ERK1/2 inhibitors act as monovalent degraders inducing ubiquitylation and proteasome-dependent turnover of ERK2, but not ERK1.
ERK1/2 inhibitors act as monovalent degraders inducing ubiquitylation and proteasome-dependent turnover of ERK2, but not ERK1.
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DOI：
10.1042/bcj20220598
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发表时间：
2023-05-15
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对小分子BRAF或MEK 1/2抑制剂（BRAFi或MEKi）的先天性或获得性抗性通常通过维持或恢复ERK 1/2活化的机制产生。这导致开发了一系列ERK 1/2抑制剂（ERKi），其抑制激酶催化活性（catERKi）或另外防止MEK 1/2对ERK 1/2的活化pT-E-pY双重磷酸化（双重机制或dmERKi）。在这里，我们发现八种不同的ERKi（catERKi或dmERKi）驱动ERK 2（最丰富的ERK亚型）的周转，对ERK 1几乎没有影响。热稳定性试验表明，ERKi在体外不会使ERK 2（或ERK 1）不稳定，表明ERK 2周转是ERKi结合的细胞结果。在单独用MEKi处理时未观察到ERK 2周转，这表明是ERK 1与ERK 2的结合驱动ERK 2周转。然而，阻断ERK 2 pT-E-pY磷酸化和从MEK 1/2解离的MEKi预处理阻止ERK 2更新。细胞的ERKi处理驱动ERK 2的多聚泛素化和蛋白酶体依赖性周转，并且Cullin-RING E3连接酶的药理学或遗传学抑制防止了这一点。我们的研究结果表明，ERKi，包括目前的临床候选人，作为“激酶降解剂”，驱动蛋白酶体依赖的营业额的主要目标，ERK 2。这可能与ERK 1/2的激酶非依赖性作用和ERKi的治疗用途有关。
Innate or acquired resistance to small molecule BRAF or MEK1/2 inhibitors (BRAFi or MEKi) typically arises through mechanisms that sustain or reinstate ERK1/2 activation. This has led to the development of a range of ERK1/2 inhibitors (ERKi) that either inhibit kinase catalytic activity (catERKi) or additionally prevent the activating pT-E-pY dual phosphorylation of ERK1/2 by MEK1/2 (dual-mechanism or dmERKi). Here, we show that eight different ERKi (both catERKi or dmERKi) drive the turnover of ERK2, the most abundant ERK isoform, with little or no effect on ERK1. Thermal stability assays show that ERKi do not destabilise ERK2 (or ERK1) in vitro, suggesting that ERK2 turnover is a cellular consequence of ERKi binding. ERK2 turnover is not observed upon treatment with MEKi alone, suggesting it is ERKi binding to ERK2 that drives ERK2 turnover. However, MEKi pre-treatment, which blocks ERK2 pT-E-pY phosphorylation and dissociation from MEK1/2, prevents ERK2 turnover. ERKi treatment of cells drives the poly-ubiquitylation and proteasome-dependent turnover of ERK2 and pharmacological or genetic inhibition of Cullin-RING E3 ligases prevents this. Our results suggest that ERKi, including current clinical candidates, act as ‘kinase degraders’, driving the proteasome-dependent turnover of their major target, ERK2. This may be relevant to the suggestion of kinase-independent effects of ERK1/2 and the therapeutic use of ERKi.