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RhoC GTPase Activation Assay
Published on: August 22, 2010
Cadherin engagement regulates Rho family GTPases
N K Noren1, C M Niessen, B M Gumbiner
1Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599-7090, USA. Nicole_Noren@med.unc.edu
The Journal of Biological Chemistry
|July 18, 2001
Summary
Cadherin-mediated cell adhesion regulates Rho GTPase activity. Cell-cell junction formation increases Rac1 and Cdc42 activity while decreasing RhoA activity, impacting actin cytoskeleton reorganization.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell-cell adherens junctions are crucial for tissue integrity and are regulated by cadherins.
- Cadherin-mediated adhesion reorganizes the actin cytoskeleton, a process influenced by Rho family GTPases.
- Understanding the interplay between cadherins and Rho GTPases (RhoA, Rac1, Cdc42) is key to cell adhesion dynamics.
Purpose of the Study:
- To investigate if cadherin-mediated adhesion regulates the activity of RhoA, Rac1, and Cdc42.
- To elucidate the role of cadherin engagement in Rho GTPase signaling pathways.
- To determine the contribution of the cadherin cytoplasmic domain in mediating these signaling events.
Main Methods:
- Comparison of Rho GTPase activity in low-density versus confluent epithelial cells.
- Calcium switch assay to induce and inhibit cell-cell junction assembly.
- Utilized Chinese hamster ovary (CHO) cells expressing C-cadherin on immobilized C-cadherin domains to mimic cadherin engagement without cell-cell contact.
- Investigated the role of the C-cadherin cytoplasmic domain by using deletion mutants.
Main Results:
- Confluent cells showed elevated Rac1 and Cdc42 activity and decreased RhoA activity compared to low-density cells.
- Induction of cell-cell junctions increased Rac1 activity, which was blocked by E-cadherin function-blocking antibodies.
- Direct cadherin engagement increased Rac1 activity and inhibited RhoA activity, without affecting Cdc42 activity.
- Deletion of the C-cadherin cytoplasmic domain abolished the observed effects on Rho GTPase activity.
Conclusions:
- Cadherin-mediated cell-cell adhesion dynamically regulates Rho GTPase activity.
- Rac1 and Cdc42 activities are upregulated, while RhoA activity is downregulated during junction formation.
- The cytoplasmic domain of cadherins is essential for mediating these Rho GTPase regulatory effects.
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