alpha4 beta1-Integrin regulates directionally persistent cell migration in response to shear flow stimulation.

Area of Science:

• Cell Biology
• Biochemistry
• Biophysics

Background:

• Alpha(4)beta(1)-integrin is crucial for cell migration in vivo.
• Previous studies indicated its role in regulating cell polarity via phosphorylation-dependent inhibition of paxillin binding.

Purpose of the Study:

• To elucidate the complex mechanism by which alpha(4)beta(1)-integrin regulates directionally persistent cell migration.
• To investigate the roles of alpha(4)-integrin phosphorylation and paxillin binding in cell migration dynamics.

Main Methods:

• Ectopic expression of alpha(4)beta(1)-integrin in CHO cells.
• Stimulation of cell migration using shear flow.
• Analysis of cell morphology, lamellipodia formation, and trailing edge dynamics.
• Mutational analysis of alpha(4)-integrin phosphorylation and paxillin binding sites.

Main Results:

• Alpha(4)beta(1)-integrin binding to fibronectin CS-1 is necessary and sufficient for persistent migration under shear flow.
• Disrupting paxillin binding enhanced fanning activity, while disrupting phosphorylation inhibited it.
• Phosphorylation-disrupting mutations led to long trailing tails, indicating a role in retraction independent of paxillin.
• Stable polarity and directional persistence were perturbed by combined mutations, not single ones, suggesting compensatory roles.

Conclusions:

• Alpha(4)beta(1)-integrin regulates cell migration through cooperative and independent pathways involving phosphorylation and paxillin binding.
• Alpha(4)-integrin phosphorylation is essential for trailing edge retraction, independent of paxillin binding.
• Paxillin binding and phosphorylation act in a compensatory manner to ensure stable cell polarity and directional persistence.