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Updated: Jul 2, 2026

Development and Application of Rapamycin-regulated Tyrosine Phosphatases
Published on: September 6, 2024
E-cadherin dis-engagement activates the Rap1 GTPase
Sirisha Asuri1, Jingliang Yan, Nivanka C Paranavitana
1Department of Biochemistry and Molecular Biology, Indiana University School of Medicine and Walther Oncology Center, Indianapolis, Indiana 46202, USA.
The Ras-related Rap1 GTPase strengthens E-cadherin junctions, aiding cell-cell contact maintenance and repair. It is activated by E-cadherin engagement through signaling pathways involving PDZ-GEF I.
Area of Science:
- Cell Biology
- Molecular Signaling
Background:
- E-cadherin based adherens junctions are crucial for cell-cell adhesion.
- These junctions are regulated by complex cellular signaling pathways.
Purpose of the Study:
- To investigate the role of the Ras-related Rap1 GTPase in E-cadherin junction regulation.
- To elucidate the signaling mechanisms by which Rap1 influences cell-cell adhesion.
Main Methods:
- Utilized MDCK cells expressing constitutively active Rap1.
- Examined E-cadherin association with Rap1 Guanine nucleotide Exchange Factors (GEFs) like C3G and PDZ-GEF I.
- Assessed Rap1 activity following E-cadherin junction disruption and PDZ-GEF I knockdown.
Main Results:
- Constitutively active Rap1 enhanced E-cadherin junctional contact and stability.
- E-cadherin disengagement activated Rap1, correlating with its association with C3G and PDZ-GEF I.
- PDZ-GEF I, but not C3G, associated with beta-catenin.
- PDZ-GEF I knockdown reduced Rap1 activation upon junction disruption.
Conclusions:
- Rap1 GTPase plays a significant role in maintaining and repairing E-cadherin based cell-cell junctions.
- Rap1 activation is mediated by an "outside-in" signaling pathway initiated by E-cadherin, involving PDZ-GEF I.
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