Heparanase uptake is mediated by cell membrane heparan sulfate proteoglycans
Heparanase uptake is mediated by cell membrane heparan sulfate proteoglycans
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DOI：
10.1074/jbc.m402131200
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发表时间：
2004-10-15
影响因子：
4.8
通讯作者：
Ilan, N
中科院分区：
文献类型：
--
作者：
Gingis-Velitski, S;Zetser, A;Ilan, N
乙酰肝素酶是一种哺乳动物糖苷内切酶，可在特定的链内位点降解硫酸乙酰肝素 (HS)，这种活性与与转移和炎症相关的细胞传播密切相关。除了其在细胞外基质组装和完整性中的结构作用外，HS 还能隔离作为储存库存在于细胞外基质中的大量多肽。乙酰肝素酶活性可释放多种生长因子、细胞因子、趋化因子和酶，并深刻影响细胞和组织功能。因此，乙酰肝素酶的生物利用度、可及性和活性应受到严格监管。我们提供的证据表明 HS 不仅是乙酰肝素酶的底物，而且是乙酰肝素酶的调节剂。向细胞培养物中添加肝素或木糖苷会导致培养基中乙酰肝素酶的显着积累，而氯酸钠则没有这种效果。此外，在HS缺陷的CHO-745突变细胞、硫酸乙酰肝素蛋白聚糖缺陷的HT-29结肠癌细胞和肝素酶处理的细胞中，细胞对乙酰肝素酶的摄取显着减少。我们还研究了乙酰肝素酶的生物合成途径，发现活性酶的半衰期约为30 h。这项和之前的定位研究表明，乙酰肝素酶在内体/溶酶体区室中驻留了相对较长的时间，并且可能在 HS 的正常周转中发挥作用。添加乙酰肝素酶后的共定位研究和细胞分级分离已确定多聚糖家族成员作为负责乙酰肝素酶摄取的候选分子，提供了限制乙酰肝素酶细胞外积累和功能的有效机制。
Heparanase is a mammalian endoglycosidase that degrades heparan sulfate (HS) at specific intrachain sites, an activity that is strongly implicated in cell dissemination associated with metastasis and inflammation. In addition to its structural role in extracellular matrix assembly and integrity, HS sequesters a multitude of polypeptides that reside in the extracellular matrix as a reservoir. A variety of growth factors, cytokines, chemokines, and enzymes can be released by heparanase activity and profoundly affect cell and tissue function. Thus, heparanase bioavailability, accessibility, and activity should be kept tightly regulated. We provide evidence that HS is not only a substrate for, but also a regulator of, heparanase. Addition of heparin or xylosides to cell cultures resulted in a pronounced accumulation of, heparanase in the culture medium, whereas sodium chlorate had no such effect. Moreover, cellular uptake of heparanase was markedly reduced in HS-deficient CHO-745 mutant cells, heparan sulfate proteoglycan-deficient HT-29 colon cancer cells, and heparinase-treated cells. We also studied the heparanase biosynthetic route and found that the half-life of the active enzyme is similar to30 h. This and previous localization studies suggest that heparanase resides in the endosomal/lysosomal compartment for a relatively long period of time and is likely to play a role in the normal turnover of HS. Co-localization studies and cell fractionation following heparanase addition have identified syndecan family members as candidate molecules responsible for heparanase uptake, providing an efficient mechanism that limits extracellular accumulation and function of heparanase.