Cellular senescence is the irreversible cell cycle arrest in response to various types of stress. Although the plasma membrane and its composition are significantly affected by cellular senescence, detailed studies on the physical properties of the plasma membrane have shown inconclusive results. In this study, we utilized both ensemble and single-molecule fluorescence imaging to investigate how membrane properties, such as fluidity, hydrophobicity, and ganglioside GM1 level are affected by cellular senescence. The diffusion coefficient of lipid probes, as well as the type of diffusion determined by an exponent α, which is the slope of the log–log plot of mean squared displacement as a function of time lag, were analyzed. We found that the number of molecules with a lower diffusion coefficient increased as cells became senescent. The changes in the population with a lower diffusion coefficient, observed after methyl-β-cyclodextrin treatment, and the increase in ceramide levels, detected using a ceramide-specific antibody, suggest that ceramide-rich lipid rafts were enhanced in senescent cells. Our results emphasize the importance of membrane properties in cellular senescence and might serve as a base for in-depth studies to determine how such domains facilitate the signaling pathway specific to cellular senescence.

中文翻译：

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通过荧光成像探测衰老细胞中细胞膜的物理特性

细胞衰老是响应各种压力的不可逆细胞周期停滞。尽管质膜及其组成受到细胞衰老的显着影响，但对质膜物理特性的详细研究显示出不确定的结果。在这项研究中，我们利用整体和单分子荧光成像来研究细胞衰老如何影响膜特性，例如流动性、疏水性和神经节苷脂 GM1 水平。分析了脂质探针的扩散系数，以及由指数 α 确定的扩散类型，即均方位移的对数-对数图的斜率作为时间滞后的函数。我们发现随着细胞衰老，具有较低扩散系数的分子数量增加。在甲基-β-环糊精处理后观察到的具有较低扩散系数的群体的变化，以及使用神经酰胺特异性抗体检测到的神经酰胺水平的增加，表明富含神经酰胺的脂筏在衰老细胞中得到增强。我们的结果强调了膜特性在细胞衰老中的重要性，并可能作为深入研究的基础，以确定这些结构域如何促进细胞衰老特有的信号通路。