Goshen R, Hochberg A A, Korner G, Levy E, Ishai-Michaeli R, Elkin M, de Groot N, Vlodavsky I
Department of Biological Chemistry, Hebrew University, Jerusalem, Israel.
Mol Hum Reprod. 1996 Sep;2(9):679-84. doi: 10.1093/molehr/2.9.679.
The role of different extracellular matrix (ECM)-degrading enzymes in the normal functioning of the placenta is well documented. Heparan sulphate proteoglycan (HSPG) is an integral constituent of the placental and decidual ECM. Because this proteoglycan specifically interacts with various macromolecules in the ECM, its degradation may disassemble the matrix. Hence, in the case of the placenta, this may facilitate normal placentation and trophoblast invasion. Crude placental specimens were collected from first and third trimester placentas. Heparanase (endo-beta-glucuronidase) was isolated and purified by ammonium sulphate precipitation followed by sequential chromatographies on carboxymethyl-, heparin- and ConA-Sepharose columns. The placental enzyme was further characterized for its molecular weight and specific inhibition by heparin, and was shown to resemble heparanase expressed by highly metastatic tumor cells and activated cells of the immune system. In order to locate the source of heparanase activity in the placenta, primary cytotrophoblast cultures were established. Intact cells, as well as conditioned medium and cell lysates, were analysed for heparanase activity using metabolically sulphate-labelled ECM as a natural substrate. Heparanase was highly active in lysates of cytotrophoblasts. This activity was also expressed by intact cytotrophoblasts seeded on ECM, but no activity could be detected in the culture medium. Incubation of the cytotrophoblasts in contact with ECM resulted in release of ECM-bound basic fibroblast growth factor (bFGF). We propose that the cytotrophoblastic heparanase facilitates placentation, through cytotrophoblast extravasation and localized neovascularization.
不同细胞外基质（ECM）降解酶在胎盘正常功能中的作用已有充分记载。硫酸乙酰肝素蛋白聚糖（HSPG）是胎盘和蜕膜ECM的重要组成部分。由于这种蛋白聚糖与ECM中的各种大分子特异性相互作用，其降解可能会使基质解体。因此，就胎盘而言，这可能有助于正常的胎盘形成和滋养层细胞浸润。从孕早期和孕晚期的胎盘收集粗制胎盘标本。通过硫酸铵沉淀，随后在羧甲基、肝素和刀豆球蛋白A琼脂糖柱上进行连续层析，分离并纯化了乙酰肝素酶（内切-β-葡糖醛酸酶）。对胎盘酶的分子量和肝素的特异性抑制作用进行了进一步表征，结果表明它类似于高转移性肿瘤细胞和免疫系统活化细胞所表达的乙酰肝素酶。为了确定胎盘中乙酰肝素酶活性的来源，建立了原代细胞滋养层培养物。使用代谢性硫酸标记的ECM作为天然底物，对完整细胞、条件培养基和细胞裂解物进行乙酰肝素酶活性分析。乙酰肝素酶在细胞滋养层细胞裂解物中具有高活性。接种在ECM上的完整细胞滋养层细胞也表达这种活性，但在培养基中未检测到活性。将细胞滋养层细胞与ECM接触孵育会导致与ECM结合的碱性成纤维细胞生长因子（bFGF）释放。我们认为，细胞滋养层的乙酰肝素酶通过细胞滋养层外渗和局部新血管形成促进胎盘形成。
