Martinez Hernandez Ana, Silbern Ivan, Geffers Insa, Tatenhorst Lars, Becker Stefan, Urlaub Henning, Zweckstetter Markus, Griesinger Christian, Eichele Gregor
Genes and Behavior Department, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany.
Front Neurosci. 2021 Jun 17;15:643391. doi: 10.3389/fnins.2021.643391. eCollection 2021.
α-synuclein (αSyn) is the main protein component of Lewy bodies, intracellular inclusions found in the brain of Parkinson's disease (PD) patients. Neurotoxic αSyn species are broadly modified post-translationally and, in patients with genetic forms of PD, carry genetically encoded amino acid substitutions. Mutations and C-terminal truncation can increase αSyn oligomerization and fibrillization. Although several genetic mouse models based on αSyn mutations and/or truncations exist, there is still a lack of mouse models for synucleinopathies not relying on overexpression. We report here two synucleinopathy mouse models, which are based on a triple alanine to proline mutation and a C-terminal truncation of αSyn, but do not overexpress the mutant protein when compared to the endogenous mouse protein. We knocked h or h (h stands for "human") into the murine locus. hαSyn is a structure-based mutant with triple alanine to proline substitutions that favors oligomers, is neurotoxic and evokes PD-like symptoms in . hαSyn lacks 21 amino acids at the C-terminus, favors fibrillary aggregates and occurs in PD. Knocking-in of h or h into the murine locus places the mutant protein under the control of the endogenous regulatory elements while simultaneously disrupting the gene. Mass spectrometry revealed that h and h mice produced 12 and 10 times less mutant protein, compared to mαSyn in wild type mice. We show phenotypes in 1 and 1.5 years old and mice, despite the lower levels of hαSyn and hαSyn expression. Direct comparison of the two mouse models revealed many commonalities but also aspects unique to each model. Commonalities included strong immunoactive state, impaired olfaction and motor coordination deficits. Neither model showed DAergic neuronal loss. Impaired climbing abilities at 1 year of age and a deviant gait pattern at 1.5 years old were specific for mice, while a compulsive behavior was exclusively detected in mice starting at 1 year of age. We conclude that even at very moderate levels of expression the two αSyn variants evoke measurable and progressive deficiencies in mutant mice. The two transgenic mouse models can thus be suitable to study αSyn-variant-based pathology and test new therapeutic approaches.
α-突触核蛋白（αSyn）是路易小体的主要蛋白质成分，路易小体是在帕金森病（PD）患者大脑中发现的细胞内包涵体。具有神经毒性的αSyn种类在翻译后经过广泛修饰，并且在患有遗传性PD的患者中携带基因编码的氨基酸替代。突变和C末端截短可增加αSyn的寡聚化和纤维化。尽管存在几种基于αSyn突变和/或截短的遗传小鼠模型，但仍然缺乏不依赖过表达的突触核蛋白病小鼠模型。我们在此报告两种突触核蛋白病小鼠模型，它们基于丙氨酸三联体到脯氨酸的突变以及αSyn的C末端截短，但与内源性小鼠蛋白相比，不表达突变蛋白。我们将h或h（h代表“人”）敲入小鼠基因座。hαSyn是一种基于结构的突变体，具有丙氨酸三联体到脯氨酸的替代，有利于寡聚体形成，具有神经毒性并在体内引发类似PD的症状。hαSyn在C末端缺少21个氨基酸，有利于纤维状聚集体形成，并且存在于PD中。将h或h敲入小鼠基因座可使突变蛋白受内源性调控元件控制，同时破坏基因。质谱分析显示，与野生型小鼠中的mαSyn相比，h和h小鼠产生的突变蛋白分别减少了12倍和10倍。尽管hαSyn和hαSyn表达水平较低，我们在1岁和1.5岁的和小鼠中显示出表型。对这两种小鼠模型的直接比较揭示了许多共性，但也有每个模型独特的方面。共性包括强烈的免疫活性状态、嗅觉受损和运动协调缺陷。两种模型均未显示多巴胺能神经元丢失。1岁时攀爬能力受损和1.5岁时步态异常是小鼠特有的，而强迫行为仅在1岁开始的小鼠中检测到。我们得出结论，即使在非常适度的表达水平下，这两种αSyn变体也会在突变小鼠中引发可测量的和进行性的缺陷。因此，这两种转基因小鼠模型可适合于研究基于αSyn变体的病理学并测试新的治疗方法。
