Pokkunuri 2020 Am J Physiol Renal Physiol
|Pokkunuri ID, Lokhandwala MF, Banday AA (2020) Protein disulfide isomerase inhibition impairs Keap1/Nrf2 signaling and mitochondrial function and induces apoptosis in renal proximal tubular cells. Am J Physiol Renal Physiol [Epub ahead of print].|
Abstract: Renal proximal tubular apoptosis plays a critical role in kidney health and disease. However, cellular molecules that trigger renal apoptosis remain elusive. Here, we evaluated the effect of inhibiting protein disulfide isomerase (PDI), a critical thioredoxin chaperone protein, on apoptosis, and the underlying mechanisms in human renal proximal tubular (HK2) cells. HK2 cells were transfected with PDI specific siRNA in the absence and presence of an antioxidant tempol. PDI siRNA transfection resulted in a decrease of ~70% in PDI protein expression and enzyme activity. PDI inhibition increased caspase-3 activity and induced profound cell apoptosis. Mitochondrial function, as assessed by mitochondrial cytochrome c levels, mitochondrial membrane potential, oxygen consumption, and ATP levels, was significantly reduced in the PDI inhibited cells. Also, PDI inhibition caused Nrf2 (nuclear factor E2 related factor 2, a redox-sensitive transcription factor) cytoplasmic sequestration, decreased superoxide dismutase, and glutathione S-transferase activities, and increased oxidative stress. In PDI inhibited cells, tempol reduced apoptosis, caspase-3 activity, and oxidative stress, and also restored Nrf2 nuclear translocation and mitochondrial function. Silencing Nrf2 in the cells abrogated the beneficial effect of tempol, while Keap1 silencing (Kelch-like ECH-associated protein 1, a Nrf2 regulatory protein) protected the cells from PDI inhibitory effects. Collectively, our data indicate that PDI inhibition diminishes Nrf2 nuclear translocation causing oxidative stress that further triggers mitochondrial dysfunction and renal cell apoptosis. These studies suggest an important role for PDI in renal cell apoptosis involving Nrf2 and mitochondrial dysfunction.
• Keywords: Apoptosis, Keap1/Nrf2, Mitochondria, Oxidative Stress, PDI • Bioblast editor: Plangger M
Labels: MiParea: Respiration, nDNA;cell genetics
Stress:Cell death Organism: Human Tissue;cell: Kidney Preparation: Homogenate