Internalization of hyaluronan by chondrocytes occurs via receptor-mediated endocytosis.
Internalization of hyaluronan by chondrocytes occurs via receptor-mediated endocytosis.
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DOI：
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发表时间：
1993-09
影响因子：
4
通讯作者：
Qiang Hua;C. Knudson;W. Knudson
中科院分区：
文献类型：
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作者：
Qiang Hua;C. Knudson;W. Knudson
一些研究表明，软骨细胞必须具有内化和降解细胞外透明质酸的能力。在目前的研究中，我们显示了直接的证据，透明质酸，事实上，内吞软骨细胞和内吞作用介导的细胞表面CD 44/透明质酸受体。牛关节软骨细胞以及大鼠软骨肉瘤软骨细胞的培养物与荧光素或3 H标记的透明质酸孵育。在放射自显影后，通过荧光显微镜或明视野/暗视野显微镜观察标记透明质酸的强烈结合和积累。用胰蛋白酶或链霉菌透明质酸酶去除细胞表面透明质酸，以区分和定量细胞内吞的透明质酸。标记的透明质酸在分布于整个细胞质中的小的离散胞内囊泡内可见。荧光素或3 H-标记的透明质酸的结合和内吞作用被完全阻断，通过添加过量的未标记的透明质酸或透明质酸六糖，透明质酸/透明质酸受体相互作用的竞争性抑制剂。结合和内吞作用也被阻断的抗CD 44单克隆抗体的加入。内吞的3 H-标记的透明质酸的表征表明，一个显着的部分透明质酸被降解的牛关节和大鼠软骨肉瘤软骨细胞。有趣的是，较高比例的结合透明质酸被牛软骨细胞内化。因此，透明质酸受体介导的内吞作用和透明质酸的降解可能为软骨组织的维持和稳态提供关键环节。
Several studies have suggested that chondrocytes must have the capacity to internalize and degrade extracellular hyaluronan. In the present study we show direct evidence that hyaluronan is, in fact, endocytosed by chondrocytes and that the endocytosis is mediated via cell surface CD44/hyaluronan receptors. Cultures of bovine articular chondrocytes as well as rat chondrosarcoma chondrocytes were incubated with either fluorescein- or 3H-labeled hyaluronan. Intense binding and accumulation of labeled hyaluronan was visualized by fluorescence microscopy or bright-field/dark-field microscopy following autoradiography. Cell surface hyaluronan was removed with either trypsin or Streptomyces hyaluronidase in order to distinguish and quantify intracellular endocytosed hyaluronan. Labeled hyaluronan was visualized within small discrete intracellular vesicles distributed throughout the cytoplasm. Binding and endocytosis of fluorescein- or 3H-labeled hyaluronan was totally blocked by the addition of excess unlabeled hyaluronan or hyaluronan hexasaccharides, competitive inhibitors of hyaluronan/hyaluronan receptor interactions. Binding and endocytosis was also blocked by the addition of anti-CD44 monoclonal antibodies. Characterization of endocytosed 3H-labeled hyaluronan demonstrated that a significant portion of the hyaluronan was degraded by both the bovine articular and rat chondrosarcoma chondrocytes. Interestingly, a higher proportion of bound hyaluronan was internalized by the bovine chondrocytes. Therefore, hyaluronan receptor-mediated endocytosis and degradation of hyaluronan may provide a critical link to the maintenance and homeostasis of cartilage tissue.