Mitochondrial Targets in Methylmalonic Acidemia

甲基丙二酸血症是一种遗传性代谢紊乱，影响1：48，000的新生儿，并导致神经功能障碍和全身性脑组织损伤，迄今为止几乎没有或没有有效的治疗。积累的甲基丙二酸（MMA）被认为是导致部分线粒体电子传递链抑制，导致能量剥夺和酸中毒类似于缺血/再灌注中发生的。这种应用是基于这样的假设，即保护免于由能量剥夺或缺血/再灌注诱导的细胞死亡的脑靶向药物可以证明在预防甲基丙二酸血症中的组织损伤中是有效的。本申请的具体目的是：1.以确定MMA对线粒体功能的影响。2.评价渗透性转变（过度Ca 2+摄取引起的非选择性线粒体内膜透化）在MMA诱导的线粒体改变中的作用。3.探讨ATP敏感性K+通道在MMA诱导的线粒体改变中的作用。4.研究MMA促进的线粒体改变及其预防对神经细胞活力和脑结构与功能的影响。这些研究将涉及使用体外模型，包括暴露于MMA的大鼠脑线粒体、细胞培养物和大鼠脑切片。研究人员还将使用涉及MMA全身和脑内注射的体内大鼠模型。将在使用的所有模型中评价ATP敏感性K+通道激动剂（如二氮嗪）和渗透性转换抑制剂（如环孢菌素A）的可能保护作用。在这项研究中获得的结果将有助于在甲基丙二酸学术界的组织损伤的机制的理解，并可能确定在这种疾病的组织保护线粒体的目标。

Methylmalonic acidemia is an inherited metabolic disorder that affects 1:48,000 newborns and leads to neurological impairment and generalized brain tissue damage, with little or no effective treatment to date. Accumulated methylmalonate (MMA) is believed to cause partial mitochondrial electron transport chain inhibition, resulting in energetic deprivation and acidosis similar to those occurring in ischemia/reperfusion. This application is based on the hypothesis that mitochondrially-targeted drugs that protect against cell death induced by energy deprivation or ischemia/reperfusion could prove effective in preventing tissue damage in methylmalonic acidemia. The specific aims of this application are: 1. to determine the effects of MMA on mitochondrial function. 2. To evaluate the role of the permeability transition, a non-selective inner mitochondrial membrane permeabilization caused by excessive Ca2+ uptake, in mitochondrial alterations induced by MMA. 3. To assess the role of ATP-sensitive K+ channels in mitochondrial alterations induced by MMA. 4. To study the effects of mitochondrial alterations promoted by MMA and their prevention on neural cell viability and brain structure and function. These studies will involve the use of in vitro models including rat brain mitochondria, cell cultures, and rat brain slices exposed to MMA. The investigators will also use in vivo rat models involving systemic and intracerebral injections of MMA. The possible protective effects of ATP-sensitive K+ channel agonists (such as diazoxide) and permeability transition inhibitors (such as cyclosporin A) will be evaluated in all models used. Results obtained in this study will contribute toward the understanding of mechanisms of tissue damage in methylmalonic academia, and potentially determine mitochondrial targets for tissue protection in this disease.