Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
Division of Pulmonary and Critical Care, Department of Medicine, Northwestern University, Chicago, IL, 60611, USA.
Sci Rep. 2022 Sep 5;12(1):15095. doi: 10.1038/s41598-022-19133-4.
Phosphorylation controls important cellular signals and its dysregulation leads to disease. While most phospho-regulation studies are focused on kinases, phosphatases are comparatively overlooked. Combining peptide arrays with SAMDI mass spectrometry, we show that tyrosine phosphatase activity is restricted by basic amino acids adjacent to phosphotyrosines. We validate this model using two β-catenin mutants associated with cancer (T653R/K) and a mouse model for intellectual disability (T653K). These mutants introduce a basic residue next to Y654, an established phosphorylation site where modification shifts β-catenin from cell-cell adhesions and towards its essential nuclear role as Wnt-signaling effector. We show that T653-basic mutant β-catenins are less efficiently dephosphorylated by phosphatases, leading to sustained Y654 phosphorylation and elevated Wnt signals, similar to those observed for Y654E phospho-mimic mutant mice. This model rationalizes how basic mutations proximal to phosphotyrosines can restrict counter-regulation by phosphatases, providing new mechanismistic and treatment insights for 6000+ potentially relevant cancer mutations.
磷酸化控制着重要的细胞信号，其失调会导致疾病。虽然大多数磷酸化调控研究都集中在激酶上，但磷酸酶相对被忽视了。我们结合肽阵列和 SAMDI 质谱法表明，酪氨酸磷酸酶的活性受到紧邻磷酸酪氨酸的碱性氨基酸的限制。我们使用两种与癌症相关的 β-连环蛋白突变体（T653R/K）和一个智力障碍的小鼠模型（T653K）验证了该模型。这些突变体在 Y654 附近引入了一个碱性残基，Y654 是一个已确定的磷酸化位点，修饰后将 β-连环蛋白从细胞-细胞黏附中转移到其作为 Wnt 信号效应物的核心核作用。我们表明，T653-碱性突变体 β-连环蛋白的磷酸酶去磷酸化效率较低，导致 Y654 持续磷酸化和 Wnt 信号升高，类似于观察到的 Y654E 磷酸模拟突变体小鼠。该模型合理地解释了为什么紧邻磷酸酪氨酸的碱性突变可以限制磷酸酶的反向调节，为 6000+ 个可能相关的癌症突变提供了新的机制和治疗见解。
