Abstract
In recent years, the Japanese population has been aging and the risk of contracting various age-related diseases has increased. Thus, there is a need to analyze components that are characteristic of aging and examine their association with diseases to detect age-related diseases at an early stage. In the present study, microRNAs (miRNAs/miRs) in serum extracellular vesicles (EVs) of 82-102-week-old mice were analyzed to identify miRNAs characteristic of aging. Increased expression of mmu-miR-21a-5p was observed. These miRNAs may be derived from senescent vascular endothelial cells, and RNA-sequencing data (GSE130727) of HUVECs induced to senesce by 4 Gy of radiation revealed that the miRNAs were involved in the cell cycle and DNA repair. Annotations to senescence-related pathways were also identified. Reduced expression of the miR-21-5p target gene, which has an identical sequence in humans and mice, was confirmed. In HUVECs induced to age under similar conditions, increased senescence-associated β-galactosidase activity and increased intracellular miR-21-5p expression were observed. A portion of the miR-21-5p was secreted extracellularly by internalizing tetraspanin-positive EVs, and miR-21-5p was secreted into the extracellular space. The present study also demonstrated that miR-21-5p expression was upregulated and extracellular secretion of miR-21-5p was enhanced during vascular endothelial cell senescence. These findings suggested that increased serum miR-21-5p represents a biomarker for vascular endothelial cell senescence.