Still and rotating myosin clusters determine cytokinetic ring constriction.

Area of Science:

• Cell Biology
• Biophysics
• Molecular Motors

Background:

• The cytokinetic ring, composed of actin and myosin, drives cell division.
• Current models assume ring organization resembles muscle sarcomeres, but evidence is lacking.

Purpose of the Study:

• To investigate the internal organization and dynamics of cytokinetic rings.
• To compare ring organization in different cell types and contrast with sarcomeric models.

Main Methods:

• Utilized micro-cavities to orient cytokinetic rings in single focal planes.
• Observed myosin distribution and dynamics during ring constriction.
• Performed theoretical analysis of acto-myosin self-organization and stress.

Main Results:

• Mammalian cells show a transition from homogeneous myosin distribution to clustered patterns during constriction.
• Fission yeast exhibits rotating myosin clusters before and during constriction.
• Theoretical models confirm self-organization and reveal distinct stress patterns.

Conclusions:

• Cytokinetic ring organization is cell-type specific and differs from sarcomeres.
• Observed patterns arise from acto-myosin self-organization.
• Distinct ring dynamics suggest functional roles in contraction (mammalian) and transport (yeast) for morphogenesis.