Institut de Biologie Paris-Seine (IBPS), Service de Microscopie éLectronique (IBPS-SME), Sorbonne Université, CNRS, 75005 Paris, France.
Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy.
Cells. 2020 Feb 15;9(2):447. doi: 10.3390/cells9020447.
The peptide ERα17p, which corresponds to the 295-311 fragment of the hinge/AF2 domains of the human estrogen receptor α (ERα), exerts apoptosis in breast cancer cells through a mechanism involving the G protein-coupled estrogen-dependent receptor GPER. Besides this receptor-mediated mechanism, we have detected a direct interaction (Kd value in the micromolar range) of this peptide with lipid vesicles mimicking the plasma membrane of eukaryotes. The reversible and not reversible pools of interacting peptide may correspond to soluble and aggregated membrane-interacting peptide populations, respectively. By using circular dichroism (CD) spectroscopy, we have shown that the interaction of the peptide with this membrane model was associated with its folding into β sheet. A slight leakage of the 5(6)-fluorescein was also observed, indicating lipid bilayer permeability. When the peptide was incubated with living breast cancer cells at the active concentration of 10 μM, aggregates were detected at the plasma membrane under the form of spheres. This insoluble pool of peptide, which seems to result from a fibrillation process, is internalized in micrometric vacuoles under the form of fibrils, without evidence of cytotoxicity, at least at the microscopic level. This study provides new information on the interaction of ERα17p with breast cancer cell membranes as well as on its mechanism of action, with respect to direct membrane effects.
肽 ERα17p 对应于人类雌激素受体 α (ERα) 的铰链/AF2 结构域的 295-311 片段，通过涉及 G 蛋白偶联雌激素依赖性受体 GPER 的机制在乳腺癌细胞中发挥凋亡作用。除了这种受体介导的机制外，我们还检测到该肽与模拟真核生物质膜的脂质体之间的直接相互作用（Kd 值在微摩尔范围内）。这种可相互作用的肽的可逆和不可逆池可能分别对应于可溶性和聚集的膜相互作用肽群体。通过使用圆二色性 (CD) 光谱，我们已经表明，肽与该膜模型的相互作用与其折叠成 β 片层有关。还观察到 5(6)-荧光素的轻微泄漏，表明脂质双层的通透性。当肽以 10 μM 的有效浓度与活的乳腺癌细胞孵育时，在球体形式下在质膜上检测到聚集物。这种似乎源于纤维形成过程的不溶性肽池以纤维的形式在微毫米级别的空泡中内化，至少在微观水平上没有细胞毒性的证据。这项研究提供了关于 ERα17p 与乳腺癌细胞膜相互作用及其直接膜效应相关作用机制的新信息。
