Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden.
Nat Commun. 2012;3:976. doi: 10.1038/ncomms1975.
Fbw7 is a ubiquitin-ligase that targets several oncoproteins for proteolysis, but the full range of Fbw7 substrates is not known. Here we show that by performing quantitative proteomics combined with degron motif searches, we effectively screened for a more complete set of Fbw7 targets. We identify 89 putative Fbw7 substrates, including several disease-associated proteins. The transcription factor NF-κB2 (p100/p52) is one of the candidate Fbw7 substrates. We show that Fbw7 interacts with p100 via a conserved degron and that it promotes degradation of p100 in a GSK3β phosphorylation-dependent manner. Fbw7 inactivation increases p100 levels, which in the presence of NF-κB pathway stimuli, leads to increased p52 levels and activity. Accordingly, the apoptotic threshold can be increased by loss of Fbw7 in a p100-dependent manner. In conclusion, Fbw7-mediated destruction of p100 is a regulatory component restricting the response to NF-κB2 pathway stimulation.
Fbw7 是一种泛素连接酶，可将几种癌蛋白靶向用于蛋白水解，但 Fbw7 的底物范围尚不完全清楚。在这里，我们通过进行定量蛋白质组学结合去稳定基序搜索，有效地筛选了更完整的一组 Fbw7 靶标。我们鉴定了 89 个推定的 Fbw7 底物，包括几种与疾病相关的蛋白质。转录因子 NF-κB2（p100/p52）是候选 Fbw7 底物之一。我们表明 Fbw7 通过保守的去稳定基序与 p100 相互作用，并以 GSK3β 磷酸化依赖性方式促进 p100 的降解。Fbw7 失活会增加 p100 的水平，在 NF-κB 途径刺激存在的情况下，会导致 p52 水平和活性增加。因此，通过 p100 依赖性方式丧失 Fbw7 可以增加细胞凋亡的阈值。总之，Fbw7 介导的 p100 破坏是限制 NF-κB2 途径刺激反应的调节成分。
