Scrib controls Cdc42 localization and activity to promote cell polarization during astrocyte migration

Area of Science:

• Cell Biology
• Molecular Biology
• Developmental Biology

Background:

• Mammalian Scribble (Scrib) is vital for cell polarization in epithelial and neuronal cells.
• Scrib's role in cell migration remains unclear, though it interacts with betaPIX, a guanine nucleotide exchange factor for Rac and Cdc42.
• Cdc42 is essential for cell polarity and migration, particularly in astrocytes.

Purpose of the Study:

• To investigate the function of Scrib in polarized cell migration using an astrocyte scratch-induced migration assay.
• To elucidate the molecular mechanisms by which Scrib influences cell polarity and migration.

Main Methods:

• Utilized siRNA to deplete Scrib and dominant-negative constructs to inhibit Scrib function.
• Employed a scratch-induced polarized migration assay in astrocytes.
• Investigated protein interactions and localization using co-localization studies and perturbation experiments.

Main Results:

• Scrib depletion or inhibition impaired astrocyte polarization, protrusion formation, and cytoskeletal reorientation.
• Scrib interacts and co-localizes with betaPIX at the leading edge of migrating astrocytes.
• Scrib and betaPIX are essential for Cdc42 activation and localization, controlling downstream pathways like APC and Dlg1 recruitment.

Conclusions:

• Scrib plays a critical role in establishing cell polarity during migration.
• Scrib interacts with betaPIX to regulate Cdc42 localization and activation.
• This interaction controls Cdc42-dependent pathways essential for cell orientation and migration.