Kap-β2/Transportin mediates β-catenin nuclear transport in Wnt signaling.
Kap-β2/Transportin mediates β-catenin nuclear transport in Wnt signaling.
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DOI：
10.7554/elife.70495
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发表时间：
2022-10-27
期刊：
影响因子：
7.7
通讯作者：
Khokha MK
中科院分区：
文献类型：
--
作者：
Hwang WY;Kostiuk V;González DP;Lusk CP;Khokha MK
Wnt信号在胚胎发育的许多方面都是必不可少的，包括初级胚胎轴的形成。此外，过量的Wnt信号驱动包括癌症在内的多种疾病，突出了其在疾病发病机制中的重要性。β-catenin是这一途径的关键效应物，它易位到细胞核并激活Wnt应答基因。然而，由于我们对β-catenin核转运缺乏了解，Wnt信号的治疗性调节一直具有挑战性。在这里，我们采用了一种非常规的方法来解决这个长期存在的问题，利用异种模型系统，出芽酵母酿酒酵母，其中包含一个保守的核运输机制。与之前的工作相反，我们证明β-catenin以ran依赖的方式在细胞核中积累，表明使用核转运受体（NTR）。事实上，对NTRs的系统和条件抑制表明，β-catenin核输入只需要Kap104，即Kap-β2/Transportin-1 （TNPO1）的同源物。我们进一步证明TNPO1和β-连环蛋白之间的直接结合是由一个保守的PY-NLS介导的。最后，利用非洲爪蟾次级轴和TCF/LEF （T细胞因子/淋巴细胞增强因子家族）报告基因检测，我们证明了我们在酵母中的结果可以直接转化到脊椎动物中。通过阐明β-catenin及其同源NTR中的核定位信号，我们的研究为一系列由Wnt信号过多引起的人类疾病提供了新的治疗靶点。事实上，我们证明了设计一个靶向TNPO1的小嵌合肽可以减少Wnt信号，作为治疗的第一步。
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 ortholog 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 (T Cell factor/lymphoid enhancer factor family) reporter assays, we demonstrate that our results in yeast can be directly translated to vertebrates. By elucidating the nuclear localization signal 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 toward therapeutics.