title: Involvement of microRNA-181a and Bim in a rat model of retinal ischemia-reperfusion injury.
abstract: OBJECTIVE
  To investigate the changes in the expression of microRNA-181a (miR-181a) and Bim in a rat model of retinal ischemia-reperfusion (RIR), to explore their target relationship in RIR and their involvement in regulating apoptosis of retinal ganglion cells (RGCs).
  
  
  METHODS
  Target gene prediction for miR-181a was performed with the aid of bioinformatics and Bim was identified as a potential target gene of miR-181a. A rat model of RIR was created by increasing the intraocular pressure. RGCs in the flatmounted retinas were labeled with Brn3, a marker for alive RGCs, by immunofluorescent staining. The changes in the number of RGCs after RIR were recorded. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to determine the expression level of miR-181a in the retina. Bim/Brn3 double immunofluorescence was used to detect the localization of Bim. The expression of Bim in the retina was determined with the aids of Western blot and qRT-PCR.
  
  
  RESULTS
  Compared with the negative control group, the density of RGCs was significantly lower in the ischemia/reperfusion (I/R)-24h and I/R-72h groups (P<0.001). The expression level of miR-181a started to decrease at 0h after RIR, and further decreased at 24h and 72h compared with the negative control group (P<0.001). Bim was significantly upregulated at 12h after RIR (P<0.05) and reached peak at 24, 72h compared with the negative control group (P<0.01). Pearson correlation analysis showed that the expression level of Bim was negatively correlated with the expression level of miR-181a and the density of RGCs.
  
  
  CONCLUSIONS
  Bim may be a potential target gene of miR-181a. Both miR-181a and Bim are involved in RGCs death in RIR. RIR may promote RGCs apoptosis in the retina via downregulation of miR-181a and its inhibition on Bim expression.
authors.affiliation: Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China; Department of Ophthalmology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, Sichuan Province, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China; Department of Ophthalmology, the Third People's Hospital of Chengdu, Chengdu 610031, Sichuan Province, China.
authors.forename: Jin-Nan
authors.initials: JN
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China.
authors.forename: Jun-Jun
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
keywords: Bim; apoptosis; microRNA-181a; retinal ganglion cells; retinal ischemia reperfusion; target gene