Reconstitution of the destruction complex defines roles of AXIN polymers and APC in β-catenin capture, phosphorylation, and ubiquitylation.
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ICR Authors
Authors
Ranes, M
Zaleska, M
Sakalas, S
Knight, R
Guettler, S
Zaleska, M
Sakalas, S
Knight, R
Guettler, S
Document Type
Journal Article
Date
2021-08-19
Date Accepted
2021-07-13
Abstract
The Wnt/β-catenin pathway is a highly conserved, frequently mutated developmental and cancer pathway. Its output is defined mainly by β-catenin's phosphorylation- and ubiquitylation-dependent proteasomal degradation, initiated by the multi-protein β-catenin destruction complex. The precise mechanisms underlying destruction complex function have remained unknown, largely because of the lack of suitable in vitro systems. Here we describe the in vitro reconstitution of an active human β-catenin destruction complex from purified components, recapitulating complex assembly, β-catenin modification, and degradation. We reveal that AXIN1 polymerization and APC promote β-catenin capture, phosphorylation, and ubiquitylation. APC facilitates β-catenin's flux through the complex by limiting ubiquitylation processivity and directly interacts with the SCFβ-TrCP E3 ligase complex in a β-TrCP-dependent manner. Oncogenic APC truncation variants, although part of the complex, are functionally impaired. Nonetheless, even the most severely truncated APC variant promotes β-catenin recruitment. These findings exemplify the power of biochemical reconstitution to interrogate the molecular mechanisms of Wnt/β-catenin signaling.
Citation
Molecular Cell, 2021, 81 (16), pp. 3246 - 3261.e11
Source Title
Molecular Cell
Publisher
CELL PRESS
ISSN
1097-2765
eISSN
1097-4164
1097-4164
1097-4164
Collections
Research Team
Struct Biol Cell Signal