Dynamic and Biphasic Regulation of Cell Migration by Ras.

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Ras proteins are traditionally viewed as positive regulators of cell proliferation and are key therapeutic targets.
• Emerging evidence suggests a more complex role for Ras in cell migration, where reduced activity can paradoxically enhance movement.

Purpose of the Study:

• To elucidate the nuanced role of Ras signaling in cell migration dynamics.
• To investigate the immediate, non-transcriptional effects of Ras activity modulation on cell movement using optogenetics.

Main Methods:

• Systematic modulation of Ras activity using RasGEF (Ras guanine nucleotide exchange factor) and RasGAP (Ras GTPase-activating protein) proteins.
• Optogenetic control to rapidly induce local or global recruitment of RasGEFs and RasGAPs to the plasma membrane.
• Assessment of cell migration dynamics, protrusion formation, cell spreading, and cortical tension measurements.

Main Results:

• Local RasGEF recruitment promoted protrusions and guided migration, while global recruitment halted migration by causing cell spreading.
• Local RasGAP recruitment suppressed protrusions and induced cell retraction, whereas global recruitment inhibited migration or maintained polarity.
• RasGEFs generally increased cortical tension, while RasGAPs decreased it, revealing a biphasic relationship between Ras activity and cellular dynamics.

Conclusions:

• Optimal Ras activity and cortical tension are critical for efficient cell migration.
• The findings challenge the traditional view of Ras as solely a positive regulator, demonstrating a biphasic impact on migration independent of transcriptional changes.
• Targeting Ras in cancer therapy requires consideration of the cell's initial state to modulate Ras activity effectively and avoid promoting metastasis.