Membrane tether formation from blebbing cells
Membrane tether formation from blebbing cells
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DOI：
10.1016/s0006-3495(99)77168-7
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发表时间：
1999-12-01
影响因子：
3.4
通讯作者：
Sheetz, MP
中科院分区：
文献类型：
--
作者：
Dai, JW;Sheetz, MP
膜张力被认为对于调节细胞功能（例如内吞作用和细胞运动）很重要。表观膜张力是根据激光镊子测量的系绳力计算得出的。膜-细胞骨架粘附和膜张力都对系留力有贡献。质膜与细胞骨架的分离发生在膜泡中，这可以消除膜-细胞骨架粘附项。在肾上皮细胞中，气泡上的系留力明显低于由细胞骨架支撑的膜上的系留力。此外，顶端和基底外侧泡上的系绳力相等。相反，来自细胞骨架支撑的膜的系绳力在顶端区域比在基底外侧区域更大，这与顶端区域更大的表观细胞骨架密度一致。我们认为，气泡上的系留力主要仅包含膜张力项，并且膜张力在细胞表面上可能是均匀的。对这一假设的额外支持来自对自发起泡的黑色素瘤细胞的观察。在黑色素瘤细胞中，泡上的系留力与泡的半径成正比，并且随着大泡的形成，其他细胞区域的系留力出现峰值。我们认为内部渗透压使气泡膨胀，并且根据拉普拉斯定律计算的压力类似于细胞内压力的独立测量。当从细胞骨架上的表观膜张力中减去膜张力项时，可以估计膜-细胞骨架粘附项。在这两个细胞系统中，膜-细胞骨架粘附是产生束缚力的主要因素。
Membrane tension has been proposed to be important in regulating cell functions such as endocytosis and cell motility. The apparent membrane tension has been calculated from tether forces measured with laser tweezers. Both membrane-cytoskeleton adhesion and membrane tension contribute to the tether force. Separation of the plasma membrane from the cytoskeleton occurs in membrane blebs, which could remove the membrane-cytoskeleton adhesion term. In renal epithelial cells, tether forces are significantly lower on blebs than on membranes that are supported by cytoskeleton. Furthermore, the tether forces are equal on apical and basolateral blebs. In contrast, tether forces from membranes supported by the cytoskeleton are greater in apical than in basolateral regions, which is consistent with the greater apparent cytoskeletal density in the apical region. We suggest that the tether force on blebs primarily contains only the membrane tension term and that the membrane tension may be uniform over the cell surface. Additional support for this hypothesis comes from observations of melanoma cells that spontaneously bleb. In melanoma cells, tether forces on blebs are proportional to the radius of the bleb, and as large blebs form, there are spikes in the tether force in other cell regions. We suggest that an internal osmotic pressure inflates the blebs, and the pressure calculated from the Law of Laplace is similar to independent measurements of intracellular pressures. When the membrane tension term is subtracted from the apparent membrane tension over the cytoskeleton, the membrane-cytoskeleton adhesion term can be estimated. In both cell systems, membrane-cytoskeleton adhesion was the major factor in generating the tether force.