Sugiura Naoaki, Adams Suzanne M, Corriveau Roderick A
Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
J Biol Chem. 2003 Oct 10;278(41):40113-20. doi: 10.1074/jbc.M301218200. Epub 2003 Jul 29.
We previously identified mNAT1 (murine N-terminal acetyltransferase 1) as an embryonic gene that is expressed in the developing brain and subsequently down-regulated, in part, by the onset of N-methyl-d-aspartate (NMDA) receptor function. By searching the data base we discovered a second closely related gene, mNAT2. mNAT1 and mNAT2 are highly homologous to yeast NAT1, a gene known to regulate entry into the G0 phase of the cell cycle. However, in the absence of further characterization, including evidence that mammalian homologues of NAT1 encode functional acetyltransferases, the significance of this relationship has been unclear. Here we focus on mNAT1. Biochemical analysis demonstrated that mNAT1 and its evolutionarily conserved co-subunit, mARD1, assemble to form a functional acetyltransferase. Transfection of mammalian cells with mNAT1 and mARD1 followed by immunofluorescent staining revealed that these proteins localize to the cytoplasm in both overlapping and separate compartments. In situ hybridization demonstrated that throughout brain development mNAT1 and mARD1 are highly expressed in areas of cell division and migration and are down-regulated as neurons differentiate. Finally, mNAT1 and mARD1 are expressed in proliferating mouse P19 embryonic carcinoma cells; treatment of these cells with retinoic acid initiates exit from the cell cycle, neuronal differentiation, and down-regulation of mNAT1 and mARD1 as the NMOA receptor 1 gene is induced. The results provide the first direct evidence that vertebrate homologues of NAT1 and ARD1 form an evolutionarily conserved N-terminal acetyltransferase and suggest that expression and down-regulation of this enzyme complex plays an important role in the generation and differentiation of neurons.
我们之前鉴定出mNAT1（小鼠N端乙酰转移酶1）是一个在发育中的大脑中表达的胚胎基因，随后部分地因N-甲基-D-天冬氨酸（NMDA）受体功能的开始而被下调。通过搜索数据库，我们发现了第二个密切相关的基因mNAT2。mNAT1和mNAT2与酵母NAT1高度同源，NAT1是一个已知调节进入细胞周期G0期的基因。然而，在没有进一步表征的情况下，包括NAT1的哺乳动物同源物编码功能性乙酰转移酶的证据，这种关系的意义尚不清楚。在这里，我们聚焦于mNAT1。生化分析表明，mNAT1及其进化上保守的共亚基mARD1组装形成一种功能性乙酰转移酶。用mNAT1和mARD1转染哺乳动物细胞，随后进行免疫荧光染色，结果显示这些蛋白质定位于细胞质中的重叠和分离区室。原位杂交表明，在整个大脑发育过程中，mNAT1和mARD1在细胞分裂和迁移区域高度表达，并随着神经元分化而下调。最后，mNAT1和mARD1在增殖的小鼠P19胚胎癌细胞中表达；用视黄酸处理这些细胞会启动细胞周期退出、神经元分化，并随着NMOA受体1基因的诱导而使mNAT1和mARD1下调。这些结果提供了首个直接证据，表明NAT1和ARD1的脊椎动物同源物形成一种进化上保守的N端乙酰转移酶，并表明这种酶复合物的表达和下调在神经元的产生和分化中起重要作用。
