Focal adhesion
In
Focal adhesions serve as the mechanical linkages to the ECM, and as a biochemical signaling hub to concentrate and direct numerous signaling proteins at sites of integrin binding and clustering.
Structure and function
Focal adhesions are integrin-containing, multi-protein structures that form mechanical links between intracellular actin bundles and the extracellular substrate in many cell types. Focal adhesions are large, dynamic
Morphology
Connection between focal adhesions and proteins of the
Adhesion dynamics with migrating cells
The dynamic assembly and disassembly of focal adhesions plays a central role in
Actin retrograde flow
The assembly of nascent focal adhesions is highly dependent on the process of retrograde actin flow. This is the phenomenon in a migrating cell where actin filaments polymerize at the leading edge and flow back towards the cell body. This is the source of traction required for migration; the focal adhesion acts as a molecular clutch when it tethers to the ECM and impedes the retrograde movement of actin, thus generating the pulling (traction) force at the site of the adhesion that is necessary for the cell to move forward. This traction can be visualized with traction force microscopy. A common metaphor to explain actin retrograde flow is a large number of people being washed downriver, and as they do so, some of them hang on to rocks and branches along the bank to stop their downriver motion. Thus, a pulling force is generated onto the rock or branch that they are hanging on to. These forces are necessary for the successful assembly, growth, and maturation of focal adhesions.[7]
Natural biomechanical sensor
Extracellular mechanical forces, which are exerted through focal adhesions, can activate
The relationship between forces on focal adhesions and their compositional maturation, however, remains unclear. For instance, preventing focal adhesion maturation by inhibiting myosin activity or stress fiber assembly does not prevent forces sustained by focal adhesions, nor does it prevent cells from migrating.[10][11] Thus force propagation through focal adhesions may not be sensed directly by cells at all time and force scales.
Their role in mechanosensing is important for durotaxis.
See also
References
External links
- MBInfo - Focal Adhesion
- MBInfo - Focal Adhesion Assembly
- MBInfo - Regulation of Focal Adhesion Assembly
- AdhesomeFAnetwork Archived 2022-07-31 at the Wayback Machine Database with all known focal adhesion proteins and their biochemical interactions
- Intercellular Connections
- Zaidel-Bar Cell Adhesion Lab