Related Experiment Video
Updated: May 15, 2026

Measuring Cell-Edge Protrusion Dynamics during Spreading using Live-Cell Microscopy
Published on: November 1, 2021
PAK-PIX interactions regulate adhesion dynamics and membrane protrusion to control neurite outgrowth
Miguel Santiago-Medina1, Kelly A Gregus, Timothy M Gomez
1Department of Neuroscience, Neuroscience Training Program, University of Wisconsin, Madison, WI 53706, USA.
Abstract:
The roles of P21-activated kinase (PAK) in the regulation of axon outgrowth downstream of extracellular matrix (ECM) proteins are poorly understood. Here we show that PAK1-3 and PIX are expressed in the developing spinal cord and differentially localize to point contacts and filopodial tips within motile growth cones. Using a specific interfering peptide called PAK18, we found that axon outgrowth is robustly stimulated on laminin by partial inhibition of PAK-PIX interactions and PAK function, whereas complete inhibition of PAK function stalls axon outgrowth. Furthermore, modest inhibition of PAK-PIX stimulates the assembly and turnover of growth cone point contacts, whereas strong inhibition over-stabilizes adhesions. Point mutations within PAK confirm the importance of PIX binding. Together our data suggest that regulation of PAK-PIX interactions in growth cones controls neurite outgrowth by influencing the activity of several important mediators of actin filament polymerization and retrograde flow, as well as integrin-dependent adhesion to laminin.
Related Concept Videos
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Mechanism of Lamellipodia Formation
Mechanism of Filopodia Formation
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Intracellular Signaling Affects Focal Adhesions
Some...
Actin Polymerization and Cell Motility
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Types of Membrane Protrusions
The microvilli, an example of stable protrusions, are finger-like projections with a...

