Li Lei, Wan Tao, Wan Min, Liu Bei, Cheng Ran, Zhang Rongying
Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China.
Cell Biol Int. 2015 May;39(5):531-9. doi: 10.1002/cbin.10424. Epub 2015 Jan 26.
Fluorescent dextrans are commonly used as macropinocytic probes to study the properties of endocytic cargoes; however, the effect of the size of dextrans on endocytic mechanisms has not been carefully analyzed. By using chemical and siRNA inhibition of individual endocytic pathways, we evaluated the internalization of two commonly used dextrans, Dex10 (dextran 10 kDa) and Dex70 (dextran 70 kDa), in mammalian HeLa cells and Caenorhabditis elegans coelomocytes. We revealed that Dex70 enters these two cell types predominantly via clathrin- and dynamin-independent and amiloride-sensitive macropinocytosis process; Dex10, on the other hand, enters the two cell types through clathrin-/dynamin-dependent micropinocytosis in addition to macropinocytosis. In addition, although different-sized dextrans follow different endocytic processes, they share common post-endocytic events. Herein, though straightforward, our studies support that the size of nanomaterials could play a paramount role in their inclusion into endocytic vesicles and suggest that care should be taken while selecting endocytic pathway markers. Based on our results, we propose that Dex70 is a better probe for macropinocytosis, whereas Dex10 and smaller molecules are better for probing general fluid-phase endocytosis, which includes macropinocytic and micropinocytic processes.
荧光葡聚糖通常用作巨胞饮探针来研究内吞货物的性质；然而，葡聚糖大小对内吞机制的影响尚未得到仔细分析。通过对单个内吞途径进行化学和RNA干扰抑制，我们评估了两种常用葡聚糖Dex10（10 kDa葡聚糖）和Dex70（70 kDa葡聚糖）在哺乳动物HeLa细胞和秀丽隐杆线虫体腔细胞中的内化情况。我们发现，Dex70主要通过不依赖网格蛋白和发动蛋白且对阿米洛利敏感的巨胞饮过程进入这两种细胞类型；另一方面，Dex10除了通过巨胞饮作用外，还通过依赖网格蛋白/发动蛋白的微胞饮作用进入这两种细胞类型。此外，尽管不同大小的葡聚糖遵循不同的内吞过程，但它们具有共同的内吞后事件。在此，虽然我们的研究很直接，但支持纳米材料的大小在其被纳入内吞小泡过程中可能起着至关重要的作用，并表明在选择内吞途径标记物时应谨慎。基于我们的结果，我们提出Dex70是用于巨胞饮作用的更好探针，而Dex10和更小的分子更适合用于探测包括巨胞饮和微胞饮过程在内的一般液相内吞作用。
