Wakeman J A, Heath P R, Pearson R C, Andrews P W
Department of Biomedical Science, University of Sheffield, UK.
Differentiation. 1997 Nov;62(2):97-105. doi: 10.1046/j.1432-0436.1997.6220097.x.
We have found that the MAL gene, which encodes a membrane proteolipid expressed during the late stages of T-lymphocyte maturation, is also activated during neuronal differentiation of NTERA2 human embryonal carcinoma cells following induction with retinoic acid. An RT-PCR fragment with a sequence identical to MAL was found amongst 30 cloned DNA fragments corresponding to genes putatively activated during NTERA2 differentiation and isolated using a differential display PCR screen. PCR and Northern blot analysis with a cloned MAL cDNA as a probe confirmed that MAL is not expressed by undifferentiated NTERA2 EC cells, but is expressed, predominantly as a 1.1 kb transcript, within 7 days of retinoic acid-induced differentiation and later in the post-mitotic neurons arising in such cultures. MAL was not expressed in the non-neuronal lineages induced by treatment of NTERA2 cells with the gratuitous inducer hexamethylene bisacetamide. Analysis of cDNA libraries constructed from EC cells, purified neurons and a sub-population of non-neuronal cells (ME311+), confirmed that expression of the MAL gene is activated in the neural lineage of NTERA2 differentiation. Using in situ hybridisation we found that MAL is expressed in the human CNS and especially in grey matter of the cerebral cortex, with less in the cerebellum and the amygdala and little or none in subcortical white matter. In contrast to reports concerning the expression pattern of a rat MAL homologue, MAL was expressed in the human brain predominantly in cell bodies which include neurons, correlating with in vitro data from the NTERA2 line.
我们发现，MAL基因编码一种在T淋巴细胞成熟后期表达的膜蛋白脂质，在用视黄酸诱导后，NTERA2人胚胎癌细胞在神经元分化过程中该基因也被激活。在用差异显示PCR筛选分离出的30个与NTERA2分化过程中可能被激活的基因对应的克隆DNA片段中，发现了一个序列与MAL相同的RT-PCR片段。以克隆的MAL cDNA为探针进行PCR和Northern印迹分析证实，未分化的NTERA2胚胎癌细胞不表达MAL，但在用视黄酸诱导分化7天内及此后在此类培养物中产生的有丝分裂后神经元中，MAL主要以1.1 kb转录本的形式表达。用游离诱导剂六亚甲基双乙酰胺处理NTERA2细胞诱导产生的非神经元谱系中不表达MAL。对由胚胎癌细胞、纯化的神经元和非神经元细胞亚群（ME311+）构建的cDNA文库进行分析，证实MAL基因在NTERA2分化的神经谱系中被激活。通过原位杂交我们发现，MAL在人类中枢神经系统中表达，尤其在大脑皮质灰质中表达，在小脑和杏仁核中表达较少，在皮质下白质中几乎不表达或不表达。与关于大鼠MAL同源物表达模式的报道相反，MAL在人类大脑中主要在包括神经元的细胞体中表达，这与来自NTERA2细胞系的体外数据相关。
