NUP98 fusion oncoproteins interact with the APC/C^Cdc20 as a pseudosubstrate and prevent mitotic checkpoint complex binding

<i>NUP98</i> is a recurrent partner gene in translocations causing acute myeloid leukemias and myelodisplastic syndrome. The expression of NUP98 fusion oncoproteins has been shown to induce mitotic spindle defects and chromosome missegregation, which correlate with the capability of NUP98 fusions to cause mitotic checkpoint attenuation. We show that NUP98 oncoproteins physically interact with the APC/C^Cdc20 in the absence of the NUP98 partner protein RAE1, and prevent the binding of the mitotic checkpoint complex to the APC/C^Cdc20. NUP98 oncoproteins require the GLEBS-like domain present in their NUP98 moiety to bind the APC/C^Cdc20. We found that NUP98 wild-type is a substrate of APC/C^Cdc20 prior to mitotic entry, and that its binding to APC/C^Cdc20 is controlled via phosphorylation of a PEST sequence located within its C-terminal portion. We identify S606, within the PEST sequence, as a key target site, whose phosphorylation modulates the capability of NUP98 to interact with APC/C^Cdc20. We finally provide evidence for an involvement of the peptidyl-prolyl isomerase PIN1 in modulating the possible conformational changes within NUP98 that lead to its dissociation from the APC/C^Cdc20 during mitosis. Our results provide novel insight into the mechanisms underlying the aberrant capability of NUP98 oncoproteins to interact with APC/C^Cdc20 and to interfere with its function.

NUP98是引发急性髓系白血病与骨髓增生异常综合征的染色体易位事件中常见的伙伴基因。已有研究证实，NUP98融合癌蛋白的表达可诱导有丝分裂纺锤体缺陷与染色体错分离，这一表型与NUP98融合蛋白引发有丝分裂检验点衰减的能力密切相关。本研究发现，在缺乏NUP98伴侣蛋白RAE1的情况下，NUP98癌蛋白可与APC/C^Cdc20（后期促进复合物Cdc20）发生物理性相互作用，并阻断有丝分裂检验点复合物与APC/C^Cdc20的结合。NUP98癌蛋白需借助其自身NUP98组分中存在的类GLEBS结构域，才能与APC/C^Cdc20结合。我们还发现，野生型NUP98在有丝分裂进入前即为APC/C^Cdc20的底物，其与APC/C^Cdc20的结合受C端区域内PEST序列的磷酸化调控。我们鉴定出PEST序列内的S606为关键磷酸化靶点，该位点的磷酸化可调控NUP98与APC/C^Cdc20的相互作用能力。最后，我们证实肽基脯氨酰异构酶PIN1参与调控NUP98内部的构象变化，该变化可促使NUP98在有丝分裂过程中与APC/C^Cdc20解离。本研究结果为解析NUP98癌蛋白异常结合APC/C^Cdc20并干扰其功能的分子机制提供了全新见解。

搜集汇总

背景与挑战

背景概述

该数据集研究了NUP98融合癌蛋白在急性髓系白血病和骨髓增生异常综合征中的作用机制，重点揭示其作为假底物与APC/CCdc20相互作用，从而阻止有丝分裂检查点复合物结合，导致有丝分裂检查点减弱和染色体错误分离。数据集还探讨了野生型NUP98作为APC/CCdc20底物的调控方式，包括通过S606位点磷酸化和PIN1酶介导的构象变化，为理解NUP98癌蛋白的异常功能提供了新见解。