Actomyosin contractility controls cell surface area of oligodendrocytes

Area of Science:

• Neuroscience
• Cell Biology
• Biophysics

Background:

• Oligodendrocytes are crucial for myelin sheath formation in the central nervous system (CNS).
• Myelination involves extensive expansion and wrapping of the oligodendrocyte plasma membrane around axons.
• The regulatory mechanisms controlling this membrane expansion remain incompletely understood.

Purpose of the Study:

• To investigate the factors controlling oligodendrocyte plasma membrane expansion.
• To determine the role of actomyosin contractility and extracellular matrix properties in cell surface area regulation.
• To explore the impact of chondroitin sulfate proteoglycans (CSPGs) on oligodendrocyte membrane extension.

Main Methods:

• Assessment of cell surface area in relation to actomyosin contractility.
• Manipulation of the physical properties of the supporting matrix.
• Treatment with actomyosin contractility inhibitors and RNA interference (RNAi) for myosin II.
• Measurement of fluid-phase endocytosis rates.

Main Results:

• Oligodendrocyte cell surface area is dependent on actomyosin contractility and modulated by matrix biophysical properties.
• Chondroitin sulfate proteoglycans (CSPGs) inhibit oligodendrocyte cell surface spreading.
• Inhibitory effects of CSPGs on plasma membrane extension are overcome by actomyosin contractility inhibitors and myosin II knockdown.
• Reductions in plasma membrane area correlate with altered fluid-phase endocytosis rates.

Conclusions:

• A novel link exists between endocytosis, cell surface extension, and actomyosin contractility in oligodendrocytes.
• These findings offer new strategies for promoting oligodendrocyte morphological differentiation in non-permissive CNS environments.
• Understanding these mechanisms is key for therapeutic approaches targeting myelin repair and regeneration.