Growing evidence suggests that aberrant transcriptional regulation is a key component of the pathogenesis of multiple neuropsychiatric disorders, which are thought to stem from an individual's inability to cope with stressful and traumatic events. Indeed, while traumatic events are very common, only susceptible individuals go on to develop psychopathologies, while others have the ability to cope and therefore remain resilient. Research into the genetic and epigenetic mechanisms underlying the pathological response to stress is crucial for the development of effective treatments to either mitigate susceptibility or enhance resilience. The mechanisms underlying resilience to stress remain not fully understood. This project concerns the transcriptional repressor RE1-Silencing Transcription factor (REST), also known as neuron-restrictive silencer factor (NRSF). REST is expressed in the central nucleus of the amygdala (CeA), a key brain site for the behavioral and endocrine responses of stress. Recent studies have suggested that REST may be a protective factor which would make neurons more resistant to stressors via the repression of downstream genes. Interestingly, we have found that REST levels are significantly elevated in the CeA of rats which are resilient to the effects of chronic social defeat stress (SDS). Several gaps still exist: i) Although REST is elevated in the amygdala of SDS resilient rats, whether the increased levels reflect increased binding of REST to target genes is unknown, as well as whether such binding alters gene expression in a region-specific manner. ii) Furthermore, it is unknown whether REST has a role in the development of behavioral vulnerability to chronic stress. The provocative, high risk/high reward hypothesis of this application is that increased function of the REST transcriptional repressor in the CeA underlies the resilience to the adverse effects of chronic stress. This hypothesis will be tested by combining an established animal model with state-of-the-art molecular and epigenetic techniques to pursue the following specific aims:
Aim 1 will determine whether elevated levels of REST in the CeA of SDS resilient rats reflect increased binding of REST to endogenous NRSE sites and the transcriptional repression of REST target genes in CeA neurons, by using chromatin immunoprecipitation assays followed by high density sequencing (ChIP-Seq), and RNA-seq.
Aim 2 will determine whether CeA REST mediates resilience to chronic social defeat stress, by overexpressing REST in the CeA in vivo using an adeno-associated viral (AAV) vector in SDS animals, and qPCR to validate REST-mediated repression of specific gene targets in the CeA that are stress responsive. The proposed experiments lay the foundation for highly relevant studies to test the hypothesis that CeA REST is a substrate that confers resilience to stress-induced psychopathologies. This research may lead to a breakthrough in our understanding of the role of REST in the adult brain and of stress-related disorders.
The proposed experiments, through this multidisciplinary approach, may reveal the transcriptional repressor REST as a substrate that is induced following stress and confers resilience to stress-induced psychopathologies. The anticipated findings will significantly improve our understanding of the etiology of stress- and trauma- related disorders and facilitate the development of novel medications.