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Aging is considered the major risk factor for neurodegenerative diseases including Parkinson's disease (PD). Telomere shortening is associated with cellular senescence. In this regard, pharmacological or genetic inhibition of telomerase activity has been used to model cellular aging. Here, we employed CRISPR-Cas9 technology to instantly remove the telomere to induce aging in a neuroblastoma cell line. Expression of both Cas9 and guide RNA targeting telomere repeats ablated the telomere, leading to retardation of cell proliferation. Instant deletion of telomere in SH-SY5Y cells impaired mitochondrial function with diminished mitochondrial respiration and cell viability. Supporting the pathological relevance of cell aging by CRISPR-Cas9 mediated telomere removal, alterations were observed in the levels of PD-associated proteins including PTEN-induced putative kinase 1, peroxisome proliferator-activated receptor coactivator 1-α, nuclear respiratory factor 1, parkin, and aminoacyl tRNA synthetase complex interacting multifunctional protein 2. Significantly, α-synuclein expression in the background of telomere removal led to the enhancement of protein aggregation, suggesting positive feed-forward interaction between aging and PD pathogenesis. Collectively, our results demonstrate that CRISPR-Cas9 can be used to efficiently model cellular aging and PD. [ABSTRACT FROM AUTHOR]

The progressive neurodegeneration in Parkinson's disease (PD) is accompanied by neuroinflammation and endothelial vascular impairment. Although the vitamin D receptor (VDR) is expressed in both dopamine neurons and brain endothelial cells, its role in the regulation of endothelial biology has not been explored in the context of PD. In a 6-hydroxydopamine (6-OHDA)-induced PD mouse model, we observed reduced transcription of the VDR and its downstream target genes, CYP24 and MDR1a. The 6-OHDA-induced transcriptional repression of these genes were recovered after the VDR ligand—1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) treatment. Similarly, reduced vascular protein expression of P-glycoprotein (P-gp), encoded by MDR1a, after 6-OHDA administration was reversed by 1,25(OH)2D3. Moreover, marked reduction of endothelial P-gp expression with concomitant α-synuclein aggregation was found in a combinatorial AAV-αSyn/αSyn preformed fibril (PFF) injection mouse model and postmortem PD brains. Supporting the direct effect of α-synuclein aggregation on endothelial biology, PFF treatment of human umbilical vein endothelial cells (HUVECs) was sufficient to induce α-synuclein aggregation and repress transcription of the VDR. PFF-induced P-gp downregulation and impaired functional activity in HUVECs completely recovered after 1,25(OH)2D3 treatment. Taken together, our results suggest that a dysfunctional VDR-P-gp pathway could be a potential target for the maintenance of vascular homeostasis in PD pathological conditions. [ABSTRACT FROM AUTHOR]

The motor and nonmotor symptoms of Parkinson's disease (PD) correlate with the formation and propagation of aberrant α-synuclein aggregation. This protein accumulation is a pathological hallmark of the disease. Our group recently showed that peucedanocoumarin III (PCIII) possesses the ability to disaggregate β sheet aggregate structures, including α-synuclein fibrils. This finding suggests that PCIII could be a therapeutic lead compound in PD treatment. However, the translational value of PCIII and its safety information have never been explored in relevant animal models of PD. Therefore, we first designed and validated a sequence of chemical reactions for the large scale organic synthesis of pure PCIII in a racemic mixture. The synthetic PCIII racemate facilitated clearance of repeated β sheet aggregate (β23), and prevented β23-induced cell toxicity to a similar extent to that of purified PCIII. Given these properties, the synthetic PCIII's neuroprotective function was assessed in 6-hydroxydopamine (6-OHDA)-induced PD mouse models. The PCIII treatment (1 mg/kg/day) in a 6-OHDA-induced PD mouse model markedly suppressed Lewy-like inclusions and prevented dopaminergic neuron loss. To evaluate the safety profiles of PCIII, high dose PCIII (10 mg/kg/day) was administered intraperitoneally to two-month-old mice. Following 7 days of PCIII treatment, PCIII distributed to various tissues, with substantial penetration into brains. The mice that were treated with high dose PCIII had no structural abnormalities in the major organs or neuroinflammation. In addition, high dose PCIII (10 mg/kg/day) in mice had no adverse impact on motor function. These findings suggest that PCIII has a relatively high therapeutic index. Given the favorable safety features of PCIII and neuroprotective function in the PD mouse model, it may become a promising disease-modifying therapy in PD to regulate pathogenic α-synuclein aggregation. [ABSTRACT FROM AUTHOR]

Ring finger protein 146 (RNF146) is an E3 ubiquitin ligase whose activity prevents poly (ADP-ribose) polymerase 1 (PARP1)-dependent neurodegeneration in Parkinson's disease (PD). Previously, we reported that rhododendrin is a chemical inducer that increases RNF146 expression. However, the molecular mechanism of rhododendrin-induced RNF146 expression is largely unknown and its translational application for the treatment of Parkinson's disease remains unexplored. Here we found that rhododendrin increased RNF146 expression via estrogen receptor β (ERβ) activation. Rhododendrin stimulated ERβ nuclear translocation and binding to the RNF146 promoter, thereby enhancing its transcription. Rhododendrin is cytoprotective against 6-hydroxydopamine (6-OHDA)-induced cell death, which is largely dependent on ERβ activity and RNF146 expression. Finally, we demonstrated that rhododendrin treatment resulted in RNF146 expression in dopaminergic neurons in mice. Moreover, dopaminergic neuron viability was markedly enhanced by pretreatment with rhododendrin in 6-OHDA-induced mouse models for PD. Our findings indicate that estrogen receptor activation plays a neuroprotective role and that rhododendrin could be a potential therapeutic agent in preventing PARP1-dependent dopaminergic cell loss in PD. [ABSTRACT FROM AUTHOR]