Targeted attenuation of elevated histone marks at SNCA alleviates α-synuclein in Parkinson's disease

Epigenetic deregulation of alpha-synuclein plays a key role in Parkinson's disease (PD). Analysis of the SNCA promoter using the ENCODE database revealed the presence of important histone post-translational modifications (PTMs) including transcription-promoting marks, H3K4me3 and H3K27ac, and repressive mark, H3K27me3. We investigated these histone marks in post-mortem brains of controls and PD patients and observed that only H3K4me3 was significantly elevated at the SNCA promoter of the substantia nigra (SN) of PD patients both in punch biopsy and in NeuN-positive neuronal nuclei samples. To understand the importance of H3K4me3 in regulation of alpha-synuclein, we developed CRISPR/dCas9-based locus-specific H3K4me3 demethylating system where the catalytic domain of JARID1A was recruited to the SNCA promoter. This CRISPR/dCas9 SunTag-JARID1A significantly reduced H3K4me3 at SNCA promoter and concomitantly decreased alpha-synuclein both in the neuronal cell line SH-SY5Y and idiopathic PD-iPSC derived dopaminergic neurons. In sum, this study indicates that alpha-synuclein expression in PD is controlled by SNCA's histone PTMs and modulation of the histone landscape of SNCA can reduce alpha-synuclein expression.

Automated summary

The epigenetic deregulation of alpha-synuclein, indicated by elevated H3K4me3 at the SNCA promoter in the substantia nigra of Parkinson's disease patients, can be diminished by a CRISPR/dCas9-based demethylating system. This study suggests that modulation of the histone landscape of SNCA can decrease alpha-synuclein expression in Parkinson's disease.