Simultaneous quantification of cell motility and protein-membrane-association using active contours

Area of Science:

• Cell Biology
• Biophysics
• Microscopy

Background:

• Quantifying dynamic protein localization at the cell membrane is crucial for understanding cell signaling and motility.
• Existing methods often struggle with tracking moving cells and analyzing complex spatio-temporal patterns.

Purpose of the Study:

• To present a novel method for quantifying dynamic fluorescence intensity changes at the cell membrane of moving cells.
• To correlate protein translocation with cell motility parameters in real-time.

Main Methods:

• Utilized an active contour method for precise cell-edge detection and tracking of cell shape and position.
• Developed a technique to follow fluorescence intensities in specific cortical subregions over space and time.
• Applied the method to study the translocation of GFP-tagged CRAC and GRP1 proteins in Dictyostelium cells during chemotaxis.

Main Results:

• Successfully correlated protein translocation (CRAC, GRP1) to the cell membrane with cell motility parameters.
• Quantified differences in the association and dissociation rates of CRAC and GRP1 proteins from the membrane.
• Demonstrated the method's ability to analyze periodic protein translocation to the leading edge in response to cAMP waves, even against noisy backgrounds.

Conclusions:

• The developed method enables robust quantification of dynamic protein distributions at the cell membrane of moving cells.
• Spatio-temporal polar plots offer a powerful tool for visualizing and analyzing protein dynamics within a cell's moving coordinate system.
• This approach facilitates large-scale statistical studies and automated comparisons of complex protein distribution patterns.