Direct laser manipulation reveals the mechanics of cell contacts in vivo
Direct laser manipulation reveals the mechanics of cell contacts in vivo
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DOI：
10.1073/pnas.1418732112
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发表时间：
2015-02-03
影响因子：
11.1
通讯作者：
Lenne, Pierre-Francois
中科院分区：
文献类型：
--
作者：
Bambardekar, Kapil;Clement, Raphael;Lenne, Pierre-Francois
细胞产生的力产生各种组织运动和组织形状变化。构成这些动力学基础的细胞骨架元件在细胞-细胞和细胞-ECM接触处起作用，以在粘附结构上施加局部力。在上皮细胞中，细胞接触处的力不平衡诱导细胞形状变化，例如顶端收缩或极化连接重塑，从而驱动组织形态发生。这些过程的动力学特征很好，但是，由于缺乏体内力学测量，细胞形状变化的力学基础在很大程度上是未知的。我们开发了一种结合光镊和光片显微镜的方法来探测早期果蝇胚胎上皮细胞连接的机械特性。我们表明，光阱可以有效地变形细胞-细胞界面和测量张力在细胞交界处，这是在100 pN的顺序。我们发现，在细胞连接处的张力平衡超过几秒钟，一个短的时间尺度相比，收缩事件，驱动形态发生运动。我们还表明，张力增加沿着细胞界面在早期组织形态发生，并成为各向异性的细胞插入在生殖带的延伸。通过进行拉-放实验，我们确定了与一个简单的粘弹性模型相一致的结力学随时间变化的特性。将本构关系纳入组织尺度模型，我们定量预测局部变形如何在整个组织中传播。
Cell-generated forces produce a variety of tissue movements and tissue shape changes. The cytoskeletal elements that underlie these dynamics act at cell-cell and cell-ECM contacts to apply local forces on adhesive structures. In epithelia, force imbalance at cell contacts induces cell shape changes, such as apical constriction or polarized junction remodeling, driving tissue morphogenesis. The dynamics of these processes are well-characterized; however, the mechanical basis of cell shape changes is largely unknown because of a lack of mechanical measurements in vivo. We have developed an approach combining optical tweezers with light-sheet microscopy to probe the mechanical properties of epithelial cell junctions in the early Drosophila embryo. We show that optical trapping can efficiently deform cell-cell interfaces and measure tension at cell junctions, which is on the order of 100 pN. We show that tension at cell junctions equilibrates over a few seconds, a short timescale compared with the contractile events that drive morphogenetic movements. We also show that tension increases along cell interfaces during early tissue morphogenesis and becomes anisotropic as cells intercalate during germ-band extension. By performing pull-and-release experiments, we identify time-dependent properties of junctional mechanics consistent with a simple viscoelastic model. Integrating this constitutive law into a tissue-scale model, we predict quantitatively how local deformations propagate throughout the tissue.