1.
Coordinated regulation of diverse F-actin organizations orchestrates F-actin pulses in the actomyosin network.
Abstract:
Pulsatile actomyosin networks emerge as a widespread mechanism driving tissue morphogenesis. Compared with myosin-II pulses, F-actin pulses are largely unexplored. By studying Drosophila oogenesis, we report that basal pulsatile actomyosin networks consist of F-actin bundle and meshwork architectures, implicating the existence of different F-actin microstructures and corresponding nucleators. Here, Rac1 and the Scar/WAVE-Arp2/3 complex (branched F-actin nucleator), exhibiting constant levels, are necessary to support F-actin pulsation, whereas pulses of Dia (unbranched F-actin nucleator) trigger F-actin pulsation. The pulsatile F-actin networks recruit the F-actin turnover regulator cofilin, thus generating cofilin pulses. Cofilin at relatively low concentration can cooperate with F-actin nucleators to amplify F-actin and enhance its pulsation, while cofilin at relatively high concentration might trigger the F-actin disassembly to attenuate its pulsation. These two different effects of cofilin on F-actin pulsation were confirmed by Zdk-cofilin optogenetics. Rac1 signaling, Dia, and cofilin are also crucial for F-actin pulses in border cell migration. Our findings thus reveal a coordinated regulation of F-actin pulses conferring actomyosin contractility in morphogenesis and cell migration.
2.
Spatiotemporal dissection of collective cell migration and tissue morphogenesis during development by optogenetics.
Abstract:
Collective cell migration and tissue morphogenesis play a variety of important roles in the development of many species. Tissue morphogenesis often generates mechanical forces that alter cell shapes and arrangements, resembling collective cell migration-like behaviors. Genetic methods have been widely used to study collective cell migration and its like behavior, advancing our understanding of these processes during development. However, a growing body of research shows that collective cell migration during development is not a simple behavior but is often combined with other cellular and tissue processes. In addition, different surrounding environments can also influence migrating cells, further complicating collective cell migration during development. Due to the complexity of developmental processes and tissues, traditional genetic approaches often encounter challenges and limitations. Thus, some methods with spatiotemporal control become urgent in dissecting collective cell migration and tissue morphogenesis during development. Optogenetics is a method that combines optics and genetics, providing a perfect strategy for spatiotemporally controlling corresponding protein activity in subcellular, cellular or tissue levels. In this review, we introduce the basic mechanisms underlying different optogenetic tools. Then, we demonstrate how optogenetic methods have been applied in vivo to dissect collective cell migration and tissue morphogenesis during development. Additionally, we describe some promising optogenetic approaches for advancing this field. Together, this review will guide and facilitate future studies of collective cell migration in vivo and tissue morphogenesis by optogenetics.
