Exploring the Reversibilty of the Smith-Magenis Syndrome Phenotype

描述（由申请人提供）：基因组疾病是常见病（每1000个新生儿中约有1个），通常是由新生重排引起的散发性疾病(3)。临床表型是位于重排基因组片段内的基因(s)的异常剂量的结果。SMS是一种基因组疾病，具有多种先天性异常，与染色体17pl 1.2中3.7 Mb的微缺失有关。通过染色体工程，我们已经生成了SMS的小鼠模型，Df(ll)17/+，概括了在人类患者中观察到的表型（21,22）。最近，维甲酸诱导的1基因（RAI1）突变已被确定为SMS的病因（11）。此外，Rail基因缺失的小鼠表现出短信相关异常（22）。该项目假设，在适当的时间恢复正常的Rail蛋白基因剂量可能会阻止至少一些在SMS小鼠模型中看到的表型的发展。这一假设涉及两个关键问题：疾病表型是否可逆？如果是这样，什么时候开始治疗会太晚呢？为了回答这些问题，我们建议：生成可以控制Rail时空表达的小鼠。我们将产生在SMS的合成关键区域具有杂合缺失的小鼠和可诱导的野生型Rail等位基因。为此，我们提出了2只转基因小鼠：1只在四环素响应启动子下游携带一份野生型Rail的额外拷贝，另1只携带在Rail特异性启动子控制下表达四环素抑制转录因子（tTA）的修饰BAG转基因。通过这种方式，Rail转基因的表达可以在疾病进展的不同阶段以依赖于Rail启动子的方式启动。2. 描述在不同时间点以适当剂量恢复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快速指标。此外，行为测试将用于评估运动活动和昼夜节律。本研究的目的是研究在Smith-Magenis综合征（SMS）小鼠模型中，当Rail基因剂量以适当的时空方式校正时，SMS的可逆性。这项研究将主要在智利的科学研究中心（CECS）与Katherina Walz博士合作进行，作为NIH拨款#RO 1 DEI5210-02的延伸。

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.