Heparanase-mediated cleavage of macromolecular heparin accelerates release of granular components of mast cells from extracellular matrices

Abstract

Heparanase cleaves macromolecular heparin in the secretory granules of connective tissue-type mast cells. We investigated roles of the cleavage under a microenvironment mimicking where the mast cells physiologically reside. A connective tissue-type mast cell line MST and mouse peritoneal cell-derived mast cells stored macromolecular heparin in the secretory granules. The cells expressing heparanase stored fragmented heparin (~10 kDa) due to heparanase-dependent cleavage of the heparin. We produced an artificial collagen-based extracellular matrix and placed the live cells or glycosaminoglycans purified from the cells in the matrix to measure the release of sulfated macromolecules into the medium. The sulfate-radiolabelled molecules from the degranulating heparanase-expressing cells and the purified glycosaminoglycans showed significantly greater release into the medium than those derived from mock cells, which was not the case in suspension culture. The mast cell granular enzyme chymase, but not β-hexosaminidase, showed significantly greater release from the degranulating heparanase-expressing cells than from mock cells. Purified chymase mixed with fragmented heparin derived from heparanase-expressing cells showed greater release from collagen gels than the enzyme alone or mixed with macromolecular heparin derived from mock cells. We propose that the cleavage of macromolecular heparin by heparanase accelerates the release of heparin and chymase from extracellular matrices.

Mast Cells Produce a Unique Chondroitin Sulfate Epitope

“…Cleavage of macromolecular heparin by heparanase is crucial for accelerating the release of heparin and chymase from the secretory granules to the extracellular matrices (Higashi et al 2014). Heparanase, however, does not cleave CS chains, and therefore would not be responsible for the results presented with regard to the CS structure detected by 2B6.…”

“…Heparanase is contained in the secretory granules with roles in the cleavage of heparin and HS, wherein the ability of heparanase to intracellularly cleave heparin in mast cells (Wang et al 2011) has been demonstrated and shown to influence the storage and release of secretory granular components. Cleavage of macromolecular heparin by heparanase is crucial for accelerating the release of heparin and chymase from the secretory granules to the extracellular matrices (Higashi et al 2014). Heparanase, however, does not cleave CS chains, and therefore would not be responsible for the results presented with regard to the CS structure detected by 2B6.…”

Mast cell glycosaminoglycans

“…Mast cells vary in their heparanase content [63]; rat skin mast cells presumably contain little heparanase, so that complete serglycin, or macromolecular heparin, can be prepared from them in spite of the fact that it provides a substrate for heparanase [62, 65]. The partial depolymerisation of serglycin heparin by heparanase has been found to aid the release of proteases on degranulation [66]. No equivalent enzyme for the depolymerisation of mast cell granule CS/DS has been identified, as far as we know.…”

Low molecular weight heparin: does it represent a clinical opportunity for preventing preeclampisa associated with fetal growth restriction?

“…Heparin bears the highest negative charge among mammalian polypeptides and its remarkable properties are safely stored in mast cells [24], while the coagulation balance is controlled by heparin sulphate proteoglycans produced by endothelial cells [25]. Heparin is released by mast cells into small vessels at sites of tissue injury where its main role is that of a key co-factor in tissue from bacteria and foreign materials [26].…”