Abstract 11938: Hypoxamir miR-210 Anti-Apoptotic Role in Acute Peripheral Ischemia
BACKGROUND: MiR-210 is a key player of cell response to hypoxia, modulating glycolysis, cell survival, cell migration and endothelial cell tubulogenesis in vitro. However, its role in vivo is poorly characterized. The aim of this study is understanding miR-210 regulation and role in a mouse model of hindlimb ischemia.
METHODS and RESULTS: After femoral artery dissection, miR-210 expression in the gastrocnemius muscle increased 4.4±0.6 fold (p<0.01) at 3 days, peaked at day 7 (8.3±0.3 fold increase, p<0.05) and declined afterwards. To investigate miR-210 role in tissue response to ischemia, its function was inhibited by LNA-anti-miR-210 injected in the tail vein. LNA-anti-miR-210 not only prevented miR-210 induction by ischemia, but also caused a >10 fold decrease of miR-210 compared to normoperfused LNA-scramble control (scr; p<0.002). As expected, miR-210 targets genes ISCU, P4HB, GPD1L and DDAH1 were de-repressed. In keeping with miR-210 inhibitory role of oxidative metabolism found in vitro, miR-210 blockade induced a shift from glycolitic to oxidative metabolism in EDL skeletal muscle, as assessed by the NADH-TR diaphorase assay (56%±12 increase, p<0.02). Evaluation of acute tissue damage showed that LNA-anti-miR-210 treatment increased >3 fold apoptosis at 8 hrs (TUNEL+ nuclei: scr=3.3%±1.2; LNA-anti-miR-210=11.6%±3.3; p<0.02). Accordingly, necrosis, measured by Evans Blue Dye staining, also increased almost 3 fold at 3 days (EBD+ area: scr=9.5%±4.5; LNA-anti-miR-210=25.6%±6.6; p<0.04). Capillary density decrease induced by ischemia at 3 days was further aggravated by miR-210 blockade (capillaries/mm2: scr=177±28; LNA-anti-miR-210=109±23; p<0.04); consequently, residual limb perfusion, measured by Laser Doppler, further declined (p<0.02).
The pro-survival role of miR-210 was confirmed by in vitro experiments showing that miR-210 blockade more than doubled apoptosis in endothelial cells exposed to 1% O2 (p<0.01). Likewise, miR-210 inhibition decreased skeletal muscle myofiber survival in response to chemical anoxia (p<0.01) and H2O2 (p<0.01), while oxidative stress was increased (p<0.02).
CONCLUSIONS: miR-210 is integral part of the tissue protective mechanisms activated in response to acute ischemia.
- © 2012 by American Heart Association, Inc.