title: Neutrophil elastase depends on serglycin proteoglycan for localization in granules.
abstract: Granule proteins play a major role in bacterial killing by neutrophils. Serglycin proteoglycan, the major intracellular proteoglycan of hematopoietic cells, has been proposed to play a role in sorting and packing of granule proteins. We examined the content of major neutrophil granule proteins in serglycin knockout mice and found neutrophil elastase absent from mature neutrophils as shown by activity assay, Western blotting, and immunocytochemistry, whereas neutrophil elastase mRNA was present. The localization of other neutrophil granule proteins did not differ between wild-type and serglycin knockout mice. Differential counts and neutrophil ultrastructure were unaffected by the lack of serglycin, indicating that defective localization of neutrophil elastase does not induce neutropenia itself, albeit mutations in the neutrophil elastase gene can cause severe congenital neutropenia or cyclic neutropenia. The virulence of intraperitoneally injected Gram-negative bacteria (Klebsiella pneumoniae) was increased in serglycin knockout mice compared with wild-type mice, as previously reported for neutrophil elastase knockout mice. Thus, serglycin proteoglycan has an important role in localizing neutrophil elastase in azurophil granules of neutrophils, while localization of other granule proteins must be mediated by other mechanisms.
authors.affiliation: Rigshospitalet, Department of Hematology, Granulocyte Research Laboratory, University of Copenhagen, Copenhagen, Denmark. niemann@dadlnet.dk
authors.forename: Carsten U
authors.initials: CU
authors.lastname: Niemann
authors.forename: Magnus
authors.initials: M
authors.lastname: Abrink
authors.forename: Gunnar
authors.initials: G
authors.lastname: Pejler
authors.forename: Rikke L
authors.initials: RL
authors.lastname: Fischer
authors.forename: Erik I
authors.initials: EI
authors.lastname: Christensen
authors.forename: Stefan D
authors.initials: SD
authors.lastname: Knight
authors.forename: Niels
authors.initials: N
authors.lastname: Borregaard
mesh_terms: D000818:Animals; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000378:metabolism; D056649:Cathepsin G; D002403:Cathepsins / Q000737:chemistry / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism*; D018093:Gelatinases / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D019272:Leukocyte Elastase / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008958:Models, Molecular; D053146:Myeloblastin / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D011509:Proteoglycans / Q000235:genetics / Q000502:physiology*; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D011509:Proteoglycans; D033921:Vesicular Transport Proteins; C075430:serglycin; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; C534096:Ctsg protein, mouse; D019272:Leukocyte Elastase; D053146:Myeloblastin; D018093:Gelatinases