TIGAR Protects Against Adenine-Induced Ferroptosis in Human Proximal Tubular Epithelial Cells by Activating the mTOR/S6KP70 Axis.

TP53-induced glycolysis and apoptosis regulator (TIGAR) acts as a switch for nephropathy, but its underlying mechanism is still unclear. The purpose of this study was to explore the potential biological significance and underlying mechanism of TIGAR in modulating adenine-induced ferroptosis in human proximal tubular epithelial (HK-2) cells. HK-2 cells under- or overexpressing TIGAR were challenged with adenine to induce ferroptosis. The levels of reactive oxygen species (ROS), iron, malondialdehyde (MDA), and glutathione (GSH) were assayed. Expression of ferroptosis-associated solute carrier family seven-member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) at the level of mRNA and protein were measured by quantitative real-time-PCR and western blotting. The phosphorylation levels of proteins in the mTOR/S6KP70 pathway were determined by western blotting. Adenine overload triggered ferroptosis in HK-2 cells, as evidenced by reduced levels of GSH, SLC7A11, and GPX4, and increased levels of iron, MDA, and ROS. TIGAR overexpression repressed adenine-induced ferroptosis and induced mTOR/S6KP70 signaling. Inhibitors of mTOR and S6KP70 weakened the ability of TIGAR to inhibit adenine-induced ferroptosis. TIGAR inhibits adenine-induced ferroptosis in human proximal tubular epithelial cells by activating the mTOR/S6KP70 signaling pathway. Therefore, activating the TIGAR/mTOR/S6KP70 axis may be a treatment for crystal nephropathies.

Electrochemical skin conductance and heart rate variability in patients with non-dialysis chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is very common now and associates with high overall and cardiovascular mortality. Numerous studies have reported that Heart rate variability (HRV) could also be used to detect cardiovascular autonomic dysfunction (CAD). We investigated the association of electrochemical skin conductance (ESC) of EZSCAN results with HRV in non-dialysis CKD patients. METHODS: In a cross-sectional study, we enrolled 248 prevalent non-dialysis CKD patients. Patients underwent a 24-h Holter (CB-2302-A, Bio Instrument, China). A time domain analysis of HRV was performed, and the following parameters were obtained: SDNN, SDANN, rMSSD, pNN50. EZSCAN device (Impeto Medical, Paris, France) measures ESC values of each participants. Mean global skin conductance computed as 0.5 * (reflecting (right + left hand)/2 + (right and left foot)/2). Log transforms data into a normal distribution for statistical analysis. RESULTS: There were 142 males and 106 females included in the present study. Patients' age was 56.6±17.08 years. Logarithm(Log) (global ESC) was independently predicted by age (P<0.01), hypertension history, estimated Glomerular filtration rate (eGFR) and log SDNN (P<0.05). While log SDANN, rMSSD and pNN50 were not independent predictors for log (global ESC). CONCLUSION: Increased global ESC significantly associated with elevated HRV, specifically SDNN in non-dialysis CKD patients. This suggested that global ESC may appear to be an important predictor of CAD, and even could be used as a cardiovascular risk factor in non-dialysis CKD patients.