Using optogenetics to link myosin patterns to contractile cell behaviors during convergent extension

Optogenetic dissection of actomyosin-dependent mechanics underlying tissue fluidity

“…In a prior study, our group demonstrated that the medial-apical myosin in activated optoGEF cells shows dynamic pulsing behavior that is correlated with enhanced apical cell area fluctuations (Herrera-Perez et al, 2021). Here, we find that in the absence of strongly planar polarized junctional myosin in optoGEF and optoGAP embryos, cell rearrangement rates increase with tissue tension associated with medial myosin (Fig.…”

“…A notable feature of these perturbations that appears to correlate with the observed rearrangement rates is the enhanced medial-apical myosin in optoGEF and decreased medial-apical myosin in optoGAP embryos. In prior work, we showed that the enhanced medial-apical myosin pool in the photoactivated optoGEF cells displays dynamic pulsing behavior that is correlated with apical cell area fluctuations (Herrera-Perez et al, 2021). Here, by studying retraction of the tissue in response to laser ablation of the medial myosin domain, we demonstrated that this enhanced medial-apical myosin pool produces enhanced active tensions.…”

“…These tools are based on the CRY2/CIB1 heterodimerization system, which can be activated by blue-light illumination (Guglielmi et al, 2015; Idevall-Hagren et al, 2012; Izquierdo et al, 2018; Kennedy et al, 2010). The optoGEF tool is based on the full-length Drosophila RhoGEF2 protein and activates actomyosin contractility (Herrera-Perez et al, 2021). In contrast, optoGAP is based on the full-length Drosophila RhoGAP71E protein and deactivates actomyosin contractility (Herrera-Perez et al, 2021).…”

“…In contrast, optoGAP is based on the full-length Drosophila RhoGAP71E protein and deactivates actomyosin contractility (Herrera-Perez et al, 2021). Photoactivation via blue light illumination of the apical surface of the germband leads to rapid accumulation of the CRY2 component of the optogenetic tools at the apical cell membrane, allowing us to perturb actomyosin contractility rapidly at minute timescales and specifically in the germband tissue during body axis elongation (Herrera-Perez et al, 2021). Employing this optogenetics approach, we analyzed how perturbing actomyosin affects cell rearrangements (a measure of tissue fluidity) using live imaging and quantitative image analysis, how it affects mechanical forces in the tissue using laser ablation assays, and how it affects mechanical properties of the tissue by analyzing the structure of epithelial cell packings.…”

“…This requires precise perturbation of actomyosin contractility patterns, specifically in the germband during body axis elongation, so that the mechanical behavior of neighboring regions of the embryo is not disturbed. Because this is not possible with traditional molecular genetics approaches, here we employed two previously described optogenetic tools, optoGEF and optoGAP, to manipulate the localization of upstream regulators of Drosophila Rho1 at the apical surface of the germband epithelium (Herrera-Perez et al, 2021). These tools are based on the CRY2/CIB1 heterodimerization system, which can be activated by blue-light illumination (Guglielmi et al, 2015; Idevall-Hagren et al, 2012; Izquierdo et al, 2018; Kennedy et al, 2010).…”