Anillin mediates unilateral furrowing during cytokinesis by limiting RhoA binding to its effectors

Area of Science:

• Cell Biology
• Developmental Biology
• Molecular Biology

Background:

• Unilateral furrow ingression involves asymmetric cell division, with one side of the cytokinetic ring leading.
• Anillin is known to regulate unilateral furrowing in C. elegans by limiting myosin II accumulation.

Purpose of the Study:

• To investigate the precise mechanism by which anillin mediates unilateral furrowing.
• To determine if anillin's role extends beyond myosin II regulation and explore its interaction with RhoA effectors.

Main Methods:

• Biochemical assays to study anillin-RhoA interactions.
• Analysis of anillin's RhoA-binding domain (RBD) and linker region.
• Investigating RhoA effector accumulation at the leading and lagging edges of the cytokinetic ring.

Main Results:

• Anillin inhibits not only myosin II but also other RhoA effectors by directly binding and blocking the RhoA effector site.
• The interaction between anillin's RBD and active RhoA is modulated by a disordered linker region.
• Differential regulation of this interaction at the leading and lagging edges results in asymmetric RhoA signaling and myosin II accumulation.

Conclusions:

• A novel RhoA GEF- and GAP-independent mechanism is identified where anillin limits RhoA activity by occupying its effector-binding site.
• Spatial control of anillin's inhibitory function on RhoA signaling is essential for unilateral furrow ingression.
• This anillin-mediated regulation contributes significantly to the overall process of animal development.