Severe Hyperosmotic Stress Issues an ER Stress-Mediated “Death Sentence” in H9c2 Cells, with p38-MAPK and Autophagy “Coming to the Rescue”

"Villains" Turning Good: Antimycin A and Rotenone, Mitochondrial Respiratory Chain Inhibitors, Protect H9c2 Cardiac Cells Against Insults Triggering the Intrinsic Apoptotic Pathway

Mitochondria are the powerhouses of cells, also involved in ROS (reactive oxygen species) generation and cellular death regulation. Thus, several diseases are associated with mitochondrial impairment, including cardiovascular disorders (CVDs). Since CVDs are currently the leading cause of death worldwide, it is very important to evaluate targeting mitochondrial effectors in clinical treatment protocols. Hence, in the present study, antimycin A and rotenone, established inhibitors of the mitochondrial electron transfer chain, were shown to halt apoptotic death induced by curcumin (50 μM) and sorbitol (0.5 M), in H9c2 cardiac cells. In particular, immunoblotting analysis revealed that they totally abolished PARP [poly(ADP-ribose) polymerase] proteolysis, under these conditions. This finding was accompanied by an enhancement of cell viability, recovery of mitochondria networks' integrity, suppression of cytochrome c release into the cytoplasm, and reversal of chromatin condensation. Chelating extracellular calcium (with EGTA) further enhanced the beneficial impact of antimycin A and rotenone on curcumin- or sorbitol-treated H9c2 cells viability. Of interest, the phosphorylation of eIF2α, indicative of the onset of the pro-survival Integrated Stress Response (IRS), was sustained under these conditions. Overall, our data highlight the anti-apoptotic effect of these compounds, unmasking their potential as mediators in novel therapeutic interventions against mitochondria-associated cardiac dysfunction.

Cyclosporine A-induced systemic metabolic perturbations in rats: A comprehensive metabolome analysis

A better understanding of cyclosporine A (CsA)-induced nephro- and hepatotoxicity at the molecular level is necessary for safe and effective use. Utilizing a sophisticated study design, this study explored metabolic alterations after long-term CsA treatment in vivo. Rats were exposed to CsA with 4, 10, and 25 mg/kg for 4 weeks and then sacrificed to obtain liver, kidney, urine, and serum for untargeted metabolomics analysis. Differential network analysis was conducted to explore the biological relevance of metabolites significantly altered by toxicity-induced disturbance. Dose-dependent toxicity was observed in all biospecimens. The toxic effects were characterized by alterations of metabolites related to energy metabolism and cellular membrane composition, which could lead to the cholestasis-induced accumulation of bile acids in the tissues. The unfavorable impacts were also demonstrated in the serum and urine. Intriguingly, phenylacetylglycine was increased in the kidney, urine, and serum treated with high doses versus controls. Differential correlation network analysis revealed the strong correlations of deoxycytidine and guanosine with other metabolites in the network, which highlighted the influence of repeated CsA exposure on DNA synthesis. Overall, prolonged CsA administration had system-level dose-dependent effects on the metabolome in treated rats, suggesting the need for careful usage and dose adjustment.