Related Experiment Video
Updated: Jun 25, 2025
06:54
A Time-Efficient Fluorescence Spectroscopy-Based Assay for Evaluating Actin Polymerization Status in Rodent and Human Brain Tissues
Published on: June 3, 2021
4.2K
Actin polymerization and longitudinal actin fibers in axon initial segment plasticity
David Micinski1,2, Pirta Hotulainen1,3
1Minerva Foundation Institute for Medical Research, Helsinki, Finland.
Frontiers in Molecular Neuroscience
|May 27, 2024
Summary
Neurons regulate excitability through axon initial segment (AIS) plasticity. This study reveals that actin cytoskeleton reorganization, particularly formin-mediated actin polymerization, is crucial for AIS plasticity.
Area of Science:
- Neuroscience
- Cell Biology
Background:
- The axon initial segment (AIS) is critical for neuronal polarity and action potential generation.
- AIS plasticity, involving changes in its size or position, is a homeostatic mechanism regulating neuronal excitability.
- The molecular mechanisms underlying AIS plasticity remain largely unknown.
Purpose of the Study:
- To investigate the role of the actin cytoskeleton in AIS plasticity.
- To elucidate the cellular and molecular mechanisms driving AIS plasticity.
Main Methods:
- Utilized 3D structured illumination microscopy (3D-SIM) to analyze AIS actin cytoskeleton dynamics.
- Investigated the requirement of actin polymerization and specific formins in AIS plasticity.
Main Results:
- Observed a transient increase in longitudinal actin fibers within the AIS 3 hours after plasticity induction.
- Demonstrated that actin polymerization, specifically formin-mediated, is essential for AIS plasticity.
- Identified Daam1, a formin protein, localizing to the ends of longitudinal actin fibers.
Conclusions:
- Active reorganization of the actin cytoskeleton is a key requirement for AIS plasticity.
- Formin proteins, such as Daam1, play a significant role in the structural changes underlying AIS plasticity.
Related Concept Videos
01:42Actin Polymerization
6.5K
Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase.
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight...
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight...
6.5K
01:13Actin Polymerization and Cell Motility
5.2K
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....
5.2K
01:14Generation of Straight or Branched Actin Filaments
2.9K
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...
2.9K
01:11Formation of Higher-order Actin Filaments
3.0K
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...
The high-order actin...
3.0K
01:19Actin Filament Depolymerization
3.1K
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...
3.1K
01:31Mechanism of Lamellipodia Formation
2.5K
Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
2.5K