E2F 1、2和3a（简称E2Fs）是E2F转录因子家族中的一个亚家族，它们在细胞周期进程、DNA复制、DNA修复、凋亡和分化中发挥着关键作用。尽管E2Fs的转录调控重点是口袋蛋白视网膜母细胞瘤蛋白复合物，但最近的研究表明，后转录后修饰和稳定性调控对多种细胞过程起着关键作用。在本研究中，我们发现S相激酶相关蛋白1（SKP1）-醛缩酶1-F-box蛋白（SCF）复合物的成分FBXO1是E2Fs的结合伴侣。此外，FBXO1与E2Fs的结合诱导K48泛素化和随后的E2Fs蛋白酶体降解。结合域分析表明，位于E2F1和3a及E2F2的二聚化域中的Arg（R）/Ile（I）和R / Val（V）基序分别作为FBXO1的半衰期标记（DMs）。值得注意的是，在DM中的RI / AA或RV / AA突变会减少FBXO1介导的泛素化并延长E2Fs的半衰期。重要的是，E2Fs的稳定性受到位于DMs RI和RV残基附近的苏氨酸残基磷酸化的影响。磷酸化预测数据库分析和特殊抑制剂分析揭示了MEK / ERK信号分子在FBXO1 / E2Fs相互作用中起关键作用，并调节E2F蛋白的周转。此外，通过抑制FBXO1升高的E2F蛋白水平和通过sh-E2F3a减少的E2F蛋白水平延迟了G1 / S细胞周期转变，结果抑制了癌细胞增殖。这些结果表明，FBXO1-E2Fs轴介导的精确E2Fs稳定性调节通过G1 / S细胞周期转变在细胞增殖中发挥关键作用。© 2023 韩国药学会。

E2F 1, 2, and 3a, (refer to as E2Fs) are a subfamily of E2F transcription factor family that play essential roles in cell-cycle progression, DNA replication, DNA repair, apoptosis, and differentiation. Although the transcriptional regulation of E2Fs has focused on pocket protein retinoblastoma protein complex, recent studies indicate that post-translational modification and stability regulation of E2Fs play key roles in diverse cellular processes. In this study, we found that FBXO1, a component of S-phase kinase-associated protein 1 (SKP1)-cullin 1-F-box protein (SCF) complex, is an E2Fs binding partner. Furthermore, FBXO1 to E2Fs binding induced K48 ubiquitination and subsequent proteasomal degradation of E2Fs. Binding domain analysis indicated that the Arg (R)/Ile (I) and R/Val (V) motifs, which are located in the dimerization domain of E2Fs, of E2F 1 and 3a and E2F2, respectively, acted as degron motifs (DMs) for FBXO1. Notably, RI/AA or RV/AA mutation in the DMs reduced FBXO1-mediated ubiquitination and prolonged the half-lives of E2Fs. Importantly, the stabilities of E2Fs were affected by phosphorylation of threonine residues located near RI and RV residues of DMs. Phosphorylation prediction database analysis and specific inhibitor analysis revealed that MEK/ERK signaling molecules play key roles in FBXO1/E2Fs' interaction and modulate E2F protein turnover. Moreover, both elevated E2Fs protein levels by knockdown of FBXO1 and decreased E2Fs protein levels by sh-E2F3a delayed G1/S cell cycle transition, resulting in inhibition of cancer cell proliferation. These results demonstrated that FBXO1-E2Fs axis-mediated precise E2Fs stability regulation plays a key role in cell proliferation via G1/S cell cycle transition.© 2023. The Pharmaceutical Society of Korea.