Bernstein Lab

 

About the Bernstein Lab

Research in the Bernstein lab focuses on how epigenetic modifications mediate neurotoxicological effects and gene-environment interactions underlying sporadic neurodegenerative diseases. Although these diseases are generally diseases of the aged, the neurodegenerative process begins long before clinical diagnosis. Thus, exposures the occur early in life may contribute to sporadic forms of disease by directly affecting the vulnerability of neurological systems. Epigenetic modifications are thought to imprint environmental experiences on the genome, resulting in stable alterations in phenotype. Thus, linking epigenetic changes with functional outcomes will help to elucidate the mechanisms underlying sporadic neurodegenerative diseases and further our understanding of the complex relationship between toxicity, epigenetics and neuronal vulnerability.

Lab Personnel

Alison Bernstein, PhD, Primary Investigator

Sierra Boyd

Joe Kochmanski, PhD

Nathan Kuhn

Epigenetics in Parkinson’s Disease

Parkinson's disease (PD), the second most common neurodegenerative disorder in the US, is characterized by progressive degeneration of dopaminergic neurons of the nigrostriatal pathway and the formation of α-syn-containing Lewy bodies. Only 5-10% of PD cases are familial, and several genes are known to cause these inherited forms of the disease. The remaining ~90% of sporadic cases are likely due to a complex interaction between genes and environmental factors. Because epigenetic marks are sensitive to the environment, established during cellular differentiation, and regulate gene expression throughout the lifespan, they are considered a potential mediator of the relationship between genes, developmental exposures and adult disease. Evidence for epigenetic regulation playing a role in PD is growing, particularly for DNA modifications. Our lab focuses on characterizing the DNA modifications that occur in human disease. To do this, we adapted magnetic assisted cell sorting to separate neuronal and non-neuronal nuclei from frozen postmortem human brain tissue. We then pair bisulfite and oxidative bisulfite conversion with the Illumina Methylation EPIC array and use a bioinformatic and statistical pipeline that we developed for analyzing data mapping the two most abundant DNA modifications, 5-methylcytosine and 5-hydroxymethylcytosine. The overall goal of this work is to identify epigenetic changes in cells that are affected in PD that contribute to neurodegeneration and could be targeted for therapeutic interventions.

 

Epigenetics in Parkinson’s Disease Toxicant Models

Epidemiological studies show an association between exposure to persistent organic pollutants and an increased risk of Parkinson’s disease (PD). When combined with post-mortem analysis and mechanistic studies, a role for specific compounds in PD emerges. One such compound is dieldrin, an organochlorine pesticide that is associated with an increased risk of PD in both epidemiological and mechanistic studies. Because dieldrin was phased out in the 1970s and 1980s, the potential for new, acute exposure to dieldrin is low. However, the health effects of past exposures will continue for decades as the population currently diagnosed with PD and those that will develop PD in the next 20-30 years were likely exposed to dieldrin prior to its phase out. Furthermore, well-established models of dieldrin exposure have demonstrated that dieldrin induces oxidative stress, is selectively toxic to dopaminergic cells, disrupts striatal dopamine (DA) activity, and may promote α-syn aggregation. In collaboration with the Sortwell lab, we have established a two-hit model of environmentally induced PD susceptibility by combining the developmental dieldrin exposure model with the α-synuclein pre-formed fibril (PFF) model. In this model, prior exposure to dieldrin increases PFF toxicity in male mice. Work in our lab focuses on characterizing the mechanisms underlying the increased toxicity, including changes in the epigenome and the transcriptome all the way up to dopaminergic function. Our work in this model utilizes a representative PD-related toxicant that has well-characterized animal exposure paradigms, and provides a roadmap for understanding how dieldrin and other environmental risk factors contribute to sporadic PD.

3D In Vitro Parkinson’s Disease Toxicant Models

To study the mechanisms by which Parkinson’s-related exposures contribute to disease, we use a 3D cellular model in a high-throughput screening format. For this project, we use magnetic particles (NanoShuttle) to assemble Lund Human Mesencephalic (LUHMES) cells into 3D spheroids, which we then differentiate into dopaminergic neurons. We can manipulate genes of interest in these cells and treat them with PD-related toxicants or α-synuclein pre-formed fibrils to study the cellular and molecular mechanisms that underly PD-related toxicity using high-throughput imaging and cytotoxicity assays. Using this in vitro system allows us to follow up on results from our human and animal studies to study mechanisms underlying how environmental risk factors increase PD risk.