探讨 Rett 综合征中 MeCP2 与氧化应激之间的可能联系。
Exploring the possible link between MeCP2 and oxidative stress in Rett syndrome.
机构信息
Institute of Biosciences and BioResources-CNR, UOS Naples, Italy; IRCCS Neuromed, Pozzilli, Italy.
Child Neuropsychiatry Unit, University General Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy.
出版信息
Free Radic Biol Med. 2015 Nov;88(Pt A):81-90. doi: 10.1016/j.freeradbiomed.2015.04.019. Epub 2015 May 8.
Rett syndrome (RTT, MIM 312750) is a rare and orphan progressive neurodevelopmental disorder affecting girls almost exclusively, with a frequency of 1/15,000 live births of girls. The disease is characterized by a period of 6 to 18 months of apparently normal neurodevelopment, followed by early neurological regression, with a progressive loss of acquired cognitive, social, and motor skills. RTT is known to be caused in 95% of the cases by sporadic de novo loss-of-function mutations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene encoding methyl-CpG binding protein 2 (MeCP2), a nuclear protein able to regulate gene expression. Despite almost two decades of research into the functions and role of MeCP2, little is known about the mechanisms leading from MECP2 mutation to the disease. Oxidative stress (OS) is involved in the pathogenic mechanisms of several neurodevelopmental and neurodegenerative disorders, although in many cases it is not clear whether OS is a cause or a consequence of the pathology. Fairly recently, the presence of a systemic OS has been demonstrated in RTT patients with a strong correlation with the patients' clinical status. The link between MECP2 mutation and the redox imbalance found in RTT is not clear. Animal studies have suggested a possible direct correlation between Mecp2 mutation and increased OS levels. In addition, the restoration of Mecp2 function in astrocytes significantly improves the developmental outcome of Mecp2-null mice and reexpression of Mecp2 gene in the brain of null mice restored oxidative damage, suggesting that Mecp2 loss of function can be involved in oxidative brain damage. Starting from the evidence that oxidative damage in the brain of Mecp2-null mice precedes the onset of symptoms, we evaluated whether, based on the current literature, the dysfunctions described in RTT could be a consequence or, in contrast, could be caused by OS. We also analyzed whether therapies that at least partially treated some RTT symptoms can play a role in defense against OS. At this stage we can propose that OS could be one of the main causes of the dysfunctions observed in RTT. In addition, the major part of the therapies recommended to alleviate RTT symptoms have been shown to interfere with oxidative homeostasis, suggesting that MeCP2 could somehow be involved in the protection of the brain from OS.
雷特综合征(RTT,MIM 312750)是一种罕见的、孤儿的进行性神经发育障碍,几乎仅影响女孩,发病率为每 15000 名活产女婴中有 1 例。该疾病的特征是在 6 至 18 个月的时间内出现明显正常的神经发育,随后出现早期神经退行性变,逐渐丧失获得的认知、社会和运动技能。已知 95%的病例是由 X 连锁甲基-CpG 结合蛋白 2(MECP2)基因的散发性从头失能突变引起的,该基因编码甲基-CpG 结合蛋白 2(MeCP2),是一种能够调节基因表达的核蛋白。尽管对 MeCP2 的功能和作用进行了近二十年的研究,但对于导致 MECP2 突变的疾病的机制知之甚少。氧化应激(OS)参与了几种神经发育和神经退行性疾病的发病机制,尽管在许多情况下尚不清楚 OS 是病理的原因还是后果。最近,已经在 RTT 患者中证明了存在全身性 OS,并且与患者的临床状况有很强的相关性。MECP2 突变与 RTT 中发现的氧化还原失衡之间的联系尚不清楚。动物研究表明,Mecp2 突变与 OS 水平升高之间可能存在直接相关性。此外,星形胶质细胞中 Mecp2 功能的恢复显著改善了 Mecp2 缺失小鼠的发育结局,并且 Mecp2 缺失小鼠大脑中的 Mecp2 基因的重新表达恢复了氧化损伤,这表明 Mecp2 功能丧失可能参与了氧化应激引起的脑损伤。从 Mecp2 缺失小鼠的大脑中氧化损伤先于症状发作的证据出发,我们评估了根据目前的文献,RTT 中描述的功能障碍是否是 OS 的结果,或者相反,是否是由 OS 引起的。我们还分析了至少部分缓解 RTT 症状的治疗方法是否可以在抵御 OS 方面发挥作用。在现阶段,我们可以提出 OS 可能是 RTT 中观察到的功能障碍的主要原因之一。此外,建议缓解 RTT 症状的大部分治疗方法已被证明可以干预氧化平衡,这表明 MeCP2 可能以某种方式参与了大脑对 OS 的保护。