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Updated: Jul 26, 2025
Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro
Published on: July 17, 2018
Phospholipid scramblase 3: a latent mediator connecting mitochondria and heavy metal apoptosis
Santosh Kumar Palanirajan1, Sathyanarayana N Gummadi2
1Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India.
Abstract:
Lead and mercury are the ubiquitous heavy metals triggering toxicity and initiating apoptosis in cells. Though the toxic effects of heavy metals on various organs are known, there is a paucity of information on the mechanisms that instigate the current study. A plausible role of phospholipid scramblase 3 (PLSCR3) in Pb2+ and Hg2+ induced apoptosis was investigated with human embryonic kidney (HEK 293) cells. After 12 h of exposure, ~30-40% of the cells were in the early stage of apoptosis with increased reactive oxygen species (ROS), decreased mitochondrial membrane potential, and increased intracellular calcium levels. Also, ~20% of the cardiolipin localized within the inner mitochondrial membrane was translocated to the outer mitochondrial membrane along with the mobilization of truncated Bid (t-Bid) to the mitochondria and cytochrome c from the mitochondria. The endogenous expression levels of PLSCR3, caspase 8, and caspase 3 were upregulated in Pb2+ and Hg2+ induced apoptosis. The activation and upregulation of PLSCR3 mediate CL translocation playing a potential role in initiating the heavy metal-induced apoptosis. Therefore, PLSCR3 could be the linker between mitochondria and heavy metal apoptosis.
Insights
Phospholipid scramblase 3 (PLSCR3) activation links heavy metals like lead and mercury to cellular apoptosis. This protein plays a key role in initiating heavy metal-induced cell death by affecting mitochondria.
Area of Science:
- Cell Biology
- Toxicology
- Biochemistry
Background:
- Heavy metals, including lead (Pb2+) and mercury (Hg2+), are known environmental toxins.
- Cellular toxicity and apoptosis are common outcomes of heavy metal exposure.
- Mechanisms underlying heavy metal-induced apoptosis require further elucidation.
Purpose of the Study:
- To investigate the role of phospholipid scramblase 3 (PLSCR3) in lead and mercury-induced apoptosis.
- To explore the cellular and mitochondrial changes associated with heavy metal exposure.
Main Methods:
- Human embryonic kidney (HEK 293) cells were exposed to lead and mercury.
- Assessed apoptosis markers, including reactive oxygen species (ROS), mitochondrial membrane potential, and intracellular calcium.
- Investigated cardiolipin (CL) translocation, Bid cleavage, and cytochrome c release.
- Measured endogenous expression levels of PLSCR3, caspase 8, and caspase 3.
Main Results:
- Exposure to Pb2+ and Hg2+ induced early apoptosis in ~30-40% of cells within 12 hours.
- Observed increased ROS, decreased mitochondrial membrane potential, and elevated intracellular calcium.
- Detected translocation of cardiolipin to the outer mitochondrial membrane, along with t-Bid mobilization and cytochrome c release.
- Found upregulation of PLSCR3, caspase 8, and caspase 3 expression.
Conclusions:
- PLSCR3 activation is implicated in initiating heavy metal-induced apoptosis.
- PLSCR3 mediates cardiolipin translocation, linking heavy metals to mitochondrial apoptotic pathways.
- PLSCR3 may serve as a crucial mediator between heavy metal exposure and the induction of apoptosis.
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