Issue 11, 2023

Increased cytotoxicity of Pb2+ with co-exposures to a mitochondrial uncoupler and mitochondrial calcium uniporter inhibitor

Abstract

Lead (Pb2+) is an important developmental toxicant. The mitochondrial calcium uniporter (MCU) imports calcium ions using the mitochondrial membrane potential (MMP), and also appears to mediate the influx of Pb2+ into the mitochondria. Since our environment contains mixtures of toxic agents, it is important to consider multi-chemical exposures. To begin to develop generalizable, predictive models of interactive toxicity, we developed mechanism-based hypotheses about interactive effects of Pb2+ with other chemicals. To test these hypotheses, we exposed HepG2 (human liver) cells to Pb2+ alone and in mixtures with other mitochondria-damaging chemicals: carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), a mitochondrial uncoupler that reduces MMP, and Ruthenium Red (RuRed), a dye that inhibits the MCU. After 24 hours, Pb2+ alone, the mixture of Pb2+ and RuRed, and the mixture of Pb2+ and FCCP caused no decrease in cell viability. However, the combination of all three exposures led to a significant decrease in cell viability at higher Pb2+ concentrations. After 48 hours, the co-exposure to elevated Pb2+ concentrations and FCCP caused a significant decrease in cell viability, and the mixture of all three showed a clear dose-response curve with significant decreases in cell viability across a range of Pb2+ concentrations. We performed ICP-MS analyses on isolated mitochondrial and cytosolic fractions and found no differences in Pb2+ uptake across exposure groups, ruling out altered cellular uptake as the mechanism for interactive toxicity. We assessed MMP following exposure and observed a decrease in membrane potential that corresponds to loss of cell viability but is likely not sufficient to be the causative mechanistic driver of cell death. This research provides a mechanistically-based framework for understanding Pb2+ toxicity in mixtures with mitochondrial toxicants.

Graphical abstract: Increased cytotoxicity of Pb2+ with co-exposures to a mitochondrial uncoupler and mitochondrial calcium uniporter inhibitor

Supplementary files

Article information

Article type
Communication
Submitted
04 Maijs 2023
Accepted
20 Jūl. 2023
First published
21 Jūl. 2023

Environ. Sci.: Processes Impacts, 2023,25, 1743-1751

Author version available

Increased cytotoxicity of Pb2+ with co-exposures to a mitochondrial uncoupler and mitochondrial calcium uniporter inhibitor

P. Lalwani, D. E. King, K. S. Morton, N. A. Rivera, J. Huayta, H. Hsu-Kim and J. N. Meyer, Environ. Sci.: Processes Impacts, 2023, 25, 1743 DOI: 10.1039/D3EM00188A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements