Heparanase Facilitates Cell Adhesion and Spreading by Clustering of Cell Surface Heparan Sulfate Proteoglycans

Abstract

Heparanase is a heparan sulfate (HS) degrading endoglycosidase participating in extracellular matrix degradation and remodeling. Apart of its well characterized enzymatic activity, heparanase was noted to exert also enzymatic-independent functions. Non-enzymatic activities of heparanase include enhanced adhesion of tumor-derived cells and primary T-cells. Attempting to identify functional domains of heparanase that would serve as targets for drug development, we have identified heparin binding domains of heparanase. A corresponding peptide (residues Lys158-Asp171, termed KKDC) was demonstrated to physically associate with heparin and HS, and to inhibit heparanase enzymatic activity. We hypothesized that the pro-adhesive properties of heparanase are mediated by its interaction with cell surface HS proteoglycans, and utilized the KKDC peptide to examine this possibility. We provide evidence that the KKDC peptide interacts with cell membrane HS, resulting in clustering of syndecan-1 and syndecan-4. We applied classical analysis of cell morphology, fluorescent and time-lapse microscopy and demonstrated that the KKDC peptide efficiently stimulates the adhesion and spreading of various cell types, mediated by PKC, Src, and the small GTPase Rac1. These results support, and further substantiate the notion that heparanase function is not limited to its enzymatic activity.

Heparanase Enhances the Insulin Receptor Signaling Pathway to Activate Extracellular Signal-regulated Kinase in Multiple Myeloma

“…One possibility is that heparanase, which is known to have multiple heparan sulfate-binding motifs, binds to the cell surface heparan sulfate proteoglycan syndecan-1, triggers clustering of syndecan-1 with the insulin receptor, and induces its dimerization and autophosphorylation. A previous study has shown that heparanase can induce the clustering of syndecan-1, thereby initiating signaling cascades that involve Rac1, Src, and the PKC pathways, resulting in enhanced cell adhesion and spreading (38). Similar to this finding, we also observed high PKC activity in heparanase-high cells and have found that heparanase-high cells spread much more avidly than do heparanase-low cells.…”

Endothelial Heparanase Regulates Heart Metabolism by Stimulating Lipoprotein Lipase Secretion From Cardiomyocytes

“…In U87 MG human glioma cells, clustering of syndecan-4 by latent heparanase or an antiheparanase antibody was sufficient to induce cell spreading, a process involving PKC activation. 17 In addition, on binding of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5P)(2)) to its cytoplasmic domain, oligomerization of syndecan-4 was promoted with a subsequent upregulation of PKCα. 42,43 In this study, it is likely that clustering of syndecan-4 with latent heparanase triggers RhoA activation.…”

Heparanase Induces Signal Transducer and Activator of Transcription (STAT) Protein Phosphorylation

“…Immunocytochemistry-Immunofluorescent staining was performed essentially as described (21,30,31). Staining was observed under a fluorescent confocal microscope.…”