Mapping of adherens junction components using microscopic resonance energy transfer imaging

Area of Science:

• Cell biology
• Biophysics
• Microscopy

Background:

• Cell adhesions are crucial for tissue integrity and cell signaling.
• Understanding the molecular organization of cytoskeletal proteins within adhesions is essential.

Purpose of the Study:

• To map the proximity of cytoskeletal proteins in cell adhesions using quantitative resonance energy transfer (RET) microscopy.
• To investigate the spatial inter-relationships of vinculin, talin, alpha-actinin, and actin.

Main Methods:

• Developed a high-resolution quantitative microscopic system with a stable field illuminator, computer-controlled filter wheels, and a sensitive CCD camera.
• Applied RET imaging to double-labeled cultured chick lens cells using fluorescent antibodies and phalloidin.
• Acquired and processed RET images to quantify protein proximity.

Main Results:

• High local densities of vinculin (15%), talin (12%), and F-actin (10%) were observed in focal adhesions.
• Alpha-actinin showed low RET values (<1%) when labeled with itself but high values (13-15%) when paired with actin.
• Vinculin and talin formed segregated clusters, distinct from homogeneous interspersion.

Conclusions:

• Quantitative RET microscopy provides high-resolution insights into molecular organization within cell adhesions.
• Vinculin and talin form distinct molecular clusters, while alpha-actinin exhibits close interaction with actin.
• The study elucidates the subcellular molecular organization of adherens-type junctions.