Subcellular localization and activation of ADAM proteases in the context of FasL shedding in T lymphocytes.
The "A Disintegrin And Metalloproteinases" (ADAMs) form a subgroup of the metzincin endopeptidases. Proteolytically active members of this protein family act as sheddases and govern key processes in development and inflammation by regulating cell surface expression and release of cytokines, growth factors, adhesion molecules and their receptors. In T lymphocytes, ADAM10 sheds the death factor Fas Ligand (FasL) and thereby regulates T cell activation, death and effector function. Although FasL shedding by ADAM10 was confirmed in several studies, its regulation is still poorly defined. We recently reported that ADAM10 is highly abundant on T cells whereas its close relative ADAM17 is expressed at low levels and transiently appears at the cell surface upon stimulation. Since FasL is also stored intracellularly and brought to the plasma membrane upon stimulation, we addressed where the death factor gets exposed to ADAM proteases. We report for the first time that both ADAM10 and ADAM17 are associated with FasL-containing secretory lysosomes. Moreover, we demonstrate that TCR/CD3/CD28-stimulation induces a partial positioning of both proteases and FasL to lipid rafts and only the activation-induced raft-positioning results in FasL processing. TCR/CD3/CD28-induced FasL proteolysis is markedly affected by reducing both ADAM10 and ADAM17 protein levels, indicating that in human T cells also ADAM17 is implicated in FasL processing. Since FasL shedding is affected by cholesterol depletion and by inhibition of Src kinases or palmitoylation, we conclude that it requires mobilization and co-positioning of ADAM proteases in lipid raft-like platforms associated with an activation of raft-associated Src-family kinases.
University of Kiel, Institute of Immunology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3 Bldg 17, D-24105 Kiel, Germany.
Henriette
H
Ebsen
University of Kiel, Institute of Immunology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3 Bldg 17, D-24105 Kiel, Germany.
Marcus
M
Lettau
University of Kiel, Institute of Immunology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3 Bldg 17, D-24105 Kiel, Germany.
Dieter
D
Kabelitz
University of Kiel, Institute of Immunology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3 Bldg 17, D-24105 Kiel, Germany. Electronic address: Ottmar.Janssen@uksh.de.
Ottmar
O
Janssen
D051722:ADAM Proteins / Q000276:immunology*; D000072197:ADAM10 Protein; D000072198:ADAM17 Protein; D053829:Amyloid Precursor Protein Secretases / Q000276:immunology*; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D002460:Cell Line; D004789:Enzyme Activation / Q000276:immunology; D053222:Fas Ligand Protein / Q000276:immunology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D008247:Lysosomes / Q000276:immunology; D008297:Male; D021962:Membrane Microdomains / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology*; D059748:Proteolysis; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D022142:Secretory Vesicles / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D018106:CD28 Antigens; D017252:CD3 Complex; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D053829:Amyloid Precursor Protein Secretases; D051722:ADAM Proteins; D000072197:ADAM10 Protein; C491236:ADAM10 protein, human; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human
ADAM proteases; Fas Ligand; Lipid rafts; Proteolysis; Secretory lysosomes; T Lymphocytes