Evidence for the Contribution of the miR-206/BDNF Pathway in the Pathophysiology of Depression.

Depression is a complex disorder with substantial impacts on individual health and has major public health implications. Depression results from complex interactions between genetic and environmental factors. Epigenetic mechanisms, including DNA methylation (DNAm), microRNAs (miRNAs), and histone modifications, can produce heritable phenotypic changes without a change in DNA sequence and have been recently proven to mediate lasting increases in the risk of depression following exposure to adverse life events. Of these, miRNAs are gaining attention for their role in the pathogenesis of many stress-associated mental disorders, including depression. One such miRNA is microRNA-206 (miR-206), which is a critical candidate for increasing the susceptibility to stress. Although miR-206 is thought to be a typical muscle-specific miRNA, it is expressed throughout the brain, particularly in the hippocampus and prefrontal cortex (PFC). Until now, only a few studies have been conducted on rodents to understand its role in stress-related abnormalities in neurogenesis. However, the precise underlying molecular mechanism of miR-206-mediated depression-like behaviours remains largely unknown. Here, we reviewed recent advances in the field of biomedical and clinical research on the role of miR-206 in the pathogenesis of depression from studies using different tissues and various experimental designs, and described how abnormalities in miR-206 expression in these tissues can affect neuronal functions. Moreover, we focused on studies investigating the brain-derived neurotrophic factor (BDNF) as a functional target of miR-206, where miR-206 has been implicated in the pathogenesis of depression by suppressing the expression of the BDNF. In summary, these studies confirm the existence of a tight correlation between the pathogenesis of depression and the miR-206/BDNF pathway.