ENDOCYTOSIS OF HYALURONIC-ACID BY RAT-LIVER ENDOTHELIAL-CELLS - EVIDENCE FOR RECEPTOR RECYCLING
ENDOCYTOSIS OF HYALURONIC-ACID BY RAT-LIVER ENDOTHELIAL-CELLS - EVIDENCE FOR RECEPTOR RECYCLING
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DOI：
10.1042/bj2570875
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发表时间：
1989-02-01
影响因子：
4.1
通讯作者：
WEIGEL, PH
中科院分区：
文献类型：
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作者：
MCGARY, CT;RAJA, RH;WEIGEL, PH
肝内皮细胞通过受体介导的内吞作用从血液中清除透明质酸 (HA) [Eriksson、Fraser、Laurent、Pertoft 和 Smedsrod (1983) Exp.。细胞研究。 144、223-238]。我们测量了培养的大鼠肝内皮细胞在37℃下内吞和降解125I-HA（Mr.apprx.44000）的能力。 C. 内吞作用在 3 小时内呈线性，然后达到稳定水平。内吞作用的速率是浓度依赖性的，每个细胞的最大速率为 250 个分子/秒。 125I-HA 的内吞作用被 150 倍过量的非放射性标记 HA 抑制超过 92%。 HA、硫酸软骨素和肝素有效竞争125I-HA的内吞作用，而葡萄糖醛酸、N-乙酰葡糖胺、DNA、RNA、聚半乳糖醛酸和葡聚糖则不竞争。在没有放线菌酮的情况下，内皮细胞在 6 小时内处理的 125I-HA 是其总（细胞表面和细胞内）特异性 HA 结合能力的 13 倍。这一结果并不是由于受体的降解和快速替换造成的，因为即使在放线菌酮存在的情况下，这些细胞在 6 小时内处理的 HA 也比其受体总含量多 6 倍。此外，在放线菌酮存在下，处理或不处理HA 6小时的细胞中均未观察到125I-HA结合能力下降，表明HA内吞后受体没有降解。在 37°C 的 HA 内吞过程中。 C，至少 65% 的细胞内 HA 受体在 30 分钟内被 HA 占据。这表明细胞内 HA 受体（占总数的 75%）在连续内吞作用期间发挥作用。高渗透压通过破坏包被坑途径来抑制脱唾液酸糖蛋白和低密度脂蛋白受体系统中的内吞作用和受体再循环[Heuser 和 Anderson (1987) J. Cell Biol.。 105、230a； Oka 和 Weigel (1988) J. Cell Biochem。 36、169-183]。高渗透压抑制肝内皮细胞中 125I-HA 内吞作用超过 90%，表明该 HA 受体使用了涂层凹坑途径。我们得出结论，肝内皮细胞HA受体在HA的连续内吞和加工过程中被循环利用。
Hyaluronic acid (HA) is cleared from the blood by liver endothelial cells through receptor-mediated endocytosis [Eriksson, Fraser, Laurent, Pertoft and Smedsrod (1983) Exp. Cell Res. 144, 223-238]. We have measured the capacity of cultured rat liver endothelial cells to endocytose and degrade 125I-HA (Mr .apprx. 44000) at 37.degree. C. Endocytosis was linear for 3 h and then reached a plateau. The rate of endocytosis was concentration-dependent and reached a maximum of 250 molecules/s per cell. Endocytosis of 125I-HA was inhibited more than 92% by a 150-fold excess of non-radiolabelled HA. HA, chondroitin sulphate and heparin effectively competed for endocytosis of 125I-HA, whereas glucuronic acid, N-acetylglucosamine, DNA, RNA, polygalacturonic acid and dextran did not compete. In the absence of cycloheximide, endothelial cells processed 13 times more 125I-HA in 6 h than their total (cell-surface and intracellular) specific HA-binding capacity. This result was not due to degradation and rapid replacement of receptors, because, even in the presence of cycloheximide, these cells processed 6 times more HA than their total receptor content in 6 h. Also, in the presence of cycloheximide, no decrease in 125I-HA-binding capacity was seen in cells processing or not processing HA for 6 h, indicating that receptors are not degraded after the endocytosis of HA. During endocytosis of HA at 37.degree. C, at least 65% of the intracellular HA receptors became occupied with HA within 30 min. This indicates that the intracellular HA receptors (75% of the total) function during continuous endocytosis. Hyperosmolarity inhibits endocytosis and receptor recycling in the asialoglycoprotein and low-density-lipoprotein receptor systems by disrupting the coated-pit pathway [Heuser and Anderson (1987) J. Cell Biol. 105, 230a; Oka and Weigel (1988) J. Cell Biochem. 36, 169-183]. Hyperosmolarity inhibited 125I-HA endocytosis in liver endothelial cells by more than 90%, suggesting use of a coated-pit pathway by this HA receptor. We conclude that liver endothelial cell HA receptors are recycled during the continuous endocytosis and processing of HA.