title: Serglycin-deficient cytotoxic T lymphocytes display defective secretory granule maturation and granzyme B storage.
abstract: Cytotoxic T lymphocytes eliminate infected and tumor cells mainly by perforin/granzyme-induced apoptosis. Earlier studies suggested that serglycin-proteoglycans form macromolecular complexes with granzymes and perforin in the cytotoxic granule. Serglycin-proteoglycans may also be involved in the delivery of the cytolytic machinery into target cells. We have developed a serglycin-deficient mouse strain, and here we studied the importance of serglycin-proteoglycans for various aspects of cytotoxic T lymphocyte function. 35SO4(2-) radiolabeling of serglycin-deficient cells demonstrated a dramatic reduction of incorporated label as compared with wild type cells, indicating that serglycin is by far the dominating proteoglycan species produced by the cytotoxic T lymphocyte. Moreover, lack of serglycin resulted in impaired ability of cytotoxic T lymphocytes to produce secretory granule of high electron density, although granule of lower electron density were produced both in wild type and serglycin-deficient cells. The serglycin deficiency did not affect the mRNA expression for granzyme A, granzyme B, or perforin. However, the storage of granzyme B, but not granzyme A, Fas ligand, or perforin, was severely defective in serglycin-deficient cells. Serglycin-deficient cells did not display defects in late cytotoxicity toward target cell lines. Taken together, these results point to a key role for serglycin in the storage of granzyme B and for secretory granule maturation but argue against a major role for serglycin in the apoptosis mediated by cytotoxic T lymphocytes.
authors.affiliation: Department of Molecular Biosciences, Swedish University of Agricultural Sciences, The Biomedical Center, Box 575, 751 23 Uppsala, Sweden.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Grujic
authors.forename: Tiago
authors.initials: T
authors.lastname: Braga
authors.forename: Agneta
authors.initials: A
authors.lastname: Lukinius
authors.forename: Maija-Leena
authors.initials: ML
authors.lastname: Eloranta
authors.forename: Stefan D
authors.initials: SD
authors.lastname: Knight
authors.forename: Gunnar
authors.initials: G
authors.lastname: Pejler
authors.forename: Magnus
authors.initials: M
authors.lastname: Abrink
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D003208:Concanavalin A / Q000494:pharmacology; D003433:Crosses, Genetic; D019281:Dimerization; D053222:Fas Ligand Protein; D006025:Glycosaminoglycans / Q000378:metabolism; D053804:Granzymes; D008213:Lymphocyte Activation / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008934:Mitogens / Q000494:pharmacology; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011509:Proteoglycans / Q000172:deficiency* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D012697:Serine Endopeptidases / Q000378:metabolism* / Q000648:ultrastructure; D013462:Sulfur Radioisotopes; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D048069:Tumor Necrosis Factors / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000172:deficiency* / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D006025:Glycosaminoglycans; D008562:Membrane Glycoproteins; D008934:Mitogens; D052899:Pore Forming Cytotoxic Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D048069:Tumor Necrosis Factors; D033921:Vesicular Transport Proteins; D019014:fas Receptor; C075430:serglycin; D003208:Concanavalin A; D054353:Perforin; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases