title: Mature and immature microRNA ratios in cultured rat cardiomyocytes during anoxia-reoxygenation.
abstract: BACKGROUND
  The critical role of microRNAs (miRNAs) in the global control of gene expression in the heart has recently been postulated; however, the mechanisms of miRNA regulation in cardiac pathology are not clear.
  
  
  OBJECTIVE
  To evaluate the levels of miR-1, miR-208a and miR-29a expressed in neonatal rat cardiomyocytes during anoxia-reoxygenation (AR).
  
  
  METHODS
  Reverse transcription coupled with real-time polymerase chain reaction was used to evaluate the level of mature and immature miRNAs in cardiomyocyte culture during AR.
  
  
  RESULTS
  THE INITIAL LEVELS OF THE MATURE AND IMMATURE MIRNAS WERE DIFFERENT: mature - miR-1 7.46±4.440, miR-208a 0.02±0.015 and miR-29a 5.60±2.060; immature - miR-1 0.02±0.007, miR-208a 0.05±0.029 and miR-29a 0.01±0.008. The most prominent changes were observed for immature miRNAs during AR, with immature miR-1 and miR-29a expressed at significantly higher levels during remote reoxygenation (AR [0.5 h/24 h]) compared with control, while the level of expressed immature miR-208a was significantly decreased during acute reoxygenation (AR [0.5 h /1 h]) and returned to control levels during remote reoxygenation (AR [0.5h /24 h]). Also, the ratios of mature to immature miRNAs were significantly increased during acute reoxygenation for miR-1 and miR-208a, returning to control levels during remote reoxygenation, while for miR-29a, this ratio had the progressive tendency to decrease under AR.
  
  
  CONCLUSIONS
  The discordance between the estimated levels of mature and immature miRNA during AR supports the hypothesis that transcriptional and post-transcriptional regulatory mechanisms at the miRNA level play a role in the response of cardiomyocytes to AR, and could be a contributing factor in the differential resistance of cardiomyocytes to AR.
authors: Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, Key State Laboratory, National Academy of Science, Kiev, Ukraine.
authors: Victor E
authors: VE
authors: Dosenko
authors: Veronika L
authors: VL
authors: Gurianova
authors: Olga V
authors: OV
authors: Surova
authors: Dmitriy A
authors: DA
authors: Stroy
authors: Alex A
authors: AA
authors: Moibenko