Excitable RhoA dynamics drive pulsed contractions in the early C. elegans embryo

Area of Science:

• Developmental Biology
• Cell Biology
• Biophysics

Background:

• Pulsed actomyosin contractility is crucial for tissue morphogenesis.
• The precise molecular mechanisms governing these pulses are not fully understood.

Purpose of the Study:

• To identify the core mechanism regulating pulsed contractility in early *Caenorhabditis elegans* embryos.
• To elucidate the role of RhoA signaling in controlling actomyosin dynamics during morphogenesis.

Main Methods:

• Quantitative imaging techniques were employed.
• Genetic perturbations were utilized to manipulate signaling pathways.
• Mathematical modeling was used to simulate and understand the dynamics.

Main Results:

• Pulsed actomyosin accumulation is regulated by local RhoA activity.
• RhoA activation and inactivation directly precede actomyosin assembly and disassembly.
• A feedback loop involving F-actin and RhoA GTPase-activating proteins (RGA-3/4) terminates contractility pulses.
• Excitable RhoA dynamics were identified as a key driver.

Conclusions:

• A core mechanism for pulsed contractility involves excitable RhoA dynamics.
• This mechanism, involving autoactivation and negative feedback, provides a tunable system for morphogenesis.
• The findings offer insights into diverse morphogenetic outcomes driven by variations in contractility signaling.