Dendritic spine pathologies in hippocampal pyramidal neurons from Rett syndrome brain and after expression of Rett-associated MECP2 mutations.
Dendritic spine pathologies in hippocampal pyramidal neurons from Rett syndrome brain and after expression of Rett-associated MECP2 mutations.
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DOI：
10.1016/j.nbd.2009.05.001
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发表时间：
2009-08
影响因子：
6.1
通讯作者：
Pozzo-Miller L
中科院分区：
文献类型：
--
作者：
Chapleau CA;Calfa GD;Lane MC;Albertson AJ;Larimore JL;Kudo S;Armstrong DL;Percy AK;Pozzo-Miller L
Rett综合征（RTT）是一种X染色体连锁的神经发育障碍，与树突棘的特征性神经病理学相关，常见于表现为精神发育迟滞（MR）的疾病。在这里，我们提出了第一个定量分析的树突棘密度在死后的脑组织从女性RTT个人，这表明，海马CA 1区锥体神经元有较低的棘密度比年龄匹配的非MR女性对照个体。大多数RTT个体携带MECP 2突变，MECP 2是编码甲基化DNA结合转录调节因子的基因。虽然已经在Mecp 2缺陷小鼠RTT模型中证明了突触传递和可塑性的改变，但关于树突棘密度和形态的观察产生了不同的结果。我们研究了MeCP 2功能障碍对树突棘结构的后果，通过过表达（两倍）MeCP 2-GFP构建体编码野生型（WT）蛋白，或在RTT个体中常见的错义突变。用WT或突变型MECP 2（R106 W或T158 M）转染的海马切片培养物内的锥体神经元在表达48小时后显示出总棘密度的显著降低。有趣的是，表达WT MECP 2 96小时的神经元中的棘密度与对照神经元中的棘密度相当，而表达突变体MECP 2的神经元在表达96小时后继续具有比对照更低的棘密度。用特异性小发夹干扰RNA（shRNA）敲低内源性Mecp 2也降低树突棘密度，但仅在表达96小时后。另一方面，操纵MeCP 2水平对CA 3锥体神经元树突复杂性的影响很小。总之，这些结果表明RTT患者海马锥体神经元中树突棘密度降低，在表达RTT相关MECP 2突变的神经元中或在shRNA介导的内源性Mecp 2敲低后也发现了独特的树突表型，表明该表型代表MeCP 2功能障碍的细胞自主后果。
Rett syndrome (RTT) is an X chromosome-linked neurodevelopmental disorder associated with the characteristic neuropathology of dendritic spines common in diseases presenting with mental retardation (MR). Here, we present the first quantitative analyses of dendritic spine density in postmortem brain tissue from female RTT individuals, which revealed that hippocampal CA1 pyramidal neurons have lower spine density than age-matched non-MR female control individuals. The majority of RTT individuals carry mutations in MECP2, the gene coding for a methylated DNA-binding transcriptional regulator. While altered synaptic transmission and plasticity has been demonstrated in Mecp2-deficient mouse models of RTT, observations regarding dendritic spine density and morphology have produced varied results. We investigated the consequences of MeCP2 dysfunction on dendritic spine structure by overexpressing (∼twofold) MeCP2-GFP constructs encoding either the wildtype (WT) protein, or missense mutations commonly found in RTT individuals. Pyramidal neurons within hippocampal slice cultures transfected with either WT or mutant MECP2 (either R106W or T158M) showed a significant reduction in total spine density after 48hrs of expression. Interestingly, spine density in neurons expressing WT MECP2 for 96hrs was comparable to that in control neurons, while neurons expressing mutant MECP2 continued to have lower spines density than controls after 96hrs of expression. Knockdown of endogenous Mecp2 with a specific small hairpin interference RNA (shRNA) also reduced dendritic spine density, but only after 96hrs of expression. On the other hand, the consequences of manipulating MeCP2 levels for dendritic complexity in CA3 pyramidal neurons were only minor. Together, these results demonstrate reduced dendritic spine density in hippocampal pyramidal neurons from RTT patients, a distinct dendritic phenotype also found in neurons expressing RTT-associated MECP2 mutations or after shRNA-mediated endogenous Mecp2 knockdown, suggesting that this phenotype represent a cell-autonomous consequence of MeCP2 dysfunction.