Lin28a Protects against Hypoxia/Reoxygenation Induced Cardiomyocytes Apoptosis by Alleviating Mitochondrial Dysfunction under High Glucose/High Fat Conditions

AIM: The aim of the present study was to investigate the role of Lin28a in protecting against hypoxia/reoxygenation (H/R)-induced cardiomyocytes apoptosis under high glucose/high fat (HG/HF) conditions. METHODS: Primary cardiomyocytes which were isolated from neonatal mouse were randomized to be treated with lentivirus carrying Lin28a siRNA, Lin28acDNA 72 h before H/R (9 h/2 h). Cardiomyocytes biomarkers release (LDH and CK), cardiomyocytes apoptosis, mitochondria biogenesis and morphology, intracellular reactive oxygen species (ROS) production, ATP content and inflammatory cytokines levels after H/R injury in high glucose/high fat conditions were compared between groups. The target proteins of Lin28a were examined by western blot analysis. RESULTS: Our results revealed that Lin28a cDNA transfection (overexpression) significantly inhibited cardiomyocyte apoptotic index, improved mitochondria biogenesis, increased ATP production and reduced ROS production as compared with the H/R group in HG/HF conditions. Lin28a siRNA transfection (knockdown) rendered the cardiomyocytes more susceptible to H/R injury as evidenced by increased apoptotic index, impaired mitochondrial biogenesis, decreased ATP production and increased ROS level. Interestingly, these effects of Lin28a were blocked by pretreatment with the PI3K inhibitor wortmannin. Lin28a overexpression increased, while Lin28a knockdown inhibited IGF1R, Nrf-1, Tfam, p-IRS-1, p-Akt, p-mTOR, p-p70s6k, p-AMPK expression levels after H/R injury in HG/HF conditions. Moreover, pretreatment with wortmannin abolished the effects of Lin28a on the expression levels of p-AKT, p-mTOR, p-p70s6k, p-AMPK. CONCLUSIONS: The present results suggest that Lin28a inhibits cardiomyocytes apoptosis by enhancing mitochondrial biogenesis and function under high glucose/high fat conditions. The mechanism responsible for the effects of Lin28a is associated with the PI3K/Akt dependent pathway.