DOWN-REGULATION OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR IN KB CELLS IS DUE TO RECEPTOR INTERNALIZATION AND SUBSEQUENT DEGRADATION IN LYSOSOMES
DOWN-REGULATION OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR IN KB CELLS IS DUE TO RECEPTOR INTERNALIZATION AND SUBSEQUENT DEGRADATION IN LYSOSOMES
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DOI：
10.1073/pnas.81.8.2384
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发表时间：
1984-01-01
期刊：
影响因子：
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通讯作者：
PASTAN, I
中科院分区：
文献类型：
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作者：
BEGUINOT, L;LYALL, RM;PASTAN, I
利用人表皮生长因子（EGF）受体（EGF- ri）单克隆抗体，观察加入EGF后KB细胞中该受体的代谢及其内化途径。对125i标记的EGF表面结合的测定表明。EGF在37度下暴露10分钟后，80%的EGF结合活性从质膜上消失。C.用EGF- ri对[35S] met标记的细胞提取物中的受体进行免疫沉淀，发现EGF使受体降解，半衰期为40 min。使用EGF- r1的免疫荧光显示EGF受体的EGF依赖性重新分布。在未暴露于EGF的细胞中，几乎所有的受体都弥漫性分布在细胞表面。加入EGF后，受体迅速内化，首先出现在受体体特征的小点状细胞器中，然后出现在更大的核周溶酶体样结构中。到120分钟时，几乎所有的免疫反应性EGF受体都从细胞中消失。免疫细胞化学在EM水平证实了这些光镜下的发现。细胞表面弥散分布的受体在EGF的存在下首先聚集成网格蛋白包覆的凹坑，然后内化到受体体中，短暂地出现在网状高尔基体中，最后出现在溶酶体中。KB细胞中EGF受体的依赖性下调和降解提供了一个显著的配体依赖性聚集和受体内化的例子，随后是配体和受体的溶酶体降解。
Using a monoclonal antibody to the human epidermal growth factor (EGF) receptor (EGF-RI), the metabolism of the receptor and the pathway of its internalization was followed in KB cells after the addition of EGF. Measurement of surface binding of 125I-labeled EGF showed that .apprx. 80% of EGF binding activity disappeared from the plasma membrane after a 10 min exposure to EGF at 37.degree. C. Immunoprecipitation of the receptor from [35S]Met-labeled cell extracts with EGF-RI showed that EGF caused the receptor to be degraded with a half-life of 40 min. Immunofluorescence using EGF-R1 showed an EGF-dependent redistribution of the EGF receptor. In cells not exposed to EGF, almost all of the receptor was diffusely distributed on the cell surface. After EGF addition, the receptor was rapidly internalized, first appearing in small punctate organelles characteristic of receptosomes and then in larger perinuclear lysosome-like structures. By 120 min almost all of the immunoreactive EGF receptor had disappeared from the cells. Immunocytochemistry at the EM level confirmed these light microscopic findings. The diffusely distributed receptor on the cell surface first clustered into clathrin-coated pits in the presence of EGF, next was internalized into receptosomes, appeared transiently in transreticular Golgi elements and finally was seen in lysosomes. This EGF-dependent down-regulation and degradation of the EGF receptor in KB cells provides a striking example of ligand-dependent clustering and internalization of a receptor, followed by degradation in lysosomes of both ligand and receptor.