Involvement of cell surface heparin sulfate in the binding of lipoprotein lipase to cultured bovine endothelial cells.
Involvement of cell surface heparin sulfate in the binding of lipoprotein lipase to cultured bovine endothelial cells.
复制标题
细胞表面硫酸肝素参与脂蛋白脂肪酶与培养的牛内皮细胞的结合。
DOI：
10.1172/jci110354
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Fanburg,BL
中科院分区：
文献类型：
--
作者：
Shimada,K;Gill,PJ;Silbert,JE;Douglas,WH;Fanburg,BL
据推测，脂蛋白脂肪酶（一种在脂肪酸摄取到组织中的重要酶）与血管内皮细胞表面结合，并且这种结合通过与肝素样糖胺聚糖的附着而发生。此外，认为肝素将酶从其与内皮的附着释放到循环中。这些假设从未在体外细胞系统中直接进行过测试。在本研究中，我们已经直接评估了脂蛋白脂肪酶，纯化从牛脱脂牛奶与单层培养的内皮细胞，从牛肺动脉分离的相互作用。原代培养的内皮细胞没有内在的脂蛋白脂酶活性，但能够定量结合脂蛋白脂酶。结合达到平衡，在0.24 nmol脂蛋白脂肪酶/mg细胞蛋白时可饱和。脂蛋白脂酶在半最大结合时的浓度为0.52 μ M。结合的脂蛋白脂酶可以脱离培养的细胞，通过增加肝素的浓度，并在和以上0.6微克/毫升的肝素，90%的细胞结合的脂蛋白脂酶活性被释放。硫酸乙酰肝素和硫酸皮肤素释放酶的程度较低，硫酸软骨素引起的脂蛋白脂肪酶的释放很少，如果有的话。释放脂蛋白脂肪酶与肝素是不相关的释放[3S]糖胺聚糖从35 S-预标记的细胞。减少脂蛋白脂酶结合内皮细胞和细胞表面相关的[3S]糖胺聚糖在35 S-预标记的细胞平行发生时，细胞用粗肝素黄杆菌酶前脂蛋白脂酶的结合和细胞用这种酶处理后脂蛋白脂酶结合。用纯化的肝素酶从细胞表面去除硫酸乙酰肝素完全抑制内皮细胞与脂蛋白脂肪酶的结合，但用软骨素ABC裂解酶去除硫酸软骨素对这种结合没有影响。这些结果提供了脂蛋白脂肪酶通过细胞表面上的硫酸乙酰肝素附着到内皮细胞的直接证据，并提供了肝素通过从该结合位点脱离而释放脂蛋白脂肪酶的证据。
It has been postulated that lipoprotein lipase, an enzyme important in the uptake of fatty acids into tissues, is bound to the vascular endothelial cell surface and that this binding occurs through attachment to heparinlike glycosaminoglycans. Furthermore, it is thought that heparin releases the enzyme from its attachment to the endothelium into the circulation. These hypotheses have never been tested directly in cell systems in vitro. In the present study we have directly evaluated the interaction of lipoprotein lipase, purified from bovine skim milk with monolayer cultures of endothelial cells, isolated from bovine pulmonary artery. Endothelial cells in primary culture had no intrinsic lipoprotein lipase activity but were able to bind lipoprotein lipase quantitatively. The binding reached equilibrium and was saturable at 0.24 nmol of lipoprotein lipase/mg of cell protein. The concentration of lipoprotein lipase at half-maximal binding was 0.52 microM. Bound lipoprotein lipase could be detached from cultured cells by increasing concentrations of heparin, and at and above 0.6 microgram/ml of heparin, 90% of the cell-bound lipoprotein lipase activity was released. Heparan sulfate and dermatan sulfate released the enzyme to a lesser extent and chondroitin sulfate caused little, if any, release of lipoprotein lipase. The release of lipoprotein lipase with heparin was not associated with a release of [3S]glycosaminoglycans from 35S-prelabeled cells. Reductions of lipoprotein lipase binding to endothelial cells and of cell surface-associated [3S]glycosaminoglycans in 35S-prelabeled cells occurred in parallel both when cells were pretreated with crude Flavobacterium heparinum enzyme before lipoprotein lipase binding and when cells were treated with this enzyme after lipoprotein lipase binding. The removal of heparan sulfate from the cell surface by purified heparinase totally inhibited the binding of lipoprotein lipase by endothelial cells, but the removal of chondroitin sulfate by chondroitin ABC lyase had no effect on this binding. These results provide direct evidence for lipoprotein lipase attachment to endothelial cells through heparan sulfate on the cell surface, and provide evidence for the release of lipoprotein lipase by heparin through a detachment from this binding site.