Boissonneault Vincent, Plante Isabelle, Rivest Serge, Provost Patrick
Centre de Recherche en Rhumatologie et Immunologie and Laboratory of Molecular Endocrinology, Centre Hospitalier de l'Université Laval Research Center/Centre Hospitalier Universitaire de Québec, Quebec, Quebec G1V 4G2, Canada.
J Biol Chem. 2009 Jan 23;284(4):1971-81. doi: 10.1074/jbc.M807530200. Epub 2008 Nov 5.
MicroRNAs (miRNAs) are key regulatory RNAs known to repress mRNA translation through recognition of specific binding sites located mainly in their 3'-untranslated region (UTR). Loss of specific miRNA control of gene expression is thus expected to underlie serious genetic diseases. Intriguingly, previous post-mortem analyses showed higher beta-amyloid precursor protein-converting enzyme (BACE) protein, but not mRNA, levels in the brain of patients that suffered from Alzheimer disease (AD). Here we also observed a loss of correlation between BACE1 mRNA and protein levels in the hippocampus of a mouse model of AD. Consistent with an impairment of miRNA-mediated regulation of BACE1 expression, these findings prompted us to investigate the regulatory role of the BACE1 3'-UTR element and the possible involvement of specific miRNAs in cultured neuronal (N2a) and fibroblastic (NIH 3T3) cells. Through various experimental approaches, we validated computational predictions and demonstrated that miR-298 and miR-328 recognize specific binding sites in the 3'-UTR of BACE1 mRNA and exert regulatory effects on BACE1 protein expression in cultured neuronal cells. Our results may provide the molecular basis underlying BACE1 deregulation in AD and offer new perspectives on the etiology of this neurological disorder.
微小RNA（miRNA）是关键的调控RNA，已知其通过识别主要位于mRNA 3'非翻译区（UTR）的特定结合位点来抑制mRNA翻译。因此，特定miRNA对基因表达的调控缺失被认为是严重遗传疾病的基础。有趣的是，先前的尸检分析显示，患有阿尔茨海默病（AD）的患者大脑中β-淀粉样前体蛋白转化酶（BACE）的蛋白水平较高，但mRNA水平并不高。在这里，我们还观察到AD小鼠模型海马中BACE1 mRNA和蛋白水平之间的相关性丧失。与miRNA介导的BACE1表达调控受损一致，这些发现促使我们研究BACE1 3'-UTR元件的调控作用以及特定miRNA在培养的神经元（N2a）和成纤维细胞（NIH 3T3）中的可能参与情况。通过各种实验方法，我们验证了计算预测结果，并证明miR-298和miR-328识别BACE1 mRNA 3'-UTR中的特定结合位点，并对培养的神经元细胞中的BACE1蛋白表达发挥调控作用。我们的结果可能为AD中BACE1失调提供分子基础，并为这种神经疾病的病因学提供新的视角。
