Transcriptomics and chromatin alterations - Septal lncRNA Meg3 is involved in social fear in mice

Social anxiety disorder is characterized by a persistent and abnormal fear and avoidance of social situations, but available treatment options are rather unspecific. Using an established mouse social fear conditioning (SFC) paradigm, we profiled gene expression and chromatin alterations after acquisition and extinction of social fear within the septum, a brain region important for social fear and social behaviors. We validated coding and non-coding RNAs and found specific isoforms of the long non-coding RNA Meg3 to be regulated depending on the success of social fear extinction. In vivo knockdown of specific Meg3 isoforms in conditioned mice resulted in impaired social fear extinction, as revealed by lower social investigation levels at the end of the extinction training, accompanied with increased baseline activity of the PI3K/AKT signaling pathway. Using ATAC-Seq and CUT&RUN, we characterized alterations in chromatin level after social fear extinction and identified Auts2 and Dclk3 as potential targets of Meg3. Overall design: RNA-seq, ATAC-Seq and Cut&Run for H3K27me3 in mouse brain septum