Plasma Membrane Rigidity Directly Influences Cell Migration

细胞生物力学的基础知识对于理解疾病的发展和进展非常重要。例如，已经认识到，癌细胞与健康细胞的不同之处在于剪切刚度降低。到目前为止，人们一直认为细胞骨架和细胞核的结构变化单独决定细胞的生物力学性质。在这种情况下，尚未研究质膜结构变化的作用。在本项目中，我们将分析，在何种程度上的质膜的脂质成分的影响弯曲刚度和细胞的迁移行为。 通过我们在全球范围内首次对从临床样本中获得的GPMV进行闪烁光谱研究，我们已经证明了分离质膜的弯曲刚度与健康和恶性细胞的脂质体之间存在相关性。在该项目中，将全面研究导致质膜弯曲刚度改变的分子原因以及这在多大程度上影响细胞的迁移行为。出发点是弯曲刚度和“巨质膜囊泡”（GPMV）的分子组成之间的相关性的调查。GPMV是从细胞中分离的质膜，其基本上保持其复杂的脂质组成，因此代表了合适的生理模型。在我们的项目中，GPMV是由来自莱比锡大学医院的乳腺癌患者的组织样本的原代细胞产生的。为了比较的目的，我们还将检查来自同一患者的健康上皮组织。为了补充原代细胞的研究，我们将应用代表癌症不同阶段的乳腺癌细胞组。GPMV的抗弯刚度将通过闪烁光谱法测定，（磷酸）脂质组成将通过质谱法和NMR测定。抗弯刚度和膜组成之间的相关性将增加哪些（磷酸）脂质类影响膜刚度的知识。此外，我们将有选择地探索氧化修饰的膜脂质对膜刚性的影响，因为“活性氧”（ROS）的形成在癌症发病机制中也起着至关重要的作用。通过单细胞在微通道中的迁移研究质膜弹性与细胞迁移的相关性。通过探测能够通过各种尺寸的孔的细胞的百分比，将对应于膜刚度分析挤压通过时间以及通过后的运动类型。我们预期，膜刚度的降低有利于细胞通过狭窄通道的迁移。

The fundamental knowledge of cell biomechanics is important to understand the development and advancement of diseases. For instance, it has been recognised that cancer cells differ from healthy ones by a reduced shear stiffness. It has been assumed so far that structural changes of the cytoskeleton and the nucleus solely determine the biomechanical properties of cells. In this context it has not yet been examined which role structural changes of the plasma membrane are playing. In the present project we will analyse, to which extent the lipid composition of the plasma membrane influences the bending stiffness and the migration behaviour of cells. With our worldwide first flicker spectroscopy studies of GPMVs, obtained from clinical samples, we have already shown that there is a correlation between the bending rigidity of isolated plasma membranes and the lipidome of healthy and malignant cells. Within this project the molecular reasons which lead to the alteration of the bending stiffness of the plasma membrane and how far this influences the migration behaviour of cells will be comprehensively examined. The starting point is the investigation of the correlation between the bending stiffness and the molecular composition of "Giant Plasma Membrane Vesicles" (GPMVs). GPMVs are plasma membranes isolated from cells which maintain essentially their complex lipid composition and therefore represent a suitable physiological model. In our project GPMVs are generated from primary cells from tissue samples obtained from breast cancer patients from the Leipzig University hospital. For comparative purposes we will also examine healthy epithelial tissue from the same patient. To complement the investigations with primary cells we will apply a breast cancer cell panel which represents different stages of cancer. The bending stiffness of the GPMVs will be determined by flicker spectroscopy and the (phospho)lipid composition by mass spectrometry and NMR. The correlation between bending stiffness and membrane composition will increase the knowledge which (phospho)lipid classes influence membrane stiffness. In addition we will explore selectively the influence of oxidatively modified membrane lipids on membrane rigidity since the formation of “reactive oxygen species” (ROS) plays also a crucial role in cancer pathogenesis. The correlation of the plasma membrane elasticity and cell migration will be investigated by the migration of single cells through micro channels. By probing the percentage of cells that are able to pass through apertures of various sizes, the squeeze-through time, as well as type of motion after passage will be analyzed in correspondence to membrane rigidity. We expect that a decrease in membrane rigidity facilitates the cell migration through narrow channels.