Rapid Assembly of a Polar Network Architecture Drives Efficient Actomyosin Contractility

Actin network architecture and dynamics play a central role in cell contractility tissue morphogenesis. Pulsed contractions driven by RhoA represent generic mode of actomyosin contractility, but the mechanisms underlying (1) how their specific emerges, (2) this supports contractile function network, remain unclear. Here, we combine quantitative microscopy, single-molecule imaging, numerical simulations simple mathematical modelling, to explore dynamic pulsed contraction. We show that during contractions, two subpopulations formins are recruited from cytoplasm bind surface early C. elegans embryo: formins, functionally inactive population, elongating which actively participate actin filaments elongation. Focusing on formin pulses, minority precede kinetic compatible with capturing rapidly saturating barbed ends available for filament then these assemble polar actin, pointing out pulse, rather than mechanical control architecture. Finally, our demonstrate geometry favors rapid Our results thus saturate convert local, biochemical gradient activity into architecture, thereby driving efficient an important evolutionary feature metazoan embryonic cycles.