MiRNA-199a-5p Protects Against Cerebral Ischemic Injury by Down-Regulating DDR1 in Rats.

Objective: To assess the effects of miR-199a-5p on cerebral ischemic injury and its underlying mechanisms.

Methods: Infarct volume, neurologic deficit scores, and brain water content were evaluated after 24 hours of reperfusion. The histopathological damage in cortical neurons was assayed by hematoxylin and eosin staining. Neuronal apoptosis was evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. The regulatory effect of miR-199a-5p on discoidin domain receptor 1 (DDR1) was investigated using a dual luciferase reporter gene assay. Expression levels of miR-199a-5p and DDR1 were detected by real-time fluorogenic polymerase chain reaction and Western blot analysis. Expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-β, and IL-6 were investigated by enzyme-linked immunosorbent assay.

Results: Our results suggest that DDR1 is the target gene of miR-199a-5p. The expression levels of miR-199a-5p and DDR1 were significantly down-regulated and up-regulated in the rats with cerebral ischemia compared with the control and sham groups, respectively. Moreover, infarct volume, neurologic score, brain water content, neuronal damage, and neuronal apoptosis were significantly decreased in the mimics group, siRNA DDR1 (siDDR1) group, and especially the mimics + siDDR1 group. The results also confirmed significantly weakened expression levels of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) in mimics, siDDR1, and especially mimics + siDDR1 rats. In addition, DDR1 silencing attenuated the effects of the miR-199a-5p inhibitor on neurologic function, infarct volume, brain water content, and proinflammatory cytokine expressions after middle cerebral artery occlusion in rats.

Conclusions: miR-199a-5p may protect against cerebral ischemic injury by down-regulating DDR1 in rats.