Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
The Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, M5G 1L7, Canada.
Sci Rep. 2019 Feb 25;9(1):2724. doi: 10.1038/s41598-019-39368-y.
The ubiquitin specific protease 7 (USP7 or HAUSP) is known to regulate a variety of cellular processes by binding and deubiquitylating specific target proteins. To gain a more comprehensive understanding of its interactions and functions, we used affinity purification coupled to mass spectrometry to profile USP7 interactions. This revealed a novel interaction with FBXO38, a poorly characterized F-box protein. We showed that USP7 stabilizes FBXO38 dependent on its catalytic activity by protecting FBXO38 from proteasomal degradation. We used a BioID approach to profile the protein interactions (and putative functions) of FBXO38, revealing an interaction with KIF20B, a Kinesin-6 protein required for efficient cytokinesis. FBXO38 was shown to function independently from an SCF complex to stabilize KIF20B. Consequently, depletion of either FBXO38 or USP7 led to dramatic decreases in KIF20B levels and KIF20B at the midbody, which were manifested in cytokinetic defects. Furthermore, cytokinetic defects associated with USP7 silencing were rescued by restoring FBXO38 or KIF20B. The results indicate a novel mechanism of regulating cytokinesis through USP7 and FBXO38.
泛素特异性蛋白酶 7（USP7 或 HAUSP）通过结合和解泛素化特定靶蛋白，已知能调节多种细胞过程。为了更全面地了解其相互作用和功能，我们使用亲和纯化结合质谱法来分析 USP7 的相互作用。这揭示了与 FBXO38 的一种新的相互作用，FBXO38 是一种特征描述较少的 F 盒蛋白。我们表明，USP7 通过保护 FBXO38 免受蛋白酶体降解，依赖其催化活性稳定 FBXO38。我们使用 BioID 方法来分析 FBXO38 的蛋白相互作用（和潜在功能），揭示了与 KIF20B 的相互作用，KIF20B 是一种有丝分裂后期必需的 Kinase-6 蛋白。FBXO38 被证明独立于 SCF 复合物发挥作用，以稳定 KIF20B。因此，FBXO38 或 USP7 的耗竭导致 KIF20B 水平和有丝分裂后期的 KIF20B 显著降低，这表现为胞质分裂缺陷。此外，USP7 沉默相关的胞质分裂缺陷通过恢复 FBXO38 或 KIF20B 得到挽救。结果表明，USP7 和 FBXO38 通过一种新的机制调节胞质分裂。
