Glutamate dehydrogenase requirement for apoptosis induced by aristolochic acid in renal tubular epithelial cells

Abstract

Ingestion of aristolochic acids (AA) contained in herbal remedies results in a renal disease and, frequently, urothelial malignancy. The genotoxicity of AA in renal cells, including mutagenic DNA adduct formation, is well-documented. However, the mechanisms of AA-induced tubular atrophy and renal fibrosis are largely unknown. Epithelial cell death is a critical characteristic of these pathological conditions. To elucidate the mechanisms of AA-induced cytotoxicity, we explored AA-interacting proteins in tubular epithelial cells (TEC). We found that AA interacts with a mitochondrial enzyme glutamate dehydrogenase (GDH) and moderately inhibits its activity. We report that AA induces cell death in GDH-knockdown TEC preferentially via non-apoptotic means, whereas in GDH-positive cells, death was executed by both the non-apoptotic and apoptotic mechanisms. Apoptosis is an energy-reliant process and demands higher adenosine 5'-triphosphate (ATP) consumption than does the non-apoptotic cell death. We found that, after AAI treatment, the ATP depletion is more pronounced in GDH-knockdown cells. When we reduced ATP in TEC cells by inhibition of glycolysis and mitochondrial respiration, cell death mode switched from apoptosis and necrosis to necrosis only. In addition, in cells incubated at low glucose and no glutamine conditions, oxaloacetate and pyruvate reduced AAI-induced apoptosis our data suggest that AAI-GDH interactions in TEC are critical for the induction of apoptosis by direct inhibition of GDH activity. AA binding may also induce changes in GDH conformation and promote interactions with other molecules or impair signaling by GDH metabolic products, leading to apoptosis.

A Natural-Like Synthetic Small Molecule Impairs Bcr-Abl Signaling Cascades and Induces Megakaryocyte Differentiation in Erythroleukemia Cells

“…Further, in all treatment groups of our study we found increased levels of two subunits of ATP synthase, whose activation may be a prerequisite for the energy-reliant apoptotic process to proceed [26]. On the other hand, we identified reduced levels of phosphoglycerate kinase 1 (after treatment with all the compounds), voltage-dependent anion-selective protein channel 2 (in K562 cells exposed to IND_S1 , IND_S7 and MEL_S3 ) and glutamate dehydrogenase 1 (in MEL_S3 -treated K562 cells), which have been proposed to act as suppressors of apoptotic phenotypes [27], [28], [29].…”

Prediction and Characterisation of the System Effects of Aristolochic Acid: A Novel Joint Network Analysis towards Therapeutic and Toxicological Mechanisms

“…Apoptosis is considered as the primary mechanism involved in the development of AAN. AA also induces TEC death via apoptosis in acute AAN by targeting the p53 signalling pathway; AA has also been observed to trigger STAT3 dephosphorylation and p53 activation to mediate TEC death via the apoptosis mechanism in acute AAN 60 61 . While AA can influence steroid and lipid metabolism in the liver 58 as it inhibits phospholipase A2, which can form fatty acid and lysophospholipid products by hydrolysing phospholipids 62 .…”

Differential Effects of the Mitochondria-Active Tetrapeptide SS-31 (D-Arg-dimethylTyr-Lys-Phe-NH2) and Its Peptidase-Targeted Prodrugs in Experimental Acute Kidney Injury

“…AA is a natural herbal compound that is toxic to the renal tubulo-interstitial compartment, leading to a rapidly progressive nephropathy, renal failure, and, in some instances, cancer of the urinary tract. AA-induced tubular toxicity involves mitochondrial permeability and injury, leading to defective activation of anti-oxidative enzymes, combined with progressive tubular atrophy, impaired regeneration, and apoptosis/autophagy of proximal tubular epithelial cells (Romanov et al, 2011; Zeng et al, 2014). The anticancer drug doxorubicin (ADR) and its metabolites accumulate in the inner mitochondrial membrane, producing excessive ROS and causing oxidative damage.…”