Lee 2005 Am J Physiol Renal Physiol
|Lee WK, Bork U, Gholamrezaei F, Thévenod F (2005) Cd2+-induced cytochrome c release in apoptotic proximal tubule cells: role of mitochondrial permeability transition pore and Ca2+ uniporter. Am J Physiol Renal Physiol 288:F27-39.|
Abstract: Cd2+ induces apoptosis of kidney proximal tubule (PT) cells. Mitochondria play a pivotal role in toxic compound-induced apoptosis by releasing cytochrome c. Our objective was to investigate the mechanisms underlying Cd2+-induced cytochrome c release from mitochondria in rat PT cells. Using Hoechst 33342 or MTT assay, 10 µM Cd2+ induced ~5–10% apoptosis in PT cells at 6 and 24 h, which was associated with cytochrome c and apoptosis-inducing factor release at 24 h only. This correlated with previously described maximal intracellular Cd2+ concentrations at 24 h, suggesting that elevated Cd2+ may directly induce mitochondrial liberation of proapoptotic factors. Indeed, Cd2+ caused swelling of energized isolated kidney cortex mitochondria (ECCd50 ~9 µM) and cytochrome c release, which were independent of permeability transition pore (PTP) opening since PTP inhibitors cyclosporin A or bongkrekic acid had no effect. On the contrary, Cd2+ inhibited swelling and cytochrome c release induced by PTP openers (POCd43– or H2O2+Cd2+). The mitochondrial Cd2+ uniporter (MCU) played a key role in mitochondrial damage: 1) MCU inhibitors (La3+, ruthenium red, Ru360) prevented swelling and cytochrome c release; and 2) ruthenium red attenuated Cd2+ inhibition of PO43–-induced swelling. Using the Cd2-sensitive fluorescent indicator FluoZin-1, Cd2+ was also taken up by mitoplasts. The aquaporin inhibitor AgNO3 abolished Cd2+-induced swelling of mitoplasts. This could be partially mediated by activation of the mitoplast-enriched water channel aquaporin-8. Thus cytosolic Cd2+ concentrations exceeding a certain threshold may directly cause mitochondrial damage and apoptotic development by interacting with MCU and water channels in the inner mitochondrial membrane.
• Keywords: Cadmium, Aquaporin, Apoptosis-inducing factor, Cyclosporin A
Stress:Cell death Organism: Rat Tissue;cell: Kidney Preparation: Intact cells, Isolated mitochondria Enzyme: Complex IV;cytochrome c oxidase, Inner mt-membrane transporter
Coupling state: OXPHOS