Promyelocytic leukemia (PML) and a suite of other proteins form nuclear bodies (NBs) where SUMOylation of PML and tumor suppression events occur in response to arsenite (As³⁺) treatment. Soluble PML is rapidly modified to the insoluble form in response to As³⁺, yet the relationship between the solubility change and nuclear localization of PML and PML-nuclear body (PML-NB) proteins remained elusive. We have investigated differences in the solubility change of well-known PML-NB proteins such as death-associated protein 6 (DAXX), SUMO, and PML in genetically engineered HEK293, and Jurkat and HL60 cells. The solubility of PML and SUMO2/3 monomers in RIPA solution decreased in 2 h in response to As³⁺. Live image analysis of GFP-PML revealed that extranuclear PML was insoluble in RIPA irrespective of the As³⁺-treatment and PML in PML-NBs, which was soluble in the untreated cells, was converted to insoluble forms by As³⁺. The solubility of DAXX was not changed by As³⁺, even though PML and DAXX co-localized completely in the subcellular compartments. Murine double mutant 2 (MDM2), which is known to interacts with intranuclear PML, did not affect the As³⁺-induced solubility change of PML. These results indicate that As³⁺ selectively reorganizes PML and SUMO2/3 monomers into insoluble forms in PML-NBs, and then PML SUMOylation proceeds.

早幼粒细胞白血病（PML）和其他一系列蛋白质形成核小体（NBs），其中对亚砷酸盐（As ³⁺）的治疗会引起PML的SUMOylation和肿瘤抑制事件的发生。可溶性PML响应于As ³⁺迅速修饰为不溶形式，但PML和PML核体（PML-NB）蛋白的溶解度变化与核定位之间的关系仍然难以捉摸。我们已经研究了基因改造的HEK293，Jurkat和HL60细胞中众所周知的PML-NB蛋白（如死亡相关蛋白6（DAXX），SUMO和PML）在溶解度变化方面的差异。PML和SUMO2 / 3单体在RIPA溶液中的溶解度在2小时内响应于As ^3+而降低。对GFP-PML进行的实时图像分析显示，核外PML不溶于RIPA，而与As ^3+处理无关，而可溶于未处理细胞的PML-NBs中的PML被As ³⁺转化为不溶形式。即使PML和DAXX完全共定位在亚细胞区室中，DAXX的溶解度也不会被As ³⁺改变。已知与核内PML相互作用的鼠双突变体2（MDM2）不影响As ³⁺诱导的PML的溶解度变化。这些结果表明，As ³⁺将PML和SUMO2 / 3单体选择性地重组为PML-NBs中的不溶形式，然后进行PML SUMOylation。