it is active in differentiated epidermal keratinocytes.
Area of Science:
- Biochemistry
- Dermatology
- Molecular Biology
Background:
- Caspase-14 is a cysteine protease predominantly found in differentiated epidermal keratinocytes.
- Its role in the stratum corneum (SC) and its activity in various skin conditions remain incompletely understood.
Purpose of the Study:
- To investigate the presence and activity of caspase-14 in the human stratum corneum.
- To compare caspase-14 activity in normal skin versus skin affected by psoriasis and seborrheic dermatitis.
Main Methods:
- Extraction of soluble proteins from human stratum corneum.
- Assay of tetrapeptide caspase substrate cleavage.
- Immunodepletion of caspase-14.
- Fractionation of parakeratotic skin extracts.
Main Results:
- Stratum corneum extracts exhibit significant caspase activity, primarily due to caspase-14.
- Caspase-14 is the predominant caspase in the SC.
- Normal SC contains processed caspase-14, while parakeratotic skin shows both procaspase-14 and processed forms.
- Peak caspase activity in parakeratotic SC correlates with processed caspase-14.
Conclusions:
- Endogenous procaspase-14 is converted to active caspase-14 subunits during terminal keratinocyte differentiation.
- These active caspase-14 subunits are present in the outermost layers of normal human skin.
- Aberrant caspase-14 processing may occur in skin diseases like psoriasis and seborrheic dermatitis.