Restless Legs Syndrome: Pathophysiology using Btbd9 Conditional Knockout Mice

描述(申请人提供)：不宁腿综合症(RLS)是一种慢性睡眠运动障碍，其特征是腿部有不适的感觉，并有无法控制的冲动移动腿部以缓解痛苦。过去的病理生理学研究将RLS与中枢多巴胺系统和铁代谢的紊乱联系在一起。家族和双胞胎研究有力地支持了基因对RLS发病机制的贡献。最近在发现与RLS相关的基因方面取得了巨大的进展。过去两年发表的三项独立研究都指出BTBD9在RLS中的作用。BTBD9蛋白的功能尚不清楚。目前的动物模型包括6-羟基多巴胺损伤的啮齿动物、缺铁小鼠和多巴胺受体3基因敲除小鼠。RLS基因的鉴定为建立RLS的基因分型模型奠定了基础，该模型将在阐明RLS的病理生理机制和开发治疗方法方面发挥更大的作用。我们研究的广泛和长期目标是使用完全和有针对性的条件基因敲除小鼠来确定：1)BTBD9蛋白在体内的功能，以及2)BTBD9蛋白的突变如何导致RLS。这个应用程序的具体目标是产生有条件的Btbd9基因敲除小鼠，并使用我们之前产生的完整的Btbd9基因敲除小鼠来回答这些问题。我们假设，不同的身体部位对RLS的病理生理学和症状有不同的贡献。我们进一步假设，BTBD9基因突变会导致中枢多巴胺系统的改变，特别是纹状体D2受体介导的间接途径。反过来，这些纹状体的改变会影响基底节的可塑性，特别是纹状体，并通过内在的和下游的影响，影响其他区域，如脊髓，导致不愉快的感觉，运动的冲动，以及其他RLS样表型。我们计划用以下具体目标来检验我们的假设。1)为了验证中枢神经系统功能改变是RLS病理生理学基础的假设，我们将建立Btbd9条件基因敲除小鼠，并分析RLS样行为和分子表型。2)为了验证Btbd9缺失扰乱多巴胺能系统的假说，我们将使用Btbd9完全敲除小鼠和Btbd9条件性敲除小鼠的多巴胺能神经元，并对纹状体和脊髓中的多巴胺能系统进行广泛而彻底的分析。3)为了验证btbd9基因缺失改变基底节回路和脊髓神经可塑性的假设，我们将对大脑皮质纹状体束和腰部进行电生理记录。 脊髓。上述特异性目标的成功完成将有助于我们确定BTBD9蛋白在体内的功能以及BTBD9突变是如何引起RLS的。这一结果将显著增加我们对RLS的病理生理学的了解，最终有助于RLS患者的治疗方法的发展。

DESCRIPTION (provided by applicant): Restless legs syndrome (RLS) is a chronic sleep motor disorder characterized by unpleasant sensations in the legs and an uncontrollable urge to move them for relief. Past pathophysiological studies have associated RLS to the disorder of the central dopaminergic system and iron metabolism. Family and twin studies strongly support a genetic contribution to the pathogenesis of RLS. Tremendous progress has been made recently of uncovering genes linked to RLS. Three independent studies published in the last two years all pointed to the role of BTBD9 in RLS. The function of BTBD9 protein is not known. Current animal models include 6-hydroxydopamine-lesioned rodents, iron deficiency mice, and dopamine receptor 3 knockout mice. The identification of the RLS genes paves the way for making genotypic model of RLS that will be more relevant in elucidating the pathophysiology of RLS and developing therapeutic treatments. The broad, long- term objective of our research is to use both complete and targeted conditional knockout mice to determine: 1) the function of the BTBD9 protein in vivo, and 2) how mutations in the BTBD9 protein can lead to RLS. The specific goal of this application is to generate conditional Btbd9 knockout mice and to use our previously generated complete Btbd9 knockout mice to answer these questions. We hypothesize that that different body regions contribute differently to the pathophysiology and symptomology of RLS. We further hypothesize that mutations in BTBD9 lead to alterations in the central dopaminergic system, in particular the striatal D2 receptor mediated indirect pathway. In turn these striatal alterations will affect plasticity in the basal ganglia, in particuar the striatum and, through intrinsic and downstream effects, other regions such as the spinal cord, leading to unpleasant sensations, an urge to move, and other RLS-like phenotypes. We plan to test our hypothesis with the following Specific Aims. 1) To test the hypothesis that functional alterations in the central nervous system underlie the pathophysiology of RLS, we will generate conditional knockout mice of Btbd9 and analyze for RLS-like behavioral and molecular phenotypes. 2) To test the hypothesis that loss of Btbd9 disrupts the dopaminergic system, we will use Btbd9 complete knockout mice and mice with Btbd9 conditionally knocked out in dopaminergic neurons only, and conduct an extensive and thorough analysis of the dopaminergic system in the striatum and spinal cord. 3) To test the hypothesis that loss of Btbd9 alters neural plasticity in basal ganglia circuitry and the spinal cord, we will perform electrophysiological recordings of the corticostriatal tract of the brain and lumbar section of the spinal cord. The successful completion of the above Specific Aims will help us to determine the function of BTBD9 protein in vivo and how the mutation of BTBD9 causes RLS. The results should significantly increase our understanding of the pathophysiology of RLS, which can ultimately aid the development of therapeutic treatments for RLS patients.