Byrne Matthew D, Petramfar Peyman, Lee Jae-Kyung, Smeyne Richard Jay
Thomas Jefferson University.
University of Georgia.
Res Sq. 2024 Nov 20:rs.3.rs-5269499. doi: 10.21203/rs.3.rs-5269499/v1.
While the etiology of most cases of Parkinson's disease (PD) are idiopathic, it has been estimated that 5-10% of PD arise from known genetic mutations. The first mutations described that leads to the development of an autosomal dominant form of PD are in the SNCA gene that codes for the protein alpha-synuclein (α-syn). α-syn is an abundant presynaptic protein that is natively disordered and whose function is still unclear. In PD, α-syn misfolds into multimeric b-pleated sheets that aggregate in neurons (Lewy Bodies/neurites) and spread throughout the neuraxis in a pattern that aligns with disease progression. Here, using IHC, HC, HPLC, and cytokine analysis, we examined the sequelae of intraparenchymal brain seeding of pre-formed fibrils (PFFs) and monomeric α-syn in C57BL/6J (WT) and A53T SNCA mutant mice. We found that injection of PFFs, but not monomeric α-syn, into the striatum of C57BL/6J mice induced spread of aggregated α-syn, loss of SNpc DA neurons and increased neuroinflammation. However, in A53T SNCA mice, we found that both PFFs and monomeric α-syn induced this pathology. This suggests that the conformation changes in α-syn seen in the A53T strain can recruit wild-type α-syn to a pathological misfolded conformation which may provide a mechanism for the induction of PD in humans with SNCA duplication/triplication.
虽然大多数帕金森病（PD）病例的病因是特发性的，但据估计，5%-10%的PD由已知基因突变引起。最早描述的导致常染色体显性形式PD发展的突变存在于编码α-突触核蛋白（α-syn）的SNCA基因中。α-syn是一种丰富的突触前蛋白，其天然无序，功能仍不清楚。在PD中，α-syn错误折叠成多聚体β折叠片，聚集在神经元中（路易小体/神经突），并以与疾病进展一致的模式在整个神经轴中扩散。在此，我们使用免疫组织化学（IHC）、高效液相色谱（HPLC）和细胞因子分析，研究了预先形成的原纤维（PFFs）和单体α-syn在脑实质内接种对C57BL/6J（野生型，WT）和A53T SNCA突变小鼠的后遗症。我们发现，向C57BL/6J小鼠纹状体注射PFFs而非单体α-syn，可诱导聚集的α-syn扩散、黑质致密部（SNpc）多巴胺能神经元丢失并增加神经炎症。然而，在A53T SNCA小鼠中，我们发现PFFs和单体α-syn均可诱导这种病理变化。这表明在A53T菌株中看到的α-syn构象变化可将野生型α-syn募集到病理性错误折叠构象，这可能为SNCA重复/三倍体的人类PD诱导提供一种机制。
