Department of Molecular Biology, Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA.
J Cell Biol. 2010 Mar 8;188(5):735-49. doi: 10.1083/jcb.200910099. Epub 2010 Mar 1.
Contractile forces generated by the actomyosin cytoskeleton within individual cells collectively generate tissue-level force during epithelial morphogenesis. During Drosophila mesoderm invagination, pulsed actomyosin meshwork contractions and a ratchet-like stabilization of cell shape drive apical constriction. Here, we investigate how contractile forces are integrated across the tissue. Reducing adherens junction (AJ) levels or ablating actomyosin meshworks causes tissue-wide epithelial tears, which release tension that is predominantly oriented along the anterior-posterior (a-p) embryonic axis. Epithelial tears allow cells normally elongated along the a-p axis to constrict isotropically, which suggests that apical constriction generates anisotropic epithelial tension that feeds back to control cell shape. Epithelial tension requires the transcription factor Twist, which stabilizes apical myosin II, promoting the formation of a supracellular actomyosin meshwork in which radial actomyosin fibers are joined end-to-end at spot AJs. Thus, pulsed actomyosin contractions require a supracellular, tensile meshwork to transmit cellular forces to the tissue level during morphogenesis.
在细胞个体中,由肌动球蛋白细胞骨架产生的收缩力在细胞水平上共同产生组织水平的力。在果蝇中胚层内陷过程中,脉冲肌动球蛋白网格收缩和细胞形状的棘轮式稳定驱动顶端收缩。在这里,我们研究了如何整合整个组织的收缩力。减少黏着连接(AJ)水平或破坏肌动球蛋白网格会导致全组织上皮撕裂,从而释放出主要沿前后(a-p)胚胎轴方向的张力。上皮撕裂允许通常沿 a-p 轴伸长的细胞向各向同性收缩,这表明顶端收缩产生各向异性的上皮张力,从而反馈控制细胞形状。上皮张力需要转录因子 Twist,它稳定顶端肌球蛋白 II,促进超细胞肌动球蛋白网格的形成,其中径向肌动球蛋白纤维在点状 AJ 处端到端连接。因此,在形态发生过程中,脉冲肌动球蛋白收缩需要一个超细胞的、拉伸的网格来将细胞力传递到组织水平。