The spatial and temporal dynamics of cell contractility plays a key role in tissue morphogenesis, wound healing, and cancer invasion. Here, we report a simple optochemical method to induce cell contractions in vivo during Drosophila morphogenesis at single-cell resolution. We employed the photolabile Ca2+ chelator o-nitrophenyl EGTA to induce bursts of intracellular free Ca2+ by laser photolysis in the epithelial tissue. Ca2+ bursts appear within seconds and are restricted to individual target cells. Cell contraction reliably followed within a minute, causing an approximately 50% drop in the cross-sectional area. Increased Ca2+ levels are reversible, and the target cells further participated in tissue morphogenesis. Depending on Rho kinase (ROCK) activity but not RhoGEF2, cell contractions are paralleled with non-muscle myosin II accumulation in the apico-medial cortex, indicating that Ca2+ bursts trigger non-muscle myosin II activation. Our approach can be, in principle, adapted to many experimental systems and species, as no specific genetic elements are required.

中文翻译：

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体内光化学控制细胞在单细胞分辨率下的收缩力。

细胞收缩的时空动态在组织形态发生，伤口愈合和癌症侵袭中起关键作用。在这里，我们报告了一种简单的光化学方法，以果蝇形态发生期间在单细胞分辨率下诱导体内细胞收缩。我们采用了光不稳定的Ca2 +螯合剂邻硝基苯基EGTA，通过上皮组织中的激光光解作用诱导细胞内游离Ca2 +的爆发。Ca2 +爆发在几秒钟内出现，并仅限于单个靶细胞。细胞在一分钟内可靠地收缩，导致横截面积下降约50％。Ca2 +水平升高是可逆的，靶细胞进一步参与组织形态发生。取决于Rho激酶（ROCK）的活性，而不取决于RhoGEF2，细胞收缩与非肌肉型肌球蛋白II积累在apico-内侧皮层中平行，表明Ca2 +爆发触发了非肌肉型肌球蛋白II激活。我们的方法原则上可以适应许多实验系统和物种，因为不需要特定的遗传要素。