Changes Of TR3 Subcellular Location In Cardiomyocytes Of Stressed Rats And Its Biological Mechanism

Objective: To investigate the changes of expression and subcellular location of TR3 in cardiomyocytes of stressed rats and its biological mechanism and to provide scientific evidences for exploring the mechanism underlying myocardium injury induced by stress. Methods: The animal model and cell model of stress-induced cardiomyocyte injury were established. The Western blotting method and confocal microscopy method were used to investigate the subcellular location of TR3 in cardiomyocytes under stress. The fluorescent probe fluid dialysis setting was used to measure the mitochondrial membrane potential in cardiomyocytes in vivo. The flow cytometry was selected to detect the apoptotic rate and mitochondrial membrane potential in cardiomyocytes in vitro. The Western blotting method was used to determine the content of cytochrome c protein in mitochondria in cardiomyocytes. The GFP-tagged TR3 deletion mutants were constructed and transfected into cardiomyocytes to explore the essential sequence of TR3 for translocating from the nucleus to the mitochondria. The immunoprecipitation method was selected to detect the serine phosphorylation of TR3 and its significance in TR3 translocation to the mitochondria in stressed cardiomyocytes. Results: Stress induced the increase of TR3 content in the mitochondria of cardiomyocytes and the translocation of TR3 from the nucleus to the mitochondria. The translocation of TR3 promoted the opening of mitochondrial membrane permeability transition pore, the release of cytochrome c from the mitochondria and the cardiomyocyte apoptosis. Treatment of stressed cardiomyocytes with leptomycin B, a non-specific blocker of nuclear export, resulted in nuclear retention of TR3 and abrogated its ability to induce the opening of mitochondrial membrane permeability transition pore, the release of cytochrome c from the mitochondria. TR3 152 amino acids from the NH₂-terminus was important in...