Transient receptor potential melastatin 4 contributes to early-stage endothelial injury induced by arsenic trioxide.

BACKGROUND/AIMS: To investigate the effect of Arsenic Trioxide (ATO) on endothelial cells injury and explore the role of transient receptor potential melastatin 4 channel (TRPM4) in ATO-induced endothelial injury. METHODS: qRT-PCR was used to examine the mRNA expression of TRPM4 in human umbilical vein endothelial cells (HUVECs). The protein levels were measured by Western blot and immunostaining. The MTT, TUNEL, and transwell assays were used to evaluate the cell viability, apoptosis, and migration, respectively. The ultrastructural changes were observed by scanning electron microscopy. The membrane potential, cytosolic [Na+]i, cytosolic [Ca2+]i and reactive oxygen species (ROS) levels were detected by fluorescent probes. Isometric tension of mesenteric artery was recorded by using a multiwire myograph system. RESULTS: ATO induced HUVEC cells injury, the significant upregulation of TRPM4 in this process was inhibited by 9-phenanthrol or siRNA. ATO-induced apoptosis and decrease in the cell viability/ migration were all partially reversed upon the treatment with 9-phenanthrol. Whereas, ATO-mediated increase in membrane potential, cytosolic [Na+]i, cytosolic [Ca2+]i and the ROS levels were also abolished by 9-phenanthrol or siRNA, suggesting that oxidative stress may be the potential mechanisms underlying ATO-induced endothelial injury. Additionally, 9-phenanthrol treatment prevented ATO-mediated impairment of acetylcholine-induced endothelium-dependent relaxations. CONCLUSION: TRPM4 is involved in endothelial injury induced by ATO and may be a promising therapeutic target for endothelial injury.

Transforming Growth Factor-ß Receptor III is a Potential Regulator of Ischemia-Induced Cardiomyocyte Apoptosis.

BACKGROUND: Myocardial infarction (MI) is often accompanied by cardiomyocyte apoptosis, which decreases heart function and leads to an increased risk of heart failure. The aim of this study was to examine the effects of transforming growth factor-ß receptor III (TGFßR3) on cardiomyocyte apoptosis during MI. METHODS AND RESULTS: An MI mouse model was established by left anterior descending coronary artery ligation. Cell viability, apoptosis, TGFßR3, and mitogen-activated protein kinase signaling were assessed by methylthiazolyldiphenyl-tetrazolium bromide assay, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunofluorescence, electron microscopy, and Western blotting. Our results demonstrated that TGFßR3 expression in the border region of the heart was dynamically changed during MI. After stimulation with H2O2, TGFßR3 overexpression in cardiomyocytes led to increased cell apoptosis and activation of p38 signaling, whereas TGFßR3 knockdown had the opposite effect. ERK1/2 and JNK1/2 signaling was not altered by TGFßR3 modulation, and p38 inhibitor (SB203580) reduced the effect of TGFßR3 on apoptosis, suggesting that p38 has a nonredundant function in activating apoptosis. Consistent with the in vitro observations, cardiac TGFßR3 transgenic mice showed augmented cardiomyocyte apoptosis, enlarged infarct size, increased injury, and enhanced p38 signaling upon MI. Conversely, cardiac loss of function of TGFßR3 by adeno-associated viral vector serotype 9-TGFßR3 short hairpin RNA attenuated the effects of MI in mice. CONCLUSIONS: TGFßR3 promotes apoptosis of cardiomyocytes via a p38 pathway-associated mechanism, and loss of TGFßR3 reduces MI injury, which suggests that TGFßR3 may serve as a novel therapeutic target for MI.