Objective: To genetically abrogate Fyn expression to reduce levodopa induced dyskinesia (LID) in the 6-OHDA mice model of Parkinson’s disease (PD), using intrastriatal-injected lentiviral (LV) particles carrying a micro-RNA against Fyn (miR-Fyn).

Background: The management of LID in one of the greatest challenges in PD research because to date there are no available pharmacological alternative therapies to PD with full clinical efficacy. We have recently proposed Fyn as a novel target to control LID (Sanz-Blasco & Bordone et al. 2017). Fyn is a Src tyrosine kinase located at the postsynaptic density zone that regulates the N-methyl-D-aspartate (NMDA) receptor by phosphorylation of the NR2B subunit at Tyr-1472 in response to dopamine D1 receptor stimulation.

Methods: Four miR-Fyn sequences under the control of synapsin promoter were designed, cloned in LV vectors and tested in vitro for silencing efficiency. We selected the one with the highest silencing proficiency and used Western blot to validate Fyn knockdown in vivo. Finally, we induced degeneration of the nigrostriatal dopaminergic pathway by injecting 6-OHDA into the medial forebrain bundle, and selected the animals with a remarked deficit of the contralateral forepaw in the cylinder test. Then, mice were challenged with L-DOPA to induce LID before or after the intrastriatal injection of miR-Fyn or a control sequence. LID were registered every 3 days for 2 weeks. Postmortem dopaminergic denervation was carefully determined by tyrosine hydroxylase (TH) immunodetection to ensure an equal level of degeneration between groups. We also determined the level of FosB-ΔFosB, a well-accepted marker of LID, and Fyn silencing by western blot.

Results: The selected miR-Fyn reduced Fyn protein by ~50% in neuronal cell line and by ~25% in the entire striatum. Considering the neuronal specificity of the transcript and the time expression of the miR-Fyn within the striatum, this was enough to significantly downregulate LID in a paradigm of dyskinesia and correlated with FosB-ΔFosB expression.

Conclusions: Our data demonstrate that Fyn is a potential target to control LID and set the grounds for its putative therapeutic use in PD.

References: Sanz-Blasco S, Bordone MP, Damianich A, Gomez G, Bernardi MA, Isaja L, Taravini IR, Hanger DP, Avale ME, Gershanik OS, Ferrario JE.The Kinase Fyn As a Novel Intermediate in L-DOPA-Induced Dyskinesia in Parkinson’s Disease. Mol Neurobiol. 2017 Aug 24. doi: 10.1007/s12035-017-0748-3.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/intrastriatal-fyn-silencing-as-a-gene-therapy-strategy-to-manage-levodopa-induced-dyskinesia-in-a-mice-model-of-parkinsons-disease/