Pentachlorobutadienyl-L-cysteine (PCBC) toxicity: the importance of mitochondrial dysfunction

Area of Science:

• Toxicology
• Biochemistry
• Cell Biology

Background:

• Pentachlorobutadienyl-L-cysteine (PCBC) is a nephrotoxicant.
• Understanding the mechanism of PCBC toxicity is crucial for developing protective strategies.

Purpose of the Study:

• To investigate the relationship between covalent binding, uptake, and toxicity of PCBC in rabbit renal proximal tubules (RPT) and mitochondria.
• To determine the role of mitochondrial bioactivation in PCBC-induced toxicity.
• To evaluate the protective effects of aminooxyacetic acid (AOAA) against PCBC toxicity.

Main Methods:

• Incubation of rabbit RPT, renal basolateral membrane vesicles, and isolated renal cortical mitochondria with PCBC.
• Measurement of PCBC covalent binding to proteins.
• Assessment of mitochondrial function, including oxidative phosphorylation and ATP levels.
• Administration of AOAA, an inhibitor of cysteine conjugate beta-lyase, to assess its protective effects.

Main Results:

• PCBC was rapidly metabolized to a reactive intermediate that covalently bound to tubular and mitochondrial proteins.
• PCBC uncoupled oxidative phosphorylation, reduced state 3 respiration, and decreased cellular ATP levels, preceding cell death.
• Mitochondria were identified as the critical subcellular target for PCBC toxicity due to mitochondrial bioactivation.
• AOAA significantly reduced PCBC covalent binding but only partially inhibited PCBC-induced toxicity and cell death, suggesting incomplete blockade of PCBC metabolism.

Conclusions:

• PCBC-induced mitochondrial dysfunction is a result of mitochondrial bioactivation.
• Mitochondria are the primary target organelle in PCBC toxicity.
• AOAA offers partial protection against PCBC toxicity by inhibiting its metabolism, but complete protection is limited by factors such as AOAA concentration within renal cells and mitochondria.