Mercury-induced apoptosis and necrosis in murine macrophages: Role of calcium-induced reactive oxygen species and p38 mitogen-activated protein kinase signaling

Sang Hyun Kim, Raghubir P. Sharma

Research output: Contribution to journalArticlepeer-review

125 Scopus citations

Abstract

The current study characterizes the mechanism by which mercury, a toxic metal, induces death in murine macrophages. The cytotoxic EC50 of mercury ranged from 62.7 to 81.1 μM by various assays in J774A.1 cultures; accordingly, we employed 70 μM of mercuric chloride in most experiments. Mercury-induced intracellular calcium modulated reactive oxygen species (ROS) production, which resulted in both cell apoptosis and necrosis indicated by annexin V binding and caspase-3 activity, and propidium-iodide binding. Calcium antagonists abolished ROS production. Mercury stimulated p38 mitogen-activated protein kinase (MAPK) and additively stimulated lipopolysaccharide-activated p38. Mercury-activated p38 was decreased by pretreatment of cells with antioxidants, N-acetylcysteine (NAC) and silymarin, indicating that mercury-induced ROS were involved in p38 activation. Mercury increased the expression of tumor necrosis factor α (TNFα); antioxidants and a specific p38 inhibitor decreased this effect. Pretreatment with antioxidants, p38 inhibitor, and anti-TNFα antibody decreased mercury-induced necrosis; however, anti-TNFα antibody did not decrease mercury-induced apoptosis. Results suggest that mercury-induced macrophage death is a mix of apoptosis and necrosis employing different pathways. P38-mediated caspase activation regulates mercury-induced apoptosis and p38-mediated TNFα regulates necrosis in these cells. Calcium regulates ROS production and mercury-induced ROS modulate downstream p38 that regulates both apoptosis and necrosis.

Original languageEnglish
Pages (from-to)47-57
Number of pages11
JournalToxicology and Applied Pharmacology
Volume196
Issue number1
DOIs
StatePublished - 1 Apr 2004

Keywords

  • 5-chloromethyl-2′,7′-dichlorodihydro-fluorescein diacetate
  • Calcium
  • Caspase 3
  • CM-HDCFDA
  • DHR
  • Dihydrorhodamine
  • ERK
  • Mercury
  • Mitogen-activated protein kinases
  • Reactive oxygen species
  • Tumor necrosis factor α

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