MicroRNAs in brain aging.

Brain aging is one of the most crucial biological processes that affect the physiological balance between health and disease. Age-associated dysfunction of brain leads to severe health problems in current aging society. MicroRNAs (miRNAs) have emerged as important regulators in most physiological processes including fine-tuning of the short-term, cellular regulatory functions as well as modulation of long-term organismal lifespan. In this review, we discuss critical roles of miRNAs in the progression of normal and pathological brain aging. 50% of all known miRNAs are found in brain including cortex and hippocampus. A significant number of expressed miRNAs were differentially regulated during aging, implicating miRNAs as regulators of brain aging. The ability of miRNAs to regulate multiple targets within a pathway or even multiple pathways allows for coordinated regulation of brain functions. miRNA-mediated, brain functional changes are evident in cognition, inflammation, neuroprotection, lipid metabolism, mitochondrial function and lifespan. Dysregulation of brain miRNAs contributes to accelerated cognitive decline and increased neurological disorders. Elucidating mechanisms by which miRNAs and their multiple targets are temporally and spatially regulated in normal and pathological brain aging will provide a deeper understanding on the process of interrelated pathways of brain aging, and a new insight into therapeutic interventions.