Tsuneoka Makoto, Koda Yoshiro, Soejima Mikiko, Teye Kwesi, Kimura Hiroshi
Division of Human Genetics, Department of Forensic Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan.
J Biol Chem. 2002 Sep 20;277(38):35450-9. doi: 10.1074/jbc.M204458200. Epub 2002 Jun 28.
Myc is a ubiquitous mediator of cell proliferation and can transactivate the expression of various genes through E-box sites. Here we report a novel gene, mina53 (Myc-induced nuclear antigen with a molecular mass of 53 kDa). The mina53 gene encodes a protein with a molecular weight of 53 kDa, which is localized in the nucleus and with part of the protein concentrated in the nucleolus. When serum-starved cells were activated by serum, the level of c-myc mRNA was elevated, and an increase in mina53 mRNA followed the elevation of c-myc mRNA. When expression of c-myc was reduced in human promyelocytic leukemia HL60 cells by phorbol 12-myristate 13-acetate, the expression of mina53 mRNA and protein was reduced. The expression of mina53 mRNA and Mina53 protein was induced by ectopic introduction of wild type c-Myc but not by a mutant c-Myc lacking the transactivation domain. When c-Myc in the c-MycER chimeric protein was activated, mina53 mRNA was increased, even in the presence of an inhibitor for protein synthesis. E-box sites are present in a region proximal to the transcription initiation sites of the mina53 gene. The gene expression from the mina53 promoter was elevated by c-Myc through E-box sites. c-Myc protein bound to the mina53 promoter region in vivo in HL60 cells in the proliferating phase but not after treatment of cells with phorbol 12-myristate 13-acetate. Specific inhibition of mina53 expression by an RNA interference method severely suppressed cell proliferation. Taken together, these results indicate that mina53 is a direct target gene of Myc, suggesting that mina53 is involved in mammalian cell proliferation.
Myc是细胞增殖的普遍介导因子，可通过E-box位点反式激活多种基因的表达。在此，我们报告一个新基因mina53（分子量为53 kDa的Myc诱导核抗原）。mina53基因编码一种分子量为53 kDa的蛋白质，该蛋白质定位于细胞核，部分集中在核仁。血清饥饿细胞被血清激活时，c-myc mRNA水平升高，随后mina53 mRNA增加。当用佛波醇12-肉豆蔻酸酯13-乙酸酯降低人早幼粒细胞白血病HL60细胞中c-myc的表达时，mina53 mRNA和蛋白的表达降低。野生型c-Myc的异位导入可诱导mina53 mRNA和Mina53蛋白的表达，而缺乏反式激活结构域的突变型c-Myc则不能。当c-MycER嵌合蛋白中的c-Myc被激活时，即使存在蛋白质合成抑制剂，mina53 mRNA仍会增加。E-box位点存在于mina53基因转录起始位点附近的区域。c-Myc通过E-box位点提高mina53启动子的基因表达。在增殖期，c-Myc蛋白在HL60细胞体内与mina53启动子区域结合，但在用佛波醇12-肉豆蔻酸酯13-乙酸酯处理细胞后则不结合。通过RNA干扰方法特异性抑制mina53的表达可严重抑制细胞增殖。综上所述，这些结果表明mina53是Myc的直接靶基因，提示mina53参与哺乳动物细胞增殖。
