Cell surface proteoglycan of mouse mammary epithelial cells is shed by cleavage of its matrix-binding ectodomain from its membrane-associated domain.
Cell surface proteoglycan of mouse mammary epithelial cells is shed by cleavage of its matrix-binding ectodomain from its membrane-associated domain.
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DOI：
10.1083/jcb.105.6.3087
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发表时间：
1987-12
期刊：
影响因子：
--
通讯作者：
Bernfield M
中科院分区：
文献类型：
--
作者：
Jalkanen M;Rapraeger A;Saunders S;Bernfield M
正常小鼠乳腺（NMuMG）上皮细胞上的细胞表面蛋白多糖包括一个亲脂结构域（可能嵌入质膜）和一个通过其糖胺聚糖链与基质组分结合的外结构域，该外结构域被蛋白酶完整释放，并被单克隆抗体282 -2检测到。抗体282 -2也在NMuMG细胞调节的培养基中检测蛋白多糖。该免疫活性蛋白聚糖通过deae -纤维素层析、异重离心和281- 2亲和层析纯化至均匀性。将免疫反应培养基中的蛋白多糖与胰蛋白酶释放的外结构域进行比较，发现这两种蛋白多糖在几个标准上是无法区分的，因为它们都含有硫酸肝素链和硫酸软骨素链；和(b)在水动力尺寸和浮力密度上相似；(c)具有相同大小的核心蛋白（Mr约53 kD）；(d)非亲脂性，通过脂质体嵌入和转移到硅处理纸上研究。对悬浮NMuMG细胞表面蛋白多糖释放的动力学研究表明，免疫反应介质蛋白多糖直接来源于细胞表面蛋白多糖。细胞的悬浮既增加了细胞表面蛋白聚糖的释放，又抑制了细胞表面蛋白聚糖的替换。这些结果表明，NMuMG细胞的细胞表面蛋白多糖可以通过其基质结合外结构域与膜相关结构域的切割而脱落，这提供了一种上皮细胞可以放松蛋白多糖介导的与基质的附着的机制。
The cell surface proteoglycan on normal murine mammary gland (NMuMG) epithelial cells consists of a lipophilic domain, presumably intercalated into the plasma membrane, and an ectodomain that binds via its glycosaminoglycan chains to matrix components, is released intact by proteases and is detected by monoclonal antibody 281-2. The antibody 281-2 also detects a proteoglycan in the culture medium conditioned by NMuMG cells. This immunoactive proteoglycan was purified to homogeneity using DEAE-cellulose chromatography, isopycnic centrifugation, and 281- 2 affinity chromatography. Comparison of the immunoreactive medium proteoglycan with the trypsin-released ectodomain revealed that these proteoglycans are indistinguishable by several criteria as both: (a) contain heparan sulfate and chondroitin sulfate chains; and (b) are similar in hydrodynamic size and buoyant density; (c) have the same size core protein (Mr approximately 53 kD); (d) are nonlipophilic as studied by liposomal intercalation and transfer to silicone-treated paper. Kinetic studies of the release of proteoglycan from the surface of suspended NMuMG cells are interpreted to indicate that the immunoreactive medium proteoglycan is derived directly from the cell surface proteoglycan. Suspension of the cells both augments the release and inhibits the replacement of cell surface proteoglycan. These results indicate that the cell surface proteoglycan of NMuMG cells can be shed by cleavage of its matrix-binding ectodomain from its membrane- associated domain, providing a mechanism by which the epithelial cells can loosen their proteoglycan-mediated attachment to the matrix.