Role of ABC efflux transporters in ALS

描述（由申请人提供）：药物渗透有限是治疗中枢神经系统疾病中经常遇到的障碍。可能导致这种现象的一种机制是atp结合盒（ABC）药物外排转运体（即p -糖蛋白或P-gp，多药耐药蛋白或MRPs，乳腺癌耐药蛋白或BCRP，又称ABCG2）在血脑屏障（BBB）和血脑脊液（BCSF）屏障的表达。ABC转运蛋白也在较小程度上定位于中枢神经系统薄壁细胞，在那里它们作为神经物质渗透的次级屏障。外排转运体还挤出分解代谢物和毒素，以防止它们在细胞中有害的积累，这是细胞适应疾病介导和环境应激的主要机制。肌萎缩性侧索硬化症（ALS）是一种运动系统的神经退行性疾病，对ABC转运蛋白的定位和调控知之甚少。我们的初步数据显示，在SOD1-G93A ALS小鼠模型以及散发性和家族性ALS患者脊髓标本匀浆中，P-gp在脊髓星形胶质细胞中的表达增加。从治疗的角度来看，这表明疾病增加了药物穿透中枢神经系统的障碍，必须克服这一障碍才能开发出有效的ALS药物治疗方法。鉴于它们的多特异性，外排转运蛋白在中枢神经系统疾病中的重要作用是毋庸置疑的，尽管一些重要问题仍未得到解答。例如：ALS如何影响外排转运蛋白的定位和功能？哪些als特异性信号通路负责P-gp的上调？ALS介导的P-gp和/或其他ABC转运蛋白上调是否会改变我们对疾病小鼠模型的治疗方式，并最终改变ALS患者的治疗方式？为了填补这一知识空白，我们提出：(1)研究P- gp和其他相关ABC药物转运体在ALS中的活性、表达和分布特征；(2)研究非神经元细胞外排转运蛋白活性是否与肌萎缩性侧索硬化症（ALS）体内和体外模型运动神经元变性有关；(3)探讨消除ABC转运蛋白功能对ALS治疗的影响。

DESCRIPTION (provided by applicant): Limited drug penetration is an obstacle that is often encountered in the treatment of CNS diseases. One mechanism that may contribute to this phenomenon is the expression of ATP-binding cassette (ABC) drug efflux transporters (i.e. P-glycoprotein or P-gp, Multi-drug resistance proteins or MRPs, breast cancer resistance protein or BCRP, a.k.a. ABCG2) at the blood brain barrier (BBB) and blood cerebrospinal fluid (BCSF) barrier. ABC transporters also localize to a lesser extent at the CNS parenchyma cells where they act as secondary barrier to neural penetration of substances. Efflux transporters also extrude catabolites and toxins to prevent their harmful accumulation in the cell, constituting the major mechanism of cell adaptation to disease-mediated and environmental stress. Little is known on ABC transporters localization and regulation in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease of the motor system. Our preliminary data show increased P-gp expression in spinal cord astrocytes of the SOD1-G93A mouse model of ALS as well as in spinal cord specimen homogenates of sporadic and familial ALS patients. From a therapeutic perspective, this suggests that the obstacle to drug penetration in the CNS is increased by the disease and must be overcome to develop effective pharmacotherapies for ALS. Given their multi-specificity, the recognition of efflux transporters as critical players in CNS diseases is unquestioned although important questions remain unanswered. For example: How does ALS affect efflux transporters localization and function? Which ALS-specific signaling pathways are responsible for up-regulation in P-gp? Will ALS-mediated up-regulation in P-gp and/or other ABC transporters change how we therapeutically treat the mouse model of the disease, and ultimately ALS patients? To fill this gap in knowledge, we propose: (1) To investigate activity, expression and distribution profile of P- gp and other relevant ABC drug transporters in ALS; (2) To study whether efflux transporter activity in non- neuronal cells contributes to motor neuron degeneration in in-vitro and in-vivo models of ALS; (3) To investigate the impact of eliminating ABC transporter function on ALS therapeutics. PUBLIC HEALTH RELEVANCE: Amyotrophic lateral sclerosis (ALS) is one of the most devastating and lethal progressive neuromuscular disorders, affecting motor neurons in the spinal cord and motor cortex. Over 30,000 people are living with this disease in the United States and approximately 5,000 Americans will be diagnosed with ALS this year. Multidrug efflux ABC transporters limit the entry into the brain and spinal cord of a large number of drugs, contributing to the poor success rate of promising drug candidates, and regulate the extrusion of a variety of substances, including catabolites and potential toxic molecules that could be harmful to cells. Modulating the activity and expression pattern of these transporters could therefore improve drug delivery into the brain and spinal cord and affect the overall cellular homeostasis. In this application we propose to study the regulation and role of these ABC transporters in ALS. Our ultimate goal is to understand the pathogenic mechanisms of ALS to improve the chances of success of pharmacotherapy for this disease.