Novel drug treatments for pyruvate dehydrogenase complex deficiency

 描述（由申请人提供）：葡萄糖作为发育和成年期间大脑中能量产生的主要可氧化燃料，因此葡萄糖代谢受损可能对大脑发育和功能产生严重后果。丙酮酸脱氢酶（PDH）复合物（PDC）的遗传缺陷与严重的神经系统畸形和脑功能受损有关。在大多数情况下，PDC缺陷是由于位于X染色体上的PDHA1基因缺陷，因此受影响的男性和女性表现出疾病的严重程度相当不同。我们已经开发了一种小鼠模型，该模型携带X连锁Pdha1基因突变。我们的研究结果表明，发育中的小鼠大脑中的PDC缺陷导致许多相同的结构缺陷，这些缺陷已在受影响的儿童中报道。标准治疗如生酮饮食和补充维生素，已被证明在PDC缺陷患者中效果较差。我们的小鼠模型提供了一个机会，探索其他化合物的功效，以增加乙酰辅酶A的形成，通过使用苯丁酸酯，一种有效的PDH激酶抑制剂，激活残留的无活性磷酸化PDC活性，或通过增强氨基酸catalysts通过线粒体代谢使用雷帕霉素，一种mTOR的抑制剂，在出生后立即生活。我们的两个具体目标是：（i）研究出生后早期用PDK激酶抑制剂丁酸苯酯治疗的潜在有益效果，目的是在残余活性PDC活性水平上增强葡萄糖氧化，以改善小脑发育，以及（ii）研究在哺乳期给予雷帕霉素以增加氨基酸氧化和减少线粒体功能障碍的有益作用，PDC缺陷小鼠小脑发育异常。我们将使用以下三个参数研究这两种药物的有益效果的功效：（i）小脑皮质的组织学和免疫组织学分析以及半定量形态测定分析，（ii）BrdU标记和免疫染色以监测产后期细胞的分化、迁移和增殖，以及（iii）断奶后期小脑功能的行为评价。这一全面的研究有望为临床上重要的遗传性代谢紊乱（如PDC缺乏症）提供新的治疗方法，该疾病限制了大脑的葡萄糖代谢。苯丁酸和雷帕霉素用于改善PDC缺陷结果的测试是新的翻译前方法。这些化合物具有很高的潜力，可为治疗PDC缺陷患者提供新的治疗方法，并可改善生活质量，挽救生命，降低医疗保健成本。

 DESCRIPTION (provided by applicant): Glucose serves as the primary oxidizable fuel for energy production in the brain during development and adulthood, and hence an impairment in glucose metabolism can have severe consequences on brain development and function. Genetic defects of the pyruvate dehydrogenase (PDH) complex (PDC) are associated with severe neurological malformations and impaired cerebral function. In the large majority of cases of PDC deficiency is due to defects in the PDHA1 gene located on chromosome X, and hence affected males and females manifest severity of the disease quite variably. We have developed a murine model that carries a mutation in the X-linked Pdha1 gene. Our findings show that PDC deficiency in the developing mouse brain results in many of the same structural defects that have been reported in affected children. The standard treatments such as ketogenic diet and supplementation of vitamins, have proven to be less effective in PDC- deficient patients. Our mouse model presents an opportunity to explore the efficacy of other compounds to increase acetyl-CoA formation by either activation of residual inactive phosphorylated PDC activity using phenylbutyrate, a potent inhibitor of PDH kinases, or by enhacing amino acid catabolism via mitochondrial metabolism using rapamycin, an inhibitor of mTOR, in the immediate postnatal life. Our two specific aims are to: (i) Investigate the potential beneficial effects of an early postnatal treatment with phenylbutyrate, an inhibitor of PDK kinases, aiming to enhance glucose oxidation at the level of residual active PDC activity to improve cerebellar development, and (ii) investigate beneficial effects of rapamycin administration during the suckling period to increase amino acid oxidation and to reduce mitochondrial dysfunction to minimize abnormal cerebellar development in PDC-deficient mice. We will investigate the efficacy for beneficial effects of these two drugs using the following three parameters: (i) histological and immuno-histological analyses and semi- quantitative morphometric analysis of cerebellar cortex, (ii) BrdU labeling and immunostaining to monitor differentiation, migration and proliferation of cells in the postnata period, and (iii) behavioral evaluation of the cerebellar function in the postweaning period. This comprehensive set of studies promises to provide insight into novel therapeutic treaments for a clinically important inherited metabolic disorder such as PDC deficiency which limits glucose metabolism by the brain. Testing of phenylbutyrate and rapamycin for improvement in PDC deficiency outcomes are novel pre-translational approaches. These compounds have a high potential to provide new therapeutic approaches for treating PDC deficient patients and could improve quality of life, save lives, and reduce health care costs.