Departamento de Física and Instituto de Física de Buenos Aires (IFIBA), CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
PLoS One. 2021 May 11;16(5):e0251411. doi: 10.1371/journal.pone.0251411. eCollection 2021.
Cells exert traction forces on the extracellular matrix to which they are adhered through the formation of focal adhesions. Spatial-temporal regulation of traction forces is crucial in cell adhesion, migration, cellular division, and remodeling of the extracellular matrix. By cultivating cells on polyacrylamide hydrogels of different stiffness we were able to investigate the effects of substrate stiffness on the generation of cellular traction forces by Traction Force Microscopy (TFM), and characterize the molecular dynamics of the focal adhesion protein zyxin by Fluorescence Correlation Spectroscopy (FCS) and Fluorescence Recovery After Photobleaching (FRAP). As the rigidity of the substrate increases, we observed an increment of both, cellular traction generation and zyxin residence time at the focal adhesions, while its diffusion would not be altered. Moreover, we found a positive correlation between the traction forces exerted by cells and the residence time of zyxin at the substrate elasticities studied. We found that this correlation persists at the subcellular level, even if there is no variation in substrate stiffness, revealing that focal adhesions that exert greater traction present longer residence time for zyxin, i.e., zyxin protein has less probability to dissociate from the focal adhesion.
细胞通过形成黏着斑来对其黏附的细胞外基质施加牵引力。牵引力的时空调节对于细胞黏附、迁移、细胞分裂和细胞外基质的重塑至关重要。通过在不同硬度的聚丙烯酰胺水凝胶上培养细胞，我们能够通过牵引力显微镜（TFM）研究基质硬度对细胞牵引力产生的影响，并通过荧光相关光谱（FCS）和荧光漂白恢复（FRAP）来描述黏着斑蛋白zyxin 的分子动力学。随着基质刚性的增加，我们观察到细胞牵引力的产生和 zyxin 在黏着斑处的停留时间都增加，而其扩散则不会改变。此外，我们发现细胞产生的牵引力与在研究的基质弹性下 zyxin 在黏附点的停留时间之间存在正相关关系。我们发现，即使在基质硬度没有变化的情况下，这种相关性在亚细胞水平上仍然存在，这表明施加较大牵引力的黏着斑，其 zyxin 的停留时间更长，也就是说，zyxin 蛋白从黏着斑解离的可能性更小。
