Neutrophil tissue inhibitor of matrix metalloproteinases-1 occurs in novel vesicles that do not fuse with the phagosome.
The human neutrophil granule location of precursors of matrix metalloproteinases (MMPs), MMP-8 and -9, has been established, but that of the tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) has not. In this study, labeling for TIMP-1, pro-MMP-8, pro-MMP-9, and established granule marker proteins reveals that TIMP-1 is mainly located in distinct oval, electron translucent organelles, a little larger than azurophil granules. A lack of labeling for the fluid phase endocytic marker, bovine serum albumin-gold, the lysosome-associated membrane protein markers, and for glycosylphosphatidylinositol-linked proteins, which are enriched in secretory vesicles, indicates the non-endosomal, non-lysosomal, and non-secretory nature of this organelle. Density gradient cofractionation with the least dense, secretory population and some pleomorphism of the organelle suggest it is a "vesicle" rather than a "granule" population. Colocalization with pro-MMP-9 or pro-MMP-8, in minor subpopulations, suggests that TIMP-1 vesicle biogenesis occurs between metamyelocytic and terminal differentiation and before secretory vesicle synthesis. Pulse-chased IgG-coated latex beads and immunolabeling show that specific and azurophil granules fuse with the phagosome whereas TIMP-1 and pro-MMP-9-containing organelles do not. This suggests that these play no role in phagosomal destruction of IgG-opsonized bacteria. Separate localization and colocalization of these proteins may, however, facilitate fine regulation of extracellular proteolysis.
Price
B
B
School of Molecular and Cellular Biosciences, Department of Biochemistry, University of Natal, Pietermaritzburg, Scottsville 3209, Natal, South Africa.
Dennison
C
C
Tschesche
H
H
Elliott
E
E
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002458:Cell Fractionation; D017364:Collagenases / Q000097:blood; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000201:enzymology / Q000648:ultrastructure; D004792:Enzyme Precursors / Q000097:blood; D006801:Humans; D008247:Lysosomes / Q000737:chemistry / Q000648:ultrastructure; D020781:Matrix Metalloproteinase 1; D020784:Matrix Metalloproteinase 8 / Q000097:blood; D009504:Neutrophils / Q000737:chemistry* / Q000201:enzymology / Q000648:ultrastructure; D015388:Organelles / Q000737:chemistry / Q000648:ultrastructure; D012710:Serum Albumin, Bovine; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000097:blood*
D004792:Enzyme Precursors; D019715:Tissue Inhibitor of Metalloproteinase-1; D012710:Serum Albumin, Bovine; D017364:Collagenases; D020784:Matrix Metalloproteinase 8; D020781:Matrix Metalloproteinase 1