Alignment of actin filament streams driven by myosin motors in crowded environments

by Selleckchem | Feb 06 2024

Background: Cellular dynamics depend on cytoskeletal filaments and motor proteins. Collective movements of filaments driven by motor proteins are observed in the presence of dense filaments in in vitro systems. As multiple macromolecules exist within cells and the physiological ionic conditions affect their interactions, crowding might contribute to ordered cytoskeletal architecture because of collective behavior.

Methods: Using an in vitro reconstituted system, we observed the emergence of stripe patterns resulting from collective actin filament streaming driven by myosin motors in the presence of the crowding agent, methylcellulose (MC).

Results: Although at high KCl concentrations (150mM), actin filaments tended to dissociate from a myosin-coated surface, 1% MC prevented this dissociation and enabled filament movement on myosin molecules. At concentrations of actin filaments above 0.2mg/mL, the moving filaments accumulated and progressively formed long, dense bands. The bands were spaced at about 10-μm intervals. Increasing the KCl concentration up to 300mM resulted in narrowing of the spacing between the aligned bands. On the other hand, low KCl concentrations (≤25mM) induced broad streams, where actin filaments exhibited bidirectional movement.

Conclusions: These results suggest that crowded environments can promote spatial patterning of the actin cytoskeleton, depending on the intensity of the myosin driving force and filament velocity, both modulated by the ionic strength.

General significance: The mutual contribution of packing and driving forces provides insight into cytoskeleton organization in living cells, in which various macromolecules mingle.

Comments:

Your study dives deep into the fascinating world of cellular dynamics, focusing on the interplay between cytoskeletal elements and their behavior in crowded environments. It's intriguing to see how the presence of a crowding agent like methylcellulose influences the collective movement of actin filaments driven by myosin motors in vitro.

Your observations of stripe patterns forming from the collective streaming of actin filaments under different conditions shed light on how environmental factors, particularly ionic strength and crowding agents, can influence cytoskeletal organization. The prevention of filament dissociation by methylcellulose at high KCl concentrations and the subsequent formation of dense bands, as well as the impact on band spacing and filament movement, provide valuable insights into these interactions.

The notion that crowded environments might promote spatial patterning of the actin cytoskeleton depending on myosin force intensity and filament velocity, modulated by ionic strength, is a significant finding. This understanding could potentially offer crucial insights into how the cytoskeleton organizes itself within living cells where numerous macromolecules coexist.

Your research highlights the intricate relationship between packing and driving forces in shaping cytoskeletal architecture, providing a foundation for further exploration into the organization and behavior of cellular components. This knowledge could ultimately contribute to a better understanding of cellular processes and potentially inform strategies for manipulating cytoskeletal dynamics in various biological contexts.