In vivo optochemical control of cell contractility at single cell resolution by Ca2+ induced myosin activation

Abstract

AbstractsThe spatial and temporal dynamics of cell contractility plays a key role in tissue morphogenesis, wound healing and cancer invasion. Here we report a simple, single cell resolution, optochemical method to induce minute-scale cell contractions in vivo during morphogenesis. We employed the photolabile Ca 2+ chelator o-nitrophenyl EGTA to induce bursts of intracellular free Ca 2+ by laser photolysis. Ca 2+ bursts appear within seconds and are restricted to individual target cells. Cell contraction reliably followed within a minute, to about half of the cross-sectional area. Increased Ca 2+ levels and contraction were reversible and the target cells further participated in tissue morphogenesis. Depending on Rho kinase (Rok) activity but not RhoGEF2, cell contractions are paralleled with non-muscle myosin-II accumulation in the apicomedial cortex, indicating that Ca 2+ bursts trigger non-muscle myosin II activation. Our approach can be easily adapted to many experimental systems and species, as no specific genetic elements are required and a widely used reagent is employed.

Calcium Signaling in Vertebrate Development and Its Role in Disease

“…This experiment provided the first evidence that calcium is necessary for neural tube closure. Recent studies using vertebrate model organisms including zebrafish, Xenopus , and mice have supported the idea that calcium is a major regulator of neural tube closure [ 4 , 66 , 67 , 68 ]. Visualization of calcium influxes during neural tube closure using genetically encoded calcium indicator showed distinct spikes and waves.…”

“…When this actin activity is imaged using F-actin marker Lifeact-EGFP at the same time as calcium activity, F-actin mesh-like structures develop in the center of the cells following the calcium transients during neural tube closure in Xenopus [ 4 ]. In addition, calcium transients trigger non-muscle myosin II activation within a minute of their occurrence in Xenopus and Drosophila [ 4 , 64 , 67 ].…”

Chemical physics in living cells — Using light to visualize and control intracellular signal transduction

“…Optochemical approaches have similarly enabled control of other cytoskeletal elements such as myosins involved in cell contraction. For instance, light-induced bursts of calcium emerging from a photolabile Ca 2+ chelator onitrophenyl EGTA could stimulate cell contraction and consequently tissue morphogenesis via local non-muscle myosin II activation [124].…”

Role of mechanosensitive ion channels in coordinated epithelial cell dynamics in Drosophila

“…In germ-band epithelium Ca 2+ uncaging induced, sudden Ca 2+ bursts trigger cell contractions (Kong et al, 2019). These findings suggest that actomyosin cytoskeleton can be actively reorganized in a Calcium-dependent manner to drive contractility (Fig 1 .12, A).…”

“…During smooth muscle contraction, it is known that myosin II activation is regulated by Ca 2+ /calmodulin complex that activates myosin light chain (MLC) via MLC kinase (Fig 1 .13, B) (Kitazawa et al, 1991). Recent studies in the epithelium, have shown that intracellular Ca 2+ dependent non-muscle myosin II activation could be mediated via Rho kinase activity (Rok) (Kong et al, 2019). Yet the detailed mechanism of how Ca 2+ can regulate actomyosin networks remained elusive so far in the non-muscle cells.…”