Abstract：
The small ubiquitin-like modifier (SUMO) protease SENP6 disassembles SUMO chains from cellular substrate proteins. We use a proteomic method to identify putative SENP6 substrates based on increased apparent molecular weight after SENP6 depletion. Proteins of the lamin family of intermediate filaments show substantially increased SUMO modification after SENP6 depletion. This is accompanied by nuclear structural changes remarkably like those associated with laminopathies. Two SUMO attachment sites on lamin A/C are close to sites of mutations in Emery-Driefuss and limb girdle muscular dystrophy. To establish a direct link between lamin SUMOylation and the observed phenotype, we developed proximity-induced SUMO modification (PISM), which fuses a lamin A/C targeting DARPin to a SUMO E3 ligase domain. This directly targets lamin A/C for SUMO conjugation and demonstrates that enhanced lamin SUMO modification recapitulates the altered nuclear structure manifest after SENP6 depletion. This shows SENP6 activity protects the nucleus against hyperSUMOylation-induced laminopathy-like alterations.
摘要：
小泛素样修饰剂(SUMO)蛋白酶SENP6从细胞底物蛋白分解SUMO链。我们使用蛋白质组学方法基于SENP6消耗后表观分子量增加来鉴定推定的SENP6底物。在SENP6耗尽后，中间丝的层蛋白家族的蛋白质显示出大量增加的SUMO修饰。这伴随着核结构的变化，就像与层粘连相关的变化一样。层粘连蛋白A/C上的两个SUMO附着位点接近Emery-Driefuss和四肢带型肌营养不良中的突变位点。为了建立层粘连蛋白SUMO化和观察到的表型之间的直接联系，我们开发了邻近诱导的SUMO修饰(PISM)，将靶向DARPin的层蛋白A/C融合到SUMOE3连接酶结构域。这直接针对层粘连蛋白A/C进行SUMO缀合，并证明增强的层粘连蛋白SUMO修饰概括了SENP6耗尽后表现出的改变的核结构。这表明SENP6活性保护细胞核免受超SUMO化诱导的层蛋白病样改变。
