Archives of Dermatological Research

, Volume 296, Issue 1, pp 30–41

Calcium entry into keratinocytes induces exocytosis of lysosomes

  • Ralph Jans
  • Marc Sartor
  • Michel Jadot
  • Yves Poumay
Original Paper

DOI: 10.1007/s00403-004-0469-0

Cite this article as:
Jans, R., Sartor, M., Jadot, M. et al. Arch Dermatol Res (2004) 296: 30. doi:10.1007/s00403-004-0469-0

Abstract

During the final steps of epidermal differentiation, extracellular calcium ions enter keratinocytes and induce transglutaminase activity and cornified envelope formation. In other cell types, entry of calcium mediated by ionophores has been reported to induce exocytosis of lysosomes. In this study, we investigated whether lysosomes of keratinocytes might exhibit a similar behaviour. Ionomycin treatment induced cornified envelope formation in keratinocytes, but also morphological changes including plasma membrane blebbing, although no immediate alteration in cell viability could be detected. The activity of the soluble lysosomal enzymes cathepsin C and β-galactosidase in the culture medium was increased upon ionomycin treatment. Cell leakage did not seem to be responsible for this phenomenon, as suggested by measurements of the cytosolic enzymes adenylate kinase and dipeptidylpeptidase III in the culture medium. Metabolic labelling followed by immunoprecipitation showed that ionomycin induced release of cathepsin D into the culture medium. Simultaneously, lysosome-associated membrane proteins (Lamps) 1 and 2 were detected at the cell surface of ionomycin-treated keratinocytes by biochemical and morphological approaches. These results suggest that upon ionomycin treatment, calcium entry stimulates exocytosis of lysosomes in keratinocytes.

Keywords

Keratinocyte Calcium Ionomycin Lysosome Exocytosis 

Abbreviations

AK

Adenylate kinase

BSA

Bovine serum albumin

DMSO

Dimethylsulphoxide

DPPIII

Dipeptidylpeptidase III

DTT

Dithiothreitol

EDTA

Ethylene diaminotetraacetic acid

EGTA

Ethylene glycol-O,O′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid

LDH

Lactate dehydrogenase

PBS

Phosphate-buffered saline

SDS

Sodium dodecylsulphate

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Ralph Jans
    • 1
  • Marc Sartor
    • 1
  • Michel Jadot
    • 2
  • Yves Poumay
    • 1
  1. 1.Département Histologie-EmbryologieFacultés Universitaires Notre-Dame de la PaixNamurBelgium
  2. 2.Unité de Recherche en Physiologie Moléculaire, Laboratoire de Chimie PhysiologiqueFacultés Universitaires Notre-Dame de la PaixNamurBelgium