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Quantitative Analysis of Cell Edge Dynamics during Cell Spreading
Published on: May 22, 2021
Arp2/3 complex interactions and actin network turnover in lamellipodia
Frank P L Lai1, Malgorzata Szczodrak, Jennifer Block
1Cytoskeleton Dynamics Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
The EMBO Journal
|March 1, 2008
Summary
Actin dynamics in cell migration are clarified. Arp2/3 complex and WAVE complex drive actin nucleation at the lamellipodium tip, separate from cortactin and cofilin activities. This reveals spatial regulation of actin network turnover.
Area of Science:
- Cell Biology
- Biochemistry
- Biophysics
Background:
- Cell migration relies on lamellipodia, dynamic actin-rich structures.
- Actin network turnover in lamellipodia is crucial but not fully understood.
- Arp2/3 complex and WAVE complex are implicated in actin filament nucleation.
Purpose of the Study:
- To investigate the dynamics of actin assembly and disassembly in lamellipodia.
- To elucidate the spatial and temporal roles of key regulatory proteins in actin network turnover.
Main Methods:
- Fluorescence Recovery After Photobleaching (FRAP) was used to study protein dynamics.
- A novel data analysis method was developed to interpret FRAP data.
- The turnover of actin, Arp2/3 complex, WAVE complex, capping protein, cortactin, and ADF/cofilin was measured.
Main Results:
- Arp2/3 complex and actin incorporation occurred exclusively at the lamellipodium tip, coinciding with WAVE complex.
- Capping protein turnover was similar to actin but restricted to the tip.
- Cortactin and ADF/cofilin showed rapid exchange throughout the lamellipodium, uncoupled from tip nucleation.
Conclusions:
- Actin nucleation by Arp2/3 and WAVE complexes at the tip is spatially segregated from cortactin and cofilin activities.
- Actin network turnover is regulated by distinct roles of capping protein at the tip and cofilin in the mesh.
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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...
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In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
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Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
01:42Actin Polymerization
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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 actin...
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