Authors :
Presenting Author: Bayleyen Yared, PhD – University of Pennsylvania
Anil Wadhawani, MD, PhD – University of Pennsylvania
Abi Chavez, PhD student – University of Pennsylvania
Sierra Dutko, BS – University of Pennsylvania
Aaron Barbour, PhD – University of Pennsylvania
Ana Cristancho, MD, PhD – University of Pennsylvania, Children's hospital of Philadelphia
Delia Talos, MD – University of Pennsylvania
Frances Jensen, MD – University of Pennsylvania
Rationale:
Early-life seizures (ELS) are associated with neurodevelopmental disorders such as intellectual disability and autism-spectrum disorders. However, cell type-specific molecular mechanisms driving persistent deficits after ELS are unknown. Using mice with targeted recombination of activated populations (TRAP) to genetically label neurons activated by kainate-induced (KA) ELS in immature mice at postnatal day (P)10, we have shown that ELS induce longstanding dysregulation of synaptic function, altered synaptic plasticity, protein expression and post-translational signaling pathways selectively in the labeled tdTomato-positive (tdT+) CA1neurons but not surrounding neurons (doi: 10.1172/JCI175167). The present study aimed to determine whether there were long lasting transcriptomic changes in these tdT+ CA1 neurons compared to surrounding tdT- CA1 neurons. Methods:
Fluorescence-activated cell sorting was used to separate tdT+ and tdT- cells from P30 micro-dissected hippocampal tissue following ELS-TRAP at P10. Subsequent single-nucleus RNA-sequencing (snRNA-seq) analysis using Seurat and enrichR enabled the identification of cell types, differential gene expression between tdT+ and tdT- CA1 neurons, and comparisons against established gene datasets relevant to synaptic function and neurological disorders. Results:
The ELS-activated neurons, marked with tdT as reporter gene under the immediate early gene cFos promoter, expressed a distinct transcriptomic signature compared to tdT- neurons from KA treated mice. We found 206 differentially expressed genes (DEGs) between groups, with 181 genes downregulated and 25 genes upregulated in tdT+ compared to tdT- neurons. Gene ontology analysis of DEGs revealed prominent dysregulation in pathways related to ion channels, synaptic receptors, and plasticity. We also identified a distinct subset of DEGs that have been previously identified as important for synaptic function (n = 35) and those related to genetic risk for autism spectrum disorders (n = 23). Notably, consistent with our prior reports, we observed transcriptional downregulation of GRIA2 (log2 fold change = -0.171, adjusted P-value = 1.679 e-22).Conclusions:
These findings show distinct enduring transcriptomic modifications that occur in ELS-activated CA1 neurons that may mediate the persistent hyperexcitability, cognitive impairment, and synaptic dysplasticity we have previously reported, providing a novel understanding of the interaction between ELS and neurodevelopmental disorders. Future studies using this dataset will enable us to examine potential targetable pathways that may yield novel clinically relevant therapies to prevent long-lasting consequences of ELS.Funding:
This work was supported by the National Institutes of Health (R37NS115439 to F.E.J.).