Kawamoto S
Laboratory of Molecular Cardiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1762, USA.
J Biol Chem. 1996 Jul 26;271(30):17613-6.
In addition to the ubiquitously expressed form of nonmuscle myosin II heavy chain-B (MHC-B), the existence of a neuron-specific MHC-B isoform, which contains a 30-nucleotide inserted sequence near the ATP binding region, has been reported (Takahashi, M., Kawamoto, S., and Adelstein, R. S.(1992) J. Biol. Chem. 267, 17864-17871). In this study, the genomic location of the neuron-specific inserted 30-nucleotide sequence found in the cDNA is determined to be a single cassette type exon, N30, in the human nonmuscle MHC-B gene. Inclusion or exclusion of exon N30 is cell type-specific, with inclusion being restricted to neuronal cells and being regulated during cell differentiation. Expression of a minigene construct that contains the alternative exon N30 along with the flanking introns and exons was studied in human neuronal retinoblastoma Y79 cells. Inclusion of the N30 exon in the mRNA from the transfected minigene occurs in differentiated Y79 cells that have been treated with butyrate but not in the undifferentiated Y79 cells and non-neuronal cell lines. Systematic deletion and mutation analysis of the minigene construct established that neuron-specific N30 exon recognition requires a cis-acting RNA sequence located approximately 1.5 kilobases downstream of the N30 exon.
除了普遍表达的非肌肉肌球蛋白II重链B（MHC-B）形式外，还报道了一种神经元特异性MHC-B同工型的存在，该同工型在ATP结合区域附近含有一个30个核苷酸的插入序列（高桥，M.，川本，S.，和阿德尔斯坦，R.S.（1992年）《生物化学杂志》267，17864 - 17871）。在本研究中，在cDNA中发现的神经元特异性插入30个核苷酸序列的基因组位置被确定为人类非肌肉MHC-B基因中的一个单盒式外显子，N30。外显子N30的包含或排除具有细胞类型特异性，包含仅限于神经元细胞，并在细胞分化过程中受到调控。在人类神经元视网膜母细胞瘤Y79细胞中研究了包含可变外显子N30以及侧翼内含子和外显子的小基因构建体的表达。转染的小基因产生的mRNA中N30外显子的包含发生在用丁酸盐处理的分化Y79细胞中，而未分化的Y79细胞和非神经元细胞系中则不发生。对小基因构建体的系统缺失和突变分析确定，神经元特异性N30外显子识别需要位于N30外显子下游约1.5千碱基处的顺式作用RNA序列。
