204

TERMINAL DIFFERENTIATION OF HUMAN KERATINOCYTES AND STRATUM CORNEUM FORMATION IS ASSOCIATED WITH CASPASE-14 ACTIVATION.

1Eckhart, L., Declercq2, W., Ban1, J., Rendl1, M., Mayer1, C., Lippens2, S., Vandenabeele2, P., Tschachler1,3, E. 1Division of Immunology, Allergy and Infectious Diseases, Department of Dermatology, University of Vienna Medical School, Vienna, Austria, 2Molecular Signaling and Cell Death Unit, Department of Molecular Biology, Flanders Interuniversity Institute for Biotechnology and Gent University, Gent, Belgium. 3Centre de Recherches et d’Investigations Epidermiques et Sensorielles (CE.R.I.E.S.), Neuilly, France.
Abstract

Programmed cell death of epidermal keratinocytes (KC) results in the formation of cornified cells, which constitute the outermost skin layer, the stratum corneum. Here we show by reverse transcription-polymerase chain reaction, western blot, and immunohistochemistry that epidermal KC express caspase-14, a member of the caspase family of pro-apoptotic proteases, in a tissue-specific manner. Caspase-14 protein abundance strongly increases during terminal differentiation of KC in vivo and in vitro. Under conditions that lead to stratum corneum formation caspase-14 cleavage products, which indicate proenzyme activation, appeared in the KC lysates. Cleavage of the enzyme was also detected in lysates from normal human epidermis and in extracts of stratum corneum. Our findings demonstrate that caspase-14 is activated during KC differentiation and strongly suggest that it is involved in the formation of the human skin barrier.

Keywords

Apoptosis, Caspase-14, EpiDerm, Human keratinocytes, Messenger RNA (mRNA), Pro-apoptotic protease, Programmed cell death, Protease, RT-PCR, Stratum corneum, Terminal differentiation

Request a copy of this paper, click here.