Protection of miR-19b in hypoxia/reoxygenation-induced injury by targeting PTEN.

OBJECTIVE: To study the role and mechanism of microRNA 19b (miR-19b) in hypoxia/reoxygenation (H/R)-induced injury by targeting PTEN.

METHODS: PC12 and BV2 cells induced by H/R were treated with miR-19b mimics/inhibitors or small interfering PTEN (si-PTEN), respectively. Lactate dehydrogenase (LDH) level, malondialdehyde (MDA), and superoxide dismutase (SOD) content was detected. Besides, cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Hoechst33342 staining, and flow cytometry, whereas mitochondrial membrane potential (MMP) tested by JC-1 assay, and reactive oxygen species (ROS) evaluated by the dichloro-dihydro-fluorescein diacetate assay. The ischemia/reperfusion (I/R) rats model was used to investigate the effects of miR-19b in vivo test. The infarct area and apoptosis rates in brain tissues were detected by 2,3,5-triphenyltetrazolium chloride and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining, respectively. miR-19b and PTEN/PI3K/Akt pathway-related proteins were detected by quantitative reverse-transcription polymerase chain reaction and western blot analysis.

RESULTS: miR-19b mimics could reduce LDH, MDA, and ROS levels and decline cell apoptosis, but enhance the viability, MMP, and SOD activity with decreased PTEN and cleaved caspase, as well as increased p-Akt/Akt and Bcl-2/Bax ratios in H/R-induced PC12 and BV2 cells. However, miR-19b inhibitors led to completely opposite results to aggravate H/R-induced cell injury. Meanwhile, si-PTEN could reverse the effect of miR-19b inhibitors on H/R-induced injury. Moreover, treatment with miR-19b agomir after I/R in vivo sufficiently decreased infarct area and reduced apoptosis rates by targeting PTEN through the regulation of the PI3K/Akt pathway.

CONCLUSION: miR-19b could inhibit oxidative stress, enhance cell MMP, promote cell survival, and inhibit cell apoptosis by targeting PTEN via the regulation of the PI3K/Akt pathway, thus playing the neuronal protective effects.