ABSTRACT
Changes in microRNAs (miRNAs) expression have been described in major depressive disorder in young and middle-aged adults. However, no study has evaluated miRNA expression in older adults with major depression (or late-life depression [LLD]). Our primary aim was to evaluate the expression of miRNAs in subjects with LLD. We first evaluated the miRNA expression using next-generation sequencing (NGS) and then we validated the miRNAs found in NGS in an independent sample of LLD patients, using RT-qPCR. Drosophila melanogaster model was used to evaluate the impact of changes in miRNA expression on behavior. NGS analysis showed that hsa-miR-184 (log2foldchangeâ¯=â¯-4.21, pâ¯=â¯1.2â¯×â¯10-03) and hsa-miR-1-3p (log2foldchangeâ¯=â¯-3.45, pâ¯=â¯1.3â¯×â¯10-02) were significantly downregulated in LLD compared to the control group. RT-qPCR validated the downregulation of hsa-miR-184 (pâ¯<â¯0.001), but not for the hsa-miR-1-3p. The knockout flies of the ortholog of hsa-miR-184 showed significantly reduced locomotor activity at 21-24â¯d.p.e (pâ¯=â¯0.04) and worse memory retention at 21-24â¯d.p.e (24h post-stimulus, pâ¯=â¯0.02) compared to control flies. Our results demonstrated that subjects with LLD have significant downregulation of hsa-miR-184. Moreover, the knockout of hsa-miR-184 in flies lead to depressive-like behaviors, being more pronounce in older flies.
