利用干细胞进行丙戊酸诱发Alpers-Huttenlocher综合征肝毒性的机理研究

Alpers-Huttenlocher综合征（AHS）是线粒体DNA聚合酶POLG突变引起的遗传疾病，临床常有难治性癫痫和肝病等症状。丙戊酸是一种广谱抗癫痫药物，但对AHS病人进行治疗时，经常会导致病人急性肝衰竭（约1/3的病人服用3个月发生肝衰竭），机制一直不明。我们已经发现AHS病人肝细胞对丙戊酸诱导凋亡敏感，并通过线粒体途径凋亡（Hepatology, 2015）。本项目将通过诱导多能干细胞（iPS）技术建立疾病模型，研究丙戊酸诱发AHS特异肝毒性的内因外因，及基于机理的药物筛选，包括：（1）AHS病人肝细胞对丙戊酸诱导凋亡敏感的线粒体机制；（2）AHS病人肝细胞对丙戊酸诱导凋亡敏感的丙戊酸代谢机制；（3）利用AHS病人iPS细胞分化为肝细胞进行基因修复与药物筛选。本研究将阐明丙戊酸诱发AHS特异肝毒性的机理，建立相应的候选治疗策略，可望为肝脏内药物的毒理研究提供干细胞研究的范例。

Alpers-Huttenlocher syndrome (AHS) is a neurometabolic disorder caused by mutations in mitochondrial DNA polymerase gamma (POLG). Diagnosis of AHS is based on the clinical triad of intractable epilepsy, and characteristic liver disease. Valproic acid is widely used to treat epilepsy, but potentially causes idiosyncratic liver injury. AHS is associated with an increased risk of developing fatal valproic acid hepatotoxicity, and approximately one third of AHS patients develop liver failure within 3 months of exposure to valproic acid. However, the mechanistic link of this clinical mystery remains unknown. We have found that AHS hepatocytes are more sensitive to valproic acid-induced apoptosis, which is through mitochondrial pathway (Hepatology, 2015). In this project, we would study the mechanism and drug screening of valproic acid-induced hepatotoxicity in Alpers-Huttenlocher syndrome in an induced pluripotent stem cell (iPSC) model. The objects include: (1) Mitochondrial mechanism of AHS hepatocytes sensitivity to valproic acid induced apoptosis; (2) Valproic acid metabolic mechanism of AHS hepatocytes sensitivity to valproic acid induced apoptosis; (3) Gene correction and drug screening during AHS iPSCs differentiation to hepatocytes. Our research will elucidate the mechanism of valproic acid-induced hepatotoxicity in AHS, enable the evaluation of drugs for the therapeutic target, and provide a hepatotoxicity study model by using iPSCs.