Shi Shasha, Li Xueni, Alderman Christopher, Wick Lars, Huang Wei, Foulon North, Zhang Lingdi, Rossi John, Hu Wenxin, Cui Shouqing, Zheng Hongjin, Taylor Derek J, Ford Heide L, Zhao Rui
Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA; Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA; Molecular Biology Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
J Biol Chem. 2025 May 23;301(7):110287. doi: 10.1016/j.jbc.2025.110287.
We have previously shown that Eya3 recruits PP2A-B55α to dephosphorylate pT58 on Myc, increasing Myc stability and enhancing primary tumor growth of triple-negative breast cancer (TNBC). However, the molecular details of how Eya3 recruits PP2A-B55α remain unclear. Here, we determined the cryo-EM structures of PP2A-B55α bound with Eya3, with an inhibitory peptide B55i, and in its unbound state. These studies demonstrate that Eya3 binds B55α through an extended peptide in the N-terminal domain of Eya3. The Eya3 peptide, PP2A-B55α substrates, and protein-peptide inhibitors including B55i bind to a similar area on the B55α surface, but the molecular details of the binding differ. We further demonstrated that the B55i peptide inhibits the B55α and Eya3 interaction in vitro. The B55i peptide expressed on a plasmid increases Myc pT58 and decreases Myc protein levels in TNBC cells, suggesting the potential of B55i or similar peptides as therapies for TNBC.
我们之前已经表明，Eya3招募PP2A-B55α去磷酸化Myc上的pT58，增加Myc的稳定性并促进三阴性乳腺癌（TNBC）原发肿瘤的生长。然而，Eya3如何招募PP2A-B55α的分子细节仍不清楚。在此，我们确定了与Eya3结合、与抑制性肽B55i结合以及处于未结合状态的PP2A-B55α的冷冻电镜结构。这些研究表明，Eya3通过Eya3 N端结构域中的一段延伸肽与B55α结合。Eya3肽、PP2A-B55α底物以及包括B55i在内的蛋白质-肽抑制剂都结合在B55α表面的相似区域，但结合的分子细节有所不同。我们进一步证明，B55i肽在体外抑制B55α与Eya3的相互作用。在质粒上表达的B55i肽可增加TNBC细胞中Myc pT58并降低Myc蛋白水平，这表明B55i或类似肽作为TNBC治疗方法的潜力。
