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Cadherin sequences that inhibit beta-catenin signaling: a study in yeast and mammalian cells
I Simcha1, C Kirkpatrick, E Sadot
1Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel, 76100.
Abstract:
Drosophila Armadillo and its mammalian homologue beta-catenin are scaffolding proteins involved in the assembly of multiprotein complexes with diverse biological roles. They mediate adherens junction assembly, thus determining tissue architecture, and also transduce Wnt/Wingless intercellular signals, which regulate embryonic cell fates and, if inappropriately activated, contribute to tumorigenesis. To learn more about Armadillo/beta-catenin's scaffolding function, we examined in detail its interaction with one of its protein targets, cadherin. We utilized two assay systems: the yeast two-hybrid system to study cadherin binding in the absence of Armadillo/beta-catenin's other protein partners, and mammalian cells where interactions were assessed in their presence. We found that segments of the cadherin cytoplasmic tail as small as 23 amino acids bind Armadillo or beta-catenin in yeast, whereas a slightly longer region is required for binding in mammalian cells. We used mutagenesis to identify critical amino acids required for cadherin interaction with Armadillo/beta-catenin. Expression of such short cadherin sequences in mammalian cells did not affect adherens junctions but effectively inhibited beta-catenin-mediated signaling. This suggests that the interaction between beta-catenin and T cell factor family transcription factors is a sensitive target for disruption, making the use of analogues of these cadherin derivatives a potentially useful means to suppress tumor progression.
Insights
Researchers studied how Armadillo/beta-catenin proteins bind to cadherin. Disrupting this interaction may offer a new strategy for suppressing tumor progression.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Armadillo (Drosophila) and beta-catenin (mammalian) are key scaffolding proteins.
- These proteins are crucial for adherens junction assembly, tissue architecture, and Wnt/Wingless signaling.
- Dysregulation of beta-catenin signaling is implicated in tumorigenesis.
Purpose of the Study:
- To investigate the scaffolding function of Armadillo/beta-catenin, specifically its interaction with cadherin.
- To identify the molecular basis of the cadherin-beta-catenin interaction.
- To explore the therapeutic potential of disrupting this interaction in cancer.
Main Methods:
- Utilized the yeast two-hybrid system to study cadherin binding independently of other partners.
- Assessed protein interactions in mammalian cells to reflect physiological conditions.
- Employed mutagenesis to pinpoint critical amino acids involved in cadherin binding.
Main Results:
- Identified minimal cadherin cytoplasmic tail segments (23 amino acids) capable of binding Armadillo/beta-catenin in yeast.
- Determined a slightly longer region required for binding in mammalian cells.
- Demonstrated that short cadherin sequences inhibit beta-catenin-mediated signaling without affecting adherens junctions.
Conclusions:
- The interaction between beta-catenin and T cell factor transcription factors is a sensitive target for disruption.
- Cadherin derivatives that inhibit beta-catenin signaling hold potential as anti-cancer therapeutics.
- Targeting the cadherin-beta-catenin interaction offers a promising avenue for tumor progression suppression.