Biology subjects

Hickey, P.

Publications and source records attributed to Hickey, P..

3 recordsLinked to original sources

bioRxiv2018

Long-range chromatin interactions on the inactive X and at Hox clusters are regulated by the non-canonical SMC protein Smchd1.

The regulation of higher order chromatin structure is complex and dynamic; however we do not yet understand the full suite of mechanisms governing architecture. Here we reveal the non-canonical SMC protein Smchd1 as a novel regulator of long-range chromatin interactions, and add it to the canon of epigenetic proteins required for Hox gene regulation. The effect of losing Smchd1-dependent chromatin interactions has varying outcomes dependent on chromatin context. At autosomal targets transcriptionally sensitive to Smchd1 deletion, we find increased short-range interactions and ectopic enhancer activation. By contrast, the inactive X chromosome is transcriptionally refractive to Smchd1 ablation, despite chromosome-wide increases in short-range interactions. There we observe spreading of H3K27me3 domains into regions not normally decorated by this mark. Together these data suggest Smchd1 has the capacity to insulate the chromatin, thereby limiting access to other chromatin modifying proteins.

molecular biology↗

bioRxiv2017

Rare Variant Burden in Known Dystonia Genes in Population Controls and Sporadic Dystonia Patients

BackgroundRare mutations in genes associated with Mendelian forms of disease are a potential mechanism for sporadic disease. The need to assess the clinical significance of such variants is increasing as personalized medicine and genome sequencing increases.\n\nObjectiveTo evaluate the rate of rare, functional variants in dystonia genes in the general population to improve interpretation of the clinical relevance of potentially pathogenic variants in dystonia cases.\n\nMethodsWe performed an \"aggregated\" collapsing analysis of exome sequence that considered rare coding variants in genes previously associated with dystonia, a rare neurological movement disorder, on 2,372 population controls of European ethnicity. We then performed a pilot study in sporadic dystonia to assess whether there was a substantially greater incidence of individuals with rare variation in dystonia genes.\n\nResultsNearly half of population controls had a rare coding variant when 148 genes associated with a dystonia phenotype were considered. When the subset of genes causing isolated dystonia (14 genes) was evaluated, 3-4% of controls harbored rare qualifying variants. Our pilot study of case exomes was powered to identify a five-fold higher or greater rate of qualifying variants in isolated dystonia genes in sporadic dystonia cases compared to population controls; we did not find such an enrichment.\n\nConclusionsWe provide the first systematic analysis of rare variation in dystonia genes considered collectively. Our findings emphasize the need to consider the overall frequency of variants in rare disease-related genes in the general population when considering their potential role in clinical presentations.

genomics↗

bioRxiv2017

Neuronal brain region-specific DNA methylation andchromatin accessibility are associated with neuropsychiatric disease heritability

Epigenetic modifications confer stable transcriptional patterns in the brain, and both normal and abnormal brain function involve specialized brain regions, yet little is known about brain region-specific epigenetic differences. Here, we compared prefrontal cortex, anterior cingulate gyrus, hippocampus and nucleus accumbens from 6 individuals, performing whole genome bisulfite sequencing for DNA methylation. In addition, we have performed ATAC-seq for chromatin accessibility, and RNA-seq for gene expression in the nucleus accumbens and prefrontal cortex from 6 additional individuals. We found substantial neuron- and brain region-specific differences in both DNA methylation and chromatin accessibility which were largely non-overlapping, and were greatest between nucleus accumbens and the other regions. In contrast, glial methylation and chromatin were relatively homogeneous across brain regions, although neuron/glia ratios varied greatly, demonstrating the necessity for cellular fractionation. Gene expression was also largely the same across glia from different brain regions and substantially different for neurons. Expression was correlated with methylation and accessibility across promoters and known enhancers. Several classes of transcription factor binding sites were enriched at regions of differential methylation and accessibility, including many that respond to synaptic activity. Finally, both regions of differential methylation and those of differential accessibility showed a surprising >10-fold enrichment of explained heritability associated with addictive behavior, as well as schizophrenia- and neuroticism-associated regions, suggesting that common psychiatric illness is mediated through brain region-specific epigenetic marks.

neuroscience↗