Major Depressive Disorder (MDD) arises from a complex interaction between genetics and environmental
influences such as stress, which leads to persistent changes in frontolimbic gene expression and cellular
function. Although MDD has been predominantly studied in the context of neuronal function, emerging evidence
indicates that dysregulation of glia may be equally important. In particular, astrocytes are key determinants of
the neuronal microenvironment and can modulate synaptic efficacy through a wide range of secreted and
contact-mediated signaling. Chronic stress can cause astrocytes to undergo broad transcriptomic changes,
which can lead to loss of normal supportive functions, and gain of potentially neurotoxic qualities, both of which
can be equally disruptive to the overall activity of surrounding circuitry[8]. Understanding this astrocyte
plasticity and how it contributes to the pathophysiology of inflammation-related psychiatric disease is a
central question in this proposal. Our laboratory has implemented FANS coupled ATAC-seq to profile the
cell type-specific regulatory landscape in human MDD orbitofrontal cortex (OFC), (Aim 1) a brain region that
processes reward-based decision-making and may mediate anhedonic symptoms in MDD. Using this approach,
I identified a key pioneer factor, ZBTB7A, which regulates chromatin structure specifically in astrocytes to
facilitate feed-forward pro-inflammatory transcriptional cycles driven by NF-kB (with which ZBTB7A also directly
interacts). In a series of studies utilizing astrocyte-specific viral manipulations, I found that overexpressing (OE)
this chromatin remodeler in rodent OFC astrocytes was sufficient to induce aberrant expression of inflammatory
genes, behavioral deficits, and neuronal hyperactivity in response to a mild stressor, compared to GFP-
expressing mice. My findings indicate that OE of Zbtb7a in OFC astrocytes initiates a change in astrocyte
phenotype that has selective, direct effects on neuronal transmission. However, understanding the specific
impact of Zbtb7a OE on astrocyte plasticity, as well as the non-cell autonomous effects of astrocytic Zbtb7a OE
requires expression profiling with single-cell resolution. Therefore, in Aim 2 I propose to perform single-nuclei
RNA sequencing (snRNA-seq) on virally-infected OFC tissues from this same cohort of Zbtb7a OE animals vs.
GFP in order to create a comprehensive cellular map and transcriptomic profile of cell-type specific changes
across neural and glial populations in the OFC. I hypothesize that Zbtb7a OE induces key gene expression
changes to elicit cell-autonomous maladaptive astrocyte phenotypes that reverse the normal adaptive role of
astrocytes in responding to mild stress. In Aim 3, I will focus on identifying laboratories for my postdoctoral work,
prioritizing expertise in multiplexed “omics” profiling, circuit-specific approaches (including spatial
transcriptomics), and electrophysiology, which will build on my current training to allow me to further investigate
the role of astrocyte plasticity in psychiatric disease. Aim 3 will also emphasize strengthening essential
professional development skills in order to facilitate my progress towards independent research.
