Pejhan Shervin, Del Bigio Marc R, Rastegar Mojgan
Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
Front Cell Dev Biol. 2020 Aug 21;8:763. doi: 10.3389/fcell.2020.00763. eCollection 2020.
Rett Syndrome (RTT) is a rare and progressive neurodevelopmental disorder that is caused by mutations in the X-linked Methyl CpG binding protein 2 () gene and is subjected to X-chromosome inactivation. RTT is commonly associated with neurological regression, autistic features, motor control impairment, seizures, loss of speech and purposeful hand movements, mainly affecting females. Different animal and cellular model systems have tremendously contributed to our current knowledge about MeCP2 and RTT. However, the majority of these findings remain unexamined in the brain of RTT patients. Based on previous studies in rodent brains, the highly conserved neuronal microRNA "" was suggested to be an inhibitor of MeCP2 expression. The neuronal itself is induced by Brain Derived Neurotrophic Factor (BDNF), a neurotransmitter modulator, which in turn is controlled by MeCP2. This makes the basis of the feedback regulatory loop in the brain. Here, we studied the components of this feedback regulatory network in humans, and its possible impairment in the brain of RTT patients. In this regard, we evaluated the transcript and protein levels of /MeCP2E1 and E2 isoforms, /BDNF, and (both and strands) by real time RT-PCR, Western blot, and ELISA in four different regions of the human RTT brains and their age-, post-mortem delay-, and sex-matched controls. The transcript level of the studied elements was significantly compromised in RTT patients, even though the change was not identical in different parts of the brain. Our data indicates that MeCP2E1/E2-BDNF protein levels did not follow their corresponding transcript trends. Correlational studies suggested that the homeostasis regulation might not be similarly controlled in different parts of the human brain. Despite challenges in evaluating autopsy samples in rare diseases, our findings would help to shed some light on RTT pathobiology, and obscurities caused by limited studies on MeCP2 regulation in the human brain.
雷特综合征（RTT）是一种罕见的进行性神经发育障碍，由X连锁的甲基CpG结合蛋白2（MeCP2）基因突变引起，并受到X染色体失活的影响。RTT通常与神经功能退化、自闭症特征、运动控制障碍、癫痫发作、言语丧失和有目的的手部运动丧失有关，主要影响女性。不同的动物和细胞模型系统为我们目前对MeCP2和RTT的认识做出了巨大贡献。然而，这些发现中的大多数在RTT患者的大脑中尚未得到检验。基于先前对啮齿动物大脑的研究，高度保守的神经元微小RNA（miR-132）被认为是MeCP2表达的抑制剂。神经元miR-132本身由脑源性神经营养因子（BDNF）诱导，BDNF是一种神经递质调节剂，而BDNF又受MeCP2控制。这构成了大脑中miR-132反馈调节回路的基础。在此，我们研究了人类中这个反馈调节网络的组成部分，以及它在RTT患者大脑中可能存在的损伤。在这方面，我们通过实时RT-PCR、蛋白质印迹法和酶联免疫吸附测定法，评估了人类RTT大脑四个不同区域及其年龄、死后延迟时间和性别匹配的对照中MeCP2/MeCP2E1和E2异构体、BDNF以及miR-132（miR-132-5p和miR-132-3p两条链）的转录本和蛋白质水平。尽管大脑不同部位的变化不尽相同，但RTT患者中所研究元素的转录本水平显著受损。我们的数据表明，MeCP2E1/E2-BDNF的蛋白质水平并未遵循其相应转录本的趋势。相关性研究表明，miR-132的稳态调节在人类大脑的不同部位可能受到不同的控制。尽管在评估罕见病的尸检样本时存在挑战，但我们的发现将有助于阐明RTT的病理生物学，以及因对人类大脑中MeCP2调节的有限研究而产生的模糊之处。
