Barbon Alessandro, Vallini Ivan, La Via Luca, Marchina Eleonora, Barlati Sergio
Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnologies, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
Brain Res Mol Brain Res. 2003 Oct 7;117(2):168-78. doi: 10.1016/s0169-328x(03)00317-6.
The properties of some glutamate receptors are modified by RNA editing. This post-transcriptional mechanism involves the enzymatic deamination of specific adenosines in the pre-mRNA of the glutamate receptors, performed by specific RNA adenosine deaminases (ADARs). This event gives rise to the substitution of a gene-encoded amino acid with a different one that modifies the physiological properties of the ion channel. Here we report an analysis of the editing levels of AMPA GluR2, and kainate GluR5 and GluR6 in a human teratocarcinoma cell line (NT2) during in vitro neural differentiation, in conjunction with an analysis of the expression levels of GluR and ADAR genes. The editing levels were analysed using a specific standardised assay based on sequence analysis. This assay can be performed on all editing sites with a high level of sensitivity and reproducibility. Whereas GluR gene expression increased during NT2 neural differentiation, the expression of ADAR genes may be detected at comparable levels even in undifferentiated NT2 cells, remaining relatively stable during the differentiation process. Furthermore, most of the glutamate receptor editing sites increased their editing levels during NT2 neural differentiation, suggesting that the level of ADAR mRNAs is not closely related to the variable editing levels detected in the GluRs analysed. In human brain tissues, the editing levels appeared finely modulated in the different areas, indicating the possible formation of ion channels with different functional properties, thus generating a complex tissue-specific regulation of receptors and modulation of excitatory stimuli.
某些谷氨酸受体的特性会被RNA编辑所修饰。这种转录后机制涉及谷氨酸受体前体mRNA中特定腺苷的酶促脱氨作用，由特定的RNA腺苷脱氨酶（ADARs）执行。这一事件导致基因编码的氨基酸被另一种不同的氨基酸取代，从而改变离子通道的生理特性。在此，我们报告了在体外神经分化过程中，对人畸胎瘤细胞系（NT2）中AMPA GluR2、海人藻酸受体GluR5和GluR6的编辑水平的分析，同时分析了GluR和ADAR基因的表达水平。编辑水平采用基于序列分析的特定标准化检测方法进行分析。该检测方法可在所有编辑位点上进行，具有高灵敏度和可重复性。虽然在NT2神经分化过程中GluR基因表达增加，但即使在未分化的NT2细胞中也能检测到ADAR基因的表达处于相当水平，在分化过程中保持相对稳定。此外，在NT2神经分化过程中，大多数谷氨酸受体编辑位点的编辑水平增加，这表明ADAR mRNA的水平与所分析的GluRs中检测到的可变编辑水平没有密切关系。在人脑组织中，不同区域的编辑水平似乎受到精细调节，这表明可能形成具有不同功能特性的离子通道，从而产生复杂的组织特异性受体调节和兴奋性刺激调节。
