Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
Interfaculty Institute for Biochemistry, University of Tübingen, 72076, Tübingen, Germany.
Acta Neuropathol Commun. 2021 Nov 8;9(1):180. doi: 10.1186/s40478-021-01283-7.
Pathologic inclusions composed of α-synuclein called Lewy pathology are hallmarks of Parkinson's Disease (PD). Dominant inherited mutations in leucine rich repeat kinase 2 (LRRK2) are the most common genetic cause of PD. Lewy pathology is found in the majority of individuals with LRRK2-PD, particularly those with the G2019S-LRRK2 mutation. Lewy pathology in LRRK2-PD associates with increased non-motor symptoms such as cognitive deficits, anxiety, and orthostatic hypotension. Thus, understanding the relationship between LRRK2 and α-synuclein could be important for determining the mechanisms of non-motor symptoms. In PD models, expression of mutant LRRK2 reduces membrane localization of α-synuclein, and enhances formation of pathologic α-synuclein, particularly when synaptic activity is increased. α-Synuclein and LRRK2 both localize to the presynaptic terminal. LRRK2 plays a role in membrane traffic, including axonal transport, and therefore may influence α-synuclein synaptic localization. This study shows that LRRK2 kinase activity influences α-synuclein targeting to the presynaptic terminal. We used the selective LRRK2 kinase inhibitors, MLi-2 and PF-06685360 (PF-360) to determine the impact of reduced LRRK2 kinase activity on presynaptic localization of α-synuclein. Expansion microscopy (ExM) in primary hippocampal cultures and the mouse striatum, in vivo, was used to more precisely resolve the presynaptic localization of α-synuclein. Live imaging of axonal transport of α-synuclein-GFP was used to investigate the impact of LRRK2 kinase inhibition on α-synuclein axonal transport towards the presynaptic terminal. Reduced LRRK2 kinase activity increases α-synuclein overlap with presynaptic markers in primary neurons, and increases anterograde axonal transport of α-synuclein-GFP. In vivo, LRRK2 inhibition increases α-synuclein overlap with glutamatergic, cortico-striatal terminals, and dopaminergic nigral-striatal presynaptic terminals. The findings suggest that LRRK2 kinase activity plays a role in axonal transport, and presynaptic targeting of α-synuclein. These data provide potential mechanisms by which LRRK2-mediated perturbations of α-synuclein localization could cause pathology in both LRRK2-PD, and idiopathic PD.
由α-突触核蛋白组成的病理性包涵体称为路易体病理，是帕金森病（PD）的标志。富亮氨酸重复激酶 2（LRRK2）的显性遗传性突变是 PD 的最常见遗传原因。路易体病理存在于大多数 LRRK2-PD 患者中，尤其是携带 G2019S-LRRK2 突变的患者中。LRRK2-PD 中的路易体病理与非运动症状的增加有关，如认知缺陷、焦虑和直立性低血压。因此，了解 LRRK2 和 α-突触核蛋白之间的关系对于确定非运动症状的机制可能很重要。在 PD 模型中，突变型 LRRK2 的表达减少了 α-突触核蛋白的膜定位，并增强了病理性 α-突触核蛋白的形成，尤其是在突触活动增加时。α-突触核蛋白和 LRRK2 都定位于突触前末端。LRRK2 在膜运输中发挥作用，包括轴突运输，因此可能影响 α-突触核蛋白的突触定位。本研究表明，LRRK2 激酶活性影响 α-突触核蛋白向突触前末端的靶向。我们使用选择性 LRRK2 激酶抑制剂 MLi-2 和 PF-06685360（PF-360）来确定降低 LRRK2 激酶活性对 α-突触核蛋白突触前定位的影响。在原代海马培养物和体内的扩展显微镜（ExM）中用于更精确地解析 α-突触核蛋白的突触前定位。使用 α-突触核蛋白-GFP 的轴突运输的活细胞成像来研究 LRRK2 激酶抑制对 α-突触核蛋白向突触前末端的轴突运输的影响。降低的 LRRK2 激酶活性增加了 α-突触核蛋白与原代神经元中突触前标志物的重叠，并增加了 α-突触核蛋白-GFP 的顺行轴突运输。在体内，LRRK2 抑制增加了 α-突触核蛋白与谷氨酸能、皮质纹状体末端和多巴胺能黑质纹状体突触前末端的重叠。这些发现表明，LRRK2 激酶活性在轴突运输和 α-突触核蛋白的突触前靶向中发挥作用。这些数据提供了潜在的机制，通过这些机制，LRRK2 介导的 α-突触核蛋白定位的扰动可能导致 LRRK2-PD 和特发性 PD 中的病理学。
