Creatine Transport Across the Blood Brain Barrier

描述（由申请人提供）：最近，我们描述了一名6岁男孩的严重表达和认知延迟，该男孩患有独特的脑肌酸（Cr）缺乏症，经质子磁共振波谱（MRS）诊断。 经进一步分析，我们发现，他有一个无义突变的X线铬转运蛋白基因（CT 1; SLC 6A 8），这导致在一个截短的（非功能性）铬转运蛋白的表达。 自该研究以来，在辛辛那提又发现了4个X连锁铬转运蛋白基因突变的家族，在全球范围内发现了近30个家族。 这些患者都有智力低下，严重的表达性语言障碍和轻度癫痫。 尽管关于脑中Cr、Cr激酶和磷酸肌酸系统的知识越来越多，但当脑肌酸转运蛋白缺乏时，没有标准化的方法用于改善脑功能。 显然需要的是这种疾病的合适的动物模型，使得可以开发和测试使肌酸穿过血脑屏障的方法。 在这个项目中，我们将开发一个铬转运蛋白基因敲除小鼠模型，这样就可以测试新的治疗模式，药物和其他疗法的疗效。对于本研究项目，我们建议测试以下假设：1）敲除这种Cr转运缺陷的小鼠可以模拟人类疾病，以及2）可以给予治疗策略以使这些小鼠的脑功能正常化。 这种小鼠基因敲除将模拟我们发现的Cr转运蛋白缺陷，即大脑缺乏转运肌酸穿过血脑屏障的能力。 为了解决假设1，我们将产生Cr转运蛋白敲除小鼠。 将测定这些小鼠脑中的Cr水平，我们将表征在Cr转运蛋白敲除小鼠中观察到的功能和生化变化。 拥有一个与人类疾病密切相关的动物模型将能够充分测试和开发旨在使肌酸穿过血脑屏障和改善脑功能的疗法。 为了解决假设2，Cr转运蛋白敲除小鼠和对照小鼠将用Cr制剂处理，所述Cr制剂可能能够转运肌酸穿过血脑屏障并改善小鼠的脑代谢和认知功能。 假设2的目标是开发方法和药物，通过使肌酸进入大脑来改善大脑能量代谢。

DESCRIPTION (provided by applicant): Recently, we described severe expressive and cognitive delays in a 6-year-old boy, who has a unique creatine (Cr) deficiency in the brain, which was diagnosed by proton magnetic resonance spectroscopy (MRS). Upon further analysis, we found that he has a nonsense mutation in the X-lined Cr transporter gene (CT1;SLC6A8), which resulted in the expression of a truncated (non-functional) Cr transporter protein. Since that study, four additional families have been recognized in Cincinnati with mutations in the X-linked Cr transporter gene and nearly 30 families worldwide. These patients all have mental retardation, severe expressive language disorder and mild epilepsy. Despite a growing body of knowledge about the Cr, Cr kinase and phosphocreatine system in the brain, there is no standardized method for improving brain function when the brain creatine transporter is deficient. What is clearly needed is a suitable animal model of this disease such that methods to get creatine across the blood brain barrier can be developed and tested. In this project we will develop a Cr transporter knockout mouse model, such that the efficacy of new treatment paradigms, drugs, and other therapies can be tested. For this research project, we propose to test the following hypotheses: 1) a mouse knockout of this Cr transport defect can model the human disease, and 2) that therapeutic strategies can be given to normalize brain function in these mice. This mouse knockout will model the Cr transporter defect we have discovered in that the brain will lack the ability to transport creatine across the blood brain barrier. To address Hypothesis 1, we will generate a Cr transporter knockout mouse. Cr levels will be determined in the brains of these mice and we will characterize the functional, and biochemical changes observed in Cr transporter knockout mice. Having an animal model that closely mirrors the human disease will enable adequate testing and development of therapies designed at getting creatine across the blood brain barrier and improving brain function. To address Hypothesis 2, the Cr transporter knockout mice and control mice will be treated with Cr formulations that may be capable of transporting creatine across the blood brain barrier and improve brain metabolism and cognitive function of the mice. The goal for Hypothesis 2 is to develop methods and drugs to improve brain energy metabolism by getting creatine into the brain.