Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA.
Department of Biology, Brandeis University, 415 South St., Waltham, MA 02453, USA.
Mol Ther. 2018 Feb 7;26(2):648-658. doi: 10.1016/j.ymthe.2017.11.020. Epub 2018 Jan 6.
Most of the peptides used for promoting cellular uptake bear positive charges. In our previous study, we reported an example of taurine (bearing negative charges in physiological conditions) promoting cellular uptake of D-peptides. Taurine, conjugated to a small D-peptide via an ester bond, promotes the cellular uptake of this D-peptide. Particularly, intracellular carboxylesterase (CES) instructs the D-peptide to self-assemble and to form nanofibers, which largely disfavors efflux and further enhances the intracellular accumulation of the D-peptide, as supported by that the addition of CES inhibitors partially impaired cellular uptake of this molecule in mammalian cell lines. Using dynamin 1, 2, and 3 triple knockout (TKO) mouse fibroblasts, we demonstrated that cells took up this molecule via macropinocytosis and dynamin-dependent endocytosis. Imaging of Drosophila larval blood cells derived from endocytic mutants confirmed the involvement of multiple endocytosis pathways. Electron microscopy (EM) indicated that the precursors can form aggregates on the cell surface to facilitate the cellular uptake via macropinocytosis. EM also revealed significantly increased numbers of vesicles in the cytosol. This work provides new insights into the cellular uptake of taurine derivative for intracellular delivery and self-assembly of D-peptides.
大多数用于促进细胞摄取的肽都带有正电荷。在我们之前的研究中，我们报告了一个例子，即牛磺酸（在生理条件下带负电荷）促进 D-肽的细胞摄取。通过酯键将牛磺酸与小的 D-肽连接，可促进该 D-肽的细胞摄取。特别地，细胞内羧酸酯酶（CES）指示 D-肽自组装并形成纳米纤维，这极大地不利于外排，并进一步增强了 D-肽的细胞内积累，这得到了 CES 抑制剂的添加部分损害了哺乳动物细胞系中该分子的细胞摄取的支持。使用动力蛋白 1、2 和 3 三重敲除（TKO）鼠成纤维细胞，我们证明了细胞通过巨胞饮作用和依赖于动力蛋白的内吞作用摄取该分子。来自内吞作用突变体的果蝇幼虫血细胞的成像证实了多种内吞作用途径的参与。电子显微镜（EM）表明，前体可以在细胞表面形成聚集体，通过巨胞饮作用促进细胞摄取。EM 还显示细胞质中囊泡的数量显著增加。这项工作为牛磺酸衍生物的细胞摄取提供了新的见解，用于细胞内递药和 D-肽的自组装。
