MicroRNA regulation of persistent stress-enhanced memory

In: Sillivan , S E , Jamieson , S , de Nijs , L , Jones , M , Snijders , C , Klengel , T , Joseph , N F , Krauskopf , J , Kleinjans , J , Vinkers , C H , Boks , M P M , Geuze , E , Vermetten , E , Berretta , S , Ressler , K J , Rutten , B P F , Rumbaugh , G & Miller , C A 2020 , ' MicroRNA regulation of persistent stress-enhanced memory ' , Molecular Psychiatry , vol. 25 , no. 5 , pp. 965-976 . https://doi.org/10.1038/s41380-019-0432-2

Abstract

Disruption of persistent, stress-associated memories is relevant for treating posttraumatic stress disorder (PTSD) and related syndromes, which develop in a subset of individuals following a traumatic event. We previously developed a stress-enhanced fear learning (SEFL) paradigm in inbred mice that produces PTSD-like characteristics in a subset of mice, including persistently enhanced memory and heightened cFos in the basolateral amygdala complex (BLC) with retrieval of the remote (30-day-old) stress memory. Here, the contribution of BLC microRNAs (miRNAs) to stress-enhanced memory was investigated because of the molecular complexity they achieve through their ability to regulate multiple targets simultaneously. We performed small-RNA sequencing (smRNA-Seq) and quantitative proteomics on BLC tissue collected from mice 1 month after SEFL and identified persistently changed microRNAs, including mir-135b-5p, and proteins associated with PTSD-like heightened fear expression. Viral-mediated overexpression of mir-135b-5p in the BLC of stress-resilient animals enhanced remote fear memory expression and promoted spontaneous renewal 14 days after extinction. Conversely, inhibition of BLC mir-135b-5p in stress-susceptible animals had the opposite effect, promoting a resilient-like phenotype. mir-135b-5p is highly conserved across mammals and was detected in post mortem human amygdala, as well as human serum samples. The mir-135b passenger strand, mir-135b-3p, was significantly elevated in serum from PTSD military veterans, relative to combat-exposed control subjects. Thus, miR-135b-5p may be an important therapeutic target for dampening persistent, stress-enhanced memory and its passenger strand a potential biomarker for responsivity to a mir-135-based therapeutic.