Livide Gabriella, Patriarchi Tommaso, Amenduni Mariangela, Amabile Sonia, Yasui Dag, Calcagno Eleonora, Lo Rizzo Caterina, De Falco Giulia, Ulivieri Cristina, Ariani Francesca, Mari Francesca, Mencarelli Maria Antonietta, Hell Johannes Wilhelm, Renieri Alessandra, Meloni Ilaria
Medical Genetics, University of Siena, Siena, Italy.
1] Medical Genetics, University of Siena, Siena, Italy [2] Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA.
Eur J Hum Genet. 2015 Feb;23(2):195-201. doi: 10.1038/ejhg.2014.81. Epub 2014 Jun 11.
Rett syndrome is a monogenic disease due to de novo mutations in either MECP2 or CDKL5 genes. In spite of their involvement in the same disease, a functional interaction between the two genes has not been proven. MeCP2 is a transcriptional regulator; CDKL5 encodes for a kinase protein that might be involved in the regulation of gene expression. Therefore, we hypothesized that mutations affecting the two genes may lead to similar phenotypes by dysregulating the expression of common genes. To test this hypothesis we used induced pluripotent stem (iPS) cells derived from fibroblasts of one Rett patient with a MECP2 mutation (p.Arg306Cys) and two patients with mutations in CDKL5 (p.Gln347Ter and p.Thr288Ile). Expression profiling was performed in CDKL5-mutated cells and genes of interest were confirmed by real-time RT-PCR in both CDKL5- and MECP2-mutated cells. The only major change in gene expression common to MECP2- and CDKL5-mutated cells was for GRID1, encoding for glutamate D1 receptor (GluD1), a member of the δ-family of ionotropic glutamate receptors. GluD1 does not form AMPA or NMDA glutamate receptors. It acts like an adhesion molecule by linking the postsynaptic and presynaptic compartments, preferentially inducing the inhibitory presynaptic differentiation of cortical neurons. Our results demonstrate that GRID1 expression is downregulated in both MECP2- and CDKL5-mutated iPS cells and upregulated in neuronal precursors and mature neurons. These data provide novel insights into disease pathophysiology and identify possible new targets for therapeutic treatment of Rett syndrome.
瑞特综合征是一种单基因疾病，由MECP2或CDKL5基因的新发突变引起。尽管它们都与同一种疾病有关，但尚未证实这两个基因之间存在功能相互作用。MeCP2是一种转录调节因子；CDKL5编码一种激酶蛋白，可能参与基因表达的调控。因此，我们推测影响这两个基因的突变可能通过失调共同基因的表达导致相似的表型。为了验证这一假设，我们使用了诱导多能干细胞（iPS细胞），这些细胞来自一名患有MECP2突变（p.Arg306Cys）的瑞特综合征患者的成纤维细胞，以及两名患有CDKL5突变（p.Gln347Ter和p.Thr288Ile）的患者的成纤维细胞。对CDKL5突变细胞进行了表达谱分析，并通过实时RT-PCR在CDKL5和MECP2突变细胞中确认了感兴趣的基因。MECP2和CDKL5突变细胞共有的唯一主要基因表达变化是GRID1，它编码谷氨酸D1受体（GluD1），是离子型谷氨酸受体δ家族的成员。GluD1不形成AMPA或NMDA谷氨酸受体。它通过连接突触后和突触前区室发挥黏附分子的作用，优先诱导皮质神经元的抑制性突触前分化。我们的结果表明，GRID1在MECP2和CDKL5突变的iPS细胞中表达下调，而在神经元前体和成熟神经元中表达上调。这些数据为疾病病理生理学提供了新的见解，并确定了瑞特综合征治疗的可能新靶点。
