A novel neuroferritinopathy mouse model (FTL 498InsTC) shows progressive brain iron dysregulation, morphological signs of early neurodegeneration and motor coordination deficits.
A novel neuroferritinopathy mouse model (FTL 498InsTC) shows progressive brain iron dysregulation, morphological signs of early neurodegeneration and motor coordination deficits.
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DOI：
10.1016/j.nbd.2014.10.023
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发表时间：
2015-09
影响因子：
6.1
通讯作者：
Levi S
中科院分区：
文献类型：
--
作者：
Maccarinelli F;Pagani A;Cozzi A;Codazzi F;Di Giacomo G;Capoccia S;Rapino S;Finazzi D;Politi LS;Cirulli F;Giorgio M;Cremona O;Grohovaz F;Levi S
神经铁蛋白病是一种罕见的遗传性疾病，由铁蛋白轻链基因(FTL)突变引起，常染色体显性遗传。它属于伴有脑铁蓄积的神经退行性变，这是一组铁调节失调与神经退行性变密切相关的疾病。我们研究了498-499InsTC突变，该突变导致L铁蛋白肽C末端最后9个氨基酸的替换和额外16个氨基酸的延长。对纯化的蛋白质进行循环伏安分析表明，这种结构修饰严重降低了蛋白质储存铁的能力。为了分析突变对体内的影响，我们在FVB和C57BL/6J株中建立了一些致病的人类FTL基因的小鼠模型。在FVB背景下的转基因小鼠显示，突变的铁蛋白在大脑中高度积累，根据磁共振成像的评分，这与铁沉积随年龄增加有关。值得注意的是，铁-铁蛋白小体的积累伴随着氧化损伤的迹象。在C57BL/6背景下，突变铁蛋白的表达和铁水平均低于FVB株。然而，这些小鼠在大脑中也表现出氧化改变。此外，与野生型神经元相比，从这些小鼠获得的出生后海马神经元在慢性铁超载和/或急性氧化应激下经历了显著的细胞死亡增加。超微结构分析显示，与铁沉积相关的脂褐素颗粒积累，特别是在我们的转基因小鼠的小脑和纹状体中。最后，对实验对象在2个月、8个月和18个月的整个发育和衰老过程中进行行为表型测试。Rotarod测试显示，随着年龄的增长，运动协调性逐渐受损，FTL突变老年小鼠从纹状体中积累更高的铁团聚体，表现出较短的从该装置坠落的潜伏期。我们的数据显示，我们的498-499InsTC小鼠模型概括了人类神经铁蛋白病的早期病理和临床特征，从而为该疾病的研究提供了一个有价值的模型。最后，我们提出了一个脂褐素形成的机制模型，该模型可以解释人类神经亚铁蛋白病的发病机制。我们建立了两种新的神经性铁蛋白病小鼠模型。核因子大脑的特点是铁/铁蛋白积聚和氧化损伤。核因子大脑显示与铁有关的脂褐素颗粒。提出了脂褐素的形成机理。NF小鼠表现出运动协调性受损的情况随着年龄的增长而增加。
Neuroferritinopathy is a rare genetic disease with a dominant autosomal transmission caused by mutations of the ferritin light chain gene (FTL). It belongs to Neurodegeneration with Brain Iron Accumulation, a group of disorders where iron dysregulation is tightly associated with neurodegeneration. We studied the 498–499InsTC mutation which causes the substitution of the last 9 amino acids and an elongation of extra 16 amino acids at the C-terminus of L-ferritin peptide. An analysis with cyclic voltammetry on the purified protein showed that this structural modification severely reduces the ability of the protein to store iron. In order to analyze the impact of the mutation in vivo, we generated mouse models for the some pathogenic human FTL gene in FVB and C57BL/6J strains. Transgenic mice in the FVB background showed high accumulation of the mutated ferritin in brain where it correlated with increased iron deposition with age, as scored by magnetic resonance imaging. Notably, the accumulation of iron–ferritin bodies was accompanied by signs of oxidative damage. In the C57BL/6 background, both the expression of the mutant ferritin and the iron levels were lower than in the FVB strain. Nevertheless, also these mice showed oxidative alterations in the brain. Furthermore, post-natal hippocampal neurons obtained from these mice experienced a marked increased cell death in response to chronic iron overload and/or acute oxidative stress, in comparison to wild-type neurons. Ultrastructural analyses revealed an accumulation of lipofuscin granules associated with iron deposits, particularly enriched in the cerebellum and striatum of our transgenic mice. Finally, experimental subjects were tested throughout development and aging at 2-, 8- and 18-months for behavioral phenotype. Rotarod test revealed a progressive impaired motor coordination building up with age, FTL mutant old mice showing a shorter latency to fall from the apparatus, according to higher accumulation of iron aggregates in the striatum. Our data show that our 498–499InsTC mouse models recapitulate early pathological and clinical traits of the human neuroferritinopathy, thus providing a valuable model for the study of the disease. Finally, we propose a mechanistic model of lipofuscine formation that can account for the etiopathogenesis of human neuroferritinopathy. We developed two new neuroferritinopathy mice models (NF). NF brains are characterized by iron/ferritin accumulation and oxidative damage. NF brains show granules of lipofuscine associated with iron. A mechanism of lipofuscine formation is proposed. NF mice show impaired motor coordination increasing with age.