Exploring the Reversibilty of the Smith-Magenis Syndrome Phenotype

描述(由申请人提供)：基因组疾病是一种常见的疾病(每1000名新生儿中约有1名)，通常是由从头重排引起的零星疾病(3)。临床表型是位于重排基因组片段(S)内的一个基因(S)剂量异常的结果。SMS是一种伴有多种先天性异常的基因组疾病，与染色体17pl 1.2中3.7Mb的微缺失有关。通过染色体工程，我们已经产生了一种小鼠模型，df(Ll)17/+，它概括了在人类患者中观察到的表型(21，22)。最近，维甲酸诱导1基因(RAI1)的突变被证实是导致SMS的原因(11)。此外，Rail基因缺失的小鼠表现出与短信相关的异常(22)。该项目假设，在适当的时间恢复Rail蛋白的正常基因剂量可能会防止至少一些在小鼠模型中看到的SMS表型的发展。这一假说涉及两个关键问题：疾病表型可逆吗？如果是这样的话，什么时候开始治疗为时已晚？为了回答这些问题，我们提出：1.建立能够控制Rail时空表达的小鼠模型。我们将培育出在SMS的共线临界区存在杂合缺失和可诱导的野生型Rail等位基因的小鼠。为此，我们建议产生2只转基因小鼠：1只在四环素反应启动子下游携带一个额外的野生型Rail拷贝，另1只携带在Rail特异性启动子控制下的表达四环素抑制转录因子(TTA)的改良BAG转基因。通过这种方式，Rail转基因基因的表达可以在疾病进展的不同阶段以Rail启动子依赖的方式启动。2.观察不同时间点适量修复Rail的表型效应。我们将进行表型分析，观察颅面发育、体重和癫痫发作，作为表型可逆性或可预防性的第一个和快速的指示。此外，行为测试将被用来评估运动活动和昼夜节律。这项建议的目的是研究Smith-Magenis Syndorme(SMS)的可逆性，当Rail基因剂量在SMS的小鼠模型中以适当的时空方式校正时。这项研究将主要在智利国家卫生研究院#RO 1 DEI5210-02号补助金的延伸部分，与Katherina Walz博士合作，在智利的城市研究中心(CECS)进行。

DESCRIPTION (provided by applicant): Genomic disorders are frequent diseases (~1 per 1000 births) and often sporadic resulting from de novo rearrangements (3). The clinical phenotype is a consequence of abnormal dosage of a gene(s) located within the rearranged genomic fragment(s). SMS is a genomic disorder with multiple congenital anomalies associated with a microdeletion of 3.7 Mb in chromosome 17pl 1.2. By chromosome engineering we have generated a mouse model for SMS, Df(ll)17/+, that recapitulates phenotypes observed in human patients (21, 22). Recently, mutations in the retinoic acid induced 1 gene (RAI1) have been identified as causative of SMS (11). Additionally, mice null for Rail exhibit SMS-related abnormalities (22). This project postulates that restoring the normal gene dosage of Rail protein at an appropriate time might prevent the development of at least some of the phenotypes seen in the mouse model for SMS. This hypothesis entails 2 critical questions: Is the disease phenotype reversible? If so, when is it too late to begin therapy? To answer these questions, we propose to: 1. Generate mice in which we can control the spatial-temporal expression of Rail. We will produce mice that harbor a heterozygous deletion in the syntenic critical region of SMS and an inducible wild-type Rail allele. For this we propose to generate 2 transgenic mice: 1 that harbors an extra copy of wild-type Rail downstream of a tetracycline-responsive promoter, and a second 1 carrying a modified BAG transgene expressing the tetracycline-inhibitable transcription factor (tTA) under the control of Rail specific promoter. In this way, expression of the Rail transgene can be initiated in a Rail promoter-dependent manner at different stages of disease progression. 2. Characterize the phenotypic effects of restoring Rail at a proper dosage at various time points. We will perform phenotypic analysis, observing craniofacial development, body weight, and seizures as a first and quick indication of reversibility or preventability of the phenotype. In addition, behavioral tests will be used to evaluate locomotor activity, and circadian rhythm. The goal of this proposal is to study the reversibility of Smith-Magenis Syndorme (SMS) when the Rail gene dosage is corrected at an appropriate spacio-temporal manner in a mouse model for SMS. This research will be done primarily in Chile at the Centre de Estudios Cientificos (CECS), in collaboration with Dr. Katherina Walz, as an extention of NIH grant #RO 1 DEI5210-02.