Regulation of behavioral response to stress by microRNA-690.

Psychiatric disorders are affected by genetic susceptibility and environmental adversities. Therefore, the regulation of gene expression under certain environments, such as stress, is a key issue in psychiatric disorders. MicroRNAs (miRNAs) have been implicated as post-transcriptional regulators of several biological processes, which can be differentially controlled through the targeting of multiple mRNAs. However, studies reporting the functions of miRNAs in relation to stress are lacking. In this study, we identified a significant increase in the expression of miRNA-690 (miR-690) in the medial prefrontal cortex (mPFC) of FK506-binding protein 51 knock-out (Fkbp5 KO) mice. In addition, the expression pattern of miR-690 was similar to the sucrose preference of the same group in WT and Fkbp5 KO mice. miR-690 was injected into the mPFC using a recombinant adeno-associated virus mediated gene delivery method. After recovery, miR-690 overexpressing mice were exposed to restraint stress for 2 weeks. In the sucrose preference test and forced swim test, the stressed miR-690 overexpressing mice showed higher sucrose preference and lower immobility time, respectively, than stressed mice injected with the control virus. In the novel object recognition test, the stressed miR-690 overexpressing mice interacted longer with the novel object than those injected with the control virus. These results showed that miR-690 might play a role in stress resilience and could provide new insights into the epigenetic regulation of stress-associated biological functions and diseases, such as depression and post-traumatic stress disorder.