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bioRxiv · 10.1101/2020.02.13.948380

β-catenin-Mediated Wnt Signal Transduction Proceeds Through an Endocytosis-Independent Mechanism

Rim, E. Y.·Kinney, L. K.·Nusse, R.
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Abstract

The Wnt pathway is a key intercellular signaling cascade that regulates development, tissue homeostasis, and regeneration. However, gaps remain in our understanding of the molecular events that take place between ligand-receptor binding and target gene transcription. Here we used a novel tool for quantitative, real-time assessment of endogenous pathway activation, measured in single cells, to answer an unresolved question in the field - whether receptor endocytosis is required for Wnt signal transduction. We combined knockdown or knockout of essential components of Clathrin-mediated endocytosis with quantitative assessment of Wnt signal transduction in mouse embryonic stem cells (mESCs). Disruption of Clathrin-mediated endocytosis did not affect accumulation and nuclear translocation of {beta}-catenin, as measured by single-cell live imaging of endogenous {beta}-catenin, and subsequent target gene transcription. Disruption of another receptor endocytosis pathway, Caveolin-mediated endocytosis, did not affect Wnt pathway activation either. These results, confirmed in multiple cell lines, suggest that endocytosis is not a general requirement for Wnt signal transduction. We show that off-target effects of a drug used to inhibit endocytosis may be one source of the discrepancy among reports on the role of endocytosis in Wnt signaling.

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Rim, E. Y., Kinney, L. K., Nusse, R.. 2020-02-14. β-catenin-Mediated Wnt Signal Transduction Proceeds Through an Endocytosis-Independent Mechanism. https://doi.org/10.1101/2020.02.13.948380

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