title: MicroRNA-322 protects hypoxia-induced apoptosis in cardiomyocytes via BDNF gene.
abstract: BACKGROUND
  Cardiomyocytes apoptosis under hypoxia condition contributes significantly to various cardiovascular diseases. In this study, we investigated the role of microRNA-322 (miR-322) in regulating hypoxia-induced apoptosis in neonatal murine cardiomyocytes in vitro.
  
  
  METHODS
  Cardiomyocytes of C57BL/6J mice were treated with hypoxia condition in vitro. Cardiomyocyte apoptosis was measured by TUNEL assay. Gene expression pattern of miR-322 was measured by qRT-PCR. Stable downregulation of miR-322 in cardiomyocytes were achieved by lentiviral transduction, and the effect of miR-322 downregulation on hypoxia-induced cardiomyocyte apoptosis was investigated. Possible regulation of miR-322 on its downstream target gene, brain derived neurotrophic factor (BDNF) was investigated in cardiomyocytes. BDNF was then genetically silenced by siRNA to evaluate its role in miR-137 mediated cardiomyocyte apoptosis protection under hypoxia condition.
  
  
  RESULTS
  Under hypoxia condition, significant apoptosis was induced and miR-322 was significantly upregulated in cardiomyocytes in vitro. Through lentiviral transduction, miR-322 was efficiently knocked down in cardiomyocytes. Downregulation of miR-322 protected hypoxia-induced cardiomyocyte apoptosis. Luciferase assay showed BDNF was the target gene of miR-322. QRT-PCR showed BDNF expression was associated with miR-322 regulation on hypoxia-induced cardiomyocyte apoptosis. Silencing BDNF in cardiomyocyte through siRNA transfection reversed the protective effect of miR-322 downregulation on hypoxia-induced apoptosis.
  
  
  CONCLUSIONS
  Our study revealed that miR-322, in association with BDNF, played important role in regulating hypoxia-induced apoptosis in cardiomyocyte.
authors.affiliation: Second Ward of Cardiovascular Surgery, Second Affiliated Hospital of Harbin Medical University Harbin 157000, China.
authors.forename: Liguo
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Second Affiliated Hospital of Harbin Medical University Harbin 157000, China.
authors.forename: Shigang
authors.initials: S
authors.lastname: Song
authors.affiliation: Second Ward of Cardiovascular Surgery, Second Affiliated Hospital of Harbin Medical University Harbin 157000, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Lv
keywords: BDNF; Cardiomyocyte; apoptosis; miR-322