Cell-type specific mechanical response and myosin dynamics during retinal lens development in Drosophila

Abstract

During organogenesis, different cell types need to work together to induce functional 30 multicellular structures. To study this process, we made use of the genetically tractable fly retina, with a focus on the mechanisms that coordinate morphogenesis between the different epithelial cell types that make up the optical lens. Our work shows that these epithelial cells present contractile apical-medial MyosinII meshworks, which control the apical area and junctional geometry of these cells during lens development. Our study 35 also suggests that MyosinII meshworks drive cell shape changes in response to external forces, and thus they mediate part of the biomechanical coupling that takes place between these cells. Importantly, our work, including mathematical modelling of forces and material stiffness during lens development, raises the possibility that increased cell stiffness acts as a mechanism for limiting this mechanical coupling. We 40 propose this might be required in complex tissues, where different cell types undergo concurrent morphogenesis and where averaging out of forces across cells could compromise individual cell apical geometry and thereby organ function. 65meshwork is pulsatile, with cycles of discrete node contraction and relaxation that occur over tens of seconds, and that can promote apical area fluctuations and AJ remodelling over similar time scales (Coravos et al., 2017). Contractile pulses appear to be self-organizing and associated with cycles of phosphorylation and dephosphorylation of the MyoII regulatory light chain, and thus cycles of 70 assembly/disassembly of the meshworks (Kasza et al., 2014;Vasquez et al., 2014;Munjal et al., 2015;Mason et al., 2016). The AJ pool of actomyosin is linked to the Cadherin system and is thought to function as part of a ratchet mechanism that can

Probing the conserved roles of Cut in the development and function of optically different insect compound eyes

“…During eye development, SCs undergo dramatic changes in organization (Cagan and Ready, 1989) and play important roles in recruiting later-developing PPCs (Nagaraj and Banerjee, 2007) and regulating the orientation of developing PRs. The specific patterning steps of SCs likely include a combination of forces driven by the actomyosin cytoskeleton, cell adhesion (Cadherins and Nephrins), endocytosis, and Notch signaling (Chan et al, 2017;Blackie et al, 2020Blackie et al, , 2021Charlton-Perkins et al, 2021). As Cut expression is detectable shortly after SC specification (Blochlinger et al, 1990;Canon and Banerjee, 2003;Charlton-Perkins et al, 2011), it is well positioned to contribute to the regulation of these patterning events.…”