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Updated: Nov 7, 2025

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

11.0K

Rac1-PAK1 regulation of Rab11 cycling promotes junction destabilization

Jennifer C Erasmus1, Kasia Smolarczyk1, Helena Brezovjakova1

  • 1National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.

The Journal of Cell Biology
|April 29, 2021
PubMed

Insights

Rac1 GTPase and its effector PAK1 drive cancer cell malignancy by internalizing E-cadherin via micropinocytosis. This process involves Rab GTPase regulation, impacting cell adhesion and motility.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Cancer Research

Background:

  • Rac1 GTPase is hyperactivated in tumors, contributing to malignancy.
  • Rac1's disruption of cell junctions involves its effector PAK1, but mechanisms remain unclear.

Purpose of the Study:

  • To elucidate the mechanisms by which Rac1 and PAK1 regulate E-cadherin and cell junctions.
  • To investigate the role of small GTPases in Rac1-mediated membrane remodeling.

Main Methods:

  • Studied E-cadherin internalization via micropinocytosis in a PAK1-dependent manner.
  • Investigated PAK1 phosphorylation of RabGDIβ and its association with Rab5 and Rab11.
  • Assessed the impact of Rab11 inhibition on E-cadherin levels.

Main Results:

  • E-cadherin is internalized via micropinocytosis dependent on PAK1, without catenin dissociation.
  • PAK1 phosphorylates RabGDIβ, promoting its association with Rab5 and Rab11, and Rab retrieval from membranes.
  • Rac1 activation leads to Rab11 activation, reducing surface E-cadherin levels.

Conclusions:

  • Rac1 activation reduces surface E-cadherin by increasing membrane uptake and counteracting Rab11-dependent delivery.
  • This crosstalk between small GTPases regulates membrane remodeling in epithelial cells.
  • Findings impact understanding of Rac1 and PAK1 roles in cancer progression and cell motility.

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