PDF(Pubmed)
Abstract：
ECHS1 Deficiency (ECHS1D) is a rare and devastating pediatric disease that currently has no defined treatments. This disorder results from missense loss-of-function mutations in the ECHS1 gene that result in severe developmental delays, encephalopathy, hypotonia, and early death. ECHS1 enzymatic activity is necessary for the beta-oxidation of fatty acids and the oxidation of branched-chain amino acids within the inner mitochondrial matrix. The pathogenesis of disease remains unknown, however it is hypothesized that disease is driven by an accumulation of toxic metabolites from impaired valine oxidation. To expand our knowledge on disease mechanisms, a novel mouse model of ECHS1D was generated that possesses a disease-associated knock-in (KI) allele and a knock-out (KO) allele. To investigate the behavioral phenotype, a battery of testing was performed at multiple time points, which included assessments of learning, motor function, endurance, sensory responses, and anxiety. Neurological abnormalities were assessed using wireless telemetry EEG recordings, pentylenetetrazol (PTZ) seizure induction, and immunohistochemistry. Metabolic perturbations were measured within the liver, serum, and brain using mass spectrometry and magnetic resonance spectroscopy. To test disease mechanisms, mice were subjected to disease pathway stressors and then survival, body weight gain, and epilepsy were assessed. Mice containing KI/KI or KI/KO alleles were viable with normal development and survival, and the presence of KI and KO alleles resulted in a significant reduction in ECHS1 protein. ECHS1D mice displayed reduced exercise capacity and pain sensation. EEG analysis revealed increased slow wave power that was associated with perturbations in sleep. ECHS1D mice had significantly increased epileptiform EEG discharges, and were sensitive to seizure induction, which resulted in death of 60% of ECHS1D mice. Under basal conditions, brain structure was grossly normal, although histological analysis revealed increased microglial activation in aged ECHS1D mice. Increased dietary valine only affected ECHS1D mice, which significantly exacerbated seizure susceptibility and resulted in death. Lastly, acute inflammatory challenge drove regression and early lethality in ECHS1D mice. In conclusion, we developed a novel model of ECHS1D that may be used to further knowledge on disease mechanisms and to develop therapeutics. Our data suggests altered metabolic signaling and inflammation may contribute to epilepsy in ECHS1D, and these alterations may be attributed to impaired valine metabolism.
摘要：
ECHS1缺乏症（ECHS1D）是一种罕见且破坏性的儿科疾病，目前尚无明确的治疗方法。这种疾病是由ECHS1基因的错义功能缺失突变导致的，这种突变会导致严重的发育迟缓。脑病,低张力,和早逝。ECHS1酶活性对于内线粒体基质内脂肪酸的β-氧化和支链氨基酸的氧化是必需的。疾病的发病机制尚不清楚,然而，据推测，疾病是由受损的缬氨酸氧化导致的有毒代谢物的积累。为了扩大我们对疾病机制的认识，产生了一种新的ECHS1D小鼠模型,该模型具有与疾病相关的敲入(KI)等位基因和敲除(KO)等位基因.为了调查行为表型，在多个时间点进行了一系列测试，其中包括学习评估，运动功能,耐力,感官反应，和焦虑。使用无线遥测脑电图记录评估神经系统异常，戊四氮（PTZ）诱发癫痫发作，和免疫组织化学。在肝脏内测量代谢扰动，血清,和大脑使用质谱和磁共振波谱。为了测试疾病机制，小鼠受到疾病途径应激源，然后存活，体重增加,并对癫痫进行了评估。含KI/KI或KI/KO等位基因的小鼠均能正常发育和存活，KI和KO等位基因的存在导致ECHS1蛋白显著减少。ECHS1D小鼠表现出降低的运动能力和疼痛感觉。EEG分析显示，慢波功率增加与睡眠扰动有关。ECHS1D小鼠癫痫样脑电图放电明显增加，对癫痫诱导敏感，导致60％的ECHS1D小鼠死亡。在基础条件下，大脑结构非常正常,尽管组织学分析显示老年ECHS1D小鼠的小胶质细胞活化增加。增加饮食缬氨酸仅影响ECHS1D小鼠，这显著加剧了癫痫的易感性，并导致死亡。最后,在ECHS1D小鼠中,急性炎症攻击导致其消退和早期致死率.总之,我们开发了一种新的ECHS1D模型，该模型可用于进一步了解疾病机制和开发治疗方法。我们的数据表明代谢信号和炎症的改变可能导致ECHS1D的癫痫，这些改变可能归因于缬氨酸代谢受损。
