Kap-β2/Transportin mediates β-catenin nuclear transport in Wnt signaling
- Yale University, United States
Abstract
Wnt signaling is essential for many aspects of embryonic development including the formation of the primary embryonic axis. In addition, excessive Wnt signaling drives multiple diseases including cancer highlighting its importance for disease pathogenesis. β-catenin is a key effector in this pathway that translocates into the nucleus and activates Wnt responsive genes. However, due to our lack of understanding of β-catenin nuclear transport, therapeutic modulation of Wnt signaling has been challenging. Here, we took an unconventional approach to address this long-standing question by exploiting a heterologous model system, the budding yeast Saccharomyces cerevisiae, which contains a conserved nuclear transport machinery. In contrast to prior work, we demonstrate that β-catenin accumulates in the nucleus in a Ran dependent manner, suggesting the use of a nuclear transport receptor (NTR). Indeed, a systematic and conditional inhibition of NTRs revealed that only Kap104, the orthologue of Kap-β2/Transportin-1 (TNPO1), was required for β-catenin nuclear import. We further demonstrate direct binding between TNPO1 and β-catenin that is mediated by a conserved PY-NLS. Finally, using Xenopus secondary axis and TCF/LEF reporter assays, we demonstrate that our results in yeast can be directly translated to vertebrates. By elucidating the NLS in β-catenin and its cognate NTR, our study suggests new therapeutic targets for a host of human diseases caused by excessive Wnt signaling. Indeed, we demonstrate that a small chimeric peptide designed to target TNPO1 can reduce Wnt signaling as a first step towards therapeutics.
Data availability
Data generated or analyzed during this study are included in the manuscript and the supporting file.Source data file has been provided for Figure 1, 2B, 3C, 4B, 4C, 6B, 7, Figure 2-figure supplement 1, Figure 2- figure supplement 2.
Article and author information
Author details
Delfina P González
Funding
National Institutes of Health (2R01HL124402)
- C Patrick Lusk
- Mustafa Khokha
National Institutes of Health (T32GM07205)
- Woong Y Hwang
- Valentyna Kostiuk
National Institutes of Health (5F30HL143878)
- Woong Y Hwang
National Institutes of Health (5F31HL149246)
- Delfina P González
Paul and Daisy Soros Fellowships for New Americans
- Woong Y Hwang
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Xenopus tropicalis and Xenopus laevis were housed and cared for in our aquatics facility according to established protocols approved by the Yale Institutional Animal Care and Use Committee (IACUC, protocol number-2021-11035).
Copyright
© 2022, Hwang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Kap-β2/Transportin mediates β-catenin nuclear transport in Wnt signaling
eLife 11:e70495.
https://doi.org/10.7554/eLife.70495
