Astrocytes and motor neuron apoptosis

描述（由申请人提供） 通过Luis Barbeito博士之间的长期合作，我们在揭示涉及过氧亚硝酸盐形成的氧化应激如何导致肌萎缩侧索硬化症（ALS）运动神经元死亡方面取得了重大进展。我们提出了一种新的机制来解释锌缺乏SOD可能导致运动神经元疾病，并在过去的7年中共同撰写了12篇关于这些主题的论文。最近，我们发现星形胶质细胞可以在运动神经元变性中发挥致病作用。众所周知，在ALS患者以及过表达ALS突变体SOD-1的转基因小鼠和大鼠中，反应性星形胶质细胞包围退化的运动神经元。我们发现，过氧亚硝酸盐触发一个持久的表型转化星形胶质细胞，促进细胞凋亡的运动神经元培养的单层依赖于一氧化氮（NO）和过氧亚硝酸盐形成的机制。初步数据表明，星形胶质细胞合成的神经生长因子（NGF）及其前体形式proNGF通过激活“低亲和力”NGF受体p75 NTR触发运动神经元凋亡。我们假设缺锌SOD加一氧化氮将激活星形胶质细胞，并通过激活NGF/p75 NTR信号通路促进运动神经元死亡的进展。为了验证这一假设，我们提出的特点是否锌缺乏SOD可以使星形胶质细胞反应，并诱导神经生长因子的合成和分泌。将在培养的运动神经元上测试不同NGF形式的促凋亡活性，并进行体内研究以分析在G93 A转基因小鼠中阻断NGF/p75 NTR途径是否影响疾病进展。这些额外的研究将为星形胶质细胞可能导致ALS运动神经元进行性死亡提供重要的见解。停止ALS中运动神经元的进行性死亡可能具有巨大的临床意义。

DESCRIPTION (provided by applicant) Through a long lasting collaboration between Dr. Luis Barbeito, we have made major progress towards l unraveling how oxidative stress involving peroxynitrite formation causes the death of motor neurons in Amyotrophic Lateral Sclerosis (ALS). We have proposed a novel mechanism to explain how Zn-deficient SOD may cause motor neuron disease and have together coauthored 12 papers on these subjects over the past 7 years. Most recently, we have found that astroglia can play a pathogenic role in motor neuron degeneration. It is well known that reactive astrocytes surround degenerating motor neurons in ALS patients as well as in transgenic mice and rats over-expressing ALS mutant SOD-1. We found that peroxynitrite triggers a long-lasting phenotypic transformation in astrocytes, which promotes apoptosis of motor neurons cultured on the monolayers by mechanisms dependent on nitric oxide (NO) and peroxynitrite formation. Preliminary data implicates astrocytic synthesis of nerve growth factor (NGF) and its precursor form proNGF in triggering motor neuron apoptosis through activation of the "low affinity" NGF receptor p75NTR. We hypothesize that zinc-deficient SOD plus nitric oxide will activate astrocytes and contribute to the progression of motor neuron death through activating NGF/p75NTR signaling. To test this hypothesis, we propose to characterize whether zinc deficient SOD can make astrocytes reactive and induce NGF synthesis and secretion. The pro-apoptotic activity of the different NGF forms will be tested on cultured motor neurons and in vivo studies will be performed to analyze whether blockade of NGF/p75NTR pathway in G93A transgenic mice affect disease progression. These additional studies will provide important insight into astrocytes could contribute to the progressive death of motor neurons in ALS. Halting the progressive death of motor neurons in ALS could be of huge clinical significance.