Novel cytokinetic ring components drive negative feedback in cortical contractility.

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Actomyosin contractility is crucial for cell shape changes, particularly during cytokinesis.
• While positive regulators of contractility are known, negative regulators and mechanical brakes remain less understood.
• The small GTPase RhoA is a key activator of cortical actomyosin contractility.

Purpose of the Study:

• To investigate the roles of GCK-1 and CCM-3 in regulating actomyosin contractility.
• To elucidate the mechanism by which GCK-1 and CCM-3 modulate RhoA activity.
• To understand the implications for cell division and related pathologies.

Main Methods:

• Recruitment assays of GCK-1 and CCM-3 to the cytokinetic ring.
• Analysis of RhoA activity and cytoskeletal component localization upon GCK-1 or CCM-3 depletion.
• Measurement of cytokinetic furrowing speed and zygote polarization dynamics.

Main Results:

• GCK-1 and CCM-3 are recruited to the cytokinetic ring by active RhoA and anillin.
• Depletion of GCK-1 or CCM-3 leads to increased RhoA activity, anillin, and nonmuscle myosin II in the ring.
• GCK-1/CCM-3 depletion accelerates furrowing and alters RhoA activity during zygote polarization.

Conclusions:

• GCK-1 and CCM-3 act as negative regulators of cortical actomyosin contractility through a feedback loop involving RhoA.
• These findings reveal a novel mechanism for controlling cell contractility.
• The study provides insights into the molecular basis of cerebral cavernous malformation pathologies.