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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
Actin filaments as tension sensors
Vitold E Galkin1, Albina Orlova, Edward H Egelman
1Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA.
Current Biology : CB
|February 11, 2012
Summary
Actin filaments (F-actin) are dynamic tension sensors, not just structural components. This finding explains actin
Area of Science:
- Mechanobiology
- Cellular mechanics
- Biophysics
Background:
- Mechanobiology studies how cells sense and respond to mechanical forces.
- The cytoskeleton, particularly actin filaments (F-actin), is crucial for cell structure, motility, and force generation.
- F-actin dynamics (polymerization/depolymerization) are well-established, but its role in force sensing is less understood.
Purpose of the Study:
- To investigate the potential role of F-actin as a dynamic tension sensor.
- To explore how F-actin's tension-sensing ability contributes to its conserved sequence and function.
Main Methods:
- Review of recent findings in mechanobiology and F-actin research.
- Analysis of actin's structural and functional properties in relation to mechanical forces.
Main Results:
- Emerging evidence suggests F-actin functions as a dynamic tension sensor.
- This tension-sensing capability may explain actin's high sequence conservation.
- F-actin's role in mechanosensitivity is highlighted, impacting structures like stress fibers and sarcomeres.
Conclusions:
- F-actin's dynamic tension-sensing property is a key aspect of its function.
- Understanding this property provides insights into cellular mechanotransduction and evolution.
- This perspective reframes F-actin's role beyond simple polymerization dynamics.
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01:14Generation of Straight or Branched Actin Filaments
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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
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01:26Tension Response at Adherens Junctions
The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
α-Catenin as a Mechanosensory Protein
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α-Catenin as a Mechanosensory Protein
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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...
01:10The 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...
01:13Actin 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.
01:12Adaptability of Cytoskeletal Filaments
The cytoskeleton is a complex dynamic structure performing varied functions based on cellular requirements. The adaptability of the individual filaments in the cytoskeleton determines their ability to perform various functions within the cell. It can undergo rapid reorganization during processes like cell division or remain stable for several hours as in the interphase. The adaptability of these filaments depends on stringent regulatory mechanisms. The microfilament and microtubules of the...