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Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles
Published on: May 5, 2022
Compressive force generation by a bundle of living biofilaments
Sanoop Ramachandran1, Jean-Paul Ryckaert
1Physique des Polymères, Université Libre de Bruxelles, Campus Plaine, CP 223, B-1050 Brussels, Belgium.
The Journal of Chemical Physics
|August 17, 2013
Summary
This study simulates self-assembling filaments to understand forces in structures like filopodia. Force depends on monomer density, revealing insights into non-ideal and confinement effects in biological systems.
Area of Science:
- Biophysics
- Computational Biology
- Materials Science
Background:
- Filopodia, crucial for cell movement and sensing, contain bundles of actin filaments.
- Understanding the forces exerted by these filament bundles is key to cell mechanics.
- Previous models often simplify filament interactions and confinement effects.
Purpose of the Study:
- To investigate compressional forces of self-assembling filament bundles on surfaces.
- To model actin bundle-like structures using particulate molecular dynamics simulations.
- To analyze non-ideal and confinement effects on filament bundle behavior.
Main Methods:
- Particulate molecular dynamics simulations of grafted, self-assembling filaments.
- Simulating chemical equilibrium between filaments and monomers.
- Analyzing filament size distribution and force-displacement relationships.
Main Results:
- Filament force is a function of rescaled free monomer density.
- Filament size distribution follows an exponential pattern.
- Non-ideal and confinement effects were successfully disentangled.
Conclusions:
- The study provides a model for forces in biological filament bundles.
- Monomer density is a critical factor determining bundle force.
- Simulation results offer a basis for refining models of cellular structures.
Related Concept Videos
01:14Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
01:39Mechanism of Filopodia Formation
Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
01:10The Role of Actin and Myosin in Non-muscle Cells
Actin and myosin or actomyosin filaments also play a significant role in cells other than those involved in muscle contraction (which occurs within the sarcomere of muscle cells). The mechanism of non-muscle cell contractile bundles was first observed in Dictyostelium and Acanthamoeba. In non-muscle cells, two bundles are commonly found: stress fibers and actomyosin adherence belts. These contractile bundles are smaller and less organized than the ones found in muscle cells. They are held...
01:11Formation of Higher-order Actin Filaments
The polymerization of G-actin monomers into filamentous F-actin is a multi-step process. Once the F-actins are formed, they can bundle together in different arrangements to form higher-order networks and regulate cellular functions. Common examples include the formation of lamellipodia and filopodia at the cell's leading edge by actin reorganization in a migrating cell. The microvilli on the brush border epithelial cells are also formed through the F-actin network.
The high-order actin networks...
The high-order actin networks...
01:13Cell-matrix's Response to Mechanical Forces
In animal cells, the extracellular matrix allows cells within tissues to withstand external stresses and transmits signals from the outside of the cell to the inside. The extracellular matrix is extensive, and its composition varies between different types of tissues. For example, the reticular fibers and ground substance make up the ECM in loose connective tissue, while collagen and bone minerals make up the ECM of bone tissue.
Anchoring junctions mechanically attach a cell to the...
Anchoring junctions mechanically attach a cell to the...
01:13Actin Polymerization and Cell Motility
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.