Direct delivery of exogenous MHC class I molecule-binding oligopeptides to the endoplasmic reticulum of viable cells
Direct delivery of exogenous MHC class I molecule-binding oligopeptides to the endoplasmic reticulum of viable cells
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DOI：
10.1073/pnas.94.15.8064
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发表时间：
1997-07-22
影响因子：
11.1
通讯作者：
Bennink, JR
中科院分区：
文献类型：
--
作者：
Day, PM;Yewdell, JW;Bennink, JR
在将细胞与结合主要组织相容性复合体（MHC）I类分子的荧光素偶联肽短暂孵育后，通过显微镜观察或与放射性标记的I类分子结合，在内质网（ER）中检测到了肽。使用一种对肽 - I类分子复合物具有高度特异性的单克隆抗体，证明了一种非荧光肽可被递送至内质网。肽的内质网定位：（i）需要内质网中适当的I类分子表达，但不需要在细胞表面表达；（ii）通过TAP（MHC编码的胞质到内质网的肽转运体）的表达而减少；（iii）被胞饮作用抑制剂阻断，但不被布雷菲德菌素A阻断。这些发现表明存在一种可能本质上是囊泡的途径，它可将细胞外小分子物质运输到内质网，而不经过高尔基体或胞质。该途径有助于将外源性肽加载到MHC I类分子上，但其进化意义可能在于其他细胞过程，例如维持内质网稳态或细胞外物质的信号传导。
After brief incubation of sells with fluorescein-conjugated peptides that bind major histocompatibility complex (MI-IC) class 1 molecules, peptides were detected within the endoplasmic reticulum (ER) by microscopy or by binding to radiolabeled class I molecules. ER delivery of a nonfluorescent peptide was demonstrated using a mAb highly specific for the peptide-class I molecule complex, ER localization of peptides: (i) required expression of appropriate class I molecules in the ER but not on the cell surface, (ii) was diminished by expression of TAP, the MHC-encoded cytosol to ER peptide transporter, and (iii) was blacked by pinocytosis inhibitors but not by brefeldin A. These findings demonstrate the existence of a pathway, likely vesicular in nature, that conveys small extracellular substances to the ER without traversing the Golgi complex or the cytosol. This pathway contributes to the loading of exogenous peptides to MHC class I molecules, but its evolutionary significance may lie in other cellular processes, such as maintaining ER homeostasis or signaling by extracellular substances.