Live Cell Force Dynamics – Do Cell Membranes Support or Resist Tension Propagation?

What are the rules of membrane tension propagation in cells? For proper function, cells need to link short-range biochemical signaling events with long-range integration of cell physiology. Forces transmitted through the plasma membrane are thought to serve as this globally integrator. However, conflicting observations have left the field divided as to whether cell membranes support or resist tension propagation. This discrepancy likely originates from the use of exogenous forces that may not accurately mimic endogenous forces. We overcome this complication by leveraging optogenetics to directly control localized actin-based protrusions or actomyosin contractions while simultaneously monitoring the propagation of membrane tension using dual-trap optical tweezers. Surprisingly, actin-driven protrusions and actomyosin contractions both elicit rapid global membrane tension propagation, whereas forces applied to cell membranes alone do not. We present a simple unifying mechanical model in which mechanical forces that engage the actin cortex drive rapid, robust membrane tension propagation through long-range membrane flows.

Key Learning Points:

• Gain a comprehensive understanding of how mechanical forces transmitted through the plasma membrane can integrate cell physiology across different regions of the cell
• Learn about the critical role of actin-driven protrusions and actomyosin contractions in eliciting rapid and robust global membrane tension propagation
• Learn how the C-Trap technique can be used in studying the dynamic behaviors of membrane tension and their implications in cell biology