Identification of Novel Drugs that Counter Huntington's Disease

描述（由申请人提供）：病理性细胞死亡发生在亨廷顿病（HD）、帕金森病、阿尔茨海默病和肌萎缩侧索硬化（ALS）的过程中，也发生在急性脑创伤和脑缺血之后。抑制半胱天冬酶（驱动程序性细胞死亡的酶）的药物可以减缓慢性变性并减少急性损伤后的损伤。由于线粒体释放细胞色素c会触发半胱天冬酶激活，因此阻断这一关键步骤应该会破坏细胞死亡程序。我们提出的药物发现方案有五个部分，构成以下五个具体目标：1）在四种神经系统疾病的细胞模型中测试抑制细胞色素c释放的化合物保护培养的神经元免受促凋亡刺激的能力。2)测定分子变化（即，半胱天冬酶激活、Bcl-2蛋白的翻译后变化、促凋亡因子从线粒体释放、线粒体膜电位的丧失）。将测试在（1）中发现具有保护作用的每种化合物对这些生化和生理过程的影响。3)在HD动物模型（R6/2小鼠）中测试那些拯救培养的神经元免于细胞死亡的实验药物。4)确定R6/2小鼠脑中因给予这些药物而产生的分子和生理变化。5)在R6/2小鼠中测试新药的有益作用是否会增加已知的HD疗法的有益作用。初步结果部分显示米诺环素对小鼠CNS的分离线粒体、培养神经元和组织具有平行作用。这样的观察激发了NINDS库中1040种化合物的筛选，以确定其阻断细胞色素c从纯化的线粒体释放的能力。潜在的假设是，如果其他药物在无细胞系统中具有与米诺环素相似的作用，则它们在体内易于具有相当的神经保护作用。显示该屏幕的结果。关于米诺环素的其他数据如下，即，该药物在细胞死亡的细胞模型中拯救神经元，并减缓R6/2小鼠的神经变性。使用上面概述的程序，我们希望识别和表征其他减缓HD进展的化合物。

DESCRIPTION (provided by applicant): Pathological cell death occurs in the course of Huntington's disease (HD), Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis (ALS) and also after acute brain trauma and cerebral ischemia. Drugs that inhibit caspases (enzymes that drive programmed cell death) slow down chronic degenerations and decrease damage following acute insult. Because the release of cytochrome c from mitochondria triggers caspase activation, blocking that critical step should derail the cell death program. Our proposed scheme for drug discovery has five portions which constitute the following five Specific Aims: 1) Testing compounds that inhibit the release cytochrome c for their ability to protect cultured neurons from pro-apoptotic stimuli in four cellular models of neurological disease. 2) Assaying molecular changes (i.e., caspase activation, post-translational changes to Bcl-2 proteins, release from mitochondria of apoptogenic factors, loss of mitochondrial membrane potentials) in these cultured cells. Each compound found to be protective in (1) will be tested for its effects on these biochemical and physiological processes. 3) Testing in an animal model of HD (the R6/2 mouse) those experimental drugs that rescue cultured neurons from cell death. 4) Determining the molecular and physiological changes in the brains of R6/2 mice that result from administration of these drugs. 5) Testing in R6/2 mice whether the beneficial effects of novel drugs add to those of known therapies for HD. The Preliminary Results section shows that minocycline has parallel effects upon isolated mitochondria, cultured neurons, and tissues of the mouse CNS. Such observations motivated a screen of 1040 compounds in an NINDS library for their ability to block cytochrome c release from purified mitochondria. The underlying assumption is that should other drugs have action similar to minocycline in the cell-free system, they are apt to have comparable neuroprotective effects in vivo. The results of this screen are presented. Additional data on minocycline follows, i.e., that the drug rescues neurons in cellular models of cell death and slows neurological degeneration in R6/2 mice. Using the program outlined above, we hope to identify and characterize other compounds that slow the progress of HD.