Cell Surface Localization of Heparanase on Macrophages Regulates Degradation of Extracellular Matrix Heparan Sulfate

Abstract

Extravasation of peripheral blood monocytes through vascular basement membranes requires degradation of extracellular matrix components including heparan sulfate proteoglycans (HSPGs). Heparanase, the heparan sulfate-specific endo-β-glucuronidase, has previously been shown to be a key enzyme in melanoma invasion, yet its involvement in monocyte extravasation has not been elucidated. We examined a potential regulatory mechanism of heparanase in HSPG degradation and transmigration through basement membranes in leukocyte trafficking using human promonocytic leukemia U937 and THP-1 cells. PMA-treated cells were shown to degrade 35S-sulfated HSPG in endothelial extracellular matrix into fragments of an approximate molecular mass of 5 kDa. This was not found with untreated cells. The gene expression levels of heparanase or the enzyme activity of the amount of cell lysates were no different between untreated and treated cells. Immunocytochemical staining with anti-heparanase mAb revealed pericellular distribution of heparanase in PMA-treated cells but not in untreated cells. Cell surface heparanase capped into a restricted area on PMA-treated cells when they were allowed to adhere. Addition of a chemoattractant fMLP induced polarization of the PMA-treated cells and heparanase redistribution at the leading edge of migration. Therefore a major regulatory process of heparanase activity in the cells seems to be surface expression and capping of the enzyme. Addition of the anti-heparanase Ab significantly inhibited enzymatic activity and transmigration of the PMA-treated cells, suggesting that the cell surface redistribution of heparanase is involved in monocyte extravasation through basement membranes.

Accumulation of Ym1 and formation of intracellular crystalline bodies in alveolar macrophages lacking heparanase

“…Interestingly, heparanase expressed on the surface of dendritic cells and macrophages has been shown to promote migration of these cells, by degrading ECM barriers (Benhamron et al, 2006;Sasaki et al, 2004). Moreover, heparanase can enhance cell adhesion independent of its enzymatic activity, and thereby contribute to cell motility (Goldshmidt et al, 2003;Sotnikov et al, 2004).…”

“…Heparanase has previously been implicated in inflammatory processes and cell migration (Benhamron et al, 2006;Edovitsky et al, 2006;Sasaki et al, 2004), although the precise impact of heparanase on leukocyte populations in vivo has not been evaluated. To address this issue, we examined the effect of heparanase deficiency on leukocytes present in bronhcoalveolar lavage (BAL) fluid.…”

“…Heparanase is highly expressed by numerous types of tumor cells, and by various cells of the immune system (Vlodavsky et al, 1992), including mast cells (Gong et al, 2003), eosinophils (Temkin et al, 2004), dendritic cells (Benhamron et al, 2006) and monocytes/macrophages (Sasaki et al, 2004). However, the role of heparanase in the context of immune cell function is only partially understood.…”

Translocation of Active Heparanase to Cell Surface Regulates Degradation of Extracellular Matrix Heparan Sulfate upon Transmigration of Mature Monocyte-Derived Dendritic Cells

“…Heparanase activity has been correlated with the metastatic potential of tumor-derived cells that facilitate cell invasion as well as with angiogenesis, autoimmunity, and inflammation (7, 9 -12). Heparanase release by degranulation has been implicated in diapedesis and extravasation of a number of immune cells, including neutrophils, macrophages, and lymphocytes (9,(13)(14)(15). However, its role in DC migration is unknown.…”

“…Interestingly, intact iDCs incubated on 35 S-labeled ECM did not show heparanase activity, as indicated by the lack of labeled heparan sulfate degradation fragments eluted in fractions [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] (Fig. 4C, left).…”