Novel biphasic traffic of endocytosed EGF to recycling and degradative compartments in lacrimal gland acinar cells.
Novel biphasic traffic of endocytosed EGF to recycling and degradative compartments in lacrimal gland acinar cells.
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内吞 EGF 向泪腺腺泡细胞中的回收和降解区室的新型双相运输。
DOI：
10.1002/jcp.10458
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Mircheff,AustinK
中科院分区：
文献类型：
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作者：
Xie,Jiansong;Qian,Limin;Wang,Yanru;Rose,ChadronM;Yang,Tao;Nakamura,Tamako;Hamm-Alvarez,SarahF;Mircheff,AustinK
本研究的目的是描述原代培养的兔泪腺腺泡上皮细胞的EGF及其受体(EGFR)的转运模式。对[125I]-EGF的摄取表现出可饱和和非饱和的温度依赖性成分，这表明受体介导和液体相内吞作用都存在。在120min内，[125I]-EGF的积累具有时间依赖性，但完整的[125I]-EGF的含量在20min时达到最大值后下降。山梨醇密度梯度离心和相分离分析表明，在37°C[125I]条件下，20min内即可得到早期的内体、基侧循环的内体、前溶酶体和溶酶体。标记的小分子似乎也到达了高尔基复合体和跨高尔基网络。完整的[~(125)I]-EGF最初积累在循环内小体中；循环内小体中的含量随后减少，到120分钟时，[~(125)I]标记的降解产物出现在前溶酶体和溶酶体中。FITC-EGF和LysoTrackerRed的共聚焦显微镜成像显示，FITC在20min时在非酸性隔间的分散体系中浓缩，在120min时在酸性隔间中浓缩。免疫荧光共聚焦显微镜和分析分级显示，细胞内的EGFR池始终大于质膜表达的池。负载[125I]-EGF的细胞释放完整EGF和[125I]标记的降解产物的混合物。观察表明，在泪腺泡细胞中，EGFR和EGF-EGFR复合体持续在质膜和一系列内膜间运输；EGF刺激产生依赖时间的信号，该信号最初减少，然后增加，EGF-EGFR运输到降解性隔膜。J.细胞。物理。199：108-125,2004-2003 Wiley-Liss，Inc.
The purpose of this study was to delineate the traffic patterns of EGF and EGF receptors (EGFR) in primary cultured acinar epithelial cells from rabbit lacrimal glands. Uptake of [125I]‐EGF exhibited saturable and non‐saturable, temperature‐dependent components, suggesting both receptor‐mediated and fluid phase endocytosis. Accumulation of [125I] was time‐dependent over a 120‐min period, but the content of intact [125I]‐EGF decreased after reaching a maximum at 20 min. Analytical fractionation by sorbitol density gradient centrifugation and phase partitioning indicated that within 20 min at 37°C [125I] reached an early endosome, basal–lateral recycling endosome, pre‐lysosome, and lysosome. Small components of the label also appeared to reach the Golgi complex andtrans‐Golgi network. Intact [125I]‐EGF initially accumulated in the recycling endosome; the content in the recycling endosome subsequently decreased, and by 120 min increased amounts of [125I]‐labeled degradation products appeared in the pre‐lysosomes and lysosomes. Confocal microscopy imaging of FITC‐EGF and LysoTrackerRed revealed FITC enriched in a dispersed system of non‐acidic compartments at 20 min and in acidic compartments at 120 min. Both confocal immunofluorescence microscopy and analytical fractionation indicated that the intracellular EGFR pool was much larger than the plasma membrane‐expressed pool at all times. Cells loaded with [125I]‐EGF released a mixture of intact EGF and [125I]‐labeled degradation products. The observations indicate that in lacrimal acinar cells, EGFR and EGF–EGFR complexes continually traffic between the plasma membranes and a system of endomembrane compartments; EGF‐stimulation generates time‐dependent signals that initially decrease, then increase, EGF–EGFR traffic to degradative compartments. J. Cell. Physiol. 199: 108–125, 2004© 2003 Wiley‐Liss, Inc.