Dual-specificity phosphatases (DUSPs) comprise a unique group of enzymes that dephosphorylate signaling proteins at both phospho-serine/threonine and phospho-tyrosine residues. Since Notch signaling is an essential pathway for neuronal cell fate determination and development that is also upregulated in Alzheimer’s disease tissues, we sought to explore whether and how DUSPs may impact Notch processing. Our results show that overexpression of DUSP15 concomitantly and dose-dependently increased the steady-state levels of recombinant Notch (extracellular domain-truncated Notch, NotchΔE) protein and its cleaved product, Notch intracellular domain (NICD). The overall ratio of NotchΔE to NICD was unchanged by overexpression of DUSP15, suggesting that the effect is independent of γ-secretase. Interestingly, overexpression of DUSP15 also dose-dependently increased phosphorylated ERK1/2. Phosphorylated ERK1/2 is known to be positively correlated with Notch protein level, and we found that DUSP15-mediated regulation of Notch was dependent on ERK1/2 activity. Together, our findings reveal the existence of a previously unidentified DUSP15-ERK1/2-Notch signaling axis, which could potentially play a role in neuronal differentiation and neurological disease.

双特异性磷酸酶 (DUSP) 包含一组独特的酶，可在磷酸丝氨酸/苏氨酸和磷酸酪氨酸残基处对信号蛋白进行去磷酸化。由于 Notch 信号传导是神经元细胞命运决定和发育的重要途径，在阿尔茨海默病组织中也上调，我们试图探索 DUSP 是否以及如何影响 Notch 加工。我们的结果表明，DUSP15 的过表达同时且剂量依赖性地增加了重组 Notch（细胞外结构域截短的 Notch，NotchΔE）蛋白及其切割产物 Notch 细胞内结构域（NICD）的稳态水平。NotchΔE 与 NICD 的总体比率因 DUSP15 的过表达而改变，表明该作用与 γ-分泌酶无关。有趣的是，DUSP15 的过表达也剂量依赖性地增加磷酸化的 ERK1/2。已知磷酸化 ERK1/2 与 Notch 蛋白水平呈正相关，我们发现 DUSP15 介导的 Notch 调节依赖于 ERK1/2 活性。总之，我们的研究结果揭示了以前未知的 DUSP15-ERK1/2-Notch 信号轴的存在，它可能在神经元分化和神经系统疾病中发挥作用。