Glial Dysfunction in Ataxia Telangiectasia

描述（由申请人提供）：该提案的重点是定义和表征遗传性疾病共济失调毛细血管扩张症（AT）中受影响的潜在新型细胞靶点。AT属于一类神经系统疾病，其中围产期发育似乎可以正常进展，但最终出现越来越严重的功能障碍。症状包括对电离辐射敏感、眼用不能、舞蹈病、手足徐动症、肌张力障碍、周围神经病、不育、7号和14号染色体易位、胸腺发育不全和导致生活质量差的肿瘤风险增加。大多数患者在生命的第二个或第三个十年早期死亡，虽然1988年首次确定了导致AT的遗传病变（称为ATM，AT突变），但尚未确定已知的治疗方法。虽然大多数研究都集中在主要病理可识别目标的生物学上，小脑神经元的进行性变性，但我们的研究揭示了AT小鼠模型CNS来源的星形胶质细胞的功能障碍。我们对ATM缺陷型星形胶质细胞的研究表明，一些关键功能受损的突变型星形胶质细胞，特别是居住在小脑，病理的主要网站。我们还表明，在共培养实验中，AT缺陷的小脑神经元显示出退化和生长障碍的迹象，而正常的野生型星形胶质细胞似乎能够保持突变神经元的完整性，并支持它们的生存。这些结果表明，星形胶质细胞功能障碍AT可能是一个重要的贡献者的神经病理。该建议扩展了我们的初步观察，我们建议在目标1中测试是否以及在何种程度上来自ATM脑的各个区域的星形胶质细胞在关键功能中受到损害，包括氧化应激的控制，生长因子的产生和细胞外环境中谷氨酸浓度的调节。在目标2中，我们将检验以下假设：星形胶质细胞群体中的缺陷已经发生在产生星形胶质细胞的前体细胞的阶段，因此是细胞内在的而不是区域强加的功能障碍。最后，我们在目标3中扩展了我们的共培养实验，以确定可用于纠正星形胶质细胞功能和拯救神经元细胞免于变性的策略。这种校正将检查三种治疗相关的可能性：在不同比例的正常星形胶质细胞和来自正常星形胶质细胞的条件培养基的存在下ATM衍生的细胞的生长，ATM衍生的小脑星形胶质细胞中异常的遗传校正和星形胶质细胞的药理学操作以减少其氧化应激。本申请的组成部分应提供有关星形胶质细胞是否导致神经元变性的明确信息。如果星形胶质细胞功能的恢复被证明是有益的，这将为AT的最终治疗提供一个全新的策略。该提案的重点是表征我们已经确定的一种新型细胞靶点，该靶点在遗传性疾病共济失调毛细血管扩张症（AT）中受到影响，AT属于一类致命的神经系统疾病，没有已知的治疗方法。我们提出的实验，将提供一个全新的战略，以治疗AT。

DESCRIPTION (provided by applicant): This proposal is focused on defining and characterizing a potentially novel cellular target that is affected in the genetic disease Ataxia telangiectasia (AT). AT belongs to a class of neurological disorders in which perinatal development can appear to progress normally, but in which increasingly severe dysfunction eventually emerges. Symptoms include sensitivity to ionizing radiation, oculomotor apraxia, chorea, athetosis, dystonia, peripheral neuropathy, infertility, translocations of chromosomes 7 and 14, underdeveloped thymus, and increased risk of neoplasms leading to poor quality of life. Most patients die during the second or early third decade of life and while the genetic lesions responsible for AT (called ATM, for AT-mutated) were first identified in 1988, no known therapy has been identified. While the majority of studies are focused on the biology of the primary pathological identifiable target, the progressive degeneration of cerebellar neurons, our studies revealed dysfunction in astrocytes derived from the CNS of a mouse model of AT. Our studies on ATM deficient astrocytes show that a number of critical functions are impaired in mutant astrocytes that specifically reside in the cerebellum, the major site of pathology. We also show in co-cultures experiments that AT-deficient cerebellar neurons shows signs of degeneration and growth impairment, while normal wildtype astrocytes seem to be able to maintain the integrity of mutant neurons and support their survival. These result suggest that the astrocytic dysfunction in AT might be a significant contributor to the neuronal pathology. This proposal extends upon our preliminary observations and we propose to test in Aim 1 whether and to what degree astrocytes derived from various regions of ATM brains are compromised in critical functions, including control of oxidative stress, production of growth factors and regulation of glutamate concentrations in the extracellular environment. In Aim 2 we will test the hypothesis that the defect in the astrocyte population is already occurring on the stage of the precursor cells that give rise to astrocytes and is hence a cell-intrinsic rather than regionally imposed dysfunction. Finally, we extend in Aim 3 our co-culture experiments to determine strategies that can be used to correct astrocyte function and rescue neuronal cells from degeneration. Such correction will examine three therapeutically relevant possibilities: growth of ATM-derived cells in the presence of varying proportions of normal astrocytes and of conditioned medium derived from normal astrocytes, genetic correction of abnormalities in ATM-derived cerebellar astrocytes and pharmacological manipulation of astrocytes to reduce their oxidative stress. The components of this application should provide clear information on whether astrocytes contribute to the neuronal degeneration. If restoration of astrocytic function proves beneficial, this would provide an entirely new strategy to the eventual treatment of AT. This proposal is focused on the characterization of a novel cellular target we have identified that is affected in the genetic disease Ataxia telangiectasia (AT), which belongs to a class of fatal neurological disorders with no known therapy. We propose experiments that would provide an entirely new strategy to the treatment of AT.