Dou Dan, Aiken Jayne, Holzbaur Erika L F
Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
bioRxiv. 2023 Jul 25:2023.07.25.550521. doi: 10.1101/2023.07.25.550521.
Gain-of-function mutations in the gene cause Parkinson's disease (PD), characterized by debilitating motor and non-motor symptoms. Increased phosphorylation of a subset of RAB GTPases by LRRK2 is implicated in PD pathogenesis. We find that increased phosphorylation of RAB3A, a cardinal synaptic vesicle precursor (SVP) protein, disrupts anterograde axonal transport of SVPs in iPSC-derived human neurons (iNeurons) expressing hyperactive -p.R1441H. Knockout of the opposing protein phosphatase 1H () in iNeurons phenocopies this effect. In these models, the compartmental distribution of synaptic proteins is altered; synaptophysin and synaptobrevin-2 become sequestered in the neuronal soma with decreased delivery to presynaptic sites along the axon. We find that RAB3A phosphorylation disrupts binding to the motor adapter MADD, potentially preventing formation of the RAB3A-MADD-KIF1A/1Bβ complex driving anterograde SVP transport. RAB3A hyperphosphorylation also disrupts interactions with RAB3GAP and RAB-GDI1. Our results reveal a mechanism by which pathogenic hyperactive LRRK2 may contribute to the altered synaptic homeostasis associated with characteristic non-motor and cognitive manifestations of PD.
该基因的功能获得性突变会导致帕金森病（PD），其特征为使人衰弱的运动和非运动症状。LRRK2对一部分RAB GTP酶的磷酸化增加与PD发病机制有关。我们发现，RAB3A（一种主要的突触小泡前体（SVP）蛋白）磷酸化增加会破坏表达活性过高的-p.R1441H的诱导多能干细胞衍生的人类神经元（iNeurons）中SVP的顺行轴突运输。在iNeurons中敲除相反的蛋白磷酸酶1H（）可模拟这种效应。在这些模型中，突触蛋白的区室分布发生改变；突触素和突触小泡蛋白-2被隔离在神经元胞体中，沿轴突向突触前位点的递送减少。我们发现，RAB3A磷酸化会破坏与运动适配器MADD的结合，可能会阻止驱动顺行SVP运输的RAB3A-MADD-KIF1A/1Bβ复合物的形成。RAB3A的过度磷酸化还会破坏与RAB3GAP和RAB-GDI1的相互作用。我们的结果揭示了一种机制，通过该机制，致病性活性过高的LRRK2可能导致与PD特征性非运动和认知表现相关的突触稳态改变。
