title: Metalloprotease-mediated shedding of enzymatically active mouse ecto-ADP-ribosyltransferase ART2.2 upon T cell activation.
abstract: T cells proteolytically shed the ectodomains of several cell surface proteins and, thereby, can alter their responsiveness and can release soluble intercellular regulators. ART2.2 is a GPI-anchored ecto-ADP-ribosyltransferase (ART) related to ADP-ribosylating bacterial toxins. ART2.2 is expressed exclusively by mature T cells. Here we show that ART2.2 is shed from the cell surface in enzymatically active form upon activation of T cells. Shedding of ART2.2 resembles that of L-selectin (CD62L) in dose response, kinetics of release, and sensitivity to the metalloprotease inhibitor Immunex Compound 3, suggesting that ART2.2, like CD62L, is cleaved by TNF-alpha-converting enzyme or by another metalloprotease. ART2.2 shed from activated T cells migrates slightly faster in SDS-PAGE analyses than does ART2.2 released upon cleavage of the GPI anchor. This indicates that shedding of ART2.2 is mediated by proteolytic cleavage close to its membrane anchor. Shed ART2.2 is enzymatically active and ADP-ribosylates several substrates in vitro. Thus, shedding of ART2.2 releases a potential intercellular regulator. Finally, using a new FACS assay for monitoring ADP-ribosylation of cell surface proteins, we demonstrate that shedding of ART2.2 correlates with a reduced sensitivity of T cell surface proteins to ADP-ribosylation. Our findings suggest that by shedding ART2.2 the activated T cell not only releases a potential intercellular regulator but also may alter its responsiveness to immune regulation by ART2.2-mediated ADP-ribosylation of cell surface proteins.
authors.affiliation: Institute for Immunology, University Hospital, Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kahl
authors.forename: M
authors.initials: M
authors.lastname: Nissen
authors.forename: R
authors.initials: R
authors.lastname: Girisch
authors.forename: T
authors.initials: T
authors.lastname: Duffy
authors.forename: E H
authors.initials: EH
authors.lastname: Leiter
authors.forename: F
authors.initials: F
authors.lastname: Haag
authors.forename: F
authors.initials: F
authors.lastname: Koch-Nolte
mesh_terms: D036002:ADP Ribose Transferases; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D002462:Cell Membrane / Q000201:enzymology; D002474:Cell-Free System / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D004789:Enzyme Activation / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006649:Histocompatibility Antigens / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D019041:L-Selectin / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008970:Molecular Weight; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D004791:Enzyme Inhibitors; D017261:Glycosylphosphatidylinositols; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D019041:L-Selectin; D000246:Adenosine Diphosphate Ribose; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; C449322:Art2a protein, mouse; C090163:Art2b protein, rat; D011493:Protein Kinase C; D010738:Type C Phospholipases; D008666:Metalloendopeptidases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D013755:Tetradecanoylphorbol Acetate