Beta-Catenin Regulates Myocardial Ischemia/Reperfusion Injury Following Heterotopic Heart Transplantation In Mice By Modulating Pten Pathways

Ischemia reperfusion (I/R) injury, an inevitable event accompanying heart transplantation, is the primary factor leading to organ failure and graft rejection. In order to prevent I/R injury, we established murine heart transplantation model with I/R and cell culture system to determine whether beta-catenin is a mediate factor in preventing I/R injury in heart transplantation. After successfully established heterotopic heart transplantation mice model, the I/R injury was induced, and two dynamic temporal were studied during different I/R phases. With the increase of ischemia and reperfusion time, heart damage was more severe. In the initial study, we observed that beta-catenin was significantly decreased, while ROCK1 and PTEN increased during the perfusion phase from day 0 to day 1, and remain the same level until 3 days later. The similar pattern that beta-catenin was down-regulated while ROCK1 and PTEN were up-regulated was also observed in the dynamic temporal ischemia study. To further investigate the role of beta-catenin signaling in I/R injury in vitro, beta-catenin over-expressing plasmid was transfected into HL-1 cells, a cardiac cell line. We noted that beta-catenin over-expressing cardiomyocytes showed decreased ROCK1/PTEN expression both at mRNA and protein levels. In addition, cobalt dichloride (CoCl2) -induced oxidative stress model was further established to mimic cardiac VR injury. We observed that CoCl2-induced activation of ROCK1/PTEN signaling pathway were attenuated by transient transfection of a beta-catenin over-expressing plasmid. Taken together, our results suggest that cardiac transplant induced IR injury is closely associated with the down-regulation of beta-catenin and up-regulation of ROCK1 and PTEN expression.