Kang Soo Im, Chang Woo-Jung, Cho Ssang-Goo, Kim Ick Young
Laboratory of Cellular and Molecular Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
J Biol Chem. 2003 Dec 19;278(51):51479-83. doi: 10.1074/jbc.M309237200. Epub 2003 Oct 3.
Promyelocytic leukemia zinc finger (PLZF) protein is a sequence-specific DNA-binding protein that represses the transcriptional activity of target genes such as those for cyclin A and the interleukin-3 receptor alpha chain. The PLZF gene becomes fused to the retinoic acid receptor alpha gene as a result of the t(11, 17)(q23;q21) chromosomal translocation that is associated with acute promyelocytic leukemia. We now show that endogenous PLZF in human promyelocytic leukemia HL-60 cells is modified by conjugation with SUMO-1 (small ubiquitin-related modifier-1) and that PLZF colocalizes with SUMO-1 in the nucleus of transfected human embryonic kidney 293T cells. Site-directed mutagenesis identified lysine 242 in the RD2 domain of human PLZF as the sumoylation site. A luciferase reporter gene assay suggested that SUMO-1 modification of this residue is required for transcriptional repression by PLZF, and an electrophoretic mobility shift assay showed that this modification increases the DNA binding activity of PLZF. PLZF-mediated regulation of the cell cycle and transcriptional repression of the cyclin A2 gene were also dependent on sumoylation of PLZF on lysine 242. These results demonstrate that PLZF is modified by SUMO-1 conjugation and that this modification regulates the biological functions of PLZF.
早幼粒细胞白血病锌指蛋白（PLZF）是一种序列特异性DNA结合蛋白，可抑制细胞周期蛋白A和白细胞介素-3受体α链等靶基因的转录活性。由于与急性早幼粒细胞白血病相关的t(11, 17)(q23;q21)染色体易位，PLZF基因与维甲酸受体α基因融合。我们现在表明，人类早幼粒细胞白血病HL-60细胞中的内源性PLZF通过与SUMO-1（小泛素相关修饰物-1）结合而被修饰，并且PLZF在转染的人胚肾293T细胞的细胞核中与SUMO-1共定位。定点诱变确定人PLZF的RD2结构域中的赖氨酸242为SUMO化位点。荧光素酶报告基因检测表明，该残基的SUMO-1修饰是PLZF转录抑制所必需的，电泳迁移率变动分析表明这种修饰增加了PLZF的DNA结合活性。PLZF介导的细胞周期调控和细胞周期蛋白A2基因的转录抑制也依赖于PLZF在赖氨酸242处的SUMO化。这些结果表明，PLZF通过SUMO-1结合而被修饰，并且这种修饰调节了PLZF的生物学功能。
