Functional Properties of Circulating Exosomes Mediated by Surface-Attached Plasma Proteins
Functional Properties of Circulating Exosomes Mediated by Surface-Attached Plasma Proteins
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DOI：
10.14740/jh412w
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发表时间：
2018-11
影响因子：
1.2
通讯作者：
T. Shtam;S. Naryzhny;A. Kopylov;E. Petrenko;R. Samsonov;R. Kamyshinsky;Yana Zabrodskaya;D. Nikitin;M. Sorokin;A. Buzdin;A. Malek
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文献类型：
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作者：
T. Shtam;S. Naryzhny;A. Kopylov;E. Petrenko;R. Samsonov;R. Kamyshinsky;Yana Zabrodskaya;D. Nikitin;M. Sorokin;A. Buzdin;A. Malek
背景
外泌体及其他类型的细胞外囊泡是循环血浆的重要组成部分。内皮细胞和血细胞释放的外泌体占血浆外泌体群体的大部分；其他细胞分泌的外泌体也可能穿过组织 - 血浆屏障进入循环血浆。显然，不同细胞来源的外泌体在内容物和功能上存在差异。然而，外泌体表面膜会与血浆成分相互作用。这种相互作用可能会改变外泌体表面的组成，从而赋予这些囊泡新的功能特性。本研究旨在评估附着于血浆外泌体表面的蛋白质的组成及其可能的功能作用。
方法
在此，通过超速离心从人血浆中分离细胞外囊泡，并用胰蛋白酶处理。通过纳米颗粒跟踪分析、蛋白质免疫印迹和定量高分辨率质谱法对经胰蛋白酶处理的和天然的外泌体进行分析。
结果
通过与丝氨酸蛋白酶（胰蛋白酶）孵育，可从健康供体血浆中分离出的外泌体上移除表面附着的蛋白质。处理过程未影响外泌体的完整性，但略微减小了其流体动力学半径。质谱分析揭示了259种外泌体蛋白质；其中79种蛋白质被完全移除，超过一半的蛋白质经胰蛋白酶处理后部分被移除。基因本体功能注释显示，从血浆外泌体表面裂解下来的蛋白质大多位于细胞外。此外，从外泌体表面裂解下来的蛋白质被认为与整合素连接激酶（ILK）、粘着斑激酶（FAK）以及其他将细胞表面与细胞内信号级联连接起来的通路有关。
结论
综上所述，我们的研究结果表明，循环外泌体的表面被血浆蛋白修饰，这些蛋白质可能会掩盖外泌体表面膜的组织特异性特征，并赋予外泌体新的、统一的特性。
Background Exosomes and other types of extracellular vesicles present an important component of circulating plasma. Exosomes released by endothelial and blood cells account for majority of plasma exosomal population; exosomes secreted by other cells might cross tissue-plasma barrier and reach circulating plasma as well. Definitely, exosomes of different cellular origins are different by content and function. However, exosomal surface membrane interacts with plasma components. This interaction may alter composition of exosomal surface and hence, provide these vesicles with new functional properties. This study was aimed to estimate composition and possible functional role of proteins attached on the surface of plasma exosomes. Methods Here, extracellular vesicles from human plasma were isolated by ultracentrifugation and treated by trypsin. Trypsinized and native exosomes were analyzed by nanoparticle tracking analysis, Western blotting and quantitative high-resolution mass spectrometry. Results Surface-attached proteins were removed from exosomes isolated from plasma of healthy donors by incubation with serine protease (trypsin). Treatment did not impact exosomes integrity while slightly reduced hydrodynamic radius. Mass spectrometry revealed 259 exosomal proteins; among them 79 proteins were completely removed and more than half of the proteins were partially removed by trypsinization. Gene ontology functional annotation revealed mostly extracellular locations of proteins cleaved from a surface of the plasma exosomes. Moreover, proteins cleaved from the exosome surface are supposed to be implicated into integrin-linked kinase (ILK), focal adhesion kinase (FAK) and other pathways connecting cell surface with intracellular signaling cascades. Conclusion Taken together, our results demonstrate that a surface of circulating exosomes is decorated by plasma proteins, and these proteins can mask tissue-specific characteristic of the exosomal surface membrane and provide exosomes with new and uniform properties.