PROJECT SUMMARY/ABSTRACT Maternal smoking is a well-recognized public health concern associated with increased neurodevelopmental disorders and other health risks in offspring. Substantial evidence indicates various adverse effects of maternal smoking or prenatal nicotine exposure on neonatal brain development, e.g., hyperactivity, reduced cognitive performance, increased anxiety and depression, and increased susceptibility to brain injury. Electronic cigarettes (e-cig) have become popular in pregnant women and young adolescents. Growing evidence suggests that maternal e-cig use affects brain development, resulting in abnormal cortical neuronal morphology and aberrant neuro-behaviors in offspring. Using a rat prenatal e-cig exposure model and single-nucleus sequencing, we recently found that prenatal e-cig exposure disrupted excitatory-inhibitory (E/I) balance, ratio of excitatory/ inhibitory neurons, in the neonatal brain. E/I balance is crucial for normal brain development and functions, and its disruption has been postulated to underlie the pathogenesis of many neurodevelopmental disorders, including autism spectrum disorders, ADHD, and other psychiatric disorders. However, the underlying genomic and epigenomic mechanisms are still not known. This investigation seeks to fill this knowledge gap. Our hypothesis is that prenatal e-cig exposure induces epigenomic reprogramming and genomic alterations in the developing brain, which cause an E/I imbalance and consequently an increased risk for neurodevelopmental disorders. Exploiting the prenatal e-cig exposure model we developed recently, we propose three specific aims. Aim 1 will determine the spatial-temporal effects of prenatal e-cig exposure on brain development and progression of E/I imbalance using spatial genomics and single-cell sequencing techniques. Aim 2 will determine the epigenomic mechanisms regulating the prenatal e-cig induced E/I imbalance. Aim 3 will investigate whether prenatal e-cig causes genomic alterations (i.e., SNVs and CNVs) that are involved in E/I imbalance. Many cutting-edge genomic and epigenomic technologies are exploited in our studies, including spatial genomics, single-nucleus RNA-seq and chromatin accessibility (snATAC-seq), and state-of-the-art bioinformatics tools. OUTCOMES: Our study will: 1) identify the brain regions that show the E/I imbalance caused by prenatal e-cig exposure; 2) identify the key genes, genomic changes and epigenomic regulations responsible for the prenatal e-cig induced E/I imbalance; 3) produce a large amount of unprecedented omics data on the rat brain prenatally exposed to e-cig. IMPACT: Using a well-established intrauterine e-cig exposure model coupled with cutting-edge genomics and epigenomics approaches, our proposed studies will elucidate the genomic and epigenomic mechanisms underlying maternal e-cig induced abnormal brain development, providing valuable new insights into the effects of e-cig on the early central nervous system dev...