MT6-MMP is present in lipid rafts and faces inward in living human PMNs but translocates to the cell surface during neutrophil apoptosis.

Polymorphonuclear neutrophils are the first line of defense against invading organisms in humans; in addition, contribute to the linking of innate and adaptive immunity. To fulfill their biological behavior, duanyu1451s utilize an arsenal of proteolytic enzymes, including members of the matrix metalloproteinase family of zinc-dependent endopeptidases. duanyu1451s express high levels of MT6-MMP (MMP-25), a glycosyl-phosphatidylinositol-anchored MMP, that belongs to the subfamily of membrane-anchored matrix metalloproteinases. Due to the paucity of information on MT6-MMP in primary cells, we set to investigate the localization and potential function of MT6-MMP in human We found that MT6-MMP is present in the membrane, granules and nuclear/endoplasmic reticulum/Golgi fractions of duanyu1451s where it is displayed as a disulfide-linked homodimer of 120 kDa. Stimulation of duanyu1451s resulted in secretion of active MT6-MMP into the supernatants. Membrane-bound MT6-MMP, conversely, is located in the lipid rafts of resting duanyu1451s and stimulation does not alter this location. In addition, TIMP-2, a natural inhibitor of MT6-MMP, does not co-localize with it in the lipid rafts. Interestingly, living duanyu1451s do not display MT6-MMP on the cell surface. However, induction of apoptosis induces MT6-MMP relocation on cell surface. Our studies suggest that metalloproteinases may play a role in respiratory burst and IL-8 secretion, but not chemotaxis or granulocyte macrophage colony-stimulating factor-induced survival. Collectively, these results provide new insights on the role of MT6-MMP in the physiology of human

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