Expansion of supra-cellular contractile rings induces cell sheet folding

Fu-Lai Wen^1*

¹International Center for Wound Repair and Regeneration, National Cheng Kung University, Tainan, Taiwan

* Presenter:Fu-Lai Wen, email:fulai@gs.ncku.edu.tw

The folding of epithelial cell sheets is a fundamental process that sculpts tissues and organs into their proper shapes required for normal physiological functions. In the absence of detailed biochemical regulations, the epithelial sheet folding may simply proceed through buckling due to mechanical compression arising extrinsically from the surroundings or intrinsically within the sheets. Previous studies hypothesized that formation of an expanding supracellular actomyosin ring within epithelial sheets could result in compression that ultimately leads to epithelial folding during tracheal development in the Drosophila (fruit fly) embryo. However, the exact mechanism remains unclear. Using a vertex-based mechanical model, here I show that expansion of supracellular contractile rings can induce a buckling instability via lowering the buckling threshold, leading to a robust cell sheet folding against fluctuations in the ring properties such as ring numbers and tensions. In particular, while elevation of contractile strength is not necessary for fold formation, the folding process is found to depend on the contractile strength of rings. These findings provide fruitful insights into how expanding supracellular actomyosin rings in epithelial sheets mediate the entire cell sheet morphogenesis.

Keywords: buckling instability, morphogenesis, mechanobiology, biophysics