Amstutz Beat, Gastaldelli Michele, Kälin Stefan, Imelli Nicola, Boucke Karin, Wandeler Eliane, Mercer Jason, Hemmi Silvio, Greber Urs F
Institute of Zoology, University of Zürich, Zürich, Switzerland.
EMBO J. 2008 Apr 9;27(7):956-69. doi: 10.1038/emboj.2008.38. Epub 2008 Mar 6.
Endocytosis supports cell communication, growth, and pathogen infection. The species B human adenovirus serotype 3 (Ad3) is associated with epidemic conjunctivitis, and fatal respiratory and systemic disease. Here we show that Ad3 uses dynamin-independent endocytosis for rapid infectious entry into epithelial and haematopoietic cells. Unlike Ad5, which uses dynamin-dependent endocytosis, Ad3 endocytosis spatially and temporally coincided with enhanced fluid-phase uptake. It was sensitive to macropinocytosis inhibitors targeting F-actin, protein kinase C, the sodium-proton exchanger, and Rac1 but not Cdc42. Infectious Ad3 macropinocytosis required viral activation of p21-activated kinase 1 (PAK1) and the C-terminal binding protein 1 of E1A (CtBP1), recruited to macropinosomes. These macropinosomes also contained the Ad3 receptors CD46 and alpha v integrins. CtBP1 is a phosphorylation target of PAK1, and is bifunctionally involved in membrane traffic and transcriptional repression of cell cycle, cancer, and innate immunity pathways. Phosphorylation-defective S147A-CtBP1 blocked Ad3 but not Ad5 infection, providing a direct link between PAK1 and CtBP1. The data show that viruses induce macropinocytosis for infectious entry, a pathway used in antigen presentation and cell migration.
内吞作用支持细胞通讯、生长和病原体感染。B 种人类腺病毒血清型 3（Ad3）与流行性结膜炎以及致命的呼吸道和全身性疾病有关。在此我们表明，Ad3 利用不依赖发动蛋白的内吞作用快速感染性进入上皮细胞和造血细胞。与利用依赖发动蛋白的内吞作用的 Ad5 不同，Ad3 的内吞作用在空间和时间上与增强的液相摄取相吻合。它对靶向 F-肌动蛋白、蛋白激酶 C、钠-质子交换体和 Rac1 而非 Cdc42 的巨胞饮作用抑制剂敏感。感染性 Ad3 的巨胞饮作用需要病毒激活 p21 激活激酶 1（PAK1）以及被招募到巨胞饮体的 E1A 的 C 末端结合蛋白 1（CtBP1）。这些巨胞饮体还包含 Ad3 受体 CD46 和αv 整合素。CtBP1 是 PAK1 的磷酸化靶点，并且在膜运输以及细胞周期、癌症和先天免疫途径的转录抑制中具有双重功能。磷酸化缺陷型 S147A-CtBP1 阻断 Ad3 感染但不阻断 Ad5 感染，这在 PAK1 和 CtBP1 之间建立了直接联系。数据表明，病毒诱导巨胞饮作用以实现感染性进入，这是抗原呈递和细胞迁移中使用的一种途径。
