Cell-penetrating peptides (CPPs) are routinely used for the delivery of macromolecules into live human cells. To enter the cytosolic space of cells, CPPs typically permeabilize the membrane of endosomes. In turn, several approaches have been developed to increase the endosomal membrane permeation activity of CPPs so as to improve delivery efficiencies. The endocytic pathway is, however, important in maintaining cellular homeostasis, and understanding how endosomal permeation impacts cells is now critical to define the general utility of CPPs. Herein, we investigate how CPP-based delivery protocols affect the endocytic network. We detect that, in some cases, cell penetration induces the activation of Chmp1b, Galectin-3, and TFEB, which are components of endosomal repair, organelle clearance, and biogenesis pathways, respectively. We also detect that cellular delivery modulates endocytosis and endocytic proteolysis. Remarkably, a multimeric analogue of the prototypical CPP TAT permeabilizes endosomes efficiently without inducing membrane damage responses. These results challenge the notion that reagents that make endosomes leaky are generally toxic. Instead, our data indicates that it is possible to enter cells with minimal deleterious effects.

中文翻译：

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细胞穿透肽的内体逃逸活性对内吞途径的影响。

细胞穿透肽（CPP）通常用于将大分子递送到活的人类细胞中。为了进入细胞的胞质空间，CPP 通常会透化内体膜。反过来，已经开发了几种方法来增加 CPP 的内体膜渗透活性，从而提高递送效率。然而，内吞途径对于维持细胞稳态非常重要，并且了解内体渗透如何影响细胞现在对于定义 CPP 的一般用途至关重要。在此，我们研究基于 CPP 的递送协议如何影响内吞网络。我们发现，在某些情况下，细胞渗透会诱导 Chmp1b、Galectin-3 和 TFEB 的激活，它们分别是内体修复、细胞器清除和生物发生途径的组成部分。我们还检测到细胞递送调节内吞作用和内吞蛋白水解作用。值得注意的是，原型 CPP TAT 的多聚体类似物可以有效地透化核内体，而不会诱导膜损伤反应。这些结果挑战了使内体渗漏的试剂通常有毒的观念。相反，我们的数据表明，进入细胞的有害影响最小。