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Role of mitochondrial dysfunction in S-(1,2-dichlorovinyl)-l-cysteine-induced apoptosis
1Program of Biochemistry, Cell Biology and Developmental Biology, Emory University, Atlanta, Georgia 30322, USA.
Abstract:
The nephrotoxicity of trichloroethylene and dichloroacetylene has previously been linked to mitochondrial dysfunction induced by the metabolite S-(1,2-dichlorovinyl)-l-cysteine (DCVC). In this study, we examined whether key biochemical steps associated with mitochondria occur in DCVC-induced apoptosis in cultured porcine proximal tubular LLC-PK1 cells. DCVC caused a decrease in mitochondrial membrane potential (mt Delta Psi) beginning at 4 h and a release of cytochrome c into the cytoplasm at 6 h. Caspase-3-like activity was detected at 6 h and extensive DNA fragmentation was observed at 8 h. Decreases in cellular ATP were not evident until 8 h and later, even though electron microscopy showed that the mitochondria were extensively swollen. Aminooxyacetic acid (AOAA), an inhibitor of cysteine-conjugate beta-lyase, protected against mitochondrial changes and apoptosis. Overexpression of the antiapoptotic Bcl-2 protein desensitized LLC-PK1 cells to DCVC-induced apoptosis. These results support the interpretation that mitochondrial release of cyt c and cyt c-dependent activation of caspase-3 could have a central role in nephrotoxicity due to haloalkene-derived cysteine S-conjugates.
Insights
The metabolite S-(1,2-dichlorovinyl)-l-cysteine (DCVC) triggers kidney cell death by disrupting mitochondria. Inhibiting DCVC metabolism or boosting anti-apoptotic proteins protects against this nephrotoxicity.
Area of Science:
- Biochemistry
- Toxicology
- Cell Biology
Background:
- Trichloroethylene and dichloroacetylene are nephrotoxic, with toxicity linked to mitochondrial dysfunction.
- The metabolite S-(1,2-dichlorovinyl)-l-cysteine (DCVC) is implicated in this mitochondrial damage.
Purpose of the Study:
- To investigate the role of mitochondrial biochemical events in DCVC-induced apoptosis.
- To determine if inhibiting DCVC metabolism or enhancing anti-apoptotic pathways can prevent kidney cell death.
Main Methods:
- Cultured porcine proximal tubular LLC-PK1 cells were treated with DCVC.
- Mitochondrial membrane potential (mt Delta Psi), cytochrome c release, caspase-3 activity, DNA fragmentation, and ATP levels were measured.
- Cells were also treated with aminooxyacetic acid (AOAA) or overexpressed with Bcl-2.
Main Results:
- DCVC decreased mt Delta Psi and released cytochrome c, followed by caspase-3 activation and DNA fragmentation.
- Mitochondrial swelling occurred, but ATP depletion was delayed.
- AOAA protected against DCVC-induced mitochondrial damage and apoptosis.
- Bcl-2 overexpression reduced sensitivity to DCVC-induced apoptosis.
Conclusions:
- Mitochondrial release of cytochrome c and subsequent caspase-3 activation play a key role in DCVC-induced nephrotoxicity.
- Inhibiting cysteine-conjugate beta-lyase or enhancing Bcl-2 offers potential protective strategies against haloalkene-derived nephrotoxicity.