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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 depolymerization factor/cofilin activation regulates actin polymerization and tension development in canine
Rong Zhao1, Liping Du, Youliang Huang
1Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
The Journal of Biological Chemistry
|October 30, 2008
Summary
Actin dynamics are crucial for airway smooth muscle contraction. This study shows that activating actin-depolymerizing factor (ADF)/cofilin is essential for actin polymerization and tension development during muscle contraction.
Area of Science:
- Cell Biology
- Muscle Physiology
- Biochemistry
Background:
- Contractile activation in airway smooth muscle stimulates actin polymerization, which is vital for tension development.
- Actin-depolymerizing factor (ADF) and cofilin are key proteins regulating actin dynamics through F-actin severing upon activation by dephosphorylation.
Purpose of the Study:
- To investigate the role of ADF/cofilin activation in regulating actin dynamics and tension development during airway smooth muscle contraction.
- To determine the signaling pathway involved in ADF/cofilin activation in response to contractile stimuli.
Main Methods:
- Two-dimensional gel electrophoresis to assess ADF/cofilin phosphorylation levels in canine tracheal smooth muscle.
- Expression of cofilin mutants (cofilin S3E) to inhibit endogenous ADF/cofilin dephosphorylation.
- Measurement of tension development and myosin light chain phosphorylation in response to acetylcholine (ACh) and potassium depolarization.
Main Results:
- Approximately 40% of ADF/cofilin was phosphorylated in unstimulated tissues, decreasing with contractile stimulation (ACh or K+ depolarization), indicating ADF/cofilin activation.
- Expression of cofilin S3E blocked ADF/cofilin dephosphorylation and ACh-induced actin polymerization, and depressed tension development without affecting myosin light chain phosphorylation.
- ACh-induced ADF/cofilin dephosphorylation was dependent on calcineurin (PP2B) activation.
Conclusions:
- ADF/cofilin activation is regulated by contractile stimulation in tracheal smooth muscle.
- Cofilin activation is a necessary step for actin polymerization and subsequent tension development in response to contractile stimuli.
- The Ca2+-dependent calcineurin pathway mediates ADF/cofilin dephosphorylation during smooth muscle contraction.
Related Concept Videos
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Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
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Arp2/3 Complex
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Arp2/3 Complex
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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.
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01:11Formation of Higher-order Actin Filaments
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The high-order actin networks...
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01:18Actin Treadmilling
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