Curated Optogenetic Publication Database

Abstract: How do cellular forces propagate through tissue to allow large-scale morphogenetic events? To investigate this question, we use an in vivo optogenetic approach to reversibly manipulate actomyosin contractility at depth within the developing zebrafish neural rod. Contractility was induced along the lateral cortices of a small patch of developing neural epithelial progenitor cells, resulting in a shortening of these cells along their mediolateral axis. Imaging the immediate response of surrounding tissue uncovered a long-range, tangential, and elastic tissue deformation along the anterior-posterior axis. Unexpectedly, this was highly asymmetric, propagating in either the anterior or the posterior direction in response to local gradients in optogenetic activation. The degree of epithelialisation did not have a significant impact on the extent of force propagation via lateral cortices. We also uncovered a dynamic oscillatory expansion and contraction of the tissue along the anterior-posterior axis, with wavelength matching rhombomere length. Together, this study suggests dynamic and wave-like propagation of force between rhombomeres along the anterior-posterior axis. It also suggests that cell generated forces are actively propagated over long distances within the tissue, and that local anisotropies in tissue organisation and contractility may be sufficient to drive directional force propagation.

Abstract: The initiation of apical-basal (AB) polarity and the process of mitotic cell division are both characterised by the generation of specialised plasma membrane and cortical domains. These are generated using shared mechanisms, such as asymmetric protein accumulation, Rho GTPase signalling, cytoskeletal reorganisation, vesicle trafficking and asymmetric phosphoinositide distribution. In epithelial tissue, the coordination of AB polarity and mitosis in space and time is important both during initial epithelial development and to maintain tissue integrity and ensure appropriate cell differentiation at later stages. Whilst significant progress has been made in understanding the mechanisms underlying cell division and AB polarity, it has so far been challenging to fully unpick the complex interrelationship between polarity, signalling, morphogenesis, and cell division. However, the recent emergence of optogenetic protein localisation techniques is now allowing researchers to reversibly control protein activation, localisation and signalling with high spatiotemporal resolution. This has the potential to revolutionise our understanding of how subcellular processes such as apical-basal polarity are integrated with cell behaviours such as mitosis and how these processes impact whole tissue morphogenesis. So far, these techniques have been used to investigate processes such as cleavage furrow ingression, mitotic spindle positioning, and in vivo epithelial morphogenesis. This review describes some of the key shared mechanisms of cell division and apical-basal polarity establishment, how they are coordinated during development and how the advance of optogenetic techniques is furthering this research field.