Trophic Factor Signaling and Motor Neuron Death

描述（由申请人提供）：肌萎缩性侧索硬化症（ALS）的中心病理事件是运动神经元的选择性变性。虽然大多数病例（-90%）是散发的，但家族性病例是由于各种不同基因的突变，如SOD1和p150glue。谷氨酸受体的过度激活（兴奋性毒性）是一个早期触发事件。利用分离的鼠类胚胎脊髓组织进行细胞培养，可以研究运动神经元因兴奋毒性损伤或基因表达突变而死亡。我们之前的体外研究表明，兴奋性毒性运动神经元死亡仅发生在通过TrkB传递的脑源性神经营养因子（BDNF）信号完整的情况下。磷脂酰肌醇3′激酶（pi3′k）信号级联被TrkB激活，pi3′k信号是bdnf诱导的运动神经元兴奋性毒性死亡的必要和充分条件。抑制Trk激活的药理学操作也可以保护运动神经元免受突变SOD1和p150glue的毒性作用。这可以通过K252a的专有衍生物（由Cephalon制药公司制造）或通过抑制腺苷A2A受体的激活来实现。在具体目标#1中，我们将检查这些药物给药后细胞内信号级联的改变。突变体SOD1与p150glue和Trk信号事件之间的潜在相互作用也将被研究。在具体目标#2中，我们将研究这些药物对Trk激活和信号传导的体内药效学。这是未来研究的前奏，我们希望在ALS动物模型中检查这些药物的功效。在具体目标#3中，我们将研究激活的PIS‘K（两种丝氨酸-茶氨酸激酶（PDK1, Akt）和RhoA和Arf家族的小单体GTP’酶）下游的信号级联，以了解哪些是唤醒运动神经元兴奋毒性敏感性所需要的。这将定义运动神经元的敏感性-毒性细胞内信号通路。相关性：提出的工作试图将基础科学观察转化为ALS的新治疗方法。针对肌萎缩侧索硬化症的新药物靶点的开发可以为其他更普遍的神经退行性疾病的新疗法提供指导。

DESCRIPTION (provided by applicant): The central pathologic event in Amyotrophic Lateral Sclerosis (ALS) is the selective degeneration of motor neurons. While most cases (-90%) are sporadic, the familial cases are due to mutations in a variety of different genes such as SOD1 and p150glued. Excessive activation of glutamate receptors (excitotoxicity) is an early triggering event. The death of motor neurons from excitotoxic insult or mutant gene expression can be studied in cell culture using dissociated rodent embryonic spinal cord tissue. Our previous in vitro work demonstrates that excitotoxic motor neuron death only occurs if Brain-derived neuronotrophic factor (BDNF) signaling via TrkB is intact. The phosphatidylinositol 3' kinase (PI3'K) signaling cascade is activated by TrkB and PI3'K signaling is necessary and sufficient for BDNF-induced excitotoxic death of motor neuron. Pharmacological manipulations that inhibit Trk activation can also protect motor neurons from the toxic effects of mutant SOD1 and p150glued. This can be accomplished using proprietary derivatives of K252a (made by Cephalon Pharmaceuticals) or by inhibiting the activation of adenosine A2A receptors. In specific aim #1 we will examine the alterations in intracellular signaling cascades that follow from administration of these agents. The potential interplay between mutant SOD1 and p150glued and Trk signaling events will also be studied. In specific aim #2, we will study the in vivo pharmacodynamics of these agents on Trk activation and signaling. This is a prelude to future studies in which we hope to examine the efficacy of these agents in animal models of ALS. In specific aim #3 we will study the signaling cascades downstream of activated PIS'K (two serine-theonine kinases (PDK1, Akt) and small monomeric GTP'ases of the RhoA and Arf families) to see which is needed to evoke excitotoxic sensitivity of motor neurons. This will define susceptibility-to-toxicity intracellular signaling pathways in motor neurons. Relevance: The proposed work attempts to translate basic science observations into new treatments for ALS. The development of new drug targets for ALS could guide the way for novel therapies for other, more prevalent, neuro-degenerative disorders.