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ADF/cofilin controls cell polarity during fibroblast migration
Helen R Dawe1, Laurie S Minamide, James R Bamburg
1MRC-Laboratory for Molecular Cell Biology and Department of Biology, University College London, London WC1E 6BT, UK.
Current Biology : CB
|February 8, 2003
Summary
ADF/cofilin (AC) proteins are crucial for cell migration. Maintaining active, nonphosphorylated AC in the lamellipodium is essential for polarized cell protrusion during fibroblast migration.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Cell migration requires morphological polarity and a single, directional lamellipodium protrusion.
- Actin filament disassembly is critical for lamellipodium protrusion during fibroblast migration.
- ADF/cofilin (AC) proteins catalyze actin filament disassembly.
Purpose of the Study:
- To investigate the role of ADF/cofilin (AC) in polarized lamellipodium protrusion in migrating fibroblasts.
- To determine the spatial distribution of active and inactive AC in migrating cells.
- To understand how AC activity influences cell polarity.
Main Methods:
- Comparison of spatial distribution of AC and phosphorylated AC (pAC) in migrating fibroblasts.
- Overexpression of constitutively active LIM kinase 1 to increase pAC levels.
- Coexpression of active, nonphosphorylatable Xenopus AC (CA XAC) or pseudophosphorylated XAC to assess rescue or polarity disruption.
Main Results:
- Active AC, but not pAC, localized to the lamellipodium.
- Overexpression of active LIM kinase 1 abolished cell polarity in 87% of cells, replacing the single lamellipodium with multiple nonpolarized ones.
- Multiple lamellipodia stained positive for pAC.
- Cell polarity was restored by coexpressing CA XAC with active LIM kinase.
- Overexpression of pseudophosphorylated XAC alone also abolished cell polarity.
Conclusions:
- Local maintenance of ADF/cofilin in its active, nonphosphorylated state within the lamellipodium is necessary for maintaining polarized protrusion during cell migration.
- Phosphorylation of ADF/cofilin inhibits its function and disrupts cell polarity.
- ADF/cofilin activity is a key regulator of cell migration polarity.