Dopamine neuron dysfunction and loss in the PrknR275W mouse model of Juvenile Parkinsonism

Mutations in the PRKN gene encoding the protein PARKIN cause Autosomal Recessive Juvenile Parkinsonism (ARJP). Harnessing this mutation to create an early-onset Parkinson’s disease (PD) mouse model would provide a unique opportunity to clarify the mechanisms involved in the neurodegenerative process and lay the groundwork for the development of neuroprotective strategies. We created a knock-in mouse carrying the homozygous Prkn R275W mutation, which is the missense mutation with the highest allelic frequency in PRKN patients. In Prkn R275W mice, we analysed the anatomical and functional integrity of the nigrostriatal pathway, including striatal DA content and evoked striatal dopamine (DA) release, as well as the motor phenotype. We report here that Prkn R275W mice show early DA neuron dysfunction, age-dependent loss of DA neurons in the substantia nigra, decreased DA content and stimulus-evoked DA release in the striatum, and progressive motor impairment. Together, these data show that the Prkn R275W mouse recapitulates key features of ARJP. Thus, these studies fill a critical need in the field by introducing a promising new PD model in which to study causative mechanisms of the disease, as well as test therapeutic strategies. ### Competing Interest Statement The authors have declared no competing interest. * ### Abbreviations β2M : beta-2 microglobulin ACh : acetylcholine ARJP : autosomal recessive juvenile parkinsonism DA : dopamine dlStr : dorsolateral striatum FSCV : fast-scan cyclic voltammetry HPLC : High-Performance Liquid Chromatography KO : knockout nAChRs : acetylcholine receptors NAc : nucleus accumbens PD : Parkinson’s disease SNc : substantia nigra pars compacta TH : tyrosine hydroxylase vStr : ventral striatum VTA : ventral tegmental area WT : wild-type * ### ABBREVIATIONS SUPPLEMENTARY TEXT β2M : beta-2 microglobulin aCSF : artificial cerebrospinal fluid BSA : bovine serum albumin DAPI : 4′,6-diamidino-2-phenylindole DDC : dopa decarboxylase dlStr : dorsolateral striatum FSCV : fast-scan cyclic voltammetry HPLC : high-performance liquid chromatography NAc : nucleus accumbens OD : optical density PBS : phosphate buffered saline PBST : PBS containing 0.3% Triton X-100 PFA : paraformaldehyde PSB : pontamine sky blue qPCR : quantitative real-time PCR RT : reverse transcriptase SDHA : succinate dehydrogenase complex flavoprotein subunit A SDS : sodium dodecyl sulfate sgRNA : single guide RNA TBS-T : tris-buffered saline containing 0.05% tween-20 TH+ : TH positive VDAC : voltage-dependent anion channels