Alves Sandro, Marais Thibaut, Biferi Maria-Grazia, Furling Denis, Marinello Martina, El Hachimi Khalid, Cartier Nathalie, Ruberg Merle, Stevanin Giovanni, Brice Alexis, Barkats Martine, Sittler Annie
INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.
CNRS FRE3617, Center for Research in Myology, Sorbonne Universités UPMC Univ Paris 06, INSERM UMRS974, Institut de Myologie, G-H Pitié-Salpêtrière, 75013, Paris, France.
Mol Neurodegener. 2016 Jul 28;11(1):58. doi: 10.1186/s13024-016-0123-2.
We used lentiviral vectors (LVs) to generate a new SCA7 animal model overexpressing a truncated mutant ataxin-7 (MUT ATXN7) fragment in the mouse cerebellum, in order to characterize the specific neuropathological and behavioral consequences of the genetic defect in this brain structure.
LV-mediated overexpression of MUT ATXN7 into the cerebellum of C57/BL6 adult mice induced neuropathological features similar to that observed in patients, such as intranuclear aggregates in Purkinje cells (PC), loss of synaptic markers, neuroinflammation, and neuronal death. No neuropathological changes were observed when truncated wild-type ataxin-7 (WT ATXN7) was injected. Interestingly, the local delivery of LV-expressing mutant ataxin-7 (LV-MUT-ATXN7) into the cerebellum of wild-type mice also mediated the development of an ataxic phenotype at 8 to 12 weeks post-injection. Importantly, our data revealed abnormal levels of the FUS/TLS, MBNL1, and TDP-43 RNA-binding proteins in the cerebellum of the LV-MUT-ATXN7 injected mice. MUT ATXN7 overexpression induced an increase in the levels of the pathological phosphorylated TDP-43, and a decrease in the levels of soluble FUS/TLS, with both proteins accumulating within ATXN7-positive intranuclear inclusions. MBNL1 also co-aggregated with MUT ATXN7 in most PC nuclear inclusions. Interestingly, no MBNL2 aggregation was observed in cerebellar MUT ATXN7 aggregates. Immunohistochemical studies in postmortem tissue from SCA7 patients and SCA7 knock-in mice confirmed SCA7-induced nuclear accumulation of FUS/TLS and MBNL1, strongly suggesting that these proteins play a physiopathological role in SCA7.
This study validates a novel SCA7 mouse model based on lentiviral vectors, in which strong and sustained expression of MUT ATXN7 in the cerebellum was found sufficient to generate motor defects.
我们使用慢病毒载体（LVs）在小鼠小脑中构建了一种新的脊髓小脑共济失调7型（SCA7）动物模型，该模型过表达截短的突变型ataxin-7（MUT ATXN7）片段，以表征该脑结构中基因缺陷的特定神经病理学和行为后果。
LV介导的MUT ATXN7在C57/BL6成年小鼠小脑中的过表达诱导了与患者中观察到的相似的神经病理学特征，如浦肯野细胞（PC）中的核内聚集体、突触标记物的丧失、神经炎症和神经元死亡。注射截短的野生型ataxin-7（WT ATXN7）时未观察到神经病理学变化。有趣的是，将表达突变型ataxin-7的LV（LV-MUT-ATXN7）局部递送至野生型小鼠小脑中也在注射后8至12周介导了共济失调表型的发展。重要的是，我们的数据揭示了注射LV-MUT-ATXN7的小鼠小脑中FUS/TLS、MBNL1和TDP-43 RNA结合蛋白的异常水平。MUT ATXN7的过表达导致病理性磷酸化TDP-43水平升高，可溶性FUS/TLS水平降低，这两种蛋白都在ATXN7阳性核内包涵体中积累。MBNL1也在大多数PC核内包涵体中与MUT ATXN7共聚集。有趣的是，在小脑MUT ATXN7聚集体中未观察到MBNL2聚集。对SCA7患者和SCA7基因敲入小鼠的死后组织进行的免疫组织化学研究证实了SCA7诱导的FUS/TLS和MBNL1核内积累，强烈表明这些蛋白在SCA7中发挥生理病理作用。
本研究验证了一种基于慢病毒载体的新型SCA7小鼠模型，其中发现MUT ATXN7在小脑中的强烈且持续表达足以产生运动缺陷。
