Quintero-Espinosa Diana, Jimenez-Del-Rio Marlene, Velez-Pardo Carlos
Neuroscience Research Group, Medical Research Institute, Faculty of Medicine, University of Antioquia (UdeA), Calle 70 No. 52-21, and Calle 62 # 52-59, Building 1, Room 412; SIU Medellin, Colombia.
Neuroscience Research Group, Medical Research Institute, Faculty of Medicine, University of Antioquia (UdeA), Calle 70 No. 52-21, and Calle 62 # 52-59, Building 1, Room 412; SIU Medellin, Colombia.
Brain Res. 2017 Feb 15;1657:253-261. doi: 10.1016/j.brainres.2016.12.023. Epub 2016 Dec 30.
Leucine-rich repeat kinase 2 (LRRK2) has been linked to familial and sporadic Parkinson's disease. However, it is still unresolved whether LRRK2 in dopaminergic (DAergic) neurons may or may not aggravate the phenotype. We demonstrate that knocking down (KD) the Lrrk gene by RNAi in DAergic neurons untreated or treated with paraquat (PQ) neither affected the number of DAergic clusters, tyrosine hydroxylase (TH) protein levels, lifespan nor locomotor activity when compared to control (i.e. TH/+) flies. KD transgenic Lrrk flies dramatically increased locomotor activity in presence of TH enzyme inhibitor alpha-methyl-para-tyrosine (aMT), whereas no effect on lifespan was observed in both fly lines. Most importantly, KD Lrrk flies had reduced lipid peroxidation (LPO) index alone or in presence of PQ and the antioxidant minocycline (MC, 0.5mM). Taken together, these findings suggest that Lrrk appears unessential for the viability of DAergic neurons in D. melanogaster. Moreover, Lrrk might negatively regulate homeostatic levels of dopamine, thereby dramatically increasing locomotor activity, extending lifespan, and reducing oxidative stress (OS). Our data also indicate that reduced expression of Lrrk in the DAergic neurons of transgenic TH>Lrrk-RNAi/+ flies conferred PQ resistance and absence of neurodegeneration. The present findings support the notion that reduced/suppressed LRRK2 expression might delay or prevent motor symptoms and/or frank Parkinsonism in individuals at risk to suffer autosomal dominant Parkinsonism (AD-P) by blocking OS-induced neurodegenerative processes in the DAergic neurons.
富含亮氨酸重复激酶2（LRRK2）与家族性和散发性帕金森病相关。然而，多巴胺能（DAergic）神经元中的LRRK2是否会加重疾病表型仍未明确。我们证明，在未处理或用百草枯（PQ）处理的DAergic神经元中，通过RNA干扰（RNAi）敲低Lrrk基因，与对照（即TH / +）果蝇相比，既不影响DAergic簇的数量、酪氨酸羟化酶（TH）蛋白水平、寿命，也不影响运动活性。KD转基因Lrrk果蝇在存在TH酶抑制剂α-甲基-对-酪氨酸（aMT）的情况下运动活性显著增加，而在两种果蝇品系中均未观察到对寿命的影响。最重要的是，单独或在存在PQ和抗氧化剂米诺环素（MC，0.5mM）的情况下，KD Lrrk果蝇的脂质过氧化（LPO）指数降低。综上所述，这些发现表明Lrrk对于黑腹果蝇DAergic神经元的存活似乎并非必需。此外，Lrrk可能对多巴胺的稳态水平产生负调节作用，从而显著增加运动活性、延长寿命并降低氧化应激（OS）。我们的数据还表明，转基因TH>Lrrk-RNAi / +果蝇的DAergic神经元中Lrrk表达降低赋予了PQ抗性且无神经退行性变。目前的研究结果支持这样一种观点，即降低/抑制LRRK2表达可能通过阻断OS诱导的DAergic神经元神经退行性过程，延迟或预防有患常染色体显性帕金森病（AD-P）风险个体的运动症状和/或明显的帕金森症。
