Evidence for intracellular cleavage of plasminogen activator inhibitor type 2 (PAI-2) in normal epidermal keratinocytes

Autor: Barbara Risse, Mark S. Baker, Nancy M. Chung, Pamela J. Jensen
Rok vydání: 2000
Předmět:
Zdroj: Journal of Cellular Physiology. 182:281-289
ISSN: 1097-4652
0021-9541
DOI: 10.1002/(sici)1097-4652(200002)182:2<281::aid-jcp17>3.0.co;2-d
Popis: Plasminogen activator inhibitor type 2 (PAI-2) is a serine proteinase inhibitor (serpin), present in high quantities in stratified squamous epithelia. Detergent extracts of human epidermis or cultured keratinocytes contain primarily active, nonglycosylated PAI-2. In keratinocytes, the vast majority of PAI-2 is retained within the cell, supporting the hypothesis that PAI-2 may serve specific intracellular function(s) through interaction with an unknown cytoplasmic proteinase. During interaction with the target proteinase, cleavage of PAI-2 within its reactive site loop leads to the formation of a more stable, “relaxed” conformation (PAI-2r). Using a monoclonal antibody specific for PAI-2r, we demonstrate here that PAI-2r is present in keratinocytes of the granular and basal layers of normal human epidermis. In addition, PAI-2r is detectable in cultured human epidermal keratinocytes, where it is concentrated in a detergent-insoluble fraction within differentiating cells. These data provide evidence for the presence of an endogenous, keratinocyte-derived proteinase that constitutively cleaves intracellular PAI-2 in normal human epidermal keratinocytes. Cleavage of PAI-2 by this proteinase may reflect specific intracellular action of PAI-2 in normal cells. Finally, we demonstrate that a commercially available anti–PAI-2 monoclonal antibody (#3750, American Diagnostica, Greenwich, CT), under native experimental conditions, preferentially recognizes the uncleaved, active form of PAI-2 and does not efficiently detect PAI-2r. J. Cell. Physiol. 182:281–289, 2000. © 2000 Wiley-Liss, Inc.
Databáze: OpenAIRE
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